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Title
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Genome sequence of Haloarcula marismortui: a halophilic archaeon from the Dead Sea.
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Authors
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N.S.Baliga,
R.Bonneau,
M.T.Facciotti,
M.Pan,
G.Glusman,
E.W.Deutsch,
P.Shannon,
Y.Chiu,
R.S.Weng,
R.R.Gan,
P.Hung,
S.V.Date,
E.Marcotte,
L.Hood,
W.V.Ng.
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Ref.
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Genome Res, 2004,
14,
2221-2234.
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PubMed id
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Abstract
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We report the complete sequence of the 4,274,642-bp genome of Haloarcula
marismortui, a halophilic archaeal isolate from the Dead Sea. The genome is
organized into nine circular replicons of varying G+C compositions ranging from
54% to 62%. Comparison of the genome architectures of Halobacterium sp. NRC-1
and H. marismortui suggests a common ancestor for the two organisms and a genome
of significantly reduced size in the former. Both of these halophilic archaea
use the same strategy of high surface negative charge of folded proteins as
means to circumvent the salting-out phenomenon in a hypersaline cytoplasm. A
multitiered annotation approach, including primary sequence similarities,
protein family signatures, structure prediction, and a protein function
association network, has assigned putative functions for at least 58% of the
4242 predicted proteins, a far larger number than is usually achieved in most
newly sequenced microorganisms. Among these assigned functions were genes
encoding six opsins, 19 MCP and/or HAMP domain signal transducers, and an
unusually large number of environmental response regulators-nearly five times as
many as those encoded in Halobacterium sp. NRC-1--suggesting H. marismortui is
significantly more physiologically capable of exploiting diverse environments.
In comparing the physiologies of the two halophilic archaea, in addition to the
expected extensive similarity, we discovered several differences in their
metabolic strategies and physiological responses such as distinct pathways for
arginine breakdown in each halophile. Finally, as expected from the larger
genome, H. marismortui encodes many more functions and seems to have fewer
nutritional requirements for survival than does Halobacterium sp. NRC-1.
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