Biology subjects

Praissman, J. L.

Publications and source records attributed to Praissman, J. L..

3 recordsLinked to original sources

bioRxiv2021

Cell Surface Glycan Engineering Reveals that Matriglycan Alone can Recapitulate Dystroglycan Binding and Function

-Dystroglycan (-DG) is uniquely modified on O-mannose sites by a repeating disaccharide (-Xyl1,3-GlcA{beta}1,3-)n termed matriglycan, which is a receptor for laminin-G domain-containing proteins and employed by old-world arenaviruses for infection. Using chemoenzymatically synthesized matriglycans printed as a microarray, we demonstrated length-dependent binding to Laminin, Lassa virus GP1, and the clinically-important antibody IIH6. Utilizing an enzymatic engineering approach, an N-linked glycoprotein was converted into a IIH6-positive Laminin-binding glycoprotein. Engineering of the surface of cells deficient for either -DG or O-mannosylation with matriglycans of sufficient length recovered infection with a Lassa-pseudovirus. Finally free matriglycan in a dose and length dependent manner inhibited viral infection of wildtype cells. These results indicate that matriglycan alone is necessary and sufficient for IIH6 staining, Laminin and LASV GP1 binding, and Lassa-pseudovirus infection and support a model in which it is a tunable receptor for which increasing chain length enhances ligand-binding capacity. O_FIG_DISPLAY_L [Figure 1] M_FIG_DISPLAY Graphical Abstract C_FIG_DISPLAY

biochemistry↗

bioRxiv2020

Generation of an Unbiased Interactome for the Tetratricopeptide Repeat Domain of O-GlcNAc Transferase Indicates a Role for the Enzyme in Intellectual Disability

The O-GIcNAc transferase (OGT) is localized to the nucleus and cytoplasm where it regulates nucleocytoplasmic proteins by modifying serine and threonine residues with a non-extended monosaccharide, {beta}-N-Acetyl-Glucosamine (O-GlcNAc). With thousands of known O-GlcNAc modified proteins but only one OGT encoded in the mammalian genome, a prevailing question is how OGT selects its substrates. Prior work has indicated that the N-terminal tetratricopeptide repeat (TPR) domain of OGT, rather than its C-terminal catalytic domain, is responsible for subcellular targeting and substrate selection. An additional impetus for exploring the OGT TPR domain interactome is the fact that missense mutations in OGT associated with X-linked intellectual disability (XLID) are primarily localized to the TPR domain without substantial impact on activity or stability of the enzyme. Therefore, we adapted the BioID labeling method to identify interactors of a TPR-BirA* fusion protein in HeLa cells. We identified 115 high confidence interactors representing both known and novel O-GlcNAc modified proteins and OGT interactors. The TPR interactors are highly enriched in processes in which OGT has a known role (e.g. chromatin remodeling, cellular survival of heat stress, circadian rhythm), as well as processes i n which OGT has yet to be implicated (e.g. pre-mRNA processing). Importantly, the identified TPR interactors are involved in several disease states but most notably are highly enriched in pathologies featuring intellectual disability. These proteins represent candidate interactors that may underlie the mechanism by which mutations in OGT lead to XLID. Furthermore, the identified interactors provide additional evidence of the importance of the TPR domain for OGT targeting and/or substrate selection. Thus, this defined interactome for the TPR domain of OGT serves as a jumping off point for future research exploring the role of OGT, the TPR domain, and its protein interactors in multiple cellular processes and disease mechanisms, including intellectual disability.

biochemistry↗

bioRxiv2020

Virus-Receptor Interactions of Glycosylated SARS-CoV-2 Spike and Human ACE2 Receptor

The current COVID-19 pandemic is caused by the SARS-CoV-2 betacoronavirus, which utilizes its highly glycosylated trimeric Spike protein to bind to the cell surface receptor ACE2 glycoprotein and facilitate host cell entry. We utilized glycomics-informed glycoproteomics to characterize site-specific microheterogeneity of glycosylation for a recombinant trimer Spike mimetic immunogen and for a soluble version of human ACE2. We combined this information with bioinformatic analyses of natural variants and with existing 3D-structures of both glycoproteins to generate molecular dynamics simulations of each glycoprotein alone and interacting with one another. Our results highlight roles for glycans in sterically masking polypeptide epitopes and directly modulating Spike-ACE2 interactions. Furthermore, our results illustrate the impact of viral evolution and divergence on Spike glycosylation, as well as the influence of natural variants on ACE2 receptor glycosylation that, taken together, can facilitate immunogen design to achieve antibody neutralization and inform therapeutic strategies to inhibit viral infection.

biochemistry↗