Bacillus subtilis spore protein SpoVAC functions as a mechanosensitive channel. Issue 4 (16th April 2014)

• Record Type: Journal Article
• Authors: Velásquez, Jeanette; Schuurman‐Wolters, Gea; Birkner, Jan Peter; Abee, Tjakko; Poolman, Bert
• Is Part Of: Molecular microbiology. Volume 92:Issue 4(2014)
• Page Start: 813
• Page End: 823
• Publication Date: 2014-04-16
• Subjects: Molecular microbiology -- Periodicals; 572.829
• DOI: 10.1111/mmi.12591
• Languages: English
• ISSNs: 0950-382X

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>A critical event during spore germination is the release of Ca‐DPA (calcium in complex with dipicolinic acid). The mechanism of release of Ca‐DPA through the inner membrane of the spore is not clear, but proteins encoded by the <italic>B</italic><italic>acillus subtilis</italic> <italic>spoVA</italic> operon are involved in the process. We cloned and expressed the <italic>spoVAC</italic> gene in <italic>E</italic><italic>scherichia coli</italic> and characterized the SpoVAC protein. We show that SpoVAC protects <italic>E</italic><italic>. coli</italic> against osmotic downshift, suggesting that it might act as a mechanosensitive channel. Purified SpoVAC was reconstituted in unilamellar lipid vesicles to determine the gating mechanism and pore properties of the protein. By means of a fluorescence‐dequenching assay, we show that SpoVAC is activated upon insertion into the membrane of the amphiphiles lysoPC and dodecylamine. Patch clamp experiments on <italic>E</italic><italic>. coli</italic> giant spheroplast as well as giant unilamellar vesicles (GUVs) containing SpoVAC show that the protein forms transient pores with main conductance values of about 0.15 and 0.1 nS respectively. Overall, our data indicate that SpoVAC acts as a mechanosensitive channel and has properties that would allow the release of Ca‐DPA and amino acids during germination of the spore.</p> </abstract>