title: Structural characterization of Salmonella typhimurium YeaZ, an M22 O-sialoglycoprotein endopeptidase homolog.
abstract: The Salmonella typhimurium "yeaZ" gene (StyeaZ) encodes an essential protein of unknown function (StYeaZ), which has previously been annotated as a putative homolog of the Pasteurella haemolytica M22 O-sialoglycoprotein endopeptidase Gcp. YeaZ has also recently been reported as the first example of an RPF from a gram-negative bacterial species. To further characterize the properties of StYeaZ and the widely occurring MK-M22 family, we describe the purification, biochemical analysis, crystallization, and structure determination of StYeaZ. The crystal structure of StYeaZ reveals a classic two-lobed actin-like fold with structural features consistent with nucleotide binding. However, microcalorimetry experiments indicated that StYeaZ neither binds polyphosphates nor a wide range of nucleotides. Additionally, biochemical assays show that YeaZ is not an active O-sialoglycoprotein endopeptidase, consistent with the lack of the critical zinc binding motif. We present a detailed comparison of YeaZ with available structural homologs, the first reported structural analysis of an MK-M22 family member. The analysis indicates that StYeaZ has an unusual orientation of the A and B lobes which may require substantial relative movement or interaction with a partner protein in order to bind ligands. Comparison of the fold of YeaZ with that of a known RPF domain from a gram-positive species shows significant structural differences and therefore potentially distinctive RPF mechanisms for these two bacterial classes.
authors.affiliation: Division of Structural Biology, The Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom.
authors.forename: C E
authors.initials: CE
authors.lastname: Nichols
authors.forename: C
authors.initials: C
authors.lastname: Johnson
authors.forename: M
authors.initials: M
authors.lastname: Lockyer
authors.forename: I G
authors.initials: IG
authors.lastname: Charles
authors.forename: H K
authors.initials: HK
authors.lastname: Lamb
authors.forename: A R
authors.initials: AR
authors.lastname: Hawkins
authors.forename: D K
authors.initials: DK
authors.lastname: Stammers
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D003001:Cloning, Molecular; D019295:Computational Biology; D018360:Crystallography, X-Ray; D008666:Metalloendopeptidases / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D019151:Peptide Library; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012486:Salmonella typhimurium / Q000201:enzymology*
chemical_list: D001426:Bacterial Proteins; D019151:Peptide Library; D011994:Recombinant Proteins; D008666:Metalloendopeptidases; C070738:O-sialoglycoprotein endopeptidase