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Publication Abstract from PubMed

Gram-positive bacteria assemble pili through class C sortase enzymes specialized in polymerizing pilin subunits into covalently linked, high-molecular-weight, elongated structures. Here we report the crystal structures of two class C sortases (SrtC1 and SrtC2) from Group B Streptococcus (GBS) Pilus Island 1. The structures show that both sortases are comprised of two domains: an 8-stranded beta-barrel catalytic core conserved among all sortase family members and a flexible N-terminal region made of two alpha-helices followed by a loop, known as the lid, which acts as a pseudo-substrate. In vitro experiments performed with recombinant SrtC enzymes lacking the N-terminal portion demonstrate that this region of the enzyme is dispensable for catalysis but may have key roles in substrate specificity and regulation. Moreover, in vitro FRET-based assays show that the LPXTG motif common to many sortase substrates is not the sole determinant of sortase C specificity during pilin protein recognition.

Structural basis for group B streptococcus pilus 1 sortases C regulation and specificity.,Cozzi R, Prigozhin D, Rosini R, Abate F, Bottomley MJ, Grandi G, Telford JL, Rinaudo CD, Maione D, Alber T PLoS One. 2012;7(11):e49048. doi: 10.1371/journal.pone.0049048. Epub 2012 Nov 8. PMID:23145064^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.