E. Morigen,"boye et al., Regulation of chromosomal replication by DnaA protein availability in Escherichia coli: effects of the datA region, BBA-GENE ST, 1521(1-3), 2001, pp. 73-80
Citations number
43
Categorie Soggetti
Molecular Biology & Genetics
Journal title
BIOCHIMICA ET BIOPHYSICA ACTA-GENE STRUCTURE AND EXPRESSION
Initiation of chromosomal replication in Escherichia coli is dependent on a
vailability of the initiator protein DnaA. We have introduced into E coli c
ells plasmids carrying the chromosomal locus datA, which has a high affinit
y for DnaA. To be able to monitor oriC initiation as a function of datA cop
y number, we introduced a minichromosome which only replicates from oriC.,
using a host cell which replicates its chromosome independently of oriC. Ou
r data show that a moderate increase in datA copy number is accompanied by
increased DnaA protein synthesis that allows oriC initiation to occur norma
lly, as measured by minichromosome copy number. As datA gene dosage is incr
eased dnaA expression cannot be further derepressed, and the minichromosome
copy number is dramatically reduced. Under these conditions the minichromo
some was maintained by integration into the chromosome. These findings sugg
est that the datA locus plays a significant role in regulating oriC initiat
ion, by its capacity to bind DnaA. They also suggest that auto regulation o
f the dnaA gene is of minor importance in regulation of chromosome initiati
on. (C) 2001 Elsevier Science B.V. All rights reserved.