Biology subjects

Yang, B.

Publications and source records attributed to Yang, B..

At least 163 records · Page 9Linked to original sources

bioRxiv2023

Structure of human NaV1.6 channel reveals Na+ selectivity and pore blockade by 4,9-anhydro-tetrodotoxin

The sodium channel NaV1.6 is widely expressed in neurons of the central and peripheral nervous systems, which plays a critical role in regulating neuronal excitability. Dysfunction of NaV1.6 has been linked to epileptic encephalopathy, intellectual disability and movement disorders. Here we present cryo-EM structures of human NaV1.6/{beta}1/{beta}2 alone and complexed with a guanidinium neurotoxin 4,9-anhydro-tetrodotoxin (4,9-ah-TTX), revealing molecular mechanism of NaV1.6 inhibition by the blocker. In the apo-form structure, two potential Na+ binding sites were revealed in the selectivity filter, suggesting a possible mechanism for Na+ selectivity and conductance. In the 4,9-ah-TTX-bound structure, 4,9-ah-TTX binds to a pocket similar to the tetrodotoxin (TTX) binding site, which occupies the Na+ binding sites and completely blocks the channel. Molecular dynamics simulation results show that subtle conformational differences in the selectivity filter affect the affinity of TTX analogues. Taken together, our results provide important insights into NaV1.6 structure, ion conductance, and inhibition.

biophysics↗

bioRxiv2023

The catalytic activity of microRNA Argonautes plays a modest role in microRNA star strand cleavage in C. elegans

Many Argonaute proteins can cleave RNA ("slicing") as part of the microRNA-induced silencing complex (miRISC), even though miRNA-mediated target repression is generally independent of target cleavage. Here we use genome editing in C. elegans to examine the role of miRNA-guided slicing in organismal development. In contrast to previous work, slicing-inactivating mutations did not interfere with normal development when introduced by CRISPR. We find that unwinding and decay of miRNA star strands is weakly defective in the absence of slicing, with the largest effect observed in embryos. Argonaute-Like Gene 2 (ALG-2) is more dependent on slicing for unwinding than ALG-1. The miRNAs that displayed the greatest (albeit minor) dependence on slicing for unwinding tend to form stable duplexes with their star strand, and in some cases, lowering duplex stability alleviates dependence on slicing. Gene expression changes were consistent with negligible to moderate loss of function for miRNA guides whose star strand was upregulated, suggesting a reduced proportion of mature miRISC in slicing mutants. While a few miRNA guide strands are reduced in the mutant background, the basis of this is unclear since changes were not dependent on EBAX-1, a factor in the Target-Directed miRNA Degradation (TDMD) pathway. Overall, this work defines a role for miRNA Argonaute slicing in star strand decay; future work should examine whether this role could have contributed to the selection pressure to conserve catalytic activity of miRNA Argonautes across the metazoan phylogeny.

molecular biology↗

bioRxiv2022

Alteration of pro-carcinogenic gut microbiota is associated with clear cell renal cell carcinoma tumorigenesis

