title: Lack of mycothiol and ergothioneine induces different protective mechanisms in Mycobacterium smegmatis.
abstract: Mycobacterium smegmatis contains the low molecular weight thiols, mycothiol (MSH) and ergothioneine (ESH). Examination of transposon mutants disrupted in mshC and egtA, involved in the biosynthesis of MSH and ESH respectively, demonstrated that both mutants were sensitive to oxidative, alkylating, and metal stress. However, the mshC mutant exhibited significantly more protein carbonylation and lipid peroxidation than wildtype, while the egtA mutant had less protein and lipid damage than wildtype. We further show that Ohr, KatN, and AhpC, involved in protection against oxidative stress, are upregulated in the egtA mutant. In the mshC mutant, an Usp and a putative thiol peroxidase are upregulated. In addition, mutants lacking MSH also contained higher levels of Coenzyme F420 as compared to wildtype and two Coenzyme F420 dependent enzymes were found to be upregulated. These results indicate that lack of MSH and ESH result in induction of different mechanisms for protecting against oxidative stress.
authors.affiliation: Department of Biology, California State University- Fresno, Fresno, California, 93740.
authors.forename: Arishma Rajkarnikar
authors.initials: AR
authors.lastname: Singh
authors.affiliation: Department of Biology, California State University- Fresno, Fresno, California, 93740.
authors.forename: Andrew
authors.initials: A
authors.lastname: Strankman
authors.affiliation: Department of Biology, California State University- Fresno, Fresno, California, 93740.
authors.forename: Ruzan
authors.initials: R
authors.lastname: Orkusyan
authors.affiliation: Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061.
authors.forename: Endang
authors.initials: E
authors.lastname: Purwantini
authors.affiliation: Department of Biology, California State University- Fresno, Fresno, California, 93740.
authors.forename: Mamta
authors.initials: M
authors.lastname: Rawat
keywords: Coenzyme F420; Mycothiol; ergothioneine; mycobacteria; oxidative stress; thiol peroxidase