Biology subjects

East, K. W.

Publications and source records attributed to East, K. W..

4 recordsLinked to original sources

bioRxiv2022

Identification and Mechanistic Basis of non-ACE2 Blocking Neutralizing Antibodies from COVID-19 Patients with Deep RNA Sequencing and Molecular Dynamics Simulations

Variants of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) continue to cause disease and impair the effectiveness of treatments. The therapeutic potential of convergent neutralizing antibodies (NAbs) from fully recovered patients has been explored in several early stages of novel drugs. Here, we identified initially elicited NAbs (Ig Heavy, Ig lambda, Ig kappa) in response to COVID-19 infection in patients admitted to the intensive care unit at a single center with deep RNA sequencing (>100 million reads) of peripheral blood as a diagnostic tool for predicting the severity of the disease and as a means to pinpoint specific compensatory NAb treatments. Clinical data were prospectively collected at multiple time points during ICU admission, and amino acid sequences for the NAb CDR3 segments were identified. Patients who survived severe COVID-19 had significantly more of a Class 3 antibody (C135) to SARS-CoV-2 compared to non-survivors (16,315 reads vs 1,412 reads, p=0.02). In addition to highlighting the utility of RNA sequencing in revealing unique NAb profiles in COVID-19 patients with different outcomes, we provided a physical basis for our findings via atomistic modeling combined with molecular dynamics simulations. We established the interactions of the Class 3 NAb C135 with the SARS-CoV-2 spike protein, proposing a mechanistic basis for inhibition via multiple conformations that can effectively prevent ACE2 from binding to the spike protein, despite C135 not directly blocking the ACE2 binding motif. Overall, we demonstrate that deep RNA sequencing combined with structural modeling offers the new potential to identify and understand novel therapeutic(s) NAbs in individuals lacking certain immune responses due to their poor endogenous production. Our results suggest a possible window of opportunity for administration of such NAbs when their full sequence becomes available. A method involving rapid deep RNA sequencing of patients infected with SARS-CoV-2 or its variants at the earliest infection time could help to develop personalized treatments using the identified specific NAbs.

immunology↗

bioRxiv2021

Enhanced Specificity Mutations Perturb Allosteric Signaling in CRISPR-Cas9

CRISPR-Cas9 is a molecular tool with transformative genome editing capabilities. At the molecular level, an intricate allosteric signaling is critical for DNA cleavage, but its role in the specificity enhancement of the Cas9 endonuclease is poorly understood. Here, solution NMR is combined with multi-microsecond molecular dynamics and graph theory-derived models to probe the allosteric role of key enhancement specificity mutations. We show that the mutations responsible for increasing the specificity of Cas9 alter the allosteric structure of the catalytic HNH domain, impacting the signal transmission from the DNA recognition region to the catalytic sites for cleavage. Specifically, the K855A mutation strongly disrupts the HNH domain allosteric structure, exerting the highest perturbation on the signaling transfer, while K810A and K848A result in more moderate effects on the allosteric intercommunication. This differential perturbation of the allosteric signaling reflects the different capabilities of the single mutants to increase Cas9 specificity, with the mutation achieving the highest specificity also strongly perturbing the signaling transfer. These outcomes reveal that the allosteric regulation is critical for the specificity enhancement of the Cas9 enzyme, and are valuable to harness the signaling network to improve the systems specificity.

biophysics↗

bioRxiv2019

NMRdock: Lightweight and Modular NMR Processing

NMR is a widely employed tool in chemistry, biology, and physics for the study of molecular structure and dynamics. Advances in computation have produced scores of software programs necessary for the processing and analysis of NMR data. However, the production of NMR software has been largely overseen by academic labs, each with their own preferred OS, environment, and dependencies. This lack of broader standardization and the complexity of installing and maintaining NMR-related software creates a barrier of entry into the field. To further complicate matters, as computation evolves, many aging software packages become deprecated. To reduce the barrier for newcomers and to prevent deprecation of aging software, we have created the NMRdock container. NMRdock utilizes containerization to package NMR processing and analysis programs into a single, easy-to-install Docker image that can be run on any modern OS. The current image contains two bedrock NMR data processing programs (NMRPipe and NMRFAM Sparky). However, future development of NMRdock aims to add modules for additional analysis programs to build a library of tools in a standardized and easy-to-implement manner. NMRdock is open source and free to download at https://compbiocore.github.io/nmrdock/.

biophysics↗

bioRxiv2019

Allosteric Motions of the CRISPR-Cas9 HNH Nuclease Probed by NMR and Molecular Dynamics

CRISPR-Cas9 is a widely employed genome-editing tool with functionality reliant on the ability of the Cas9 endonuclease to introduce site-specific breaks in double-stranded DNA. In this system, an intriguing allosteric communication has been suggested to control its DNA cleavage activity through flexibility of the catalytic HNH domain. Here, solution NMR experiments and a novel Gaussian accelerated Molecular Dynamics (GaMD) simulation method are used to capture the structural and dynamic determinants of allosteric signaling within the HNH domain. We reveal the existence of a millisecond timescale dynamic pathway that spans HNH from the region interfacing the adjacent RuvC nuclease and propagates up to the DNA recognition lobe in full-length CRISPR-Cas9. These findings reveal a potential route of signal transduction within the CRISPR-Cas9 HNH nuclease, advancing our understanding of the allosteric pathway of activation. Further, considering the role of allosteric signaling in the specificity of CRISPR-Cas9, this work poses the mechanistic basis for novel engineering efforts aimed at improving its genome editing capability.\n\n\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=117 SRC=\"FIGDIR/small/660613v4_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (64K):\norg.highwire.dtl.DTLVardef@13429c5org.highwire.dtl.DTLVardef@1a2493borg.highwire.dtl.DTLVardef@175e120org.highwire.dtl.DTLVardef@f1852_HPS_FORMAT_FIGEXP M_FIG C_FIG

biophysics↗