Increasing evidence suggests that gut microbiota is involved in the occurrence and progression of urinary system diseases such as clear cell renal cell carcinoma (ccRCC). However, the mechanism of how alteration of gut metagenome promotes ccRCC remains unclear. Here we aim to elucidate the association of specific gut bacteria and their metabolites with ccRCC. In a pilot case-control study among 30 ccRCC patients and 30 healthy controls, 16S ribosomal RNA (rRNA) gene sequencing were analyzed from fecal samples collected prior to surgery or hospitalization. Alpha diversity and beta diversity analysis of the gut microbiota were performed, and differential taxa were identified by multivariate statistics. Meanwhile, serum metabolism was measured by UHPLC-MS, and differential genes were identified based on the TCGA database. Random Forests revealed the relative abundances of 20 species differed significantly between the RCC group and the Control group, among which 9 species, such as Desulfovibrionaceae, were enriched in the RCC group, and 11 species, such as four kinds of Lactobacillus, were less abundant. Concomitantly, serum level of taurine, which was considered to be consumed by Desulfovibrionaceae and released by Lactobacillus, has decreased in the RCC group. In addition, macrophage-related genes such as Gabbr1 was upregulated in ccRCC patients from our results. IMPORTANCETo our knowledge, few studies investigate the correlation of gut microbiota and ccRCC tumorigenesis. Overall, our sequencing data suggest that changes in the composition of specific gut microbiota, especially Lactobacillus and Desulfovibrionaceae, may be involved in ccRCC. Numerous serum metabolites, for example, taurine, which were modified in concert with dysregulation of gut microbiota, were associated with metabolic status during ccRCC development. Furthermore, through comparative analysis of clinical indicators, we found that gut dysbiosis could potentially reshape systemic inflammation, which participated in ccRCC tumorigenesis and we performed bioinformatics analysis to draw this conclusion. In Summary, it could be concluded from our study that the reduction of protective bacteria Lactobacillus, proliferation of sulfide-degrading bacteria Desulfovibrionaceae, reduction of taurine, and enrichment of macrophage related genes might be the risk predictors of ccRCC.

microbiology↗

bioRxiv2022

STOmics-GenX: CRISPR based approach to improve cell identity specific gene detection from spatially resolved transcriptomics

The spatial organisation of cells defines the biological functions of tissue ecosystems from development to disease. Recently, an array of technologies have been developed to query gene expression in a spatial context. These include techniques such as employing barcoded oligonucleotides, single-molecule fluorescence in situ hybridization (smFISH), and DNA nanoball (DNB)-patterned arrays. However, resolution and efficiency vary across platforms and technologies. To obtain spatially relevant biological information from spatially resolved transcriptomics, we combined the Stereo-seq workflow with CRISPRclean technology to develop the STOmics-GenX pipeline. STOmics-GenX not only allowed us to reduce genomic, mitochondrial, and ribosomal reads, but also lead to a [~]2.1-fold increase in the number of detected genes when compared to conventional Stereo-seq (STOmics). Additionally, the STOmics-GenX pipeline resulted in an improved detection of cell type specific genes, thereby improving cellular annotations. Most importantly, STOmics-GenX allowed for enhanced detection of clinically relevant biomarkers such as Alpha-fetoprotein (AFP), enabling the identification of two spatially distinct subsets of hepatocytes in hepatocellular carcinoma tissue. Thereby, combining CRISPRclean technology with STOmics not only allowed improved gene detection but also paved the way for spatial precision oncology by improved detection of clinically relevant biomarkers.

molecular biology↗

bioRxiv2022

Changes of platelet morphology, ultrastructure and function in patients with acute ischemic stroke based on super-resolution microscopy.

Platelets are important in acute ischemic stroke (AIS) thrombosis. The observation and evaluation of platelet ultrastructure and efficacy of antiplatelet drug in AIS patients is difficult due to microscopic limitations and sensitivity of platelet. The new super-resolution microscope (SIM) can accurately, quickly analyze the platelet ultrastructure and antiplatelet drug in AIS patients. We applied SIM to observe the morphology and ultrastructure of platelets with AIS patients in different state. SIM images were analyzed to specify the dense granules and granules change of platelets in AIS patients. Testing platelet factor 4 (PF4) to reflect platelet releasing function. We observed that platelet activation in AIS patients was greater after stimulation, with granule showing a pattern of parenchymatous masses. SIM images analyzing showed diameter of platelets, average size of granules, area% of granules per field and mean area of granules per platelet in AIS patient were lower than healthy people. Platelet releasing function was suppressed at rest stage and more efficacy release after stimulation. 2MeSamp inhibited parenchymatous masses of granules and reduced PF4 release of platelets after stimulation. According to the results, the structure and function of platelets in AIS patients are indeed altered. Additionally, SIM could be used as a new method to indicates the onset of AIS and assess antiplatelet drugs.

