Biology subjects

Sojitra, M.

Publications and source records attributed to Sojitra, M..

8 recordsLinked to original sources

bioRxiv2026

Mapping Glycan Binding Profiles of the Gut Bacteria using Liquid Glycan Array (LiGA)

Glycan-microbe interactions are central to gut colonization and host-microbiota communication. Here, we apply a DNA-encoded Liquid Glycan Array (LiGA) to quantify interactions between live gut bacteria and multivalent natural or mirror glycans. LiGA comprises glycosylated M13 bacteriophage bearing silent DNA barcodes that encode glycan identity and density. Using LiGA, we profiled glycan binding across 16 Limosilactobacillus reuteri strains isolated from murine, porcine, poultry, and human hosts, and then extended the approach to profile glycan binding of taxonomically diverse bacteria from three phyla Bacillota, Bacteroidota, Pseudomonadota consisting of nine different species. Recent discussion of mirror-image microorganisms raise a question whether these microorganisms could interact with present-day life by engaging naturally chiral glycans. We demonstrated that this question can be assessed by testing the binding of mirror-image glycans to natural bacteria. Evaluation of enantiomers of common glycan revealed cross-chiral recognition by Escherichia coli and L. reuteri, indicating that these bacteria can used mirror-image glycans to engage for adhesion and potential colonization. By symmetry the same arguments extends to mirror microorganisms and glycans of naturally chirality. We established that LiGA enables efficient characterization of bacterial glycan binding and provides new insights into intestinal microbial ecology.

biochemistry↗

bioRxiv2025

Discovering Glycosylation-Dependent Protein Function by Thermal Proteome Profiling

Protein glycosylation regulates essential cellular processes including protein folding, stability, and cell-cell interactions; however, how aberrant glycosylation impacts protein function and interaction networks remains poorly understood. Here we combine mass spectrometry-based proteomics, chemical glycobiology, and molecular dynamics simulations to systematically investigate glycosylation dependent protein stability and function. By perturbing the secretory pathway at defined steps, we generated proteins with distinct glycan structures and analyzed their functional consequences using thermal proteome profiling. This approach revealed that cells mount convergent stress responses to diverse glycosylation perturbations, characterized by coordinated trafficking reorganization. This reorganization effectively redirects protein flux from secretion toward degradation. We further identified that perturbing terminal glycan modifications, particularly sialylation and fucosylation, exerts the most profound effects on cell surface protein function. We studied in detail how loss of fucosylation restricts the conformational dynamics of key domains in integrin alpha 4, reducing VCAM-1 binding affinity and suggesting a potential therapeutic strategy for multiple sclerosis. Overall, our systematic approach uncovered extensive complexity in how glycosylation regulates protein function beyond simple glycoform identification and provides a resource for dissecting essential glycan-protein relationships.

systems biology↗

bioRxiv2025

Evaluation of Multiplexed Liquid Glycan Array (LiGA) for Serological Detection of Glycan-binding Antibodies

We test the performance of the multiplexed liquid glycan array (LiGA) technology in serological assays. Specifically, we use LiGA to detect ABO blood group antibodies in human serum. This LiGA, which we name ABO-LiGA, contains ABO blood group trisaccharide glycans with an ethylazido aglycone conjugated to groups of ten multi-barcoded M13 particles carrying dibenzocyclooctyne (DBCO) on p8 proteins. ELISA clonal binding assays to anti-A/B antibodies confirmed the functional performance of ABO-clones and aligned with next-generation sequencing (NGS) of the mixed clones. Multiple DNA-barcoded technical replicates in LiGA allow for quantification of reproducibility and robustness as determined by the Z-score using NGS. We then tested ABO-LiGA for specific detection of IgG and IgM anti-A and anti-B IgG and IgM antibodies in human serum samples. Comparison of antibody binding responses in sera from 31 healthy donors to ABO-LiGA with an ABO-Luminex-based method revealed consistent responses to LiGA-ABO but also minor deficiencies of ABO-LiGA such as low robustness of the current assay format and a limited ability to detect low intensity antibody responses. Some results point to undesired interactions of serum antibodies with small-footprint glycans conjugated to phage via the bulky DBCO moiety. This report illuminates the path for future development of LiGA-based serological assays and suggests the need to develop alternative methods for conjugating glycans to phage to avoid liabilities of the hydrophobic DBCO moiety.

