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REGULATION OF THE SALMONELLA-TYPHIMURIUM-METF GENE BY THE METR PROTEIN
被引:39
作者:
COWAN, JM
[1
]
URBANOWSKI, ML
[1
]
TALMI, M
[1
]
STAUFFER, GV
[1
]
机构:
[1] UNIV IOWA, DEPT MICROBIOL, IOWA CITY, IA 52242 USA
关键词:
D O I:
10.1128/JB.175.18.5862-5866.1993
中图分类号:
Q93 [微生物学];
学科分类号:
071005 ;
100705 ;
摘要:
The metF gene in Escherichia coli and Salmonella typhimurium is under negative transcriptional control by the MetJ repressor. Expression of an S. typhimurium metF-lacZ gene fusion is repressed up to 10-fold by methionine addition to the growth medium in E. coli hosts encoding wild-type MetJ repressor; this repression is not seen in metJ mutants. metR mutations which eliminate the MetR activator protein result in two- to threefold-more-severe repression by the MetJ repressor. In a metJ metR double mutant, however, the level of metF-lacZ expression is the same as in a metJ mutant, suggesting that MetR antagonizes MetJ-mediated methionine repression of the metF promoter. A DNA footprint analysis showed that MetR binds to a DNA fragment carrying the metF promoter and protects two separate regions from DNase I digestion: a 46-bp region from position -50 to -95 upstream of the transcription initiation site and a 24-bp region from about position +62 to +85 downstream of the transcription initiation site and within the metF structural gene. Nucleotide changes in each of the MetR-binding sites away from the consensus sequence disrupt MetR-mediated regulation of the metF-lacZ fusion.
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页码:5862 / 5866
页数:5
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