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Penicillin‐binding protein SpoVD disulphide is a target for StoA in Bacillus subtilis forespores
Author(s) -
Liu Yiming,
Carlsson Möller Mirja,
Petersen Lise,
Söderberg Christopher A. G.,
Hederstedt Lars
Publication year - 2010
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2009.06964.x
Subject(s) - bacillus subtilis , penicillin binding proteins , biology , biochemistry , endospore , escherichia coli , microbiology and biotechnology , bacteria , gene , spore , genetics
Summary The bacterial endospore is a dormant and heat‐resistant form of life. StoA (SpoIVH) in Bacillus subtilis is a membrane‐bound thioredoxin‐like protein involved in endospore cortex synthesis. It is proposed to reduce disulphide bonds in hitherto unknown proteins in the intermembrane compartment of developing forespores. Starting with a bioinformatic analysis combined with mutant studies we identified the sporulation‐specific, high‐molecular‐weight, class B penicillin‐binding protein SpoVD as a putative target for StoA. We then demonstrate that SpoVD is a membrane‐bound protein with two exposed redox‐active cysteine residues. Structural modelling of SpoVD, based on the well characterized orthologue PBP2x of Streptococcus pneumoniae , confirmed that a disulphide bond can form close to the active site of the penicillin‐binding domain restricting access of enzyme substrate or functional association with other cortex biogenic proteins. Finally, by exploiting combinations of mutations in the spoVD , stoA and ccdA genes in B. subtilis cells, we present strong in vivo evidence that supports the conclusion that StoA functions to specifically break the disulphide bond in the SpoVD protein in the forespore envelope. The findings contribute to our understanding of endospore biogenesis and open a new angle to regulation of cell wall synthesis and penicillin‐binding protein activity.