Biology subjects

Guo, C.

Publications and source records attributed to Guo, C..

At least 55 records · Page 3Linked to original sources

bioRxiv2025

Adaptive mutations at lysine residues of PRRSV nsp12 enable evasion of host proteasomal and selective autophagic degradation

Ubiquitin signaling in viral infections can either enhance immune responses and degrade viral proteins or be exploited by viruses to target host antiviral factors. Porcine reproductive and respiratory syndrome virus (PRRSV) poses a significant threat to the pig industry, with its non-structural proteins (nsps) critical for virulence and replication. Here, we investigated the role of ubiquitination in the stability of PRRSV-encoded nsps and found that nsp12 was specifically degraded via the ubiquitin-proteasome system. Mechanistically, nsp12 underwent K48- and K63-linked polyubiquitination at lysine residues 89, 91, 127, and 130. RNF114 served as an E3 ubiquitin ligase for nsp12, with its enzymatic activity essential for both nsp12 degradation and viral replication. Additionally, nsp12 underwent ubiquitin-dependent selective autophagy through receptor-mediated recognition, wherein NBR1, SQSTM1, and NDP52 bridged its interaction with LC3 for autophagic degradation. Evolutionary analyses revealed that PRRSV nsp12 acquired non-lysine residues at positions 89, 127, and 130 during viral adaptation. Correspondingly, recombinant PRRSV strains carrying the K91/127/130R mutations within nsp12 exhibited enhanced replication, while a revertant strain with the R89K mutation in nsp12 showed attenuated infectivity. Mass spectrometry analysis further identified significant enrichment of ubiquitination-related modifications among nsp12-interacting proteins. These findings provide valuable insights for anti-PRRSV drug design and highlight the challenge posed by adaptive mutations in viral proteins to the swine industry. Author SummaryUbiquitination plays crucial roles in both proteasomal degradation and selective autophagy during viral infections, yet its impact on the stability of porcine reproductive and respiratory syndrome virus (PRRSV) nonstructural proteins (nsps) remains unexplored. Here, we found that nsp12 was targeted for proteasomal degradation through K48/K63-linked polyubiquitination at lysine residues 89, 91, 127, and 130, which requires the involvement of E3 ubiquitin ligase RNF114. Furthermore, nsp12 underwent receptor-mediated selective autophagic degradation through the action of NBR1, SQSTM1, and NDP52. Using reverse genetics technology, mutations of lysine to arginine in PRRSV nsp12 enhanced viral replication, whereas the reverse mutations reduced its infectivity. Our findings demonstrate that PRRSV evades host degradation by acquiring adaptive mutations within nsp12, which counteract ubiquitin-dependent clearance thus enhancing viral fitness. This novel mechanism illustrates a key viral immune evasion strategy and underlines the challenge in controlling PRRSV.

microbiology↗

bioRxiv2025

Imaging cellular activity simultaneously across all organs of a vertebrate reveals body-wide circuits

All cells in an animal collectively ensure, moment-to-moment, the survival of the whole organism in the face of environmental stressors1,2. Physiology seeks to elucidate the intricate network of interactions that sustain life, which often span multiple organs, cell types, and timescales, but a major challenge lies in the inability to simultaneously record time-varying cellular activity throughout the entire body. We developed WHOLISTIC (WHole Organism Live Imaging System for recording Tissue and IntraCellular activity), a method to image second-timescale, time-varying intracellular dynamics across cell-types of the vertebrate body. By advancing and integrating volumetric fluorescence microscopy, machine learning, and pancellular transgenic expression of calcium sensors in transparent young Danio rerio (zebrafish) and with proof of concept in adult Danionella, the method enables real-time recording of cellular dynamics across the organism. Calcium is a universal intracellular messenger, with a large array of cellular processes depending on changes in calcium concentration across varying time-scales, making it an ideal proxy of cellular activity3. Using this platform to screen the dynamics of most cells in the body, we discovered unexpected responses of specific cell types to stimuli, such as chondrocyte reactions to cold, meningeal responses to ketamine, and state-dependent activity, such as oscillatory ependymal-cell activity during periods of extended motor quiescence. At the organ scale, the method uncovered pulsating traveling waves along the kidney nephron. At the multi-organ scale, we uncovered muscle synergies and independencies, as well as muscle-organ interactions. Integration with optogenetics allowed us to all-optically determine the causal direction of brain-body interactions. At the whole-organism scale, the method captured the rapid brainstem-controlled redistribution of blood flow across the body. Finally, we advanced Whole-Body Expansion Microscopy4 to provide ground-truth molecular and ultrastructural anatomical context, explaining the spatiotemporal structure of activity captured by WHOLISTIC. Together, these innovations establish a new paradigm for systems biology, bridging cellular and organismal physiology, with broad implications for both fundamental research and drug discovery.