cell biology↗

bioRxiv2022

Genome editing of an African elite rice variety confers resistance against endemic and emerging Xanthomonas oryzae pv. oryzae strains

Bacterial leaf blight (BB) of rice, caused by Xanthomonas oryzae pv. oryzae (Xoo), threatens global food security and the livelihood of small-scale rice producers. Analyses of Xoo collections from Asia, Africa and the Americas demonstrated surprising continental segregation, despite robust global rice trade. Here, we report unprecedented BB outbreaks in Tanzania. The causative strains, unlike endemic Xoo, carry Asian-type TAL effectors targeting the sucrose transporter SWEET11a and suppressing Xa1. Phylogenomics clustered these strains with Xoo strains from China. African rice varieties do not carry suitable resistance genes. To protect African rice production against this emerging threat, we developed a hybrid CRISPR-Cas9/Cpf1 system to edit six TALe-binding elements in three SWEET promoters of the East African elite variety Komboka. The edited lines show broad-spectrum resistance against Asian and African strains of Xoo, including strains recently discovered in Tanzania. This strategy could help to protect global rice crops from BB pandemics.

plant biology↗

bioRxiv2022

Mutations Affecting Polar Nuclei Number, Antipodal Cell Cluster Size, Cellularization, and Nuclear Localization in Maize Embryo Sacs

The maize female gametophyte is comprised of four cell types: two synergids, an egg cell, a central cell, and a variable number of antipodal cells. In maize, these cells are produced after three rounds of free-nuclear divisions followed by cellularization, differentiation, and proliferation of the antipodal cells. Cellularization of the eight-nucleate syncytium produces seven cells with two polar nuclei in the central cell. Nuclear localization is tightly controlled in the embryo sac as evidenced by the regular, stereotypical position of the nuclei in all syncytial stages of female gametophyte development. This leads to precise allocation of the nuclei into the cells upon cellularization. Nuclear positioning within the syncytium is highly correlated with their identity after cellularization. Two mutants are described with extra polar nuclei, abnormal antipodal cell morphology, and reduced antipodal cell number, which is correlated with a frequent loss of auxin signaling in the antipodal cell cluster. Mutations in one of these genes, indeterminate gametophyte2 encoding a MICROTUBULE ASSOCIATED PROTEIN65-3 homolog, shows a requirement for MAP65-3 in cellularization of the syncytial embryo sac and that the identity of the nuclei in the syncytial female gametophyte can be changed very late before cellularization.

plant biology↗

bioRxiv2022

Comparing acute IOP-induced lamina cribrosa deformations pre-mortem and post-mortem

PurposeLamina cribrosa (LC) deformations caused by elevated intraocular pressure (IOP) are believed to contribute to glaucomatous neuropathy and have therefore been extensively studied, in many conditions from in-vivo to ex-vivo. We compare acute IOP-induced global and local LC deformations immediately before (pre-mortem) and after (post-mortem) sacrifice by exsanguination. MethodsThe optic nerve heads of three healthy monkeys 12-15 years old were imaged with spectral-domain optical coherence tomography under controlled IOP pre-mortem and post-mortem. Volume scans were acquired at baseline IOP (8-10 mmHg) and at 15, 30, and 40 mmHg IOP. A digital volume correlation technique was used to determine the IOP-induced 3D LC deformations (strains) in regions visible pre-mortem and post-mortem. ResultsBoth conditions exhibited similar nonlinear relationships between IOP increases and LC deformations. Median effective and shear strains were, on average over all eyes and pressures, smaller post-mortem than pre-mortem, by 14% and 11%, respectively (Ps < 0.001). Locally, however, the differences in LC deformation between conditions were variable. Some regions were subjected pre-mortem to triple the strains observed post-mortem, and others suffered smaller deformations pre-mortem than post-mortem. ConclusionsIncreasing IOP acutely caused nonlinear LC deformations with an overall smaller effect post-mortem than pre-mortem. Locally, deformations pre-mortem and post-mortem were sometimes substantially different. We suggest that the differences may be due to weakened mechanical support from the unpressurized central retinal vessels post-mortem. Translational RelevanceAdditional to the important pre-mortem information, comparison with post-mortem provides a unique context essential to understand the translational relevance of all post-mortem biomechanics literature. PrecisThe authors compared in monkeys acute IOP-induced deformations of the lamina cribrosa pre-mortem and post-mortem. Deformation trends were similar pre-mortem and post-mortem, but deformations pre-mortem were generally smaller than those post-mortem, with substantial local variations. The differences are likely due to loss of vessel support post-mortem.

