A single-base-pair mutation changes the specificities of both a transcription activation protein and its binding site.
The C1 protein of bacteriophage P22 binds to a unique site in the -35 region of the PRE promoter and activates transcription of the phage c2 repressor gene. This -35 target has an approximate direct repeat that overlaps the 5' end of the c1 coding region. We have isolated a single-base-pair mutation in this region that changes the PRE -35 target as well as the amino-terminal region of the C1 protein. Although the mutant C1 protein activates the mutant PRE promoter, it fails to activate the wild-type PRE promoter. This suggests that a single-base-pair mutation changes the specificities of both a protein and its target site. These studies also indicate that C1 binding to DNA is influenced by contacts made through residues near the amino terminus.
Retallack
D M
DM
Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor 48109-0620.
Johnson
L L
LL
Ziegler
S F
SF
Strauch
M A
MA
Friedman
D I
DI
D000595:Amino Acid Sequence; D017100:Bacteriophage P22 / Q000235:genetics*; D010582:Bacteriophage lambda / Q000235:genetics*; D001483:Base Sequence; D015964:Gene Expression Regulation, Bacterial; D015967:Gene Expression Regulation, Viral; D008969:Molecular Sequence Data; D017354:Point Mutation; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors / Q000235:genetics*; D014764:Viral Proteins / Q000235:genetics
D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D014764:Viral Proteins; C039000:cII protein, bacteriophage lambda