Real-time kinetics of electrogenic Na+ transport by rhodopsin from the marine flavobacterium Dokdonia sp. PRO95

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Bogachev , A V , Bertsova , Y V , Verkhovskaya , M L , Mamedov , M D & Skulachev , V P 2016 , ' Real-time kinetics of electrogenic Na + transport by rhodopsin from the marine flavobacterium Dokdonia sp . PRO95 ' Scientific Reports , vol. 6 , 21397 . DOI: 10.1038/srep21397

Title: Real-time kinetics of electrogenic Na+ transport by rhodopsin from the marine flavobacterium Dokdonia sp. PRO95
Author: Bogachev, Alexander V.; Bertsova, Yulia V.; Verkhovskaya, Marina L.; Mamedov, Mahir D.; Skulachev, Vladimir P.
Contributor: University of Helsinki, Institute of Biotechnology
Date: 2016-02-11
Language: eng
Number of pages: 11
Belongs to series: Scientific Reports
ISSN: 2045-2322
URI: http://hdl.handle.net/10138/162519
Abstract: Discovery of the light-driven sodium-motive pump Na+-rhodopsin (NaR) has initiated studies of the molecular mechanism of this novel membrane-linked energy transducer. In this paper, we investigated the photocycle of NaR from the marine flavobacterium Dokdonia sp. PRO95 and identified electrogenic and Na+-dependent steps of this cycle. We found that the NaR photocycle is composed of at least four steps: NaR519 + hv -> K-585 -> (L-450 M-495) -> O-585 -> NaR519. The third step is the only step that depends on the Na+ concentration inside right-side-out NaR-containing proteoliposomes, indicating that this step is coupled with Na+ binding to NaR. For steps 2, 3, and 4, the values of the rate constants are 4x10(4) s(-1), 4.7 x 10(3) M-1 s(-1), and 150 s(-1), respectively. These steps contributed 15, 15, and 70% of the total membrane electric potential (Delta psi similar to 200 mV) generated by a single turnover of NaR incorporated into liposomes and attached to phospholipid-impregnated collodion film. On the basis of these observations, a mechanism of light-driven Na+ pumping by NaR is suggested.
Subject: CYTOCHROME-C-OXIDASE
PHOTOSYNTHETIC REACTION-CENTER
TRANSLOCATING NADH
SINGLE-TURNOVER
BINDING-SITE
O-H
PUMP
MECHANISM
MEMBRANE
PROTEIN
1183 Plant biology, microbiology, virology
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