Biology subjects

Zhou, C.-Z.

Publications and source records attributed to Zhou, C.-Z..

10 recordsLinked to original sources

bioRxiv2024

Integration of protein and coding sequences enables mutual augmentation of the language model

Recent language models have significantly accelerated our understanding on the massive biological data, using protein or DNA/RNA sequences as a single-language modality. Here we present a dual-language foundation model, which integrates both protein and coding sequences (CDS) for pre-training. Compared to the benchmark models, it shows a superior performance up to [~]20% on both protein and mRNA-related discriminative tasks, and gains the capacity to de novo generate coding sequences of [~]50% increased protein yield. Moreover, the model also possesses the knowledge transferability from the pre-training data to the upstream 5 untranslated regions. These findings indicate the intrinsic correlations between protein and its CDS, as well as the coding region and beyond. It provides a new paradigm that leverages the multiple-language foundation model to interpret the hidden context of distinct corpora/biological languages, which could be further applied to mine the yet-unknown biological information/correlation beyond the Central Dogma.

bioinformatics↗

bioRxiv2023

Nonribosomal peptide synthetases require dynamic interaction between modular domains

Nonribosomal peptide synthetases (NRPSs) are large multidomain enzymes for the synthesis of a variety of bioactive peptides in a modular and pipelined fashion. Here, we investigated how the condensation (C) domain and the adenylation (A) domain cooperate with each other for the efficient catalytic activity in microcystin NRPS modules. We solved two crystal structures of the microcystin NRPS modules, representing two newly identified conformations in the NRPS catalytic cycle. Our data reveals that the dynamic interaction between the C and the A domains in these modules are mediated by the conserved "RXGR" motif, and this interaction is important for the adenylation activity. Furthermore, the "RXGR" motif-mediated dynamic interaction and its functional regulation is prevalent in different NRPSs modules possessing both the A and the C domains. This study provides new insight into the catalytic mechanism of NRPSs and should inspire novel ideas in NRPS enzyme engineering in synthetic biology.

biochemistry↗

bioRxiv2023

PII signal transduction superfamily acts as a valve plug to control bicarbonate and ammonia homeostasis among different bacterial phyla

Life on Earth relies on carbon and nitrogen assimilation by RubisCO and GS-GOGAT enzymes, respectively, whose activities depend on a constant supply of inorganic carbon (Ci) and nitrogen (N). Members of the PII signal transduction superfamily are among the most ancient and widespread cell signaling proteins in nature. One of their most highly conserved functions is controlling Ci- and N-transporters, a feature found in different phyla of the Archaea and in both Gram-positive and Gram-negative bacteria. Recently, we identified the PII-like protein SbtB as Ci-sensing module, mainly controlling the HCO3- transporter SbtA in cyanobacteria. Similar to canonical PII proteins, SbtB is able to bind the adenine nucleotides ATP and ADP. Unlike those, it also binds AMP and preferentially binds the second messenger cAMP and c-di-AMP. The functional significance of the binding of different adenyl-nucleotides to SbtB has remained elusive, particularly in the context of the interaction of SbtB with SbtA. By a combination of structural, biochemical and physiological analysis, we revealed that by binding to SbtA, SbtB acts as unidirectional valve, preventing the reverse transport of intracellular enriched bicarbonate. This mechanistic principle holds true for the PII protein from Bacillus acting on the ammonium transporter AmtB, suggesting an evolutionary conserved role for PII superfamily proteins in controlling unidirectional flow of different transporters.

microbiology↗

bioRxiv2022

Structural insights into human ABCC4 mediated transport of platelet agonist and inhibitor

The activation and accumulation of human platelets contributes to hemostasis and thrombosis, the imbalance of which would cause cardiovascular diseases, an increasing threat to the global health. Human ABC transporter ABCC4 that pumps out the platelet agonist and anti-platelet drug such as aspirin, might become a promising target for preventing cardiovascular diseases. Here we solve the structures of human ABCC4 in the apo and two complexed forms, all of which adopt a typical architecture of type-IV ABC transporters in an inward-facing conformation. Structure of ABCC4 complexed with U46619, an analog of the unstable TXA2, provides the first structural evidence that the platelet agonist TXA2 is also exported via ABCC4. The dipyridamole-complexed structure reveals the inhibitory mechanism of dipyridamole against ABCC4. Structural comparisons enabled us to identify a transmembrane pocket in ABCC4 that provides a defined space for the rational design of specific anti-platelet drugs.

