DasSarma, S., Kennedy, S. P., Berquist, B., Ng, W. V., Baliga, N. S., Spudich, J. L., Krebs, M. P., Eisen, J. A., Johnson, C. H., Hood, L.
Genomic Perspective on the Photobiology of Halobacterium Species NRC-1, a Phototrophic, Phototactic, and UV-tolerant Haloarchaeon
Photosynthesis Research. 2001 Jan 01; 70(1): 3-17.
Halobacterium species display a variety of responses to light, including phototrophic growth, phototactic behavior, and photoprotective mechanisms. The complete genome sequence of Halobacterium species NRC-1 (Proc Natl Acad Sci USA 97: 12176-12181, 2000), coupled with the availability of a battery of methods for its analysis makes this an ideal model system for studying photobiology among the archaea. Here, we review: (1) the structure of the 2.57 Mbp Halobacterium NRC-1 genome, including a large chromosome, two minichromosomes, and 91 transposable IS elements; (2) the purple membrane regulon, which programs the accumulation of large quantities of the light-driven proton pump, bacteriorhodopsin, and allows for a period of phototrophic growth; (3) components of the sophisticated pathways for color-sensitive phototaxis; (4) the gas vesicle gene cluster, which codes for cell buoyancy organelles; (5) pathways for the production of carotenoid pigments and retinal, (6) processes for the repair of DNA damage; and (7) putative homologs of circadian rhythm regulators. We conclude with a discussion of the power of systems biology for comprehensive understanding of Halobacterium NRC-1 photobiology.