biochemistry↗

bioRxiv2023

Multivalent DNA-encoded lectins on phage enable detecting compositional glycocalyx differences

Selective detection of disease-associated changes in the cellular glycocalyx is a foundation of modern targeted therapies. Detecting minor changes in the density and identity of glycans on the cell surface is a technological challenge exacerbated by lack of 1:1 correspondence between cellular DNA/RNA and glycan structures on cell surface. We demonstrate that multivalent displays of up to 300 lectins on DNA-barcoded M13 phage on a liquid lectin array (LiLA), detects subtle differences in composition and density of glycans on cells ex vivo and in immune cells or organs in animals. For example, constructs displaying 73 copies of diCBM40 lectin per 700x5 nm virion ({varphi}-CBM73) exhibit non-linear ON/OFF-like recognition of sialoglycans on the surface of normal and cancer cells. In contrast, a high-valency {varphi}-CBM290 display, or soluble diCBM40, exhibit canonical progressive scaling in binding with increased epitope density; these constructs cannot amplify the subtle differences detected by {varphi}-CBM73. Similarly, multivalent displays of diCBM40 and Siglec-7 detect differences in the glycocalyx between stem-like and non-stem populations in cancer cells that are not detected with soluble lectins. Multivalent display of lectins on M13 scaffold with protected DNA inside the phage offer non-destructive detection of minor differences in glycocalyx in cells in vitro and in vivo not feasible to currently available technologies.

biochemistry↗

bioRxiv2023

Measuring carbohydrate recognition profile of lectins on live cells using liquid glycan array (LiGA)

Glycans constitute a significant fraction of biomolecular diversity on the surface of cells across all the species in all kingdoms of life. As the structure of glycans is not encoded by the DNA of the host organisms, it is impossible to use cutting-edge DNA technology to study the role of cellular glycosylation or to understand how cell-surface glycome is recognized by glycan-binding proteins (GBPs). To address this gap, we recently described a genetically-encoded liquid glycan array (LiGA) platform that allows profiling of glycan:GBP interactions on the surface of live cells in vitro and in vivo using next-generation sequencing (NGS). LiGA is a library of DNA-barcoded bacteriophages coated with 5-1500 copies of a glycan; the DNA barcode inside each bacteriophage encodes the structure and density of the displayed glycans. Deep sequencing of the glycophages associated with live cells yields a glycan-binding profile of GBPs displayed on the surface of such cells. This protocol provides detailed instructions of using LiGA to probe cell surface receptors and includes information on the preparation of glycophages, analysis by MALDI-TOF MS, the assembly of a LiGA library, and its deep-sequencing. Using the protocol detailed in this report, we measure a glycan-binding profile of the immunomodulatory SiglecLJ1, -2, -6, -7, and -9 expressed on the surface of different cell types and uncover previously unknown environment-dependent recognition of glycans by Siglec-receptors on the surface of live cells. Protocols similar to the one described in this report will make it possible to measure the precise glycan-binding profile of any GPBs displayed on the surface of any cell types.

biochemistry↗

bioRxiv2022

Chemoenzymatic Synthesis of Genetically-Encoded Multivalent Liquid N-glycan Arrays

