Control of transmembrane ion fluxes to select halorhodopsin-deficient and other energy-transduction mutants of Halobacterium halobium.
- 1 July 1982
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 79 (14), 4308-4312
- https://doi.org/10.1073/pnas.79.14.4308
Abstract
We describe a selection method for mutants altered in the generation and regulation of transmembrane ion flux in Halobacterium halobium. The method is based on experimental control of ion fluxes by a combination of light, ionophore, and external pH to generate an imbalance in the cells' proton circulation through their membranes. The steady-state proton circulation is increased by the introduction of a small inward proton leak with a protonophore. The cells are then illuminated to excite halorhodopsin, which hyperpolarizes the membrane and drives protons into the cells. As a result, wild-type cells suffer cytoplasmic acidification, which causes a dramatic loss of motility and suppresses their growth. These properties can be used to select for mutants that escape cytoplasmic acidification because either they lack halorhodopsin function or they have a greater capacity to eject protons during the illumination. In a popular selected by this method, 97% of the individual cells were demonstrably altered in ion flux properties. Cells were selected with alterations in the halobacterial rhodopsin, specifically with deficiencies in membrane potential generation by halorhodopsin and with increased cellular proton ejection by bacteriorhodopsin. We describe properties of one of the halorhodopsin-deficient strains, Flx37.Keywords
This publication has 19 references indexed in Scilit:
- Bacteriorhodopsin and Related Pigments of HalobacteriaAnnual Review of Biochemistry, 1982
- Photosensitive phosphoproteins in Halobacteria: regulatory coupling of transmembrane proton flux and protein dephosphorylation.The Journal of cell biology, 1981
- Exclusive formation of all-trans-phytoene by a colorless mutant of Halobacterium halobiumCanadian Journal of Microbiology, 1980
- Action spectrum and quantum efficiency for proton pumping in Halobacterium halobiumBiochemistry, 1980
- The steady-state counterclockwise/clockwise ratio of bacterial flagellar motors is regulated by protonmotive forceJournal of Molecular Biology, 1980
- ATP synthesis linked to light-dependent proton uptake in a red mutant strain of Halobacterium lacking bacteriorhodopsinArchives of Biochemistry and Biophysics, 1980
- A second mechanism for sodium extrusion in Halobacteriumhalobium: A light-driven sodium pumpBiochemical and Biophysical Research Communications, 1979
- Potassium Uniport and ATP Synthesis in Halobacterium halobiumEuropean Journal of Biochemistry, 1978
- Two possible roles of bacteriorhodopsin; a comparative study of strains of Halobacterium halobium differing in pigmentationBiochemical and Biophysical Research Communications, 1977
- Existence of electrogenic hydrogen ion/sodium ion antiport in Halobacterium halobium cell envelope vesiclesBiochemistry, 1976