title: DNA binding of the cell cycle transcriptional regulator GcrA depends on N6-adenosine methylation in Caulobacter crescentus and other Alphaproteobacteria.
abstract: Several regulators are involved in the control of cell cycle progression in the bacterial model system Caulobacter crescentus, which divides asymmetrically into a vegetative G1-phase (swarmer) cell and a replicative S-phase (stalked) cell. Here we report a novel functional interaction between the enigmatic cell cycle regulator GcrA and the N6-adenosine methyltransferase CcrM, both highly conserved proteins among Alphaproteobacteria, that are activated early and at the end of S-phase, respectively. As no direct biochemical and regulatory relationship between GcrA and CcrM were known, we used a combination of ChIP (chromatin-immunoprecipitation), biochemical and biophysical experimentation, and genetics to show that GcrA is a dimeric DNA-binding protein that preferentially targets promoters harbouring CcrM methylation sites. After tracing CcrM-dependent N6-methyl-adenosine promoter marks at a genome-wide scale, we show that these marks recruit GcrA in vitro and in vivo. Moreover, we found that, in the presence of a methylated target, GcrA recruits the RNA polymerase to the promoter, consistent with its role in transcriptional activation. Since methylation-dependent DNA binding is also observed with GcrA orthologs from other Alphaproteobacteria, we conclude that GcrA is the founding member of a new and conserved class of transcriptional regulators that function as molecular effectors of a methylation-dependent (non-heritable) epigenetic switch that regulates gene expression during the cell cycle.
authors.affiliation: Interdisciplinary Research Institute USR3078, CNRS-Université Lille Nord de France, Villeneuve d'Ascq, France.
authors.forename: Antonella
authors.initials: A
authors.lastname: Fioravanti
authors.forename: Coralie
authors.initials: C
authors.lastname: Fumeaux
authors.forename: Saswat S
authors.initials: SS
authors.lastname: Mohapatra
authors.forename: Coralie
authors.initials: C
authors.lastname: Bompard
authors.forename: Matteo
authors.initials: M
authors.lastname: Brilli
authors.forename: Antonio
authors.initials: A
authors.lastname: Frandi
authors.forename: Vincent
authors.initials: V
authors.lastname: Castric
authors.forename: Vincent
authors.initials: V
authors.lastname: Villeret
authors.forename: Patrick H
authors.initials: PH
authors.lastname: Viollier
authors.forename: Emanuele G
authors.initials: EG
authors.lastname: Biondi
mesh_terms: D000241:Adenosine / Q000235:genetics; D020561:Alphaproteobacteria / Q000254:growth & development; D000595:Amino Acid Sequence; D016935:Caulobacter crescentus / Q000235:genetics* / Q000254:growth & development; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D019175:DNA Methylation / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics; D044127:Epigenesis, Genetic; D015964:Gene Expression Regulation, Bacterial; D008780:Methyltransferases / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D014158:Transcription, Genetic
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D008780:Methyltransferases; D000241:Adenosine