共 51 条
THE TDH AND SERA OPERONS OF ESCHERICHIA-COLI - MUTATIONAL ANALYSIS OF THE REGULATORY ELEMENTS OF LEUCINE-RESPONSIVE GENES
被引:58
作者:
REX, JH
[1
]
ARONSON, BD
[1
]
SOMERVILLE, RL
[1
]
机构:
[1] PURDUE UNIV,DEPT BIOCHEM,W LAFAYETTE,IN 47907
关键词:
D O I:
10.1128/jb.173.19.5944-5953.1991
中图分类号:
Q93 [微生物学];
学科分类号:
071005 ;
100705 ;
摘要:
The tdh promoter of Escherichia coli is induced seven- to eightfold when cells are grown in the presence of exogenous leucine. A scheme was devised to select mutants that exhibited high constitutive expression of the tdh promoter. The mutations in these strains were shown to lie within a previously identified gene (lrp) that encodes Lrp (leucine-responsive regulatory protein). By deletion analysis, the site of action of Lrp was localized to a 25-bp region between coordinates -69 and -44 of the tdh promoter. Disruption of a 12-bp presumptive target sequence found in this region of tdh resulted in constitutively derepressed expression from the tdh promoter. Similar DNA segments (consensus, TTTATTCtNaAT) were also identified in a number of other promoters, including each of the Lrp-regulated promoters whose nucleotide sequence is known. The sequence of the promoter region of serA, an Lrp-regulated gene, was determined. No Lrp consensus target sequence was present upstream of serA, suggesting that Lrp acts indirectly on the serA promoter. A previously described mutation in a leucine-responsive trans-acting factor, LivR (J. J. Anderson, S. C. Quay, and D. L. Oxender, J. Bacteriol. 126:80-90, 1976), resulted in constitutively repressed expression from the tdh promoter and constitutively induced expression from the serA promoter. The possibility that LivR and Lrp are allelic is discussed.
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页码:5944 / 5953
页数:10
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