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First published online June 5, 2003; 10.1104/pp.103.020644 Plant Physiology 132:1315-1321 (2003) © 2003 American Society of Plant Biologists Arabidopsis D-Type Cyclin CYCD4;1 Is a Novel Cyclin Partner of B2-Type Cyclin-Dependent Kinase1Institute of Molecular and Cellular Biosciences, The University of Tokyo, Yayoi 1–1–1, Bunkyo-ku, Tokyo 113–0032, Japan (A.K., C.U.-H., J.L., H.U., M.U.); Laboratory of Plant Molecular Genetics, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1–1–1, Bunkyo-ku, Tokyo 113–8657, Japan (J.L.); and Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Hongo 7–3–1, Bunkyo-ku, Tokyo 113–0033, Japan (M.I.)
B-type cyclin-dependent kinases (CDKs) are unique to plants and are assumed to be involved in the control of the G2-to-M phase progression and mitotic events. However, little is known about their cyclin partners. In Arabidopsis, we isolated cDNA encoding the D-type cyclin CYCD4;1 by a yeast (Saccharomyces cerevisiae) two-hybrid screening using CDKB2;1 as bait. In vitro pull-down assay showed that CYCD4;1 bound to CDKB2;1 and CDKA;1. Protein complexes of CYCD4;1-CDKA;1 and CYCD4;1-CDKB2;1 in insect cells exhibited histone H1-kinase activity. Promoter analysis using the luciferase reporter gene showed that CDKB2;1 was expressed from early G2 to M phase, whereas CYCD4;1 was expressed throughout the cell cycle. In situ hybridization of plant tissues revealed that both CDKB2;1 and CYCD4;1 transcripts accumulated in the shoot apical meristem, leaf primordia, vasculature of leaves, and tapetal cells in anthers. Our results suggest that CDKB2;1 and CYCD4;1 may form an active kinase complex during G2/M phase and control the development of particular tissues.
Progression through the eukaryotic cell cycle is controlled by a family of cyclin-dependent kinases (CDKs). The kinase activity of CDKs is dependent on binding to cyclins. As in animals, plants have several types of CDKs and cyclins; thus, distinct CDK-cyclin complexes are involved in transition between different phases of the cell cycle (for review, see Mészáros et al., 2000  ; Stals and Inzé,
2001; Criqui and Genschik,
2002; Oakenfull et al.,
2002).
Key checkpoints are assumed to operate at the G1/S and G2/M transitions. In
animal cells, progression from G1 to S phase is mediated by complexes of CDK4
or CDK6 and D-type cyclins, which are induced by growth factors at the mRNA
level. These complexes phosphorylate and inactivate the retinoblastoma protein
(RB), and then active E2F transcription factors are released from binding with
Rb to induce transcription of genes involved in S phase progression (for
review, see Harbour and Dean,
2000
Entry into mitosis is triggered by CDK1 (Cdc2) in animal cells, whereas two
different types of CDKs, A-type CDK (CDKA) and B-type CDK (CDKB), are assumed
to play a role in mitotic entry and progression in plants (for review, see
Stals and Inzé, 2001 Here, we show that Arabidopsis B2-type CDK CDKB2;1 can interact with CYCD1;1 and CYCD4;1 in vitro, and the CDKB2;1-CYCD4;1 complex purified from insect cells has a histone H1 kinase activity. Analysis of promoter activities of CDKB2;1 and CYCD4;1 demonstrated that CDKB2;1 is expressed from early G2 to M phase, whereas CYCD4;1 is expressed throughout the cell cycle. The results of in situ hybridization revealed that CDKB2;1 and CYCD4;1 are transcribed in tissues overlapping each other, suggesting that CDKB2;1 and CYCD4;1 may form an active kinase complex to control G2/M phase transition and mitotic events.
