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Structure and functional properties of Bacillus subtilis endospore biogenesis factor StoA
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Crow, Allister, Liu, Yiming, Möller, Mirja Carlsson, Le Brun, Nick E. and Hederstedt, Lars (2009) Structure and functional properties of Bacillus subtilis endospore biogenesis factor StoA. Journal of Biological Chemistry, 284 (15). pp. 10056-10066. doi:10.1074/jbc.M809566200 ISSN 0021-9258.
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Official URL: http://dx.doi.org/10.1074/jbc.M809566200
Abstract
Bacillus subtilis StoA is an extracytoplasmic thiol-disulfide oxidoreductase (TDOR) important for the synthesis of the endospore peptidoglycan cortex protective layer. Here we demonstrate that StoA is membrane-associated in B. subtilis and report the crystal structure of the soluble protein lacking its membrane anchor. This showed that StoA adopts a thioredoxin-like fold with N-terminal and internal additions that are characteristic of extracytoplasmic TDORs. The CXXC active site of the crystallized protein was found to be in a mixture of oxidized and reduced states, illustrating that there is little conformational variation between redox states. The midpoint reduction potential was determined as -248 mV versus normal hydrogen electrode at pH 7 consistent with StoA fulfilling a reductive role in endospore biogenesis. pKa values of the active site cysteines, Cys-65 and Cys-68, were determined to be 5.5 and 7.8. Although Cys-68 is buried within the structure, both cysteines were found to be accessible to cysteine-specific alkylating reagents. In vivo studies of site-directed variants of StoA revealed that the active site cysteines are functionally important, as is Glu-71, which lies close to the active site and is conserved in many reducing extracytoplasmic TDORs. The structure and biophysical properties of StoA are very similar to those of ResA, a B. subtilis extracytoplasmic TDOR involved in cytochrome c maturation, raising important general questions about how these similar but non-redundant proteins achieve specificity. A detailed comparison of the two proteins demonstrates that relatively subtle differences, largely located around the active sites of the proteins, are sufficient to confer specificity.
Item Type: | Journal Article | ||||||
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Divisions: | Faculty of Science, Engineering and Medicine > Science > Life Sciences (2010- ) | ||||||
Journal or Publication Title: | Journal of Biological Chemistry | ||||||
Publisher: | American Society for Biochemistry and Molecular Biology | ||||||
ISSN: | 0021-9258 | ||||||
Official Date: | 2009 | ||||||
Dates: |
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Volume: | 284 | ||||||
Number: | 15 | ||||||
Page Range: | pp. 10056-10066 | ||||||
DOI: | 10.1074/jbc.M809566200 | ||||||
Status: | Peer Reviewed | ||||||
Publication Status: | Published | ||||||
Access rights to Published version: | Open Access (Creative Commons) |
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