neuroscience↗

bioRxiv2025

Tracking the Evolutionary Patterns of RNA Modifications from Bryophyte to Flowering Plants by Mass Spectrometry

RNA modifications are critical for the regulation of gene expression. Comprehensive profiling of RNA modifications is a prerequisite for unravelling their identities and functions. The plant hormone auxin plays pivotal roles in regulating plant growth, development, and environmental responses. In contrast to the extensive studies in animals, there is a paucity of knowledge regarding the existence and functions of RNA modifications in plants. This is due to the low abundance of modified ribonucleosides and the lack of accurate analytical methods. This study employs a state-of-the-art hydrophilic interaction liquid chromatography-tandem-mass spectrometry (HILIC-MS/MS) platform to achieve the sensitive detection of 12 nucleosides at the pM to nM level. Utilizing this platform, we were able to identify N4,2-O-dimethylcytidine (m4Cm) in plants by LC-MS/MS for the first time, which provided direct evidence for the widespread of this modification in plants. Moreover, a comprehensive investigation was undertaken to examine the 12 types of RNA modifications and their response patterns to auxin in a range of prototype plants, spanning from bryophyte (Marchantia polymorpha) to flowering plants (Arabidopsis thaliana, Oryza sativa, and Zea mays). The evolutionary patterns of the 12 RNA modifications were depicted from bryophyte to flowering plants, and their potential functions in plant growth, development, and auxin responses were revealed.

biochemistry↗

bioRxiv2025

Multifunctional Injectable GelMA Hydrogels with MSN-Mediated Spatiotemporal Icariin Release for Enhanced Osseointegration in Bone Defects

The repair of bone defects is faced with the dual challenges of limited autograft donors and single function of artificial materials. The development of new materials with mechanical adaptability, drug-controlled release and osteogenic induction has become a research hotspot in bone tissue engineering. Here, we developed an injectable photocrosslinkable hydrogel by integrating icariin (ICA)-loaded mesoporous silica nanoparticles (MSN) into gelatin methacryloyl (GelMA). The amino-functionalized MSN enhanced compressive modulus by 1.5-fold (p < 0.05) and enabled pH-responsive ICA release (91.2{+/-}4.2% cumulative release over 15 days). Our in vitro findings revealed the composite hydrogel promoted BMSC proliferation was 1.43{+/-}0.04 times that of GelMA group. And express excellent osteogenic differentiation ability (ALP activity: 3.25-fold; Mineralization: 5.01-fold). In vivo study, Micro-CT revealed significantly higher bone volume fraction (BV/TV) in rat calvarial defects at 12 weeks, with histology confirming mature trabecular bone formation. This MSN-mediated spatiotemporal delivery system synchronizes immunomodulation and osteogenesis, offering a promising strategy for non-load-bearing osseointegration.

bioengineering↗

bioRxiv2025

KIF5A downregulation in spinal muscular atrophy links axonal regeneration defects with ALS

Spinal muscular atrophy (SMA) is a devastating neuromuscular disorder caused by mutations in the Survival Motor Neuron 1 (SMN1) gene, leading to decreased SMN levels and motor neuron dysfunction. SMN-restoring therapies offer clinical benefit, but the downstream molecular consequences of SMN reduction remain incompletely understood. Here, we demonstrate that SMN deficiency results in downregulation of KIF5A in human neurons and in a mouse model of SMA. We provide evidence that reduced SMN levels impair axon regeneration, which is rescued by KIF5A overexpression and that the RNA-binding protein SMN functions to stabilize KIF5A mRNA. These findings provide evidence of a molecular link between SMA and ALS pathophysiology, highlighting KIF5A as a new SMN target. Our findings suggest SMN-independent interventions targeting KIF5A could represent a complementary therapeutic approach for SMA and other motor neuron diseases.

neuroscience↗

bioRxiv2025

Revalidation of Manis aurita, based on integrative morphological and genomic evidence