biochemistry↗

bioRxiv2022

DNA looping mediates cooperative transcription activation

Transcription factors respond to multi-level stimuli and co-occupy promoter regions of target genes to activate RNA polymerase (RNAP) in a cooperative manner. To decipher the molecular mechanism, here we report two cryo-electron microscopy structures of Anabaena transcription activation complexes (TACs): NtcA-TAC composed of RNAP holoenzyme, promoter and a global activator NtcA, and NtcA-NtcB-TAC comprising an extra context-specific regulator NtcB. Structural analysis showed that NtcA binding makes the promoter DNA bend by [~]50{o}, which facilitates RNAP to contact NtcB at the distal upstream NtcB box. The sequential binding of NtcA and NtcB induces looping back of promoter DNA towards RNAP, enabling the assembly of a fully activated TAC bound with two activators. Together with biochemical assays, we propose a DNA looping mechanism of cooperative transcription activation in bacteria.

molecular biology↗

bioRxiv2021

Structural insights into the activation of autoinhibited human lipid flippase ATP8B1 upon substrate binding

The human P4-type ATPase ATP8B1 in complex with the auxiliary noncatalytic protein CDC50A or CDC50B mediates the transport of cell membrane lipids from the outer to the inner membrane leaflet, which is crucial to maintain the asymmetry of membrane lipid. Its dysfunction usually leads to imbalance of bile acid circulation, and eventually causing intrahepatic cholestasis diseases. Here we found that both ATP8B1-CDC50A and ATP8B1-CDC50B possess a higher ATPase activity in the presence of the most favored substrate phosphatidylserine (PS); and moreover, the PS-stimulated activity could be augmented upon the addition of bile acids. The cryo-electron microscopy structures of ATP8B1-CDC50A at 3.36 [A] and ATP8B1-CDC50B at 3.39 [A] enabled us to capture an unprecedented phosphorylated and autoinhibited state, with the N- and C-terminal tails separately inserting into the cytoplasmic inter-domain clefts of ATP8B1. The PS-bound ATP8B1-CDC50A structure at 3.98 [A] indicated the autoinhibited state could be released upon PS binding. Structural analysis combined with mutagenesis revealed the residues that determine the substrate specificity, and a unique positively charged loop in the phosphorylated domain of ATP8B1 for the recruitment of bile acids. Altogether, we updated the Post-Albers transport cycle, with an extra autoinhibited state of ATP8B1, which could be activated upon substrate binding. These findings not only provide structural insights into the ATP8B1-mediated restoration of human membrane lipid asymmetry during bile acid circulation, but also advance our understanding on the molecular mechanism of P-type ATPases.

biochemistry↗

bioRxiv2021

Structural basis of substrate recognition and translocation by human ABCD1

Human ATP-binding cassette (ABC) transporter ABCD1 transports CoA esters of saturated/monounsaturated very long chain fatty acid from cytosol to the peroxisome for {beta}-oxidation. Dysfunction of human ABCD1 usually causes the severe progressive genetic disorder X-linked adrenoleukodystrophy, which eventually affects the adrenal glands and/or the central nervous system. Here, we report three cryo-EM structures of human ABCD1 in various states. The apo-form ABCD1 at 3.53 [A] resolution adopts an inward-facing conformation, harboring a phosphatidyl ethanolamine (PE) molecule at each lateral entry of substrate cavity. In the substrate-bound ABCD1 structure at 3.59 [A] resolution, two molecules of C22:0-CoA (one of the physiological substrates of ABCD1) is symmetrically bound to the transmembrane domains (TMDs). Each C22:0-CoA adopts an unpresented L-shape configuration: the CoA portion inserts into a polar pocket at the TMD at a pose parallel to the membrane plane, whereas the acyl chain portion perpendicular to membrane plane is embedded in a hydrophobic pocket at the opposite TMD. Upon binding the two C22:0-CoA molecules, which resemble a pair of hinges crossing the two TMDs, the two nucleotide-binding domains (NBDs) of ABCD1 approach towards each other. Addition ATP to the substrate-bound ABCD1 enabled us to reveal an ATP-bound structure at 2.79 [A], which shows an outward-facing conformation with the dimerized NBDs succeeding substrate release. These three structures combined with biochemical assays exhibit a snapshot of ABCD1-mediated substrate recognition, translocation and release. These findings provide the structural insights into the transport mechanism of ABC transporters that transport amphipathic molecules with long acyl chains.

