title: Role of the Cro repressor carboxy-terminal domain and flexible dimer linkage in operator and nonspecific DNA binding.
abstract: A series of mutations comprising single and multiple substitutions, deletions, and extensions within the carboxy-terminal domain of the bacteriophage lambda Cro repressor have been constructed. These mutations generally affect the affinity of repressor for specific and nonspecific DNA. Additionally, substitution of the carboxy-terminal alanine with several amino acids capable of hydrogen-bonding interactions leads to improved specific binding affinities. A mutation is also described whereby cysteine links the two Cro monomers by a disulfide bond. As a consequence, a significant improvement in nonspecific binding and a concomitant reduction in specific binding are observed with this mutant. These results provide evidence that the carboxy terminus of Cro repressor is an important DNA binding domain and that a flexible connection between the two repressor monomers is a critical factor in modulating the affinity of wild-type repressor for DNA.
authors: Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309-0215.
authors: A J
authors: AJ
authors: Hubbard
authors: L P
authors: LP
authors: Bracco
authors: S J
authors: SJ
authors: Eisenbeis
authors: R B
authors: RB
authors: Gayle
authors: G
authors: G
authors: Beaton
authors: M H
authors: MH
authors: Caruthers
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D009875:Operator Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics*
chemical_list: D012097:Repressor Proteins; D004247:DNA