Thiol-containing microbial proteins and enzymes

Thiol-containing microbial enzymes and proteins refer to a diverse group of proteins in bacteria and other microbes that possess cysteine residues with reactive thiol (-SH) groups, enabling critical roles in redox homeostasis and stress responses. These thiols are maintained in a reduced state by low molecular weight thiol-redox buffers such as glutathione (GSH) in Gram-negative bacteria, bacillithiol (BSH) in Firmicutes like Bacillus and Staphylococcus, and mycothiol (MSH) in Actinomycetes. Under oxidative stress from reactive oxygen species (ROS), reactive chlorine species (RCS), or electrophiles, protein thiols oxidize to sulfenic acids and form reversible mixed disulfides known as S-thiolations (e.g., S-bacillothiolation, S-mycothiolation), protecting against irreversible overoxidation to sulfinic or sulfonic acids. This modification regulates enzyme activities, such as the redox-sensing repressor OhrR and methionine synthase MetE in Bacillus subtilis, and maltodextrin phosphorylase MalP in Corynebacterium glutamicum. Enzymes like glutaredoxins, bacilliredoxins (Brx), and mycoredoxins (Mrx1) reduce these S-thiolations to restore protein function. In pathogens, these mechanisms enhance survival during host infections by countering immune-generated oxidants. While not a specific therapeutic target, the broad class influences microbial virulence and antibiotic resistance indirectly through redox pathways.

Other names

Protein thiols in microbesMicrobial cysteine-containing proteinsBacterial thiol proteins