Two E2F sites in the Arabidopsis MCM3 promoter have different roles in cell cycle activation and meristematic expression.
The commitment to DNA replication is a key step in cell division control. The Arabidopsis MCM3 homologue forms part of the mini chromosome maintenance (MCM) complex involved in the initiation of DNA replication at the transition G(1)/S. Consistent with its role at the G(1)/S transition we show that the AtMCM3 gene is transcriptionally regulated at S phase. The 5' region of this gene contains several E2F consensus binding sites, two of which match the human consensus closely and whose roles have been studied here. The identity of the two sequences as E2F binding sites has been confirmed by electrophoretic mobility shift assay analyses. Furthermore the promoter is activated by AtE2F-a and AtDP-a factors in transient expression studies. One of the E2F binding sites is shown to be responsible for the G(2)-specific repression of the promoter in synchronized cell suspension cultures. In contrast, the second E2F binding site has a role in meristem-specific expression in planta as deletion of this site eliminates the expression of a reporter gene in root and apical meristems. Thus two highly similar E2F binding sites in the promoter of the MCM3 gene are responsible for different cell cycle regulation or developmental expression patterns depending on the cellular environment.
Stevens
Rebecca
R
Institut de Biotechnologie des Plantes, CNRS UMR 8618, Bât 630, Université de Paris-Sud, 91405 Orsay, France. stevens@ibp.u-psud.fr
Mariconti
Luisa
L
Rossignol
Pascale
P
Perennes
Claudette
C
Cella
Rino
R
Bergounioux
Catherine
C
D017360:Arabidopsis / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins; D016193:G1 Phase; D017353:Gene Deletion; D017930:Genes, Reporter; D006801:Humans; D064126:Minichromosome Maintenance Complex Component 3; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D016196:S Phase; D013997:Time Factors; D014158:Transcription, Genetic
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C066470:MCM3 protein, human; D009687:Nuclear Proteins; D012333:RNA, Messenger; D064126:Minichromosome Maintenance Complex Component 3