Genomic perspective on the photobiology of Halobacterium species NRC-1, a phototrophic, phototactic, and UV-tolerant haloarchaeon.
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.
Dassarma
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Center of Marine Biotechnology, University of Maryland Biotechnology Institute, Baltimore, MD, 21202, USA, dassarma@umbi.umd.edu.
Kennedy
S P
SP
Berquist
B
B
Victor Ng
W
W
Baliga
N S
NS
Spudich
J L
JL
Krebs
M P
MP
Eisen
J A
JA
Johnson
C H
CH
Hood
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L