bioengineering↗

bioRxiv2022

Mapping global land sharing-sparing patterns between human and wildlife

Understanding the global patterns of land sharing-sparing between humans and wildlife is essential for pragmatic conservation implementation, yet analytical foundations and indicator-based assessments are still lacking. By integrating distributions of 30,664 terrestrial vertebrates and human pressures, we provide a series of spatial explicit Human-Nature Indices (HNIs) before classifying the global lands into four categories. We found that the Co-occurring (C) regions, where lands are shared by humans and wildlife, are not insignificant (16.91% of global land). For land-sparing, the Diversity-intact (D) and the Anthropic (A) regions account for 45.64% and 1.41% of the land, respectively. The patterns of HNIs, varying considerably among taxonomic groups, are determined mainly by the expansion of human-dominated land use. Land sharing and sparing could work as complementary strategies to support biodiversity and human development toward ambitious and pragmatic 30 by 30 goals. Our results highlight that those regions should adopt different conservation strategies according to their sharing-sparing patterns and distribution of protected areas.

ecology↗

bioRxiv2022

Identifying Lymph Node Metastasis-related Factors in Breast Cancer using Differential Modular and Mutational Structural Analysis

Complex diseases are generally caused by disorders of biological networks and/or mutations in multiple genes. Network theory provides useful tools to study the underlying laws governing complex diseases. Within this framework, comparisons of network topologies, including the node, edge, and community, between different disease states can highlight key factors within these dynamic processes. Here, we propose a differential modular analysis approach that integrates protein-protein interactions with gene expression profiles for modular analysis, and introduces inter-modular edges and date hubs to identify the "core network module" that quantifies the significant phenotypic variation. Then, based on this core network module, key factors including functional protein-protein interactions, pathways, and drive mutations are predicted by the topological-functional connection score and structural modeling. We applied the approach to analyze the lymph node metastasis (LNM) process in breast cancer. The functional enrichment analysis showed that both inter-modular edges and date hubs play important roles in cancer metastasis and invasion, and in metastasis hallmarks. The structural mutation analysis suggested that the LNM of breast cancer may be the outcome of the dysfunction of rearranged during transfection (RET) proto-oncogene-related interactions and the non-canonical calcium signaling pathway via an allosteric mutation of RET. We believe that the proposed method can provide new insights into disease progression such as cancer metastasis. Author summaryMetastasis is the hallmark of cancer that is responsible for the greatest number of cancer-related deaths. However, it remains poorly understood. PPI networks not only provide a static picture of cellular function and biological processes, but also have emerged as new paradigms in the study of the dynamic process of disease progression, including cancer metastasis. Herein, a network-based strategy was proposed based on the integration of expression profiles with protein interactions, by filtering with "date hubs" and "inter-modular edges", demonstrating that different network modules may provide robust predictors to represent the dynamic mechanisms involved in metastasis formation. Furthermore, the mapping of protein structure and mutation data on the network module level provides insight into signaling mechanisms; helps understand the mechanism of disease-related mutations; and helps in drug discovery. The application of our method to study the LNM in breast cancer highlights network modules defining protein communities that respond to therapeutics, and the implications of detailed structural and mechanistic insight into oncogenic activation and how it can advance allosteric precision oncology.

