TY - JOUR

T1 - Regulation of chromosomal replication by DnaA protein availability in Escherichia coli

T2 - effects of the datA region

AU - Morigen, null

AU - Boye, Erik

AU - Skarstad, Kirsten

AU - Løbner-Olesen, Anders

PY - 2001

Y1 - 2001

N2 - Initiation of chromosomal replication in Escherichia coli is dependent on availability of the initiator protein DnaA. We have introduced into E. coli cells plasmids carrying the chromosomal locus datA, which has a high affinity for DnaA. To be able to monitor oriC initiation as a function of datA copy number, we introduced a minichromosome which only replicates from oriC, using a host cell which replicates its chromosome independently of oriC. Our data show that a moderate increase in datA copy number is accompanied by increased DnaA protein synthesis that allows oriC initiation to occur normally, as measured by minichromosome copy number. As datA gene dosage is increased dnaA expression cannot be further derepressed, and the minichromosome copy number is dramatically reduced. Under these conditions the minichromosome was maintained by integration into the chromosome. These findings suggest that the datA locus plays a significant role in regulating oriC initiation, by its capacity to bind DnaA. They also suggest that auto regulation of the dnaA gene is of minor importance in regulation of chromosome initiation.

AB - Initiation of chromosomal replication in Escherichia coli is dependent on availability of the initiator protein DnaA. We have introduced into E. coli cells plasmids carrying the chromosomal locus datA, which has a high affinity for DnaA. To be able to monitor oriC initiation as a function of datA copy number, we introduced a minichromosome which only replicates from oriC, using a host cell which replicates its chromosome independently of oriC. Our data show that a moderate increase in datA copy number is accompanied by increased DnaA protein synthesis that allows oriC initiation to occur normally, as measured by minichromosome copy number. As datA gene dosage is increased dnaA expression cannot be further derepressed, and the minichromosome copy number is dramatically reduced. Under these conditions the minichromosome was maintained by integration into the chromosome. These findings suggest that the datA locus plays a significant role in regulating oriC initiation, by its capacity to bind DnaA. They also suggest that auto regulation of the dnaA gene is of minor importance in regulation of chromosome initiation.

KW - Bacterial Proteins/chemistry

KW - Chromosomes, Bacterial/physiology

KW - DNA Replication

KW - DNA-Binding Proteins/chemistry

KW - Escherichia coli/genetics

KW - Gene Expression Regulation, Bacterial

KW - Plasmids

M3 - Journal article

C2 - 11690638

VL - 1521

SP - 73

EP - 80

JO - Biochimica et Biophysica Acta, Gene Structure and Expression

JF - Biochimica et Biophysica Acta, Gene Structure and Expression

SN - 0167-4781

IS - 1-3

ER -