The Escherichia coli melR gene encodes a DNA-binding protein with affinity for specific sequences located in the melibiose-operon regulatory region.
Crude extracts, made from Escherichia coli cells carrying a plasmid in which the melR gene was expressed from the galP2 promoter, were used as a source of MelR protein. Using DNase I footprinting and gel retardation assays, we show that MelR binds to two sites located from nucleotides (nt) -49 to -75 and -85 to -113, upstream from the melAB transcription start point. The two sites contain identical 18-bp sequences. Specific binding is unaltered by deletions that remove 1 or 6 amino acids (aa) from the C terminus of MelR, but is abolished by deletion of 16, 24 or more aa residues. Sequence homologies between MelR and other DNA-binding proteins are discussed.
Webster
C
C
School of Biochemistry, University of Birmingham, U.K.
Gardner
L
L
Busby
S
S
D000595:Amino Acid Sequence; D001483:Base Sequence; D002872:Chromosome Deletion; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000235:genetics*; D004187:Disaccharides; D004926:Escherichia coli / Q000235:genetics*; D005798:Genes, Bacterial; D005809:Genes, Regulator; D008553:Melibiose / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D009710:Nucleotide Mapping; D009876:Operon; D010957:Plasmids; D011401:Promoter Regions, Genetic; D015183:Restriction Mapping
D004268:DNA-Binding Proteins; D004187:Disaccharides; D008553:Melibiose