Structural highlights
Publication Abstract from PubMedAbstract Three peroxiredoxins (Prxs) were identified in Thermotoga maritima, which possesses neither glutathione nor typical thioredoxins: one of the Prx6 class; one 2-Cys PrxBCP; and a unique hybrid protein containing an N-terminal 1-Cys PrxBCP domain fused to a flavin mononucleotide-containing nitroreductase (Ntr) domain. No peroxidase activity was detected for Prx6, whereas both bacterioferritin comigratory proteins (BCPs) were regenerated by a NADH/thioredoxin reductase/glutaredoxin (Grx)-like system, constituting a unique peroxide removal system. Only two of the three Grx-like proteins were able to support peroxidase activity. The inability of TmGrx1 to regenerate oxidized 2-Cys PrxBCP probably results from the thermodynamically unfavorable difference in their disulfide/dithiol E(m) values, -150 and -315 mV, respectively. Mutagenesis of the Prx-Ntr fusion, combined with kinetic and structural analyses, indicated that electrons are not transferred between its two domains. However, their separate activities could function in a complementary manner, with peroxide originating from the chromate reductase activity of the Ntr domain reduced by the Prx domain. In the Absence of Thioredoxins, What Are the Reductants for Peroxiredoxins in Thermotoga maritima?,Couturier J, Prosper P, Winger AM, Hecker A, Hirasawa M, Knaff DB, Gans P, Jacquot JP, Navaza A, Haouz A, Rouhier N Antioxid Redox Signal. 2012 Sep 24. PMID:22866991[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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