Identification of CYCD4;1 as an Interacting Protein with CDKB2;1 in Yeast Cells
To identify proteins that interact with CDKB2;1 in Arabidopsis, we carried
out a yeast two-hybrid screening. The full-length coding region of the
CDKB2;1 cDNA was fused in-frame with the GAL4 DNA-binding domain and
used as bait. Screening was performed with an Arabidopsis cDNA library derived
from mRNA of suspension cultured cells. About 2.1 x 105
clones were screened on a medium lacking His, and, finally, 98 clones turned
out to be His+ and LacZ+. Among them, 81 clones encoded
a homolog of yeast p13Suc1, named Csk1At
(De Veylder et al., 1997
Arabidopsis encodes mainly four classes of D-type cyclins (CYCD1–4)
on the genome (Vandepoele et al.,
2002
Next, we determined the type of CDK that interacts with CYCD1;1 or CYCD4;1 in the pull-down assay. For this purpose, CDKA;1, CDKB1;1, and CDKB2;1 were fused to GST and immobilized on the beads. As shown in Figure 3, CYCD1;1 was retained on any of the CDKs to almost the same extent, whereas CYCD4;1 tightly bound to CDKA;1 and CDKB2;1 but very weakly to CDKB1;1. These results indicate that CYCD4;1 can be a partner of CDKB2;1 and CDKA;1 in vitro.
In the next step, we determined whether activation of CDKA;1 or CDKB2;1 was dependent on interaction with CYCD4;1. CDKA;1 or CDKB2;1 fused to 6x His tag and/or CYCD4;1 fused to FLAG tag were expressed in insect cells via a baculovirus-mediated system. Immunoblotting showed that each protein was properly produced with expected molecular size (Fig. 4). To test whether CDKA;1 or CDKB2;1 makes protein complexes with CYCD4;1, protein extract was immunoprecipitated with anti-CDKA;1 or anti-CDKB2;1 antibody and assayed by western blotting. As shown in Figure 4, His-CDKA;1 or His-CDKB2;1 was equally immunoprecipitated with the antibody, and FLAG-CYCD4;1 was included in the immunoprecipitates in the case of co-expression. These results indicate that His-CDKA;1 or His-CDKB2;1 formed a complex with FLAG-CYCD4;1 in insect cells.
The same immunoprecipitates were subjected to kinase assay using histone H1 as a substrate. Almost no phosphorylation was detected with extracts from either CDK- or cyclin-expressing cells, whereas an intense band of phosphorylation was noted with immunoprecipitates containing His-CDKA;1 or His-CDKB2;1 and FLAG-CYCD4:1 (Fig. 4). These results indicate that His-CDKA;1 or His-CDKB2;1 was activated by making a complex with FLAG-CYCD4;1 in insect cells.
It has been reported that CDKA;1 is expressed throughout the cell
cycle (Hemerly et al., 1993 First, we determined the transcription start site of CDKB2;1 and CYCD4;1 genes by 5'-RACE method. Nucleotide sequences of amplified fragments showed that the transcripts of CDKB2;1 and CYCD4;1 start from the adenine nucleotides 89 and 129 bp upstream of the start codon, respectively. Therefore, an Arabidopsis genomic DNA containing the promoter region of CDKB2;1 (0.9 kb) or CYCD4;1 (2.5 kb) was fused to the luciferase reporter gene (LUC), and the promoter-LUC constructs were introduced into BY-2 cells by Agrobacterium tumefaciens-mediated transformation. Stably transformed cell lines were treated with aphidicolin to arrest cells at the early S phase, and the LUC activity was measured after removal of aphidicolin. The mitotic index showed a peak 7 to 8 h after aphidicolin removal in transgenic BY-2 cells (Fig. 5). The LUC activity driven by the CDKB2;1 promoter increased from 2 to 3 h, and a marked increase was observed at 7 to 8 h (Fig. 5A), suggesting that the transcripts of CDKB2;1 accumulated from early G2 to M phase. In the case of CYCD4;1 promoter, a low but significant level of LUC activity was observed throughout the cell cycle, and it showed a slight peak from G1 to S phase, namely 0 to 1 h and 9 to 12 h after aphidicolin removal (Fig. 5B). These results indicate that the dynamics of expression of CDKB2;1 and CYCD4;1 overlap each other, suggesting that they form an active kinase complex and function during G2 to M phase.
