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Escherichia coli DnaA interacts with HU in initiation at the E. coli replication origin
Author(s) -
Chodavarapu Sundari,
Felczak Magdalena M.,
Yaniv Josette Rouvière,
Kaguni Jon M.
Publication year - 2008
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.1365-2958.2007.06094.x
Subject(s) - dnaa , biology , nucleoid , escherichia coli , origin of replication , plasmid , seqa protein domain , dimer , dna replication , microbiology and biotechnology , dna , minichromosome , protein subunit , gene , genetics , chemistry , chromatin , organic chemistry
Summary Escherichia coli HU protein is a dimer encoded by two closely related genes whose expression is growth phase‐dependent. As a major component of the bacterial nucleoid, HU binds to DNA non‐specifically, but acts at the chromosomal origin ( oriC ) during initiation by stimulating strand opening in vitro . We show that the α dimer of HU is more active than other forms of HU in initiation of an oriC ‐containing plasmid because it more effectively promotes strand opening of oriC . Other results demonstrate that HU stabilizes the DnaA oligomer bound to oriC , and that the α subunit of HU interacts with the N‐terminal region of DnaA. These observations support a model whereby DnaA interacts with the α dimer or the αβ heterodimer, depending on their cellular abundance, to recruit the respective form of HU to oriC . The greater activity of the α dimer of HU at oriC may stimulate initiation during early log phase compared with the lesser activity of the αβ heterodimer or the β dimer.