The role of membranes and transport in the salt tolerance of halobacteria. [Halobacterium halobium]
In halobacteria two light-driven membrane pumps have been investigated: bacteriorhodopsin, which extrudes protons from the cell, and halorhodopsin, a recently discovered translocator for sodium ions. Bacteriorhodopsin and halorhodopsin are retinal proteins, and upon illumination of these pigments, a series of photochemical intermediates are produced which relax within 10 to 20 msec, and in an unknown way are coupled to the vectorial uptake and release of protons or sodium ions, respectively. There is reason to believe that the main pathway of sodium transport is not halorhodopsin, however. Rapid sodium extrusion from halobacterial cells is via a sodium/proton antiporter, which, by exchanging sodium ions for protons across the membrane will utilize the energy of the proton gradient to drive sodium transport. As far as it is known, such exchange is a more widespread mechanism for sodium transport in procaryotes, but primary pumps for sodium do exist in mammalian cells, and have been suggested to operate in plants as well. 50 refs.
- Research Organization:
- California Univ., Irvine (USA). Dept. of Physiology and Biophysics
- DOE Contract Number:
- AS03-80ER10637
- OSTI ID:
- 6906053
- Report Number(s):
- DOE/ER/10637-T2; ON: DE87003012
- Resource Relation:
- Other Information: Portions of this document are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
Similar Records
Bioenergetics of salt tolerance. Final report
The bioenergetics of salt tolerance: Final report (Irvine Laboratory)
Related Subjects
14 SOLAR ENERGY
BACTERIA
BIOLOGICAL ADAPTATION
MEMBRANE PORES
BIOLOGICAL MODELS
SODIUM CHLORIDES
MEMBRANE TRANSPORT
PHOTOSYNTHESIS
RECEPTORS
RHODOPSIN
ALKALI METAL COMPOUNDS
CHEMICAL REACTIONS
CHLORIDES
CHLORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
MEMBRANE PROTEINS
MICROORGANISMS
ORGANIC COMPOUNDS
PHOTOCHEMICAL REACTIONS
PIGMENTS
PROTEINS
SODIUM COMPOUNDS
SYNTHESIS
550700* - Microbiology
140505 - Solar Energy Conversion- Photochemical
Photobiological
& Thermochemical Conversion- (1980-)