title: Transpeptidase activity of penicillin-binding protein SpoVD in peptidoglycan synthesis conditionally depends on the disulfide reductase StoA.
abstract: Endospore cortex peptidoglycan synthesis is not required for bacterial growth but essential for endospore heat resistance. It therefore constitutes an amenable system for research on peptidoglycan biogenesis. The Bacillus subtilis sporulation-specific class B penicillin-binding protein (PBP) SpoVD and many homologous PBPs contain two conserved cysteine residues of unknown function in the transpeptidase domain - one as residue x in the SxN catalytic site motif and the other in a flexible loop near the catalytic site. A disulfide bond between these residues blocks the function of SpoVD in cortex synthesis. With a combination of experiments with purified proteins and B. subtilis mutant cells, it was shown that in active SpoVD the two cysteine residues most probably interact by hydrogen bonding and that this is important for peptidoglycan synthesis in vivo. It was furthermore demonstrated that the sporulation-specific thiol-disulfide oxidoreductase StoA reduces SpoVD and that requirement of StoA for cortex synthesis can be suppressed by two completely different types of structural alterations in SpoVD. It is concluded that StoA plays a critical role mainly during maturation of SpoVD in the forespore outer membrane. The findings advance our understanding of essential PBPs and redox control of extra-cytoplasmic protein disulfides in bacterial cells.
authors.affiliation: Microbiology Group, Department of Biology, Lund University, Sölvegatan 35, Lund, SE- 223 62, Sweden.
authors.forename: Ewa
authors.initials: E
authors.lastname: Bukowska-Faniband
authors.affiliation: Microbiology Group, Department of Biology, Lund University, Sölvegatan 35, Lund, SE- 223 62, Sweden.
authors.forename: Lars
authors.identifier: 0000-0002-6650-6296
authors.initials: L
authors.lastname: Hederstedt
mesh_terms: D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism; D004220:Disulfides / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D010088:Oxidoreductases / Q000378:metabolism; D046915:Penicillin-Binding Proteins / Q000378:metabolism; D010457:Peptidoglycan / Q000096:biosynthesis / Q000378:metabolism; D010458:Peptidyl Transferases / Q000378:metabolism; D011490:Protein Disulfide Reductase (Glutathione) / Q000378:metabolism*; D013171:Spores, Bacterial / Q000254:growth & development
chemical_list: D001426:Bacterial Proteins; D004220:Disulfides; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D046915:Penicillin-Binding Proteins; D010457:Peptidoglycan; C085450:SpoVD protein, Bacillus subtilis; D010088:Oxidoreductases; D011490:Protein Disulfide Reductase (Glutathione); D010458:Peptidyl Transferases