Systematic protein interactome analysis of glycosaminoglycans revealed YcbS as a novel bacterial virulence factor

Abstract

Microbial pathogens have evolved several strategies for interacting with host cell components, such as glycosaminoglycans (GAGs). Some microbial proteins involved in host–GAG binding have been described; however, a systematic study on microbial proteome–mammalian GAG interactions has not been conducted. Here, we used Escherichia coli proteome chips to probe four typical mammalian GAGs, heparin, heparan sulphate (HS), chondroitin sulphate B (CSB), and chondroitin sulphate C (CSC), and identified 185 heparin-, 62 HS-, 98 CSB-, and 101 CSC-interacting proteins. Bioinformatics analyses revealed the unique functions of heparin- and HS-specific interacting proteins in glycine, serine, and threonine metabolism. Among all the GAG-interacting proteins, three were outer membrane proteins (MbhA, YcbS, and YmgH). Invasion assays confirmed that mutant E. coli lacking ycbS could not invade the epithelial cells. Introducing plasmid carrying ycbS complemented the invading defects at ycbS lacking E. coli mutant, that can be further improved by overexpressing ycbS. Preblocking epithelial cells with YcbS reduced the percentage of E. coli invasions. Moreover, we observed that whole components of the ycb operon were crucial for invasion. The displacement assay revealed that YcbS binds to the laminin-binding site of heparin and might affect the host extracellular matrix structure by displacing heparin from laminin.

Expression and Functional Characterization of Various Chaperon-Usher Fimbriae, Curli Fimbriae, and Type 4 Pili of Enterohemorrhagic Escherichia coli O157:H7 Sakai

“…We only detected significant involvement of Ycb fimbriae of E. coli O157:H7 Sakai in adhesion to MDCK cells, and a slight increase in adhesion to Caco2 cells, probably highlighting the importance of Ycb fimbriae in intestinal infection. A ycb mutant strain was not altered in binding to spinach leaves (Saldana et al, 2011), and the binding properties of Ycb fimbriae to laminin (Samadder et al, 2009) and heparin (Hsiao et al, 2016) further support a role in intestinal infection.…”

A Systems View of the Heparan Sulfate Interactome

“…20 Studies of bacteria have applied similar strategies to identify novel HS-binding virulence factors. 21 Toxins from viperid snake venoms and antimicrobial compounds from egg white have been identified as well. 22,23…”

“…20 Studies of bacteria have applied similar strategies to identify novel HS-binding virulence factors. 21 Toxins from viperid snake venoms and antimicrobial compounds from egg white have been identified as well. 22,23 Although many HSBPs have been reported over the years, membrane-bound and membrane-associated HSBPs are often difficult to characterize due to low abundance, solubility issues, protease resistance, and contamination by intracellular proteins (e.g., histones) that strongly bind to heparin-affinity matrices and outcompete less abundant membrane proteins.…”

GAG-DB, the New Interface of the Three-Dimensional Landscape of Glycosaminoglycans

“…These proteins are involved in a variety of biological processes such as extracellular matrix assembly, cell signaling, development, and angiogenesis [ 10 , 13 , 14 ]. Besides, glycosaminoglycans play a role in host-pathogen interactions by binding to bacterial, viral, and parasite proteins [ 15 , 16 , 17 , 18 , 19 , 20 ]. The significance of the understanding and mastering the molecular features underlying the interaction of GAGs to proteins was magistrally demonstrated by the development of the antithrombotic drugs as reviewed in [ 21 ].…”