A light-driven sodium ion pump in marine bacteria

Light-driven proton-pumping rhodopsins are widely distributed in many microorganisms. They convert sunlight energy into proton gradients that serve as energy source of the cell. Here we report a new functional class of a microbial rhodopsin, a light-driven sodium ion pump. We discover that the marin...

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Bibliographic Details
Published in:Nature communications 2013-04, Vol.4 (1), p.1678
Main Authors: Inoue, Keiichi, Ono, Hikaru, Abe-Yoshizumi, Rei, Yoshizawa, Susumu, Ito, Hiroyasu, Kogure, Kazuhiro, Kandori, Hideki
Format: Article
Language:English
Subjects:
631/326/41/1969
631/45/49/1142
631/57/2272
Bacteria
Chloride
E coli
Energy
Flavobacterium - metabolism
Humanities and Social Sciences
Light
Lithium
Marine Biology
Microorganisms
Models, Molecular
multidisciplinary
Mutation
Potassium
Protons
Science
Science (multidisciplinary)
Sodium
Sodium-Potassium-Exchanging ATPase - chemistry
Sodium-Potassium-Exchanging ATPase - genetics
Sodium-Potassium-Exchanging ATPase - metabolism
Water Microbiology
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Summary:Light-driven proton-pumping rhodopsins are widely distributed in many microorganisms. They convert sunlight energy into proton gradients that serve as energy source of the cell. Here we report a new functional class of a microbial rhodopsin, a light-driven sodium ion pump. We discover that the marine flavobacterium Krokinobacter eikastus possesses two rhodopsins, the first, KR1, being a prototypical proton pump, while the second, KR2, pumps sodium ions outward. Rhodopsin KR2 can also pump lithium ions, but converts to a proton pump when presented with potassium chloride or salts of larger cations. These data indicate that KR2 is a compatible sodium ion–proton pump, and spectroscopic analysis showed it binds sodium ions in its extracellular domain. These findings suggest that light-driven sodium pumps may be as important in situ as their proton-pumping counterparts. Light-driven proton-pumping rhodopsins are widely distributed in microorganisms and convert sunlight energy into proton gradients. Inoue et al . report the discovery of a light-driven sodium ion pump from marine bacteria.
ISSN:2041-1723
DOI:10.1038/ncomms2689