Lysine-91 of the tetraheme c-type cytochrome CymA is essential for quinone interaction and arsenate respiration in Shewanella sp. strain ANA-3.

ABSTRACT: The tetraheme c-type cytochrome, CymA, is essential for arsenate respiratory reduction in Shewanella sp. ANA-3, a model arsenate reducer. CymA is predicted to mediate electron transfer from quinols to the arsenate respiratory reductase (ArrAB). Here, we present biochemical and physiological evidence that CymA interacts with menaquinol (MQH(2)) substrates. Fluorescence quench titration with the MQH(2) analog, 2-n-heptyl-4-hydroxyquinoline-N-oxide (HOQNO), was used to demonstrate quinol binding of E. coli cytoplasmic membranes enriched with various forms of CymA. Wild-type CymA bound HOQNO with a K (d) of 0.1-1 microM. It was also shown that the redox active MQH(2) analog, 2,3-dimethoxy-1,4-naphthoquinone (DMNH(2)), could reduce CymA in cytoplasmic membrane preparations. Based on a CymA homo

SUBMITTER: Zargar K 

PROVIDER: S-EPMC2762525 | biostudies-literature | 2009 Nov

REPOSITORIES: biostudies-literature