Pangolins face severe conservation threats globally, necessitating accurate taxonomy for effective conservation. Previous genomic research on the Chinese pangolin (Manis pentadactyla) identified two deeply divergent lineages (MPA and MPB), suggesting underestimated species diversity. The recent description of M. indoburmanica (corresponding to MPB), however, did not assess its relationship with historical names, particularly the subspecies M. p. aurita, leaving the groups taxonomic status uncertain. To resolve this issue, we employed an integrative framework, analyzing genomic and morphological data from museum specimens including the lectotype of M. p. aurita to clarify phylogenetic relationships and taxonomy within M. pentadactyla sensu lato. Our results demonstrate that MPB, which includes both M. indoburmanica and M. p. aurita, is geographically restricted to the southern Himalayas and thus distinct from other M. pentadactyla populations. Genomic analyses indicate the two clades diverged [~]1.8 Ma and have remained largely isolated, with only minimal gene flow with congeners. Furthermore, morphometric analyses of both cranial and external features reveal consistent and significant differentiation between the Himalayan lineage (MPB) and M. pentadactyla sensu stricto. Collectively, these congruent findings provide unequivocal support for the revalidation of Manis aurita Hodgson, 1836, thereby establishing it as a distinct extant species of Asian pangolin.

evolutionary biology↗

bioRxiv2025

Antigenic and Virological Characteristics of SARS-CoV-2 Variant BA.3.2, XFG, and NB.1.8.1

The emergence of the SARS-CoV-2 saltation variant BA.3.2, which harbors over 50 mutations relative to its ancestral BA.3 lineage, has raised concerns about its potential to drive outbreaks similar to BA.2.86/JN.1. Concurrently, variants such as NB.1.8.1, LF.7.9, XEC.25.1, XFH, and XFG exhibit enhanced growth advantages over LP.8.1.1, necessitating a comparative analysis of their antigenic and virological characteristics. Here, we evaluated the infectivity, ACE2-binding efficiency, and immune evasion of these variants. Pseudovirus assays revealed BA.3.2s robust antibody evasion, including resistance to Class 1/4 monoclonal antibodies; however, its ACE2 engagement efficiency was markedly reduced due to a closed spike conformation, leading to low infectivity. While XFG and LF.7.9 demonstrated strong immune escape associated with A475V and N487D mutations, their reduced receptor-binding efficiency suggested a need for compensatory adaptations. In contrast, NB.1.8.1 retained high ACE2 affinity and humoral immune evasion, supporting its potential for future dominance. Collectively, BA.3.2s current profile limits its ability to compete with emerging variants like NB.1.8.1. Sustained monitoring of BA.3.2s evolution-- particularly for mutations stabilizing an open RBD conformation or enhancing escape from Class 1 antibodies--is essential to assess its outbreak potential.

immunology↗

bioRxiv2025

A real-time detection and non-destructive warning method for zebrafish body surface anomalies based on improved YOLOv8 framework

The detection of anomalies on fish surfaces is of critical importance for assessing fish health status, preventing fish disease outbreaks, predicting changes in water quality, enhancing fish welfare. The zebrafish (Danio rerio), a key model organism, has been increasingly utilized in various fields, including medicine, genetics and environmental toxicology. This has led to a corresponding increase in demand for intelligent management and detection systems. However, traditional methods of fish disease detection may have irreversible effects on fish, particularly small species, and often fail to meet the precision, non-destructive warning, and real-time requirements for zebrafish detection. To address this issue, this study proposes a novel method based on the YOLOv8 framework, designated ESC-YOLOv8-seg. This method significantly enhances the precision and speed of detecting surface abnormalities on small fish in complex settings by integrating the EMA the SPPELAN and C2f-Faster modules, and adding a detection head tailored for small targets. Furthermore, the integration of positional information and surface features enables the method to achieve real-time monitoring and non-destructive early warning of fish surface abnormalities. The proposed method enhances precision in small target detection and achieves high accuracy in discerning subtle differences among detection targets. In real aquaculture settings, it can reach an average speed of 106 FPS with a detection accuracy of 98%. Although this study has been designed to meet the specific needs of zebrafish scientific research, it is highly generalisable and can be applied to the real-time detection of underwater surface abnormalities in a range of fish species in aquaculture.

bioinformatics↗

bioRxiv2025

Exogenous melatonin mitigates drought stress by promoting the living cortical area of roots in cotton

