Regulation of the Activity of the Dual-Function DnaA Protein in Caulobacter crescentus.

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Serval ID
serval:BIB_92298CDFBFC2
Type
Article: article from journal or magazin.
Collection
Publications
Title
Regulation of the Activity of the Dual-Function DnaA Protein in Caulobacter crescentus.
Journal
PLoS One
Author(s)
Fernandez-Fernandez C., Gonzalez D., Collier J.
ISSN
1932-6203 (Electronic)
ISSN-L
1932-6203
Publication state
Published
Issued date
2011
Peer-reviewed
Oui
Volume
6
Number
10
Pages
e26028
Language
english
Abstract
DnaA is a conserved essential bacterial protein that acts as the initiator of chromosomal replication as well as a master transcriptional regulator in Caulobacter crescentus. Thus, the intracellular levels of active DnaA need to be tightly regulated during the cell cycle. Our previous work suggested that DnaA may be regulated at the level of its activity by the replisome-associated protein HdaA. Here, we describe the construction of a mutant DnaA protein [DnaA(R357A)]. The R357 residue in the AAA+ domain of the C. crescentus DnaA protein is equivalent to the R334 residue of the E. coli DnaA protein, which is required for the Regulatory Inactivation of DnaA (RIDA). We found that the expression of the DnaA(R357A) mutant protein in C. crescentus, but not the expression of the wild-type DnaA protein at similar levels, causes a severe phenotype of over-initiation of chromosomal replication and that it blocks cell division. Thus, the mutant DnaA(R357A) protein is hyper-active to promote the initiation of DNA replication, compared to the wild-type DnaA protein. DnaA(R357A) could not replace DnaA in vivo, indicating that the switch in DnaA activity once chromosomal replication has started may be an essential process in C. crescentus. We propose that the inactivation of DnaA is the main mechanism ensuring that chromosomal replication starts only once per cell cycle. We further observed that the R357A substitution in DnaA does not promote the activity of DnaA as a direct transcriptional activator of four important genes, encoding HdaA, the GcrA master cell cycle regulator, the FtsZ cell division protein and the MipZ spatial regulator of cell division. Thus, the AAA+ domain of DnaA may play a role in temporally regulating the bifunctionality of DnaA by reallocating DnaA molecules from initiating DNA replication to transcribing genes within the unique DnaA regulon of C. crescentus.
Pubmed
Web of science
Open Access
Yes
Create date
25/10/2011 10:48
Last modification date
20/08/2019 15:55
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