systems biology↗

bioRxiv2022

AcaFinder: genome mining for anti-CRISPR associated genes

Anti-CRISPR (Acr) proteins are encoded by (pro)viruses to inhibit their hosts CRISPR-Cas systems. Genes encoding Acr and Aca (Acr associated) proteins often co-localize to form acr-aca operons. Here, we present AcaFinder as the first Aca genome mining tool. AcaFinder can: (i) predict Acas and their associated acr-aca operons using guilt-by-association (GBA); (ii) identify homologs of known Acas using an HMM (Hidden Markov model) database; (iii) take input genomes for potential prophages, CRISPR-Cas systems, and self-targeting spacers (STSs); and (iv) provide a standalone program (https://github.com/boweny920/AcaFinder) and a web server (http://aca.unl.edu/Aca). AcaFinder was applied to mining over 16,000 prokaryotic and 142,000 gut phage genomes. After a multi-step filtering, 36 high-confident new Aca families were identified, which is three times of the 12 known Aca families. Seven new Aca families were from major human gut bacteria (Bacteroidota, Actinobacteria, Fusobacteria) and their phages, while most known Aca families were from Proteobacteria and Firmicutes. A complex association network between Acrs and Acas was revealed by analyzing their operonic co-localizations. It appears very common in evolution that the same aca genes can recombine with different acr genes and vice versa to form diverse acr-aca operon combinations. ImportanceAt least four bioinformatics programs have been published for genome mining of Acrs since 2020. In contrast, no bioinformatics tools are available for automated Aca discovery. As the self-transcriptional repressor of acr-aca operons, Aca can be viewed as anti-anti-CRISPRs, with a great potential in the improvement of CRISPR-Cas technology. Although all the 12 known Aca proteins contain a conserved Helix-Turn-Helix (HTH) domain, not all HTH-containing proteins are Acas. However, HTH-containing proteins with an adjacent Acr homologs encoded in the same genetic operon are likely Aca proteins. AcaFinder implements this guilt-by-association (GBA) idea and the idea of using HMMs of known Acas for homologs into one software package. Applying AcaFinder in screening prokaryotic and gut phage genomes reveals a complex acr-aca operonic co-localization network between different families of Acrs and Acas.

bioinformatics↗

bioRxiv2022

Dynamic modelling and analysis of autophagy in the clearance of aggregated α-synuclein in Parkinson's disease

The widely-accepted hallmark pathology of Parkinsons disease (PD) is the presence of Lewy bodies (LB) with characteristic abnormal aggregated -synuclein (Syn). Growing physiological evidences suggest that there is a pivotal role for the autophagy-lysosome pathway in the clearance of misfolded Syn (Syn*) for maintaining homeostasis and neural cell function. In this work, we establish a new mathematical model for Syn* degradation through the autophagy pathway. The qualitative simulations discover the tri-stability phenomena and dynamical behaviors of Syn*, i.e., the coexistence of three stable steady states, in which the lower, medium and upper steady states correspond to the healthy, critical and diseased stages of pathological mechanism of PD, respectively. Diverse analyses on codimension-1 and -2 bifurcations suggest that autophagy can control the switches among the stable steady states for the aggregation of Syn*. It is also found that the double negative crosstalk feedback between autophagy and apoptosis is important to the robustness of tri-stability of Syn* for this biodynamic system. Our novel results may be valuable for making further therapeutic strategies in prevention and treatment for PD. Author summarySyn* is one of the most and primary remarkable targets for the universal neurodegenerative disease of PD. Efficient clearance mechanism of autophagy, contains a lot of molecular components to maintain the cellular homeostasis and cell renewal, could be the possible therapy for PD. Understand the complexity of autophagy in degrading Syn* requires the integration of both theoretical and experimental points of view. Here, we have proposed a novel mathematical model that analyses the temporal and dynamic behaviors of the biosystem for autophagy degrades Syn* to access PD states. The model explains that the tri-stability is of particularly relevance to this biosystem that switch among the healthy, critical and disease states, and captures that the critical intermedium state exits for preventing the system transform healthy to disease state directly, and further illustrates that the molecular signaling feedback loops of autophagy may be important for the robustness of tri-stability. Our work deepens the researches of PD by uncovering the important buffering medium state and providing promising potential therapeutic insights.