The root cortex plays a critical role in water absorption, influencing root function and metabolic activity. However, the effects of melatonin on root cortical cells and its role in drought resistance remain unclear. This study examines the impact of exogenous melatonin on the root cortex of cotton under drought stress, focusing on its relationship with water uptake and drought resilience. Cotton plants were treated with 8% PEG6000 for drought stress and 100 {micro}M melatonin by foliar application. The results demonstrated that melatonin application significantly increased the living cortical area of roots under drought stress, with notable increases of 26.34% and 59.00% at distances of 1 cm and 13 cm from the root tip, respectively. Melatonin also enhanced root cortical thickness, promoted osmotic regulation, increased respiratory enzyme activity, and improved water and nutrient uptake. Furthermore, melatonin application promoted both root and shoot growth. Notably, the living cortical area positively correlated with osmotic substance accumulation, root respiration, and absorption capacity under drought conditions. In conclusion, exogenous melatonin alleviates drought-induced damage by enhancing the living cortical area, optimizing osmotic regulation, and improving root absorption, thus promoting cotton growth and drought resistance. These findings highlight melatonin as a promising regulator for enhancing drought resistance. HighlightExogenous melatonin increases root cortical integrity of cotton roots under drought stress, improves the absorption of water and nutrients, promotes the growth of cotton, and enhances its drought resistance.

physiology↗

bioRxiv2025

Multi-Omics Analysis of Wound Microbiome and Staphylococcus aureus in Pressure Ulcer

This study employs a multi-omics approach to investigate the wound microbiome and Staphylococcus aureus in pressure ulcers. Metagenomic sequencing and associated technologies were utilized to examine bacterial populations, identify dominant species, and study biofilm formation in S. aureus through metabolomic and proteomic characteristics. The results revealed a significant reduction in microbial diversity in pressure ulcer samples compared to controls, with Staphylococcus, Corynebacterium, and Klebsiella being the most prevalent genera. Functional prediction analysis indicated differences in pathogenic invasiveness and biofilm formation factors among the groups. The presence of antimicrobial resistance genes was higher in the pressure ulcer group, particularly in Staphylococcus spp. strains. Whole-genome sequencing of 29 S. aureus isolates identified various clonal complexes and spa types, with the majority possessing genes conferring resistance to {beta}-lactam antimicrobials and virulence factors. Histopathological examination and fluorescent in situ hybridization confirmed the presence of S. aureus in biofilm structures. In vitro biofilm formation tests and metabolomic and proteomic analyses provided insights into the interactions between S. aureus strains and their biofilm formation, revealing enriched pathways related to metabolic processes and membrane composition. This research offers a scientific foundation for understanding the colonization patterns of S. aureus biofilms in pressure ulcer wounds.

microbiology↗

bioRxiv2025

A Novel COE-D8-Fosfomycin Conjugate Effectively Against First-line Antibiotic Resistant Uropathogenic Escherichia coli

Recurrent urinary tract infections (UTIs) are increasingly associated with antibiotic resistance, posing significant clinical challenges. This study evaluates the antimicrobial efficacy of the membrane-intercalating conjugated oligoelectrolyte COE-D8 against uropathogenic Escherichia coli (UPEC). Among 93 clinical UPEC isolates, over 50% demonstrated resistance to first-line antibiotics, with compound sulfamethoxazole showing the highest resistance (75% at a minimum inhibitory concentration (MIC) >512 g/mL). COE-D8 significantly reduced resistance rates, achieving less than 50% at 32 g/mL and below 5% at 512 g/mL, while demonstrating at least fourfold faster bacterial elimination than standard antibiotics. Mechanistic studies revealed that COE-D8 disrupts bacterial membranes, inducing rapid lysis. However, its cytotoxicity in mammalian cells at 2 g/mL limits clinical application. To address this, a combination therapy with fosfomycin was explored, significantly reducing COE-D8 toxicity by at least fourfold in vitro. In mouse models, fosfomycin co-administration mitigated COE-D8-induced toxicity and prevented mortality at higher doses without compromising antimicrobial efficacy. These findings highlight the potential of COE-D8, particularly in combination with fosfomycin, as a promising strategy to combat antibiotic-resistant UPEC while addressing toxicity challenges.

microbiology↗

bioRxiv2025

Ultraviolet B Induces Cutaneous Lupus Erythematosus by Triggering a Ribotoxic-Stress-Response-Dependent MIF-p38 Feedback Loop in Keratinocytes

