Biology subjects

Castorina, L. V.

Publications and source records attributed to Castorina, L. V..

4 recordsLinked to original sources

bioRxiv2026

HLA Alleles Imprint Distinct Biases in the Usage Preferences of TCR Vβ segments

T cells must co-recognize peptide and HLA, yet the extent to which this specificity is shaped by germline-encoded TCR-HLA contacts versus selection during thymic development has remained difficult to quantify. Leveraging population-scale TCR{beta} repertoires linked to donor HLA genotypes, we construct allele-specific V{beta} usage profiles and normalize them to repertoire-wide baselines to derive interpretable HLA-TCR V{beta} preference vectors. We demonstrate that different HLA alleles imprint distinct biases in the usage frequency of TCR V{beta} gene segments among the public TCRs that engage those alleles; consistent with germline-encoded TCR-HLA contact preferences, certain V{beta} genes are over-represented for particular HLA alleles. Similarities in HLA amino-acid sequence predict similarities in both their V{beta} preferences and peptide-binding motifs; a residue-level analysis disentangles HLA positions primarily associated with TCR engagement from those associated with peptide motifs. The TCR-associated HLA positions localize to canonical TCR-facing helices, whereas peptide-associated HLA positions track binding pockets, revealing distinct molecular routes by which HLA polymorphism shapes the TCR and peptide sides of recognition. CMV exposure stratifications confirmed these patterns are not explained by a few dominant infections. Together, these data support that germline-encoded constraints set the landscape of TCR-HLA compatibility, while thymic and peptide-driven forces tune the realized repertoire. These HLA-specific V{beta} biases are a biological prior that should provide a baseline for better understanding of TCR-pHLA specificity as a whole and should be accounted for in future evaluation of any TCR-pHLA specificity prediction methods.

immunology↗

bioRxiv2025

Crowdsourced Protein Design: Lessons From the Adaptyv EGFR Binder Competition

In this report, we summarize and analyze the 2024 Adaptyv protein design competition. Participants used computational and Machine Learning (ML) methods of their choice to design proteins that bind the Epidermal Growth Factor Receptor (EGFR), a key drug target involved in cell growth, differentiation, and cancer development. Over 1,800 designs were submitted across two rounds. Of these, 601 proteins were selected and characterized for expression and binding affinity to EGFR, with competitors both optimizing existing binders (KD = 1.21 nM) and creating de novo binders (KD = 82 nM). All selected designs were experimentally validated using Adaptyvs automated Bio-Layer Interferometry (BLI) pipeline. This competition illustrates the potential of crowdsourcing to drive creativity and innovation in protein design. However, it also exposed key challenges, such as the lack of standardized benchmarks, experimental design targets, and robust computational metrics for method comparison. We anticipate that future competitions will address these gaps and further motivate progress in computational protein design.

bioengineering↗

bioRxiv2025

From Atoms to Fragments: A Coarse Representation for Functional and Efficient Protein Design

MotivationAlthough deep learning has accelerated protein design, current protein representations such as sequences or full-atom structures scale non-linearly with protein length. We propose a sparse and interpretable representation for proteins, based on evolutionarily conserved fragments. Specifically, we use a curated set of 40 functional and evolutionarily conserved fragments as an alphabet to build Fragment Graphs and Fragment Sets. These fragment-based representations are both lightweight and functionally informative, capturing up to 55% more variance using fewer than [Formula] of the dimensions required by traditional methods. ResultsOn a dataset of 215 functionally diverse proteins, our approach creates more coherent functional clusters than traditional sequence- and structure-based methods, even among proteins with [≤] 30% sequence identity. Fragment-based searches of protein databases achieve accuracies comparable to traditional methods, while using 90% fewer tokens per protein. These searches execute [~]68.7x faster than RMSD-based structural methods and [~]1.64x faster than sequence-based methods, even including fragment pre-processing overhead. Additionally, we show that our representation effectively guides RFDiffusion for protein backbone generation with functional recovery rates higher than 40%. In summary, our fragment-based representation offers a scalable and interpretable alternative for the next generation of protein design tools for backbone design, sequence design, and functional similarity searches within protein structure databases. Availabilityhttps://github.com/wells-wood-research/tessera (Documentation to be made available upon acceptance)

bioinformatics↗

bioRxiv2023

Assessing the Generalization Capabilities of TCR Binding Predictors via Peptide Distance Analysis

Understanding the interaction between T Cell Receptors (TCRs) and peptide-bound Major Histocompatibility Complexes (pMHCs) is crucial for comprehending immune responses and developing targeted immunotherapies. While recent machine learning (ML) models show remarkable success in predicting TCR-pMHC binding within training data, these models often fail to generalize to peptides outside of their training distributions, raising concerns about their applicability in therapeutic settings. Understanding and improving the generalization of these models is therefore critical to ensure real-world applications. To address this issue, we evaluate the effect of the distance between training and testing peptide distributions on ML model empirical risk assessments, using sequence-based and 3D structure-based distance metrics. In our analysis we use several state-of-the-art models for TCR-peptide binding prediction: Attentive Variational Information Bottleneck (AVIB), NetTCR-2.0 and -2.2, and ERGO II (pre-trained autoencoder) and ERGO II (LSTM). In this work, we introduce a novel approach for assessing the generalization capabilities of TCR binding predictors: the Distance Split (DS) algorithm. The DS algorithm controls the distance between training and testing peptides based on both sequence and structure, allowing for a more nuanced evaluation of model performance. We show that lower 3D shape similarity between training and test peptides is associated with a harder out-of-distribution task definition, which is more interesting when measuring the ability to generalize to unseen peptides. However, we observe the opposite effect when splitting using sequence-based similarity. These findings highlight the importance of using a distance-based splitting approach to benchmark models. This could then be used to estimate a confidence score on predictions on novel and unseen peptides, based on how different they are from the training ones. Additionally, our results may hint that employing 3D shape to complement sequence information could improve the accuracy of TCR-pMHC binding predictors.

immunology↗