title: Sortase D forms the covalent bond that links BcpB to the tip of Bacillus cereus pili.
abstract: Bacillus cereus and other Gram-positive bacteria elaborate pili via a sortase D-catalyzed transpeptidation mechanism from major and minor pilin precursor substrates. After cleavage of the LPXTG sorting signal of the major pilin, BcpA, sortase D forms an amide bond between the C-terminal threonine and the amino group of lysine within the YPKN motif of another BcpA subunit. Pilus assembly terminates upon sortase A cleavage of the BcpA sorting signal, resulting in a covalent bond between BcpA and the cell wall cross-bridge. Here, we show that the IPNTG sorting signal of BcpB, the minor pilin, is cleaved by sortase D but not by sortase A. The C-terminal threonine of BcpB is amide-linked to the YPKN motif of BcpA, thereby positioning BcpB at the tip of pili. Thus, unique attributes of the sorting signals of minor pilins provide Gram-positive bacteria with a universal mechanism ordering assembly of pili.
authors.affiliation: Department of Microbiology, University of Chicago, Chicago, IL 60637, USA.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Budzik
authors.forename: So-Young
authors.initials: SY
authors.lastname: Oh
authors.forename: Olaf
authors.initials: O
authors.lastname: Schneewind
mesh_terms: D000577:Amides / Q000378:metabolism; D019881:Aminoacyltransferases / Q000235:genetics / Q000378:metabolism*; D000881:Anthrax / Q000235:genetics / Q000378:metabolism; D001408:Bacillus anthracis / Q000235:genetics / Q000378:metabolism; D001409:Bacillus cereus / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism*; D002846:Chromatography, Affinity; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D036781:Fimbriae Proteins / Q000235:genetics / Q000378:metabolism*; D010861:Fimbriae, Bacterial / Q000235:genetics / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013379:Substrate Specificity
chemical_list: D000577:Amides; D001426:Bacterial Proteins; D010446:Peptide Fragments; C509823:sortase D; D036781:Fimbriae Proteins; D019881:Aminoacyltransferases; C120542:sortase A; D003546:Cysteine Endopeptidases