Caulobacter crescentus (CB15) initiates chromosome replication only in stalked cells and not in swarmers. To better understand this dimorphic control of chromosome replication, we isolated replication origins (oris) from freshwater Caulobacter (FWC) and marine Caulobacter (MCS) species. Previous studies implicated integration host factor (IHF) and CcrM DNA methylation sites in replication control. However, ori IHF and CcrM sites identified in the model FWC CB15 were only conserved among closely related FWCs. DnaA boxes and CtrA binding sites are established CB15 ori components. CtrA is a two-component regulator that blocks chromosome replication selectively in CB15 swarmers. DnaA boxes and CtrA sites were found in five FWC and three MCS oris. Usually, a DnaA box and a CtrA site were paired, suggesting that CtrA binding regulates DnaA activity. We tested this hypothesis by site-directed mutagenesis of an MCS10 ori which contains only one CtrA binding site overlapping a critical DnaA box. This overlapping site is unique in the whole MCS10 genome. Selective DnaA box mutations decreased replication, while selective CtrA binding site mutations increased replication of MCS10 ori plasmids. Therefore, both FWC and MCS oris use CtrA to repress replication. Despite this similarity, phylogenetic analysis unexpectedly shows that CtrA usage evolved separately among these Caulobacter oris. We discuss consensus oris and convergent ori evolution in differentiating bacteria.
AbrahamW. R.,
StromplC.,
MeyerH.,
LindholstS.,
MooreE. R.,
ChristR.,
VancanneytM.,
TindallB. J.,
BennasarA.other authors1999; Phylogeny and polyphasic taxonomy of Caulobacter species. Proposal of Maricaulis gen. nov. with Maricaulis maris (Poindexter) comb. nov. as the type species, and emended description of the genera Brevundimonas and Caulobacter . Int J Syst Bacteriol 49:1053–1073
BellefontaineA.-F.,
PierreuxC. E.,
MertensP.,
VandenhauteJ.,
LetessonJ.-J.,
De BolleX.2002; Plasticity of a transcriptional regulatory network among alpha-proteobacteria is supported by the identification of CtrA targets in Brucella abortus . Mol Microbiol 43:945–960
BrassingaA. K. C.,
SiamR.,
MarczynskiG. T.2001; Conserved gene cluster at replication origins of the alpha-proteobacteria Caulobacter crescentus and Rickettsia prowazekii . J Bacteriol 183:1824–1829
Castilla-LlorenteV.,
Munoz-EspinD.,
VillarL.,
SalasM.,
MeijerW. J.2006; Spo0A, the key transcriptional regulator for entrance into sporulation, is an inhibitor of DNA replication. EMBO J 25:3890–3899
DittaG.,
StanfieldS.,
CorbinD.,
HelinskiD. R.1980; Broad host range DNA cloning system for Gram-negative bacteria. Proc Natl Acad Sci U S A 77:7347–7351
DomianI. J.,
QuonK. C.,
ShapiroL.1997; Cell type-specific phosphorylation and proteolysis of a transcriptional regulator controls the G1 to S transition in a bacterial cell cycle. Cell 90:415–424
FullerR. S.,
FunnellB. E.,
KornbergA.1984; The DnaA protein complex with the E. coli chromosomal replication origin ( oriC ) and other DNA sites. Cell 38:889–900
LaubM. T.,
ChenS. L.,
ShapiroL.,
McAdamsH. H.2002; Genes directly controlled by CtrA, a master regulator of the Caulobacter cell cycle. Proc Natl Acad Sci U S A 99:4632–4637
MuirR. E.,
GoberJ. W.2005; Role of integration host factor in the transcriptional activation of flagellar gene expression in Caulobacter crescentus . J Bacteriol 187:949–960
NiermanW. C.,
FeldblyumT. V.,
LaubM. T.,
PaulsenI. T.,
NelsonK. E.,
EisenJ.,
HeidelbergJ. F.,
AlleyM. R. K.,
OhtaN.other authors2001; Complete genome sequence of Caulobacter crescentus . Proc Natl Acad Sci U S A 98:4136–4141
OgasawaraN.,
MoriyaS.,
YoshikawaH.1991; Initiation of chromosome replication: structure and function of oriC and DnaA protein in eubacteria. Res Microbiol 142:851–859
QuonK. C.,
YangB.,
DomianI. J.,
ShapiroL.,
MarczynskiG. T.1998; Negative control of bacterial DNA replication by a cell cycle regulatory protein that binds at the chromosome origin. Proc Natl Acad Sci U S A 95:120–125
SiamR.,
BrassingaA. K.,
MarczynskiG. T.2003; A dual binding site for integration host factor and the response regulator CtrA inside the Caulobacter crescentus replication origin. J Bacteriol 185:5563–5572
SmithD. W.,
GarlandA. M.,
HermanG.,
EnnsR. E.,
BakerT. A.,
ZyskindJ. W.1985; Importance of state of methylation of oriC GATC sites in initiation of DNA replication in Escherichia coli . EMBO J 4:1319–1326
StephensC. M.,
ZweigerG.,
ShapiroL.1995; Coordinate cell cycle control of a Caulobacter DNA methyltransferase and the flagellar genetic hierarchy. J Bacteriol 177:1662–1669
StephensC. M.,
ReisenauerA.,
WrightR.,
ShapiroL.1996; A cell cycle-regulated bacterial DNA methyltransferase is essential for viability. Proc Natl Acad Sci U S A 93:1210–1214
WrightR.,
StephensC.,
ShapiroL.1997; The CcrM DNA methyltransferase is widespread in the alpha subdivision of proteobacteria, and its essential functions are conserved in Rhizobium meliloti and Caulobacter crescentus . J Bacteriol 179:5869–5877
WuJ.,
OhtaN.,
NewtonA.1998; An essential, multicomponent signal transduction pathway required for cell cycle regulation in Caulobacter . Proc Natl Acad Sci U S A 95:1443–1448
Zakrzewska-CzerwinskaJ.,
JakimowiczD.,
Zawilak-PawlikA.,
MesserW.2007; Regulation of the initiation of chromosomal replication in bacteria. FEMS Microbiol Rev 31:378–387
ZyskindJ. W.,
ClearyJ. M.,
BrusilowW. S. A.,
HardingN. E.,
SmithD. W.1983; Chromosome replication origin from the marine bacterium Vibrio harveyi functions in Escherichia coli : oriC consensus sequence. Proc Natl Acad Sci U S A 80:1164–1168