To study the spatial expression patterns of CDKB2;1 and
CYCD4;1, we performed in situ hybridizations using probes specific
for transcripts of CDKB2;1 and CYCD4;1. RNA probes were
prepared from cDNAs and labeled with digoxygenin. By using an antisense probe
of CDKB2;1, a patchy pattern of hybridization signals was observed in
the vegetative shoot apical meristem and young leaf primordia
(Fig. 6A). It is likely that
the patchy pattern reflects the G2/M phase-specific expression of
CDKB2;1 as described above. The signal was also seen in the middle of
growing leaves and tended to correlate with the provascular strands
(Fig. 6A). Hybridization of
transverse leaf sections with the same probe confirmed CDKB2;1 expression in
vascular tissues (Fig. 6C, arrows). Similar results were obtained with the probe of CYCD4;1. The
transcripts of CYCD4;1 were detected in the shoot apical meristem,
leaf primordia (Fig. 6B), and
vascular tissues (Fig. 6D). The
control WUSCHEL probe produced hybridization signals underneath the
outer layer of the shoot apex as described previously
(Mayer et al., 1998
In yeast two-hybrid screening with CDKB2;1 as bait, we identified a D-type cyclin, CYCD4;1, and an Arabidopsis homologue of yeast p13Suc1, Cks1At. However, we could not isolate cDNA clones encoding mitotic cyclins, although at least two mitotic cyclins, CYCA2;2 and CYCB2;1, bound to CDKB2;1 in in vitro pull-down assay (Fig. 2B). This might be due to the toxic effect of some of the plant mitotic cyclins on yeast growth (Umeda et al., 1999a ); hence,
cells overexpressing these cyclins might not be able to survive on selection
media.
The result of in vitro pull-down assay showed that CDKB2;1 efficiently
bound to CYCD1;1 and CYCD4;1, whereas CYCD4;1 interacted with both CDKA;1 and
CDKB2;1 but not with CAKB1:1. Mészáros et al.
(2000 At present, we do not have suitable antibodies against CYCD4;1; thus, the protein complex of CDKB2;1 and CYCD4;1 could not be identified by immunoprecipitation. Moreover, any effort to overproduce CYCD4:1 protein in plant cells failed, probably due to its unstable nature or toxic effect of overexpression. Instead, we showed that CYCD4;1 formed protein complexes with CDKA;1 and CDKB2;1 in insect cells, and they were active in terms of histone H1-kinase activity. These results indicate that CYCD4;1 functions as a cyclin subunit by controlling kinase activities of CDKA;1 and CDKB2;1 in living cells. To our knowledge, Arabidopsis CYCD4;1 is the first D-type cyclin that is shown to make an active kinase complex with B2-type CDK. Because histone H1 may not be an adequate substrate for the CDKB2;1/CYCD4;1 complex, it is important to identify another physiological substrates. Considering that the involvement of D-type cyclins during the G2/M phase has not been demonstrated in other organisms, the substrates for CDKB2;1/CYCD4;1 may be associated with some plant-specific events.
We analyzed the promoter activities of CDKB2;1 and
CYCD4;1 in transgenic BY-2 cells. Our results showed that the
promoter activity of CDKB2;1 was restricted from early G2 to M phase,
whereas that of CYCD4;1 was observed throughout the cell cycle. Thus,
there is an overlap of the dynamics of CDKB2;1 and CYCD4;1 expression,
suggesting that CYCD4;1 could bind to and activate CDKB2;1 during G2/M phase.
Menges et al. (2002
In planta, transcripts of both CDKB2;1 and CYCD4;1 were
detected in shoot apical meristem, young leaf primordia, vascular tissues, and
anthers. De Veylder et al.
