Abstract
A method for isolating phototaxis-deficient (Pho-) mutants of Halobacterium halobium was developed. The procedure makes use of a flashing repellent light to induce frequent reversals of swimming direction by responsive cells, thereby impeding their migration along a small capillary and resulting in a spatial separation of the parent population and a population enriched for Pho- cells. Two classes of Pho- mutants were obtained by this selection scheme: those which have lost the chemotactic response (Che-) as well as phototaxis sensitivity (general taxis mutants), and those which are defective in steps specific to phototaxis (photosignaling mutants). In the latter class, several retinal synthesis mutants were isolated, as well as a strain which fit the expected properties of a mutant lacking a functional photoreceptor protein. On the basis of spectroscopic and swimming behavior studies, the retinal-containing protein, slow-cycling or sensory rhodopsin (SR), was previously proposed to be a dual-function sensory receptor mediating both attractant and repellent photosensing. The receptor mutant Pho81 fulfills two predictions which provide direct genetic evidence for this proposal. The mutant has lost SR photoactivity as determined by spectroscopic measurements, and it has simultaneously lost both attractant and repellent phototaxis sensitivity. Comparison of [3H]retinal-labeled membrane proteins from the mutant and its SR-containing parent implicated a 25,000 Mr polypeptide as the chromophoric polypeptide of SR.
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- Adler J. Chemotaxis in bacteria. Science. 1966 Aug 12;153(3737):708–716. doi: 10.1126/science.153.3737.708. [DOI] [PubMed] [Google Scholar]
- Alam M., Oesterhelt D. Morphology, function and isolation of halobacterial flagella. J Mol Biol. 1984 Jul 15;176(4):459–475. doi: 10.1016/0022-2836(84)90172-4. [DOI] [PubMed] [Google Scholar]
- Bogomolni R. A., Spudich J. L. Identification of a third rhodopsin-like pigment in phototactic Halobacterium halobium. Proc Natl Acad Sci U S A. 1982 Oct;79(20):6250–6254. doi: 10.1073/pnas.79.20.6250. [DOI] [PMC free article] [PubMed] [Google Scholar]
- CLAYTON R. K. On the interplay of environmental factors affecting taxis and motility in Rhodospirillum rubrum. Arch Mikrobiol. 1958;29(2):189–212. doi: 10.1007/BF00409860. [DOI] [PubMed] [Google Scholar]
- Ehrlich B. E., Schen C. R., Spudich J. L. Bacterial rhodopsins monitored with fluorescent dyes in vesicles and in vivo. J Membr Biol. 1984;82(1):89–94. doi: 10.1007/BF01870735. [DOI] [PubMed] [Google Scholar]
- Hildebrand E. What does Halobacterium tell us about photoreception? Biophys Struct Mech. 1977 Apr 21;3(1):69–77. doi: 10.1007/BF00536457. [DOI] [PubMed] [Google Scholar]
- Macnab R. M., Koshland D. E., Jr The gradient-sensing mechanism in bacterial chemotaxis. Proc Natl Acad Sci U S A. 1972 Sep;69(9):2509–2512. doi: 10.1073/pnas.69.9.2509. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Spudich E. N., Bogomolni R. A., Spudich J. L. Genetic and biochemical resolution of the chromophoric polypeptide of halorhodopsin. Biochem Biophys Res Commun. 1983 Apr 15;112(1):332–338. doi: 10.1016/0006-291x(83)91835-1. [DOI] [PubMed] [Google Scholar]
- Spudich E. N., Spudich J. L. Biochemical characterization of halorhodopsin in native membranes. J Biol Chem. 1985 Jan 25;260(2):1208–1212. [PubMed] [Google Scholar]
- Spudich E. N., Spudich J. L. Control of transmembrane ion fluxes to select halorhodopsin-deficient and other energy-transduction mutants of Halobacterium halobium. Proc Natl Acad Sci U S A. 1982 Jul;79(14):4308–4312. doi: 10.1073/pnas.79.14.4308. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Spudich J. L., Bogomolni R. A. Mechanism of colour discrimination by a bacterial sensory rhodopsin. Nature. 1984 Dec 6;312(5994):509–513. doi: 10.1038/312509a0. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Spudich J. L., Bogomolni R. A. Spectroscopic discrimination of the three rhodopsinlike pigments in Halobacterium halobium membranes. Biophys J. 1983 Aug;43(2):243–246. doi: 10.1016/S0006-3495(83)84345-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Spudich J. L. Genetic demonstration of a sensory rhodopsin in bacteria. Prog Clin Biol Res. 1984;164:221–229. [PubMed] [Google Scholar]

