The DnaAcos allele of Escherichia coli: hyperactive initiation is caused by substitution of A184V and Y271H, resulting in defective ATP binding and aberrant DNA replication control.
Chromosomal DNA replication is regulated at the level of commitment to this biochemical pathway. In Escherichia coli, DnaA protein appears to regulate this process. A mutant form, DnaAcos, carrying four amino acid substitutions, is apparently defective in responding to regulatory signals, because it induces hyperactive initiation from the bacterial replication origin (oriC). In this report, the phenotype of hyperactive initiation is shown to be the result of two specific amino acid substitutions. One (A184V) immediately adjacent to a Walker A box (P loop motif) causes a defect in ATP binding (Carr and Kaguni, 1996, Mol Microbiol 20: 1307-1318). The second amino acid substitution (Y271H) appears to stabilize the activity of the mutant protein carrying the A184V substitution. The mutant protein carrying both amino acid substitutions (A184V + Y271H) is defective in modulating the frequency of initiation from oriC, as demonstrated by marker frequency analysis of oriC and a locus near the replication terminus. These results indicate that a defect in ATP binding results in aberrant control of DNA replication.
Simmons
Lyle A
LA
Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-1319, USA.
Kaguni
Jon M
JM
D000255:Adenosine Triphosphate / Q000378:metabolism; D000483:Alleles; D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D051738:Origin Recognition Complex; D016133:Polymerase Chain Reaction; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C066312:DnaA protein, Bacteria; C114650:OriC chromosomal replication origin; D051738:Origin Recognition Complex; D014764:Viral Proteins; D000255:Adenosine Triphosphate