
Acetate formation in the photoheterotrophic bacterium C hloroflexus aurantiacus involves an archaeal type ADP ‐forming acetyl‐ C o A synthetase isoenzyme I
Author(s) -
Schmidt Marcel,
Schönheit Peter
Publication year - 2013
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 - 10.1111/1574-6968.12312
Subject(s) - acetate kinase , biochemistry , enzyme , biology , bacteria , acetyl coa , isozyme , archaea , gene , escherichia coli , genetics
The bacterium C hloroflexus aurantiacus excreted significant amounts of acetate during photohetero trophic growth on glucose and in resting cell suspensions. Up to 1.5 mol acetate per mol glucose were formed. In acetate‐forming cells, the activities of phosphotransacetylase and acetate kinase, usually involved in acetate formation in Bacteria , could not be detected; instead, the cells contained an acetyl‐ C o A synthetase ( ADP ‐forming) ( ACD ) (acetyl‐ C o A + ADP + P i → acetate + ATP + C o A ), an enzyme so far reported in prokaryotes to be specific for acetate‐forming Archaea . ACD , which was induced 10‐fold during growth on glucose, was purified and the encoding gene was identified as C aur_3920 . The recombinant enzyme, a homotetrameric 300‐kDa protein composed of 75‐kDa subunits, was characterized as functional ACD . Substrate specificities and kinetic constants for acetyl‐ C o A /acetate and other acyl‐ C o A esters/acids were determined, showing similarity of the C . aurantiacus ACD to archaeal ACD I isoenzymes, which are involved in acetate formation from sugars. This is the first report of a functional ACD involved in acetate formation in the domain of Bacteria .