Faculty Collaboration Database

Role of the tetraheme cytochrome CymA in anaerobic electron transport in cells of Shewanella putrefaciens MR-1 with normal levels of menaquinone. J Bacteriol 2000 Jan;182(1):67-75

Date

12/30/1999

Pubmed ID

10613864

Pubmed Central ID

PMC94241

DOI

10.1128/JB.182.1.67-75.2000

Scopus ID

2-s2.0-0033989646 (requires institutional sign-in at Scopus site)   185 Citations

Abstract

Shewanella putrefaciens MR-1 possesses a complex electron transport system which facilitates its ability to use a diverse array of compounds as terminal electron acceptors for anaerobic respiration. A previous report described a mutant strain (CMTn-1) deficient in CymA, a tetraheme cytochrome c. However, the interpretation of the electron transport role of CymA was complicated by the fact that CMTn-1 was also markedly deficient in menaquinones. This report demonstrates that the depressed menaquinone levels were the result of the rifampin resistance phenotype of the parent of CMTn-1 and not the interruption of the cymA gene. This is the first report of rifampin resistance leading to decreased menaquinone levels, indicating that rifampin-resistant strains should be used with caution when analyzing electron transport processes. A site-directed gene replacement approach was used to isolate a cymA knockout strain (MR1-CYMA) directly from MR-1. While MR1-CYMA retained menaquinone levels comparable to those of MR-1, it lost the ability to reduce iron(III), manganese(IV), and nitrate and to grow by using fumarate as an electron acceptor. All of these functions were restored to wild-type efficacy, and the presence of the cymA transcript and CymA protein was also restored, by complementation of MR1-CYMA with the cymA gene. The requirement for CymA in anaerobic electron transport to iron(III), fumarate, nitrate, and manganese(IV) is therefore not dependent on the levels of menaquinone in these cells. This represents the first successful use of a suicide vector for directed gene replacement in MR-1.

Author List

Myers JM, Myers CR

MESH terms used to index this publication - Major topics in bold

Anaerobiosis
Cytochrome c Group
Drug Resistance, Microbial
Electron Transport
Enzyme Inhibitors
Fumarates
Genetic Complementation Test
Genetic Engineering
Iron
Manganese
Mutation
Nitrates
Quinones
Rifampin
Shewanella putrefaciens
Vitamin K