title: Comparative and functional analysis of sortase-dependent proteins in the predicted secretome of Lactobacillus salivarius UCC118.
abstract: Surface proteins are important factors in the interaction of probiotic and pathogenic bacteria with their environment or host. We performed a comparative bioinformatic analysis of four publicly available Lactobacillus genomes and the genome of Lactobacillus salivarius subsp. salivarius strain UCC118 to identify secreted proteins and those linked to the cell wall. Proteins were identified which were predicted to be anchored by WXL-binding domains, N- or C-terminal anchors, GW repeats, lipoprotein anchors, or LysM-binding domains. We identified 10 sortase-dependent surface proteins in L. salivarius UCC118, including three which are homologous to mucus-binding proteins (LSL_0152, LSL_0311, and LSL_1335), a collagen-binding protein homologue (LSL_2020b), two hypothetical proteins (LSL_1838 and LSL_1902b), an enterococcal surface protein homologue (LSL_1085), a salivary agglutinin-binding homologue (LSL_1832b), an epithelial binding protein homologue (LSL_1319), and a proteinase homologue (LSL_1774b). However, two of the genes are gene fragments and four are pseudogenes, suggesting a lack of selection for their function. Two of the 10 genes were not transcribed in vitro, and 1 gene showed a 10-fold increase in transcript level in stationary phase compared to logarithmic phase. The sortase gene was deleted, and three genes encoding sortase-dependent proteins were disrupted. The sortase mutant and one sortase-dependent protein (mucus-binding homologue) mutant showed a significant reduction in adherence to human epithelial cell lines. The genome-wide investigation of surface proteins can thus help our understanding of their roles in host interaction.
authors.affiliation: Department of Microbiology, University College Cork, Cork, Ireland.
authors.forename: Jan-Peter
authors.initials: JP
authors.lastname: van Pijkeren
authors.forename: Carlos
authors.initials: C
authors.lastname: Canchaya
authors.forename: Kieran A
authors.initials: KA
authors.lastname: Ryan
authors.forename: Yin
authors.initials: Y
authors.lastname: Li
authors.forename: Marcus J
authors.initials: MJ
authors.lastname: Claesson
authors.forename: Barbara
authors.initials: B
authors.lastname: Sheil
authors.forename: Lothar
authors.initials: L
authors.lastname: Steidler
authors.forename: Liam
authors.initials: L
authors.lastname: O'Mahony
authors.forename: Gerald F
authors.initials: GF
authors.lastname: Fitzgerald
authors.forename: Douwe
authors.initials: D
authors.lastname: van Sinderen
authors.forename: Paul W
authors.initials: PW
authors.lastname: O'Toole
mesh_terms: D019881:Aminoacyltransferases / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002874:Chromosome Mapping; D002876:Chromosomes, Bacterial; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers; D004847:Epithelial Cells / Q000382:microbiology; D006801:Humans; D007700:Kinetics; D007778:Lactobacillus / Q000201:enzymology* / Q000235:genetics; D008565:Membrane Proteins / Q000378:metabolism; D010957:Plasmids; D016133:Polymerase Chain Reaction
chemical_list: D001426:Bacterial Proteins; D017931:DNA Primers; D008565:Membrane Proteins; D019881:Aminoacyltransferases; C120542:sortase A; D003546:Cysteine Endopeptidases