title: NlpC/P60 domain-containing proteins of Mycobacterium avium subspecies paratuberculosis that differentially bind and hydrolyze peptidoglycan.
abstract: A subset of proteins containing NlpC/P60 domains are bacterial peptidoglycan hydrolases that cleave noncanonical peptide linkages and contribute to cell wall remodeling as well as cell separation during late stages of division. Some of these proteins have been shown to cleave peptidoglycan in Mycobacterium tuberculosis and play a role in Mycobacterium marinum virulence of zebra fish; however, there are still significant knowledge gaps concerning the molecular function of these proteins in Mycobacterium avium subspecies paratuberculosis (MAP). The MAP genome sequence encodes five NlpC/P60 domain-containing proteins. We describe atomic resolution crystal structures of two such MAP proteins, MAP_1272c and MAP_1204. These crystal structures, combined with functional assays to measure peptidoglycan cleavage activity, led to the observation that MAP_1272c does not have a functional catalytic core for peptidoglycan hydrolysis. Furthermore, the structure and sequence of MAP_1272c demonstrate that the catalytic residues normally required for hydrolysis are absent, and the protein does not bind peptidoglycan as efficiently as MAP_1204. While the NlpC/P60 catalytic triad is present in MAP_1204, changing the catalytic cysteine-155 residue to a serine significantly diminished catalytic activity, but did not affect binding to peptidoglycan. Collectively, these findings suggest a broader functional repertoire for NlpC/P60 domain-containing proteins than simply hydrolases.
authors.affiliation: National Animal Disease Center, USDA-Agricultural Research Service, Ames, Iowa.
authors.forename: John P
authors.initials: JP
authors.lastname: Bannantine
authors.affiliation: School of Biological Sciences, University of Missouri-Kansas City, Kansas City, Missouri.
authors.forename: Cari K
authors.initials: CK
authors.lastname: Lingle
authors.affiliation: Department of Microbiology & Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma.
authors.forename: Philip R
authors.initials: PR
authors.lastname: Adam
authors.affiliation: School of Biological Sciences, University of Missouri-Kansas City, Kansas City, Missouri.
authors.forename: Kasra X
authors.initials: KX
authors.lastname: Ramyar
authors.affiliation: School of Biological Sciences, University of Missouri-Kansas City, Kansas City, Missouri.
authors.forename: William J
authors.initials: WJ
authors.lastname: McWhorter
authors.affiliation: National Animal Disease Center, USDA-Agricultural Research Service, Ames, Iowa.
authors.forename: Judith R
authors.initials: JR
authors.lastname: Stabel
authors.affiliation: Department of Microbiology & Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma.
authors.forename: William D
authors.initials: WD
authors.lastname: Picking
authors.affiliation: School of Biological Sciences, University of Missouri-Kansas City, Kansas City, Missouri.
authors.forename: Brian V
authors.initials: BV
authors.lastname: Geisbrecht
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D020134:Catalytic Domain; D002473:Cell Wall; D018360:Crystallography, X-Ray; D006868:Hydrolysis; D008958:Models, Molecular; D016927:Mycobacterium avium subsp. paratuberculosis / Q000737:chemistry / Q000378:metabolism*; D009238:N-Acetylmuramoyl-L-alanine Amidase / Q000737:chemistry* / Q000378:metabolism*; D010457:Peptidoglycan / Q000378:metabolism*; D000072417:Protein Domains
chemical_list: D001426:Bacterial Proteins; D010457:Peptidoglycan; D009238:N-Acetylmuramoyl-L-alanine Amidase
keywords: Johne's disease; Mycobacterium; antigens; crystal structure; paratuberculosis; peptidoglycan; proteins