Published in

Elsevier, Journal of Biological Chemistry, 17(287), p. 14215-14225, 2012

DOI: 10.1074/jbc.m112.348813

Links

Tools

Export citation

Search in Google Scholar

Menaquinone-7 Is Specific Cofactor in Tetraheme Quinol Dehydrogenase CymA

Journal article published in 2012 by Duncan G. G. McMillan ORCID, Sophie J. Marritt, Julea N. Butt, Lars J. C. Jeuken
This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

Full text: Download

Green circle
Preprint: archiving allowed
Upload
Green circle
Postprint: archiving allowed
Upload
Green circle
Published version: archiving allowed
Upload
Policy details
Data provided by SHERPA/RoMEO

Abstract

Little is known about enzymatic quinone-quinol interconversions in the lipid membrane when compared with our knowledge of substrate transformations by globular enzymes. Here, the smallest example of a quinol dehydrogenase in nature, CymA, has been studied. CymA is a monotopic membrane tetraheme c-type cytochrome belonging to the NapC/NirT family and central to anaerobic respiration in Shewanella sp. Using protein-film electrochemistry, it is shown that vesicle-bound menaquinone-7 is not only a substrate for this enzyme but is also required as a cofactor when converting other quinones. Here, we propose that the high concentration of quinones in the membrane negates the evolutionary pressure to create a high affinity active site. However, the instability and reactivity of reaction intermediate, semiquinone, might require a cofactor that functions to minimize damaging side reactions.