Bacillus subtilis genome-wide screening to search sortase and its potential substrates

Introduction: Gram positive bacteria utilize their cell wall for anchoring and display of surface proteins. one important mechanism of protein anchoring utilizes sortase, a transpeptidase which catalyse the covalent anchoring of proteins on the cell wall. Sortase in S.aureus recognize an amino acid sequence disignated sorting motif, present close to the C-terminal end of the substrate proteins, cleave between T and G residues in this motif and catalyse anchoring of the polypeptide chain to the peptide crossbridge linking the peptidoglycan strands in a transpeptidation reaction. Genome project revealed that B.subtilis contain two putative sortases (YhcS and YwpE) but the sorting sequences recognized by them and the substrateshas not be known. In this study we were interested in identifying these two types of sortase and their substrates. Methods: Bioinformatics tools like protein sequence alignment was used to find sortase and its potential substrates in B.subtilis genome. Results: Two different putative sortase genes present in the B.subtilis genome, Yhcs and YwpE. Bioanformatics analysis showed that they contain representative domains of sortase family. Also B. subtilis has two putative sortase substrates: YhcR and YfkN. Both substrates have a signal sequence at the N-terminal and a cell wall anchoring motif at the C-terminal containing 3 parts (sortase cleavage signal; LPDTS/A, Transmembrane Hydrophobic domain; Charged tail). Conclusion: YwpE is a 120 aa and YhcS is a 198 aa protein with homology to sortase family and have putative sortase activity. YhcS is more likely to be the more sortase (if any) of B.subtilis by structure and map.

sortase, substrate, transpeptidation