(1999
Recently, the patterns of cell cycling during leaf vein development have
been reported in Arabidopsis by using a CYCB1;1::GUS reporter
construct (Kang and Dengler
2002
Our results from in situ hybridization showed that both CYCD4;1
and CDKB2;1 were expressed in tapetum of anthers. The tapetal cells
are initially uninucleate but become binucleate before meiosis of the pollen
mother cells, (Misra, 1962
In conclusion, Arabidopsis CYCD4;1 probably forms an active kinase complex
with CDKB2;1 during G2/M phase in specific tissues. The cell cycle is
integrated into complex pathways of morphogenesis and histogenesis in plants
(for review, see Meijer and Murray,
2001
Yeast (Saccharomyces cerevisiae) Two-Hybrid Screening
The entire open reading frame (ORF) of CDKB2;1 was amplified from
an Arabidopsis cDNA mixture by PCR with primers that included the recognition
sequence for EcoRI at both the N- and C-terminal ends. The amplified
fragment was cloned into the pBluescript II SK– (Stratagene,
La Jolla, CA) to produce pBSII-CDKB2;1, and its nucleotide sequence
was confirmed. After digestion with EcoRI, the fragment was subcloned
into the EcoRI site of pAS2–1 (CLONTECH Laboratories, Palo
Alto, CA). The resultant plasmid pAS-CDKB2;1 was introduced into the
yeast strain Y190, which was then transformed with the Arabidopsis cDNA
library that was prepared in the pACT2 vector (CLONTECH) derived from mRNA of
suspension-cultured cells (Németh
et al., 1998
In vitro translation of Arabidopsis cyclins was conducted with
[35S]Met by using the TNT Coupled Reticulocyte Lysate Systems
(Promega, Madison, WI). cDNAs of D-type cyclins CYCA2;2 and CYCB2;1 were
subcloned into the pBluescript II SK– vector and used as
template for in vitro transcription. The ORFs of CDKA;1 and
CDKB1;1 were amplified by PCR with primers that included the
recognition sequence for EcoRI at both the N- and C-terminal ends.
The fragments were ligated to pBluescript II SK– to produce
pBSII-CDKA;1 and pBSII-CDKB1;1, and their nucleotide
sequences were confirmed. After digestion with EcoRI, the fragments
and the ORF of CDKB2;1 were subcloned into the EcoRI site of
pGEX-1
The plasmids for expression in baculovirus-infected insect cells were
constructed as follows. pBSII-CDKA;1 and pBSII-CDKB2;1 were
digested with EcoRI, and the insert fragments were cloned into the
EcoRI site of pFASTBAC HTa (Gibco BRL, Gaithersburg, MD) to be in
frame with the 6x His. The ORF of CYCD4;1 was amplified by PCR
with primers that included the recognition sequence for EcoRI at both
the N- and C-terminal ends. The fragment was cloned into pBluescript II
SK– to produce pBSII-CYCD4;1, and the nucleotide
sequence was confirmed. After digested with EcoRI, the fragment was
subcloned into the EcoRI site of pFAST-BAC-FLAG1
(Yamaguchi et al., 2000
Transfection of insect Sf9 cells was performed as described by Yamaguchi et
al. (2000
The plasmid pDO432 (Ow et al.,
1986
Transcription start sites of CDKB2;1 and CYCD4;1 were
determined by 5'-RACE using the RML-RACE kit (Ambion, Austin, TX),
according to the instructions provided by the manufacturer. The promoter
region of CDKB2;1 (–835 to +50 bp) was amplified with a primer
that included the recognition sequence for BamHI at the 3' end.
After confirming the nucleotide sequence, the fragment was digested with
BamHI and HindIII, whose recognition sequence resides 835 bp
upstream of the transcription start site, and the
HindIII-BamHI fragment was cloned into the
HindIII/BamHI sites of pPZP211-LUC. The promoter
region of CYCD4;1 (–2,362 to +129 bp) was amplified by PCR with
primers that included the recognition sequence for SalI at both the
5' and 3' ends. The fragment was cloned into the pCR-XL-TOPO
vector (Invitrogen, San Diego), and the nucleotide sequence was confirmed.
After digestion with SalI, the fragment was subcloned into the
SalI site of pPZP211-LUC. The resultant plasmids were used
to transform tobacco (Nicotiana tabacum) BY-2 cells. For
synchronization of BY2 cells, 7-d-old culture was diluted to 1:10 (v/v), mixed
with 5 mg L–1 aphidicolin, and cultured for 24 h.
To restart the cell cycle, aphidicolin was removed by washing the cells with
1,000 mL of fresh medium. LUC assay was performed as described by Ito et al.