Ultraviolet B (UVB) is one of the most common triggers of cutaneous lupus erythematosus (CLE), but the mechanism is still unclear. Here, we discovered that the expression of macrophage migration inhibitory factor (MIF), a multipotent cytokine, was significantly increased in keratinocytes of lupus patients in scRNA-seq data and clinical samples. We further discovered that UVB exposure induced MIF releasing from lupus keratinocytes and contributed to the tissue remodeling and inflammation by regulating the expression of matrix metalloproteinases (MMPs) and pro-inflammatory cytokines in keratinocytes and fibroblasts. Mechanistically, UVB exposure triggered a ribotoxic stress response (RSR) in lupus keratinocytes, which was featured by the increased level of phospho-ZAK. The RSR induced MIF releasing through the activation of p38 and GSDMD cleavage. The released MIF could further promote the activation of p38 through its receptor CD74, forming a positive feedback loop triggered by UVB exposure in lupus keratinocytes. Intradermal injection of a Mif-shRNA AAV significantly improved the skin lesions in lupus mice. To further investigate the potentials of MIF as a therapeutic target, we developed a microneedle patch capable of intradermal administration of a MIF inhibitor, which effectively protected lupus mice from skin lesions induced by UVB exposure. In conclusion, our findings suggest a novel mechanism by which UVB exposure contributes to the development of CLE by triggering a positive feedback loop of MIF-p38 in lupus keratinocytes. Our results also demonstrate the translational potentials of microneedle patch targeting MIF in the treatment of CLE.

immunology↗

bioRxiv2024

Natural speech re-synthesis from direct cortical recordings using a pre-trained encoder-decoder framework

Reconstructing perceived speech stimuli from neural recordings is not only advancing the understanding of the neural coding underlying speech processing but also an important building block for brain-computer interfaces and neuroprosthetics. However, previous attempts to directly re-synthesize speech from neural decoding suffer from low re-synthesis quality. With the limited neural data and complex speech representation space, it is hard to build decoding model that directly map neural signal into high-fidelity speech. In this work, we proposed a pre-trained encoder-decoder framework to address these problems. We recorded high-density electrocorticography (ECoG) signals when participants listening to natural speech. We built a pre-trained speech re-synthesizing network that consists of a context-dependent speech encoding network and a generative adversarial network (GAN) for high-fidelity speech synthesis. This model was pre-trained on a large naturalistic speech corpus and can extract critical features for speech re-synthesize. We then built a light-weight neural decoding network that mapped the ECoG signal into the latent space of the pre-trained network, and used the GAN decoder to synthesize natural speech. Using only 20 minutes of intracranial neural data, our neural-driven speech re-synthesis model demonstrated promising performance, with phoneme error rate (PER) at 28.6%, and human listeners were able to recognize 71.6% of the words in the re-synthesized speech. This work demonstrates the feasibility of using pre-trained self-supervised model and feature alignment to build efficient neural-to-speech decoding model.

neuroscience↗

bioRxiv2024

Successful establishment of an exogenous gene expression system in Chlamydomnas chloroplast based on viral replication elements

Currently, transformation in unicellular green alga (Chlamydomonas reinhardtii) chloroplast is hindered by a low yield of target products, possibly due to the heterogeneity of the chloroplast genome. In this study, an expression platform was established in C. reinhardtii by leveraging replicative elements from beet curly top geminivirus, which led to a high level of heterologous gene expression, as previously reported in Nicotiana tabacum. Platform performance was verified by the successful expression of a linearized mvenus cassette, achieving a higher expression level than that obtained using the homologous-recombination-based approach. This study provides a new strategy in microalgae synthetic biology and opens new avenue for accumulating valuable bioproducts at high concentrations.

