title: Ribokinase from Escherichia coli K12. Nucleotide sequence and overexpression of the rbsK gene and purification of ribokinase.
abstract: The nucleotide sequence of a 1455-base pair TaqI-HinfI fragment of the rbs operon of Escherichia coli K12 has been determined. It includes the 3' terminus of rbsB (the gene for ribose-binding protein) and the entire rbsK gene, encoding ribokinase. Potential consensus promoter sequences and a stable stem-loop structure are present in the rbsB-rbsK intercistronic region. The regulatory significance of these sequence features is discussed with respect to the rbs operon. rbsK has been cloned downstream from the Serratia marcescens trp promoter on a multicopy plasmid. Cells harboring this plasmid, when grown on minimal ribose plus ampicillin, express ribokinase at the level of 2% of the soluble protein, and induction with indoleacrylic acid raises ribokinase levels another 8-fold. Ribokinase has been purified to homogeneity (216 mumol/min/mg) from a strain harboring this plasmid. Protein sequence analyses of peptides generated by cyanogen bromide cleavage and o-iodosobenzoic acid cleavage confirmed the translation initiation site and the reading frame of the DNA sequence. Amino acid compositions of native ribokinase and the C-terminal dodecapeptide agree with the predicted amino acid compositions, confirming the accuracy of the DNA sequence and the translation termination site.
mesh_terms: D000595:Amino Acid Sequence; D001482:Base Composition; D001483:Base Sequence; D003001:Cloning, Molecular; D004262:DNA Restriction Enzymes; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D005796:Genes; D005798:Genes, Bacterial; D009876:Operon; D010770:Phosphotransferases / Q000235:genetics* / Q000302:isolation & purification; D017853:Phosphotransferases (Alcohol Group Acceptor); D010957:Plasmids
chemical_list: D010770:Phosphotransferases; D017853:Phosphotransferases (Alcohol Group Acceptor); C022534:ribokinase; D004262:DNA Restriction Enzymes