(1998
Arabidopsis tissues were fixed in FAA (50% [v/v] ethanol, 5% [v/v] acetic
acid, and 3.7% [v/v] formaldehyde), and 8-µm paraffin sections were
hybridized with digoxygenin-labeled probes as described previously
(Braissant and Wahli, 1998
We thank Dr. Csaba Koncz for the Arabidopsis cDNA library for yeast two-hybrid screening. We are also grateful to Prof. Dirk Inzé and Dr. Christiane Genetello for cyclin cDNAs and to Dr. Takashi Araki for the WUSCHEL cDNA fragment. Received January 20, 2003; returned for revision March 15, 2003; accepted March 29, 2003.
Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.103.020644.
1 This work was supported by a Grant-in-Aid for Scientific Research on
Priority Areas (grant no. 14036212) and by Research for the Future from the
Japan Society for the Promotion of Science. * Corresponding author; e-mail mumeda{at}imcbns.iam.u-tokyo.ac.jp; fax 81–3–5841–8466.
Boniotti MB, Gutierrez C (2001) A cell-cycle-regulated kinase activity phosphorylates plant retinoblastoma protein and contains, in Arabidopsis, a CDKA/cyclin D complex. Plant J 28: 341–350[CrossRef][Web of Science][Medline]
Boudolf V, Rombauts S, Naudts M, Inzé D, De Veylder L
(2001) Identification of novel cyclin-dependent kinases
interacting with the CKS1 protein of Arabidopsis. J Exp
Bot 52:
1381–1382
Braissant O, Wahli W (1998) Differential
expression of peroxisome proliferator-activated receptor-alpha, -beta, and
-gamma during rat embryonic development. Endocrinology
139:
2748–2754 Cockcroft CE, den Boer BG, Healy JM, Murray JAH (2000) Cyclin D control of growth rate in plants. Nature 405: 575–579[CrossRef][Medline] Criqui MC, Genschik P (2002) Mitosis in plants: how far we have come at the molecular level? Curr Opin Plant Biol 5: 487–493[CrossRef][Web of Science][Medline] De Veylder L, Segers G, Glab N, Casteels P, Van Montagu M, Inzé D (1997) The Arabidopsis Cks1At protein binds the cyclin-dependent kinases Cdc2aAt and Cdc2bAt. FEBS Lett 412: 446–452[CrossRef][Web of Science][Medline] De Veylder L, De Almeida Engler J, Burssens S, Manevski A, Lescure B, Van Montagu M, Engler G, Inzé D (1999) A new D-type cyclin of Arabidopsis thaliana expressed during lateral root primordia formation. Planta 208: 453–462[CrossRef][Web of Science][Medline] Hajdukiewicz P, Svab Z, Maliga P (1994) The small, versatile pPZP family of Agrobacterium binary vectors for plant transformation. Plant Mol Biol 25: 989–994[CrossRef][Web of Science][Medline]
Harbour JW, Dean DC (2000) The Rb/E2F pathway:
expanding roles and emerging paradigms. Genes Dev
14:
2393–2409
Healy JMS, Menges M, Doonan JH, Murray JAH
(2001) The Arabidopsis D-type cyclins CycD2 and CycD3
both interact in vivo with the PSTAIRE cyclin-dependent kinase Cdc2a
but are differentially controlled. J Biol Chem
276:
7041–7047 Hemerly AS, de Almeida Engler J, Bergounioux C, Van Montagu M, Engler G, Inzé D, Ferreira P (1995) Dominant negative mutants of the Cdc2 kinase uncouple cell division from iterative plant development. EMBO J 14: 3925–3936[Web of Science][Medline] Hemerly AS, Ferreira P, de Almeida Engler J, Van Montagu M, Engler G, Inzé D (1993) cdc2a expression in Arabidopsis is linked with competence for cell division. Plant Cell 5: 1711–1723[Abstract]
Himanen K, Boucheron E, Vanneste S, de Almeida Engler J,
Inzé D, Beeckman T (2002) Auxin-mediated cell
cycle activation during early lateral root initiation. Plant
Cell 14:
