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Title 

Na+-dependent NADH : quinone oxidoreductase in the respiratory chain of the marine bacterium Marinomonas vaga

Authors 

Young Jae KimYong Ha Park

Publisher 

The Korean Society for Applied Microbiology

Issue Date 

1996

Citation 

Journal of Microbiology and Biotechnology, vol. 6, no. 6, pp. 391-396

Keywords 

Halophilic marine bacteriaMarinomonas vagaNa+ pumpNa+-dependent NADHquinone oxidoreductaseRespiratory chain

Abstract 

The Gram-negative marine bacterium Marinomonas vaga, which requires 0.5 M NaCl concentration for optimal growth, is slightly halophilic. The growth of M. vaga was highly resistant to the proton conductor, carbonyl cyanide m-chlorophenylhydrazone (CCCP) under alkaline pH conditions (pH 8.5) but very sensitive to CCCP under acidic pH conditions (pH 6.5). These results suggest that the respiratory chain-linked NADH oxidase system of M. vaga may lead to generation of a Na+ electrochemical gradient. In order to examine the existence of Na+-stimulated NADH oxidase in M. vaga, membrane fractions were prepared by the osmotic lysis method. The membrane-bound NADH oxidase oxidized both NADH and deamino-NADH as substrates and required Na+ for maximum activity. The maximum activity of NADH oxidase was obtained at about pH 8.5 in the presence of 0.2 M NaCl. The site of Na+-dependent activation in the NADH oxidase system was at the NADH:quinone oxidoreductase segment. The NADH oxidase and NADH:quinone oxidoreductase were very sensitive to the respiratory chain inhibitor, 2-heptyl-4-hydroxyquinoline-N-oxide (HQNO) in the presence of 0.2 M NaCl but highly resistant to another respiratory inhibitor, rotenone. Based on these findings, we conclude that M. vaga possesses the Na+-dependent NADH:quinone oxidoreductase that may function as an electrogenic Na+ pump.

ISSN 

1017-7825

Appears in Collections

1. Journal Articles > Journal Articles

Registered Date

2017-04-19


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