Biophysical Features of Bacillithiol, the Glutathione Surrogate of Bacillus subtilis and other Firmicutes

Sharma, Sunil V., Arbach, Miriam, Roberts, Alexandra A., MacDonald, Colin J., Groom, Murree, and Hamilton, Chris J. (2013) Biophysical Features of Bacillithiol, the Glutathione Surrogate of Bacillus subtilis and other Firmicutes. ChemBioChem, 14 (16). pp. 2160-2168.

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Bacillithiol (BSH) is the major low-molecular-weight (LMW) thiol in many low-G+C Gram-positive bacteria (Firmicutes). Evidence now emerging suggests that BSH functions as an important LMW thiol in redox regulation and xenobiotic detoxification, analogous to what is already known for glutathione and mycothiol in other microorganisms. The biophysical properties and cellular concentrations of such LMW thiols are important determinants of their biochemical efficiency both as biochemical nucleophiles and as redox buffers. Here, BSH has been characterised and compared with other LMW thiols in terms of its thiol pKa, redox potential and thiol–disulfide exchange reactivity. Both the thiol pKa and the standard thiol redox potential of BSH are shown to be significantly lower than those of glutathione whereas the reactivities of the two compounds in thiol–disulfide reactions are comparable. The cellular concentration of BSH in Bacillus subtilis varied over different growth phases and reached up to 5 mM, which is significantly greater than previously observed from single measurements taken during mid-exponential growth. These results demonstrate that the biophysical characteristics of BSH are distinctively different from those of GSH and that its cellular concentrations can reach levels much higher than previously reported.

Item ID: 34285
Item Type: Article (Research - C1)
ISSN: 1439-7633
Keywords: ionization potentials; NMR spectroscopy; redox chemistry; thiol–disulfide exchange; thiols
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2013 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Funders: BBSRC
Projects and Grants: BB/ H013504/1, EU FP-7 ITN grant, number 215009
Date Deposited: 10 Sep 2014 00:49
FoR Codes: 03 CHEMICAL SCIENCES > 0305 Organic Chemistry > 030505 Physical Organic Chemistry @ 20%
06 BIOLOGICAL SCIENCES > 0601 Biochemistry and Cell Biology > 060101 Analytical Biochemistry @ 60%
03 CHEMICAL SCIENCES > 0306 Physical Chemistry (incl Structural) > 030602 Chemical Thermodynamics and Energetics @ 20%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970103 Expanding Knowledge in the Chemical Sciences @ 50%
97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 50%
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