Biology subjects

Rollins, Z. A.

Publications and source records attributed to Rollins, Z. A..

4 recordsLinked to original sources

bioRxiv2022

Automated protein-protein structure prediction of the T cell receptor-peptide major histocompatibility complex

T Cell Receptor (TCR) recognition of a peptide-major histocompatibility complex (pMHC) is a crucial component of the adaptive immune response. The identification of therapeutically relevant TCR-pMHC pairs is a significant bottleneck in the implementation of TCR-based immunotherapies but may be augmented by computational methodologies. The ability to computationally design TCRs to target a specific pMHC will require an automated integration of next-generation sequencing, protein-protein structure prediction, molecular dynamics (MD), and TCR ranking. We present a generic pipeline to evaluate patient-specific, sequence-based TCRs to a target pMHC. Using the three most frequently expressed TCRs from 16 colorectal cancer patients, we predicted the protein-protein structure of the TCRs to the target CEA peptide-MHC using Modeller and ColabFold. Then, these TCR-pMHC structures were compared by performing an automated molecular dynamics equilibration. ColabFold generates starting configurations that require, on average, a ~2.5X reduction in simulation time to equilibrate TCR-pMHC structures compared to Modeller. In addition, the structural differences between Modeller and ColabFold are demonstrated by an increase in root mean square deviation (~0.20 nm) between clusters of equilibrated configurations, which can impact the number of hydrogen bonds and Lennard-Jones contacts between the TCR and pMHC. Finally, we identify a TCR ranking criteria that may be used to prioritize TCRs for evaluation of in vitro immunogenicity.

biophysics↗

bioRxiv2021

T Cell Receptor Non-Equilibrium Kinetics

An atomic-scale mechanism describing the role of mechanosensing in T Cell Receptor (TCR) recognition of peptides in the binding groove of the peptide-major histocompatibility complex (pMHC) may inform the design of novel TCRs for immunotherapies. Using steered molecular dynamic simulations, our study demonstrates that mutations to peptides in the binding groove of the pMHC - which are known to discretely alter the T cell response to an antigen - influence MHC conformation and thus the overall strength of the TCR-pMHC bond including duration and length under constant load. Moreover, physiochemical features of the TCR-pMHC dynamic bond strength, such as hydrogen bonds and Lennard-Jones contacts, correlate with the immunogenic response elicited by the specific peptide in the MHC groove. Thus, formation of transient TCR-pMHC bonds is a characteristic of immunogenic peptides and is mediated by stabilized interactions.x

biophysics↗

bioRxiv2021

The Atomic-Level Physiochemical Determinants of T Cell Receptor Dissociation Kinetics

The rational design of T Cell Receptors (TCRs) for immunotherapy has stagnated due to a limited understanding of the dynamic physiochemical features of the TCR that elicit an immunogenic response. The physiochemical features of the TCR-peptide major histocompatibility complex (pMHC) bond dictate bond lifetime which, in turn, correlates with immunogenicity. Here, we: i) characterize the force-dependent dissociation kinetics of the bond between a TCR and a set of pMHC ligands using Steered Molecular Dynamics (SMD); and ii) implement a machine learning algorithm to identify which physiochemical features of the TCR govern dissociation kinetics. Our results demonstrate that the total number of hydrogen bonds between the CDR2{beta}-MHC({beta}), CDR1-Peptide, and CDR3{beta}-Peptide are critical features that determine bond lifetime. We propose that amino acid substitutions to these hypervariable regions of the TCR can efficiently manipulate immunogenicity and thus be used in the rational design of TCRs for immunotherapy.

immunology↗

bioRxiv2020

Organ-on-a-chip model of vascularized human bone marrow niches

Animal models of bone marrow have limited spatial and temporal resolution to observe biological events (intravasation and cellular egress) and are inadequate to dissect dynamic events at the niche level (100 microns). Utilizing microfluidic and stem cell technology, we present a 3D in vitro model of human bone marrow that contains perivascular and endosteal niches complete with dynamic, perfusable vascular networks. We demonstrate that our model can perform in vivo functions including maintenance and differentiation of CD34+ hematopoietic stem/progenitor cells (HSPC) for up to fourteen days, egress of myeloid progenitors, and expression of markers consistent with in vivo human bone marrow. The platform design enables the addition of tissue niches at a later timepoint to probe mechanisms such as tumor cell migration. Overall, we present a novel organ-on-a-chip platform that is capable of recapitulating the human bone marrow microenvironment to observe hematopoietic phenomena at high spatial and temporal resolution.

bioengineering↗