biophysics↗

bioRxiv2021

Integration of the cyanophage-encoded phosphate binding protein into the cyanobacterial phosphate uptake system

To acquire phosphorus, cyanobacteria use the typical bacterial ABC-type phosphate transporter, which is composed of a periplasmic high-affinity phosphate-binding protein PstS and a channel formed by two transmembrane proteins PstC and PstA. The pstS gene has been identified in the genomes of cyanophages that infect the unicellular cyanobacteria Prochlorococcus and Synechococcus. However, it is unknown how the cyanophage PstS interplays with the host PstC and PstA to function as a chimeric ABC transporter. Here we showed that the cyanophage P-SSM2 PstS protein was abundant in the infected Prochlorococcus NATL2A cells and the host phosphate uptake rate was enhanced after infection. This is consistent with our biochemical and structural analyses showing that the phage PstS protein is indeed a high-affinity phosphate-binding protein. We further modeled the complex structure of phage PstS with host PstCA and revealed three putative interfaces that may facilitate the formation of the chimeric ABC transporter. Our results provide insights into the molecular mechanism by which cyanophages enhance the phosphate uptake rate of cyanobacteria. Phosphate acquisition by infected bacteria can increase the phosphorus contents of released cellular debris and virus particles, which together constitute a significant proportion of the marine dissolved organic phosphorus pool.

microbiology↗

bioRxiv2020

Inhibition of Streptococcus pneumoniae autolysins highlight distinct differences between chemical and genetic inactivation

Despite renewed interest, development of chemical biology methods to study peptidoglycan metabolism has lagged in comparison to the glycobiology field in general. To address this, a panel of diamides were screened against the Gram-positive pathogen Streptococcus pneumoniae to identify inhibitors of bacterial growth. The screen identified the diamide fgkc as a narrow spectrum bacteriostatic inhibitor of S. pneumoniae growth with an MIC of 7.8 M. The diamide inhibited detergent-induced autolysis in a concentration dependent manner indicating peptidoglycan degradation as the mode-of-action. Genetic screening of autolysin mutants suggested LytB, an endo-N-acetylglucosaminidase, involved in cell division as the potential target. Surprisingly, biochemical, and phenotypic analysis contradicted the genetic screen results. Phenotypic studies with the{Delta} lytb strain illustrate the difference between genetic and chemical inactivation of autolysins. These findings suggest that meta-phenotypes including autolytic activity, cell morphology, and genetic screening can be the result of the complex interaction of one or more possible pathways that are connected to cell wall metabolism.

biochemistry↗

bioRxiv2020

Analysis of Structure and function by the LysR-Type Transcriptional Regulator CbbR of Nostoc sp. PCC 7120

The LysR-type Calvin-Benson-Bassham cycle transcriptional regulator CbbR plays an important role in CO2 fixation in carbon metabolism in nature, which regulates the gene expression of the key enzyme RibisCO in the Calvin-Benson-Bassham (CBB) cycle. In this study, we optimized the conditions for the transformation, expression, and purification of CbbR in the model algae Nostoc sp. PCC 7120, obtained nick-DNA fragments that could tightly bind to CbbR_7120, and finally obtained CbbR protein crystals. These findings provide great assistance for the final crystallization of CbbR to solve the crystal structure of CbbR, and lay the foundation for understanding the mechanism of CO2 fixation in the CBB cycle.

biochemistry↗