Structure of lymphostatin, a large multi-functional virulence factor of pathogenic Escherichia coli

TL;DR

This paper reveals the structure of lymphostatin, a key virulence factor in harmful E. coli, showing how it interacts with host cells to cause disease.

Contribution

The study provides the first high-resolution structure of lymphostatin using cryo-electron microscopy.

Findings

Lymphostatin has six distinct domains and three conformations observed at different pH levels.

Long linkers connect the domains and block the catalytic sites of glycosyltransferase and protease domains.

Lymphostatin binds to T-lymphocytes and HEK-293T cells, forming clusters that are internalized.

Abstract

Lymphostatin is a key virulence factor of enteropathogenic and enterohaemorrhagic Escherichia coli, playing roles in bacterial colonisation of the gut and in the inhibition of lymphocyte proliferation and proinflammatory responses. The protein’s glycosyltransferase and cysteine protease motifs are required for activity against lymphocytes, but high-resolution structural information has proven elusive. Here, we describe the structure of lymphostatin from enteropathogenic E. coli O127:H6, determined by electron cryo-microscopy at different pH values. We observe three conformations of a highly complex molecule with two glycosyltransferase domains, one PaToxP-like protease domain, an ADP-ribosyltransferase domain, a vertex domain and a delivery domain. Long linkers hold these domains together and occlude the catalytic sites of the N-terminal glycosyltransferase and protease domains. Lymphostatin binds to bovine T-lymphocytes and HEK-293T cells, forming clusters at the plasma membrane that are internalized. With six distinct domains, lymphostatin can be regarded as a multitool of pathogenic Escherichia coli, enabling complex interactions with host cells.

Lymphostatin is a large protein required for Escherichia coli virulence. Here, Griessmann et al. use electron cryo-microscopy to describe the structure of lymphostatin determined at different pH values, showing three conformations, six distinct domains, and long inter-domain linkers that occlude the catalytic sites of the N-terminal glycosyltransferase and protease domains.

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