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Open complex formation by DnaA initiation protein at the Escherichia coli chromosomal origin requires the 13‐mers precisely spaced relative to the 9‐mers
Author(s) -
Hsu Julia,
Bramhill David,
Thompson Chris M.
Publication year - 1994
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 - 10.1111/j.1365-2958.1994.tb00369.x
Subject(s) - dnaa , biology , escherichia coli , origin of replication , genetics , mutant , seqa protein domain , dna , dna binding protein , dna replication , microbiology and biotechnology , gene , transcription factor
Summary The 245 bp chromosomal origin, oriC , of Escherichia coli contains two iterated motifs. Three 13‐mers tandemly repeated at one end of the origin and four 9‐mers in a nearby segment of oriC are highly conserved in enteric bacteria, as is the distance separating these two sequence clusters. Mutant origins were constructed with altered spacing of the 9‐mers relative to the 13‐mers. Loss or addition of even a single base drastically reduced replication, both in vivo and in vitro. Spacing mutant origins bound effectively to DnaA protein but failed to support efficient open complex formation. These results suggest that interaction with the 9‐mers positions at least one subunit of DnaA to recognize directly the nearest 13‐mer for DNA melting.