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lac repressor mutants with double or triple exchanges in the recognition helix bind specifically to lac operator variants with multiple exchanges.
Author(s) -
Sartorius J.,
Lehming N.,
Kisters B.,
WilckenBergmann B.,
MüllerHill B.
Publication year - 1989
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.1460-2075.1989.tb03500.x
Subject(s) - biology , genetics , combinatorics , mathematics
Several lac repressor mutants have been isolated which repress beta‐galactosidase synthesis in Escherichia coli up to 200‐fold. They do so by binding specifically to particular symmetrical lac Oc operator variants. The mutations in the lac repressor are localized in two separate parts of the recognition helix comprising (i) residues 1 and 2 which interact with base pairs 4 and 5 of lac operator and (ii) residue 6 which recognizes operator base pair 6. Mutations of residues 1 and 2 may be combined with a mutation of residue 6. The resulting mutant protein binds specifically to an operator variant with three symmetric exchanges in base pairs 4, 5 and 6.