systems biology↗

bioRxiv2022

A Peronophythora litchii RXLR effector PlAvh202 enhances plant susceptibility by destabilizing host SAMS

Oomycete pathogens can secret hundreds of effectors into plant cells to interfere with plant immune system during infection. Here we identified a cytoplasmic RXLR effector from the most destructive pathogen of litchi, Peronophythora litchii, and named it as PlAvh202. PlAvh202 could suppress cell death triggered by INF1 and Avr3a/R3a in Nicotiana benthamiana, and was essential for P. litchii virulence. In addition, PlAvh202 also suppressed plant immune responses and promoted the susceptibility of N. benthamiana to Phytophthora capsici. Further research revealed that PlAvh202 could suppress ethylene (ET) production by targeting and destabilizing plant S-adenosyl-L-methionine synthetase (SAMS), a key enzyme in ET biosynthesis pathway, in a 26S proteasome-dependent manner. Transient expression of LcSAMS3 induced ET production and enhanced plant resistance, whereas inhibition of ET biosynthesis promoted P. litchii infection, supporting that LcSAMS and ET positively regulate litchi immunity towards P. litchii. Overall, these findings highlight that SAMS can be targeted by oomycete RXLR effector to manipulate ET-mediated plant immunity.

plant biology↗

bioRxiv2022

SiGra: Single-cell spatial elucidation through image-augmented graph transformer

The recent advances in high-throughput molecular imaging push the spatial transcriptomics technologies to the subcellular resolution, which breaks the limitations of both single-cell RNA-seq and array-based spatial profiling. The latest released single-cell spatial transcriptomics data from NanoString CosMx and MERSCOPE platforms contains multi-channel immunohistochemistry images with rich information of cell types, functions, and morphologies of cellular compartments. In this work, we developed a novel method, Single-cell spatial elucidation through image-augmented Graph transformer (SiGra), to reveal spatial domains and enhance the substantially sparse and noisy transcriptomics data. SiGra applies hybrid graph transformers over a spatial graph that comprises high-content images and gene expressions of individual cells. SiGra outperformed state-of-the-art methods on both single-cell spatial profiles and spot-level spatial transcriptomics data from complex tissues. The inclusion of immunohistochemistry images improved the model performance by 37% (95%CI: 27% - 50%). SiGra improves the characterization of intratumor heterogeneity and intercellular communications in human lung cancer samples, meanwhile recovers the known microscopic anatomy in both human brain and mouse liver tissues. Overall, SiGra effectively integrates different spatial modality data to gain deep insights into the spatial cellular ecosystems.

bioinformatics↗

bioRxiv2022

SIC50: Determination of IC50 by an optimized Sobel operator and a vision transformer

As a measure of cytotoxic potency, half-maximal inhibitory concentration (IC50) is the concentration at which a drug exerts half of its maximal inhibitory effect against target cells. It can be determined by various methods that require applying additional reagents or lysing the cells. Here, we describe a label-free Sobel-edge-based method, which we name SIC50, for the evaluation of IC50. SIC50 classifies pre-processed phase-contrast images with a state-of-art vision transformer and allows for the continuous assessment of IC50 in a faster and more cost-efficient manner. We have validated this method using four drugs and 1536-well plates, as well as built a first-of-its-kind web application. We anticipate this method will assist in the high-throughput screening of chemical libraries (e.g., small molecule drugs, siRNA, and microRNA and drug discovery.

bioengineering↗

bioRxiv2022

Molecular and structural characterization of lenalidomide-mediated sequestration of eIF3i