synthetic biology↗

bioRxiv2024

Mapping Pesticide-Induced Metabolic Alterations in Human Gut Bacteria

Pesticides can modulate gut microbiota (GM) composition, but their specific effects on GM remain largely elusive. Our study demonstrated that pesticides inhibit or promote growth in various GM species, even at low concentrations, and can accumulate in GM to prolong their presence in the host. Meanwhile, the pesticide induced changes in GM composition are associated with significant alterations in gut bacterial metabolism that reflected by the changes of hundreds of metabolites. We generated a pesticide-GM-metabolites (PMM) network that not only reveals pesticide-sensitive gut bacteria species but also report specific metabolic changes in 306 pesticide-GM pairs (PGPs). Using an in vivo mice model, we further demonstrated a PGPs interactions and verified the inflammation-inducing effects of pesticides on the host through dysregulated lipid metabolism of microbes. Taken together, our findings generate a PMM interactions atlas, and shed light on the molecular level of how pesticides impact host health by modulating GM metabolism. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=140 SRC="FIGDIR/small/623895v1_ufig1.gif" ALT="Figure 1"> View larger version (62K): org.highwire.dtl.DTLVardef@17ed5f5org.highwire.dtl.DTLVardef@10d3e0org.highwire.dtl.DTLVardef@c61b43org.highwire.dtl.DTLVardef@27d035_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2024

Processing reliant on granule cells is essential for motor learning but dispensable for many cerebellar-dependent behaviors

Cerebellar dysfunction leads to motor, learning, emotional, and social deficits. It is assumed that these deficits arise from impaired processing of mossy fiber inputs that activate granule cells (GCs) that in turn excite Purkinje cells (PCs). However, high-frequency spontaneous PC firing might also influence behaviors. To clarify how the cerebellum regulates behaviors, we compared the effects of disrupting either GC signaling, which selectively perturbs cerebellar processing, or PC signaling, which disrupts cerebellar processing and spontaneous PC firing. We find that both GC and PC signaling are required for eyeblink conditioning and vestibulo-ocular reflex (VOR) learning. However, disrupting PC signaling impairs baseline VOR, anxiety, and social behaviors, but abolishing GC signaling does not. This establishes that cerebellar processing is essential for motor learning, but is not required for many cerebellum-dependent behaviors. This suggests that such behaviors could be rescued by elevating firing in downstream targets, as shown previously for social deficits.

neuroscience↗

bioRxiv2024

Self-Authenticating Genomic Materials with Advanced Genome Signatures

The authenticity and integrity of synthetic genomic materials containing valuable intellectual property are essential for advancing scientific knowledge and enhancing biosafety. Existing DNA tags and watermarks, however, have limited efficacy due to low mutation tolerance and inadequate digital encoding capacity. Here, we present "Genome Signature", a biochemically stable and tamper-resistant DNA labeling system that enables the creation of self-authenticating genomes. Central to this system is a novel Golomb-ruler-derived Genome-Comb, which efficiently maps extensive nucleotide sequences onto limited codons within endogenous genes, significantly improving error correction and data encoding across millions of nucleotides. Our method successfully recorded a 4.5 million-nucleotide genome in living E. coli. The Genome Signature autonomously identifies and corrects mutations and effectively encodes data within codon orders, ensuring genome integrity and authenticity. Furthermore, it allows precise tracking of sequences across different cells, potentially revolutionizing the development of reliable genomic materials in synthetic biology.

synthetic biology↗

bioRxiv2024

Structural Model of Bacteriophage P22 Scaffolding Protein in a Procapsid by Magic-Angle Spinning NMR

Icosahedral dsDNA viruses such as the tailed bacteriophages and herpesviruses have a conserved pathway to virion assembly that is initiated from a scaffolding protein driven procapsid formation. The dsDNA is actively packaged into procapsids, which undergo complex maturation reactions to form infectious virions. In bacteriophage P22, scaffolding protein (SP) directs the assembly of coat proteins into procapsids that have a T=7 icosahedral arrangement, en route to the formation of the mature P22 capsid. Other than the C-terminal helix-turn-helix involved in interaction with coat protein, the structure of the P22 303 amino acid scaffolding protein within the procapsid is not understood. Here, we present a structural model of P22 scaffolding protein encapsulated within the 23 MDa procapsid determined by magic angle spinning NMR spectroscopy. We took advantage of the 10-fold sensitivity gains afforded by the novel CPMAS CryoProbe to establish the secondary structure of P22 scaffolding protein and employed 19F MAS NMR experiments to probe its oligomeric state in the procapsid. Our results indicate that the scaffolding protein has both -helical and disordered segments and forms a trimer of dimers when bound to the procapsid lattice. This work provides the first structural information for P22 SP beyond the C-terminal helix-turn-helix and demonstrates the power of MAS NMR to understand higher-order viral protein assemblies involving structural components that are inaccessible to other structural biology techniques.

biochemistry↗