Peptidoglycan reshaping by a noncanonical peptidase for helical cell shape in Campylobacter jejuni

Kyungjin Min,Dusan Hesek,Jinshil Kim,Mijoon Lee,Sangryeol Ryu,B Moon Kim,Doo Ri An,Neha Rana,Se Won Suh,Ji Su Park,Shahriar Mobashery,Hye-Jin Yoon,Hyung Ho Lee

doi:10.1038/s41467-019-13934-4

Abstract

Assembly of the peptidoglycan is crucial in maintaining viability of bacteria and in defining bacterial cell shapes, both of which are important for existence in the ecological niche that the organism occupies. Here, eight crystal structures for a member of the cell-shape-determining class of Campylobacter jejuni, the peptidoglycan peptidase 3 (Pgp3), are reported. Characterization of the turnover chemistry of Pgp3 reveals cell wall d,d-endopeptidase and d,d-carboxypeptidase activities. Catalysis is accompanied by large conformational changes upon peptidoglycan binding, whereby a loop regulates access to the active site. Furthermore, prior hydrolysis of the crosslinked peptide stem from the saccharide backbone of the peptidoglycan on one side is a pre-requisite for its recognition and turnover by Pgp3. These analyses reveal the noncanonical nature of the transformations at the core of the events that define the morphological shape for C. jejuni as an intestinal pathogen.

Highlights

Of the peptidoglycan is crucial in maintaining viability of bacteria and in defining bacterial cell shapes, both of which are important for existence in the ecological niche that the organism occupies
In order to investigate the role of Pgp[3] in peptidoglycan turnover, we performed assays using seven synthetic muramyl peptide substrates, each prepared in multistep syntheses by known procedures[21,22,23] (Supplementary Fig. 2 and Supplementary Methods)
The peptidase activity was documented with the Escherichia coli sacculus as its macromolecular substrate (Supplementary Fig. 3)

Summary

Introduction

Of the peptidoglycan is crucial in maintaining viability of bacteria and in defining bacterial cell shapes, both of which are important for existence in the ecological niche that the organism occupies. Prior hydrolysis of the crosslinked peptide stem from the saccharide backbone of the peptidoglycan on one side is a pre-requisite for its recognition and turnover by Pgp[3]. These analyses reveal the noncanonical nature of the transformations at the core of the events that define the morphological shape for C. jejuni as an intestinal pathogen. The helical shape of C. jejuni is important for bacterial colonization during infection, to move through the mucus layer of the gastrointestinal tract, and for entry into host cells by a corkscrew-like motility[2]. C. jejuni infection is considered to be the most prevalent cause of bacterial diarrheal diseases worldwide, triggering severe complications such as inflammatory bowel disease, reactive arthritis, and Guillain-Barré syndrome[5,6]

Methods

Results

Conclusion