The molecular cloning of the gene encoding the Escherichia coli 75-kDa helicase and the determination of its nucleotide sequence and gentic map position.
A previously unreported DNA unwinding enzyme, referred to as the 75-kDa helicase, was recently purified from Escherichia coli cell extracts and biochemically characterized (Wood, E. R., and Matson, S. W. (1987) J. Biol. Chem. 262, 15269-15276). In order to initiate the genetic analysis of the 75-kDa helicase, the gene encoding this enzyme was cloned. DNA sequencing confirmed the identity of the gene since the predicted amino acid sequence of the encoded polypeptide precisely matched the sequence of the first 27 NH2-terminal amino acid residues of the 75-kDa helicase as determined by peptide sequencing. The predicted amino acid sequence of the 75-kDa helicase is similar in several regions to the amino acid sequences of two other E. coli helicases, Rep protein and helicase II. The gene encoding the 75-kDa helicase was mapped to 22 min on the E. coli chromosome. We propose that this newly defined locus be referred to as helD, and, to avoid confusion with other E. coli helicases with a similar molecular size, we propose that the 75-kDa helicase be referred to as helicase IV.
Wood
E R
ER
Department of Biology, University of North Carolina, Chapel Hill 27599.
Matson
S W
SW
D000251:Adenosine Triphosphatases / Q000235:genetics*; D000595:Amino Acid Sequence; D010582:Bacteriophage lambda / Q000235:genetics; D001483:Base Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D004265:DNA Helicases; D004264:DNA Topoisomerases, Type I / Q000235:genetics*; D004268:DNA-Binding Proteins; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009693:Nucleic Acid Hybridization; D015345:Oligonucleotide Probes; D011401:Promoter Regions, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D013604:T-Phages / Q000235:genetics; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D015345:Oligonucleotide Probes; D000251:Adenosine Triphosphatases; C059716:helD protein, E coli; D004265:DNA Helicases; D004264:DNA Topoisomerases, Type I