title: Atomic model of a cell-wall cross-linking enzyme in complex with an intact bacterial peptidoglycan.
abstract: The maintenance of bacterial cell shape and integrity is largely attributed to peptidoglycan, a highly cross-linked biopolymer. The transpeptidases that perform this cross-linking are important targets for antibiotics. Despite this biomedical importance, to date no structure of a protein in complex with an intact bacterial peptidoglycan has been resolved, primarily due to the large size and flexibility of peptidoglycan sacculi. Here we use solid-state NMR spectroscopy to derive for the first time an atomic model of an l,d-transpeptidase from Bacillus subtilis bound to its natural substrate, the intact B. subtilis peptidoglycan. Importantly, the model obtained from protein chemical shift perturbation data shows that both domains-the catalytic domain as well as the proposed peptidoglycan recognition domain-are important for the interaction and reveals a novel binding motif that involves residues outside of the classical enzymatic pocket. Experiments on mutants and truncated protein constructs independently confirm the binding site and the implication of both domains. Through measurements of dipolar-coupling derived order parameters of bond motion we show that protein binding reduces the flexibility of peptidoglycan. This first report of an atomic model of a protein-peptidoglycan complex paves the way for the design of new antibiotic drugs targeting l,d-transpeptidases. The strategy developed here can be extended to the study of a large variety of enzymes involved in peptidoglycan morphogenesis.
authors.affiliation: University Grenoble Alpes, IBS , F-38044 Grenoble, France.
authors.forename: Paul
authors.initials: P
authors.lastname: Schanda
authors.forename: Sébastien
authors.initials: S
authors.lastname: Triboulet
authors.forename: Cédric
authors.initials: C
authors.lastname: Laguri
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Bougault
authors.forename: Isabel
authors.initials: I
authors.lastname: Ayala
authors.forename: Morgane
authors.initials: M
authors.lastname: Callon
authors.forename: Michel
authors.initials: M
authors.lastname: Arthur
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Simorre
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology*; D020134:Catalytic Domain; D002473:Cell Wall / Q000201:enzymology*; D008958:Models, Molecular; D009154:Mutation; D010457:Peptidoglycan / Q000378:metabolism*; D010458:Peptidyl Transferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding
chemical_list: D010457:Peptidoglycan; D010458:Peptidyl Transferases