Functional analysis of cyclin-dependent kinase inhibitors of Arabidopsis.
Cyclin-dependent kinase inhibitors, such as the mammalian p27(Kip1) protein, regulate correct cell cycle progression and the integration of developmental signals with the core cell cycle machinery. These inhibitors have been described in plants, but their function remains unresolved. We have isolated seven genes from Arabidopsis that encode proteins with distant sequence homology with p27(Kip1), designated Kip-related proteins (KRPs). The KRPs were characterized by their domain organization and transcript profiles. With the exception of KRP5, all presented the same cyclin-dependent kinase binding specificity. When overproduced, KRP2 dramatically inhibited cell cycle progression in leaf primordia cells without affecting the temporal pattern of cell division and differentiation. Mature transgenic leaves were serrated and consisted of enlarged cells. Although the ploidy levels in young leaves were unaffected, endoreduplication was suppressed in older leaves. We conclude that KRP2 exerts a plant growth inhibitory activity by reducing cell proliferation in leaves, but, in contrast to its mammalian counterparts, it may not control the timing of cell cycle exit and differentiation.
De Veylder
L
L
Vakgroep Moleculaire Genetica, Departement Plantengenetica, Vlaams Interuniversitair Instituut voor Biotechnologie, Universiteit Gent, K.L. Ledeganckstraat 35, B-9000 Gent, Belgium.
Beeckman
T
T
Beemster
G T
GT
Krols
L
L
Terras
F
F
Landrieu
I
I
van der Schueren
E
E
Maes
S
S
Naudts
M
M
Inzé
D
D
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins; D002135:Calcium-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism*; D003001:Cloning, Molecular; D050760:Cyclin-Dependent Kinase Inhibitor p27; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D016547:Kinesins; D008938:Mitosis; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D010641:Phenotype; D018515:Plant Leaves / Q000166:cytology / Q000502:physiology; D030821:Plants, Genetically Modified; D017385:Sequence Homology; D025521:Tumor Suppressor Proteins
D029681:Arabidopsis Proteins; D002135:Calcium-Binding Proteins; D018797:Cell Cycle Proteins; D004791:Enzyme Inhibitors; D009124:Muscle Proteins; D025521:Tumor Suppressor Proteins; C074152:kinesin-II; D050760:Cyclin-Dependent Kinase Inhibitor p27; C434472:CDKA1 protein, Arabidopsis; D018844:Cyclin-Dependent Kinases; D016547:Kinesins