Bacillithiol (BSH) functions as a general thiol reductant, analogous to glutathione, in a wide range of bacterial species. Bacilliredoxins reduce those proteins that are modified by disulfide bond formation with BSH (S-bacillithiolation) [1]. This entry represents BrxC from Bacillus subtilis (formerly known as YtxJ) and similar bacterial proteins related to BSH. BrxC is a monothiol bacilliredoxin responsible for the removal of BSH from oxidized cytosolic proteins. It can also debacillithiolate the mixed disulfide form of the bacilliredoxin BrxB [2,3]. It has a similar fold to thioredoxin. The homologue in Deinococcus radiodurans, named AbxC, plays a role in the response to oxidative stress [4].

1: The Role of Bacillithiol in Gram-Positive Firmicutes. Chandrangsu P, Loi VV, Antelmann H, Helmann JD; Antioxid Redox Signal. 2018;28:445-462. PMID:28301954

2: Biosynthesis and functions of bacillithiol, a major low-molecular-weight thiol in Bacilli. Gaballa A, Newton GL, Antelmann H, Parsonage D, Upton H, Rawat M, Claiborne A, Fahey RC, Helmann JD; Proc Natl Acad Sci U S A. 2010;107:6482-6486. PMID:20308541

3: The Bacillus subtilis monothiol bacilliredoxin BrxC (YtxJ) and the Bdr (YpdA) disulfide reductase reduce S-bacillithiolated proteins. Gaballa A, Su TT, Helmann JD; Redox Biol. 2021;42:101935. PMID:33722570

4: Atypical Bacilliredoxin AbxC Plays a Role in Responding to Oxidative Stress in Radiation-Resistant Bacterium Deinococcus radiodurans. Jeong S, Jung JH, Kim MK, de Groot A, Blanchard L, Ryu S, Bahn YS, Lim S; Antioxidants (Basel). 2021; [Epub ahead of print] PMID:34356381