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Quality and position of the three lac operators of E. coli define efficiency of repression.
Author(s) -
Oehler S.,
Amouyal M.,
Kolkhof P.,
WilckenBergmann B.,
MüllerHill B.
Publication year - 1994
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1994.tb06637.x
Subject(s) - psychological repression , lac operon , lac repressor , biology , repressor , operon , cooperativity , rna polymerase , operator (biology) , escherichia coli , enzyme repression , beta galactosidase , dna , genetics , microbiology and biotechnology , gene , gene expression
Repression of the lac promoter may be achieved in two different ways: either by interference with the action of RNA polymerase or by interference with CAP activation. We investigated cooperative repression of the Escherichia coli lac operon by systematic conversion of its three natural operators (O1, O2 and O3) on the chromosome. We find that cooperative repression by tetrameric Lac repressor increases with both quality and proximity of the interacting operators. A short distance of 92 bp allows effective repression by two very weak operators (O3, O3). The cooperativity of lac operators is discussed in terms of a local increase of repressor concentration. This increase in concentration depends on flexible DNA which allows loop formation.