Two Arabidopsis cyclin A3s possess G1 cyclin-like features.
A-type cyclins (CYCAs) are a type of mitotic cyclin and are closely related to cyclin B. Plant CYCAs are classified into three subtypes (CYCA1-CYCA3), among which CYCA3 has been suggested to show a biased expression during the G1-to-S phase. We characterised Arabidopsis CYCA3s (CYCA3;1-CYCA3;4) in terms of expression pattern and protein function. CYCA3;1 and CYCA3;2 transcripts were highly accumulated at the G1/S phase, whereas CYCA3;4 was constantly expressed during the cell cycle. Expressions of CYCA3;1 and CYCA3;2 were observed in actively dividing tissues, such as root and shoot apical meristems and lateral root primordia. Overexpression of CYCA3;1 or CYCA3;2 distorted apical dominance in Arabidopsis, indicating that they have critical functions in shoot meristems. In insect cells, CYCA3;1 formed an active kinase complex with CDKA;1, an orthologue of the yeast Cdc2/Cdc28p, and phosphorylated retinoblastoma-related protein, a key regulator in the transition from the G1 to the S phase. Our results suggest that Arabidopsis CYCA3;1 and CYCA3;2 are distinct members of the G1 cyclin family that play an important role in meristematic tissues.
Graduate School of Biological Sciences, Nara Institute of Science and Technology, Takayama 8916-5, Ikoma, Nara 630-0101, Japan.
Ikuo
I
Takahashi
Shoko
S
Kojima
Norihiro
N
Sakaguchi
Chikage
C
Umeda-Hara
Masaaki
M
Umeda
D000818:Animals; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002453:Cell Cycle; D049109:Cell Proliferation; D002478:Cells, Cultured; D016213:Cyclins / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D007313:Insecta / Q000166:cytology; D018519:Meristem / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics
D029681:Arabidopsis Proteins; D016213:Cyclins; D018749:RNA, Plant