Alteration by site-directed mutagenesis of the conserved lysine residue in the consensus ATP-binding sequence of the RecB protein of Escherichia coli.
The RecB and RecD subunits of the RecBCD enzyme of Escherichia coli contain amino acid sequences similar to a consensus mononucleotide binding motif found in a large number of other enzymes. We have constructed by site-directed mutagenesis a lysine-to-glutamine mutation in this sequence in the RecB protein. The mutant enzyme (RecB-K29Q-CD) has essentially no nuclease or ATP hydrolysis activity on double-stranded DNA, showing the importance of RecB for unwinding double-stranded DNA. However, ATP hydrolysis stimulated by single-stranded DNA is reduced by only about 5-8-fold compared to the wild-type, nuclease activity on single-stranded DNA is reduced by less than 2-fold, and the nuclease activity of the RecB-K29Q-CD enzyme requires ATP. The effects of the RecB mutation suggest that the RecD protein hydrolyzes ATP and can stimulate the RecBCD enzyme nuclease activity on single-stranded DNA.
Hsieh
S
S
Department of Chemistry and Biochemistry, University of Maryland, College Park 20742.
Julin
D A
DA
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000595:Amino Acid Sequence; D001483:Base Sequence; D016384:Consensus Sequence; D017124:Conserved Sequence; D004269:DNA, Bacterial; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins; D043211:Exodeoxyribonuclease V; D005090:Exodeoxyribonucleases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006868:Hydrolysis; D007700:Kinetics; D008239:Lysine / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed
D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D000255:Adenosine Triphosphate; D005090:Exodeoxyribonucleases; D043211:Exodeoxyribonuclease V; C468322:exodeoxyribonuclease V, E coli; D000251:Adenosine Triphosphatases; D008239:Lysine