Open AccessHydrogenase mutants of Alcaligenes eutrophus H16 show alterations in the electron transport system
Author(s) -
Kömen Ralf,
Schmidt Karin,
Friedrich Bärbel
Publication year - 1992
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1992.tb05412.x
Subject(s) - hydrogenase , mutant , electron transport chain , biochemistry , oxidase test , cytochrome c oxidase , cytochrome , wild type , respiratory chain , cytochrome c , chemistry , biology , gene , enzyme , mitochondrion
Mutations in the genes coding for the soluble and the membrane‐bound hydrogenase of Alcaligenes eutrophus strain H16 significantly affected the expression of respiratory chain components. In lithoautotrophically grown wild type cells electron flow mainly proceeded via the cytochrome c oxidases. Mutants defective in the membrane‐bound hydrogenase contained a 2‐ to 3‐fold higher cytochrome a content than the wild type and cytochrome c oxidase of the aa 3 ‐type was preferentially used by these cells for substrate oxidation. Mutants impaired in the soluble hydrogenase revealed slow growth on hydrogen, presumably due to inefficient reverse electron flow mechanisms which provide the cells with NADH for autotrophic CO 2 ‐fixation. In this class of mutants the two quinol oxidases of the o ‐ and d ‐type in addition to the co ‐type oxidase were the predominant electron‐transport branches.