A hallmark of cellular glycosylation is its chemical complexity and heterogeneity, which can be challenging to capture synthetically. Using chemoenzymatic synthesis on M13 phage, we produce a genetically-encoded liquid glycan array (LiGA) of biantennary complex type N-glycans. Ligation of azido-functionalized sialylglycosyl-asparagine derived from egg yolk to phage functionalized with 50-1000 copies of dibenzocyclooctyne produced divergent intermediate that can be trimmed by glycosidases and extended by glycosyltransferases to yield a library of phages with different N-glycans. Post-reaction analysis by MALDI-TOF MS provided a rigorous approach to confirm N-glycan structure and density, both of which were encoded in the bacteriophage DNA. The binding of this N-glycan LiGA by ten lectins, including CD22 or DC-SIGN expressed on live cells, uncovered an optimal structure/density combination for recognition. Injection of the LiGA into mice identified glycoconjugates with structures and avidity necessary for enrichment in specific organs. This work provides an unprecedented quantitative evaluation of the interaction of complex N-glycans with GBPs in vitro and in vivo.

biochemistry↗

bioRxiv2021

DNA-Encoded Multivalent Display of Protein Tetramers on Phage: Synthesis and In Vivo Aplications

Phage display links phenotype of displayed polypeptides with DNA sequence in phage genome and offers a universal method for discovery of proteins with novel properties. Injection of phage-displayed libraries in living organisms further provides a unique and powerful approach to optimize biochemical, pharmacological and biological properties of the displayed peptides, antibodies and other proteins in vivo. However, over 60% of the proteome is comprised of multi-domain proteins, and display of large multi-subunit proteins on phages remains a challenge. Majority of protein display systems are based on monovalent phagemid constructs but methods for robust display of multiple copies of large proteins are scarce. Here, we describe a DNA-encoded display of a [~]200 kDa tetrameric protein tetrameric L-asparaginase on M13 phage produced by ligation of SpyCatcher-Asparaginase fusion (ScA) to prospectively barcoded phage clones displaying SpyTag peptide. Starting from the SpyTag display on p3 minor coat protein or p8 major coat protein yielded constructs with five copies of ScA displayed on p3 (ScA5-phage) and 50 copies of ScA on p8 protein (ScA50-phage). ScA remained active after conjugation. It could be easily produced directly from lysates of bacteria that express ScA. Display constructs of different valency can be injected into mice and analyzed by deep-sequencing of the DNA barcodes associated phage clones. In these multiplexed studies, we observed a density-dependent clearance rate in vivo. A known clearance mechanism of L-asparaginase is endocytosis by phagocytic cells. Our observations, thus, link the increase in density of the displayed protein with the increased rate of the endocytosis by cells in vivo. In conclusion, we demonstrate that a multivalent display of L-asparaginase on phage could be used to study the circulation life of this protein in vivo and such approach opens the possibility to use DNA sequencing to investigate multiplexed libraries of other multi-subunit proteins in vivo. Abstract Graphic O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=95 SRC="FIGDIR/small/432100v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@18edf0org.highwire.dtl.DTLVardef@ad55c6org.highwire.dtl.DTLVardef@1da47d8org.highwire.dtl.DTLVardef@1a2ec32_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2020

Genetically Encoded, Multivalent Liquid Glycan Array (LiGA)

The Central Dogma of Biology does not allow for the study of glycans using DNA sequencing. We report a "Liquid Glycan Array" (LiGA) platform comprising a library of DNA barcoded M13 virions that display 30-1500 copies of glycans per phage. A LiGA is synthesized by acylation of phage pVIII protein with a dibenzocyclooctyne, followed by ligation of azido-modified glycans. Pulldown of the LiGA with lectins followed by deep sequencing of the barcodes in the bound phage decodes the optimal structure and density of the recognized glycans. The LiGA is target agnostic and can measure the glycan-binding profile of lectins such as CD22 on cells in vitro and immune cells in a live mouse. From a mixture of multivalent glycan probes, LiGAs identifies the glycoconjugates with optimal avidity necessary for binding to lectins on living cells in vitro and in vivo; measurements that cannot be performed with canonical glass slide-based glycan arrays. DedicationThe paper is dedicated to Laura L. Kiessling on the occasion of her 60th birthday.

biochemistry↗