AUTHOR=Peng Hui , Zhang Yixiang , Trinidad Jonathan C. , Giedroc David P. 

TITLE=Thioredoxin Profiling of Multiple Thioredoxin-Like Proteins in Staphylococcus aureus

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.02385

DOI=10.3389/fmicb.2018.02385

ISSN=1664-302X

ABSTRACT=<p>Hydrogen sulfide (H<sub>2</sub>S) is thought to signal through protein <italic>S</italic>-sulfuration (persulfidation; <italic>S</italic>-sulfhydration) in both mammalian systems and bacteria. We previously profiled proteome <italic>S</italic>-sulfuration in <italic>Staphylococcus aureus</italic> (<italic>S. aureus</italic>) and identified two thioredoxin-like proteins, designated TrxP and TrxQ, that were capable of reducing protein persulfides as a potential regulatory mechanism. In this study, we further characterize TrxP, TrxQ and the canonical thioredoxin, TrxA, by identifying candidate protein substrates in <italic>S. aureus</italic> cells using a mechanism-based profiling assay where we trap mixed disulfides that exist between the attacking cysteine of a FLAG-tagged Trx and a persulfidated cysteine on the candidate substrate protein in cells. Largely non-overlapping sets of four, 32 and three candidate cellular substrates were detected for TrxA, TrxP, and TrxQ, respectively, many of which were previously identified as global proteome <italic>S</italic>-sulfuration targets including for example, pyruvate kinase, PykA. Both TrxA (<italic>k</italic><sub>cat</sub> = 0.13 s<sup>-1</sup>) and TrxP (<italic>k</italic><sub>cat</sub> = 0.088 s<sup>-1</sup>) are capable of reducing protein persulfides on PykA, a model substrate detected as a candidate substrate of TrxP; in contrast, TrxQ shows lower activity (<italic>k</italic><sub>cat</sub> = 0.015 s<sup>-1</sup>). This work reveals that protein <italic>S</italic>-sulfuration, central to H<sub>2</sub>S and reactive sulfur species (RSS) signaling, may impact cellular activities and appears to be regulated in <italic>S. aureus</italic> largely by TrxP under conditions of sulfide stress.</p>