S ‐nitrosomycothiol reductase and mycothiol are required for survival under aldehyde stress and biofilm formation in Mycobacterium smegmatis

We show that Mycobacterium smegmatis mutants disrupted in mscR , coding for a dual function S ‐nitrosomycothiol reductase and formaldehyde dehydrogenase, and mshC , coding for a mycothiol ligase and lacking mycothiol (MSH), are more susceptible to S ‐nitrosoglutathione (GSNO) and aldehydes than wild type. MSH is a cofactor for MscR, and both mshC and mscR are induced by GSNO and aldehydes. We also show that a mutant disrupted in egtA , coding for a γ‐glutamyl cysteine synthetase and lacking in ergothioneine, is sensitive to nitrosative stress but not to aldehydes. In addition, we find that MSH and S ‐nitrosomycothiol reductase are required for normal biofilm formation in M. smegmatis , suggesting potential new therapeutic pathways to target to inhibit or disrupt biofilm formation. © 2016 IUBMB Life, 68(8):621–628, 2016