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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
Author(s) -
Simmons Lyle A.,
Kaguni Jon M.
Publication year - 2003
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2003.03333.x
Subject(s) - dnaa , biology , seqa protein domain , dna replication , mutant , ter protein , origin recognition complex , pre replication complex , amino acid , replication factor c , dna , origin of replication , escherichia coli , microbiology and biotechnology , genetics , mutation , control of chromosome duplication , gene , eukaryotic dna replication
Summary 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.