Open AccessNorM of Vibrio parahaemolyticus Is an Na + -Driven Multidrug Efflux Pump
Author(s) -
Yuji Morita,
Atsuko Kataoka,
Sumiko Shiota,
Tohru Mizushima,
Tomofusa Tsuchiya
Publication year - 2000
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.182.23.6694-6697.2000
Subject(s) - efflux , vibrio parahaemolyticus , biology , antiporter , membrane transport protein , transporter , vibrio , biochemistry , bacteria , membrane , gene , genetics
NorM ofVibrio parahaemolyticus apparently is a new type of multidrug efflux protein, with no significant sequence similarity to any known transport proteins. Based on the following experimental results, we conclude that NorM is an Na+ -driven Na+ /drug antiporter. (i) Energy-dependent ethidium efflux from cells possessing NorM was observed in the presence of Na+ but not of K+ . (ii) An artificially imposed, inwardly directed Na+ gradient elicited ethidium efflux from cells. (iii) The addition of ethidium to cells loaded with Na+ elicited Na+ efflux. Thus, NorM is an Na+ /drug antiporting multidrug efflux pump, the first to be found in the biological world. Judging from the similarity of the NorM sequence to those of putative proteins in sequence databases, it seems that Na+ /drug antiporters are present not only inV. parahaemolyticus but also in a wide range of other organisms.