Lenalidomide is a ligand of the E3 ligase substrate adaptor cereblon (CRBN) that achieves its clinical effects in part by promotion of substrate recruitment and degradation. In contrast to prior substrates, eIF3i is recruited but not degraded upon complex formation with lenalidomide and CRBN, although the structural details and mechanistic outcomes of this interaction are unresolved. Here, we characterize the structural basis and mechanistic outcomes of lenalidomide-induced sequestration of eIF3i from the eIF3 complex. Identification of the binding interface on eIF3i by a covalent lenalidomide probe and chemical proteomics rationalizes the sequestration event. We further connect eIF3i and CRBN to known lenalidomide effects on angiogenic markers, Akt1 phosphorylation, and associated antiangiogenesis phenotypes. Finally, we find that eIF3i sequestration is observed in MM.1S and MOLM13 cells after the degradation of other substrates, such as IKZF1. The defined binding interface elucidated by chemical proteomics, and connection of eIF3i sequestration to phenotypic outcomes of lenalidomide open future directions in designing new chemical adaptors for protein sequestration as a strategy to selectively control translational profiles and downstream cellular function.

biochemistry↗

bioRxiv2022

High-throughput nanopore sequencing of Treponema pallidum tandem repeat genes arp and tp0470 reveals clade-specific patterns and recapitulates global whole genome phylogeny

Sequencing of most Treponema pallidum (T. pallidum) genomes excludes repeat regions in tp0470 and the tp0433 gene, encoding the acidic repeat protein (arp). As a first step to understanding the evolution and function of these genes and the proteins they encode, we developed a protocol to nanopore sequence tp0470 and arp genes from 212 clinical samples collected from ten countries on six continents. Both tp0470 and arp repeat structures recapitulate the whole genome phylogeny, with subclade-specific patterns emerging. The number of tp0470 repeats is on average appears to be higher in Nichols-like clade strains than in SS14-like clade strains. Consistent with previous studies, we found that 14-repeat arp sequences predominate across both major clades, but the combination and order of repeat type varies among subclades, with many arp sequence variants limited to a single subclade. Although strains that were closely related by whole genome sequencing frequently had the same arp repeat length, this was not always the case. Structural modelling of TP0470 suggested that the eight residue repeats form an extended -helix, predicted to be periplasmic. Modeling of the ARP revealed a C-terminal sporulation-related repeat (SPOR) domain, predicted to bind denuded peptidoglycan, with repeat regions possibly incorporated into a highly charged {beta}- sheet. Outside of the repeats, all TP0470 and ARP amino acid sequences were identical. Together, our data, along with functional considerations, suggests that both TP0470 and ARP proteins may be involved in T. pallidum cell envelope remodeling and homeostasis, with their highly plastic repeat regions playing as-yet-undetermined roles.

microbiology↗

bioRxiv2022

A dolabralexin-deficient mutant provides insight into specialized diterpenoid metabolism in maize (Zea mays).

Two major groups of maize (Zea mays) specialized metabolites, termed kauralexins and dolabralexins, serve as known or predicted diterpenoid defenses against pathogens, herbivores, and other environmental stressors. To consider physiological roles of the recently discovered dolabralexin pathway, we examined dolabralexin structural diversity, tissue-specificity, and stress-elicited production in a defined biosynthetic pathway mutant. Metabolomics analyses support a larger number of dolabralexin pathway products than previously known. We identified dolabradienol as a previously undetected pathway metabolite and characterized its enzymatic production. Transcript and metabolite profiling showed that dolabralexin biosynthesis and accumulation predominantly occurs in primary roots and shows quantitative variation across genetically diverse inbred lines. Generation and analysis of CRISPR-Cas9-derived loss-of- function Kaurene Synthase-Like 4 (Zmksl4) mutants demonstrated dolabralexin production deficiency, thus supporting ZmKSL4 as the diterpene synthase responsible for the conversion of geranylgeranyl pyrophosphate precursors into dolabradiene and downstream pathway products. Zmksl4 mutants further display altered root-to-shoot ratios and root architecture in response to water deficit, consistent with an interactive role of maize dolabralexins in plant vigor during abiotic stress.

plant biology↗