2339–2351 Hirayama T, Imajuku Y, Anai T, Matsui M, Oka A (1991) Identification of two cell-cycle-controlling cdc2 gene homologs in Arabidopsis thaliana. Gene 105: 159–165[CrossRef][Web of Science][Medline]
Ito M, Iwase M, Kodama H, Lavisse P, Komamine A, Nishihama
R, Machida Y, Watanabe A (1998) A novel cis-acting
element in promoters of plant B-type cyclin genes activates M phase-specific
transcription. Plant Cell 10:
331–341 Joubès J, Chevalier C, Dudits D, Heberle-Bors E, Inzé D, Umeda M, Renaudin JP (2000) CDK-related protein kinases in plants. Plant Mol Biol 43: 607–620[CrossRef][Web of Science][Medline] Kang J, Dengler N (2002) Cell cycling frequency and expression of the homeobox gene ATHB-8 during leaf vein development in Arabidopsis. Planta 216: 212–219[CrossRef][Web of Science][Medline] Mayer KF, Schoof H, Haecker A, Lenhard M, Jurgens G, Laux T (1998) Role of WUSCHEL in regulating stem cell fate in the Arabidopsis shoot meristem. Cell 95: 805–815[CrossRef][Web of Science][Medline] Meijer M, Murray JAH (2001) Cell cycle controls and the development of plant form. Curr Opin Plant Biol 4: 44–49[CrossRef][Web of Science][Medline]
Menges M, Hennig L, Gruissem W, Murray JAH
(2002) Cell cycle-regulated gene expression in
Arabidopsis. J Biol Chem
277:
41987–42002 Menges M, Murray JAH (2002) Synchronous Arabidopsis suspension cultures for analysis of cell-cycle gene activity. Plant J 30: 203–212[CrossRef][Web of Science][Medline] Mészáros T, Miskolczi P, Ayaydin F, Pettkó-Szandtner A, Peres A, Magyar Z, Horváth GV, Bakó L, Fehér A, Dudits D (2000) Multiple cyclin-dependent kinase complexes and phosphatases control G2/M progression in alfalfa cells. Plant Mol Biol 43: 595–605[CrossRef][Web of Science][Medline] Misra RC (1962) Contribution to the embryology of Arabidopsis thalianum (Gay and Monn.) Agra Univ J Res 11: 191–199 Nakagami H, Sekine M, Murakami H, Shinmyo A (1999) Tobacco retinoblastoma-related protein phosphorylated by a distinct cyclin-dependent kinase complex with Cdc2/cyclin D in vitro. Plant J 18: 243–252[CrossRef][Web of Science][Medline]
Németh K, Salchert K, Putnoky P, Bhalerao R,
Koncz-Kálmán Z, Stankovic-Stangeland B, Bakó L,
Mathur J, Ökrész L, Stabel S et al. (1998)
Pleiotropic control of glucose and hormone responses by PRL1, a nuclear WD
protein, in Arabidopsis. Genes Dev
12:
3059–3073
Oakenfull EA, Riou-Khamlichi C, Murray JAH
(2002) Plant D-type cyclins and the control of G1 progression.
Philos Trans R Soc Lond B Biol Sci
357:
749–760
Ow DW, Wood KV, DeLuca M, de Wet JR, Helinski DR, Howell SH
(1986) Transient and stable expression of the firefly luciferase
gene in plant cells and transgenic plants. Science
234:
856–859
Porceddu A, Stals H, Reichheld JP, Segers G, De Veylder L, De
Pinho Barrôco R, Casteels P, Van Montagu M, Inzé D, Mironov V
(2001) A plant-specific cyclin-dependent kinase is involved in
the control of G2/M progression in plants. J Biol Chem
276:
36354–36360 Potuschak T, Doerner P (2001) Cell cycle controls: genome-wide analysis in Arabidopsis. Curr Opin Plant Biol 4: 501–506[CrossRef][Web of Science][Medline] Rechsteiner M, Rogers SW (1996) PEST sequences and regulation by proteolysis. Trends Biochem Sci 21: 267–271[CrossRef][Web of Science][Medline]
Riou-Khamlichi C, Huntley R, Jacqmard A, Murray JAH
(1999) Cytokinin activation of Arabidopsis cell division
through a D-type cyclin. Science
283:
1541–1544
Riou-Khamlichi C, Menges M, Healy JM, Murray JAH
(2000) Sugar control of the plant cell cycle: differential
regulation of Arabidopsis D-type cyclin gene expression. Mol
Cell Biol 20:
4513–4521 Roudier F, Fedorova E, Gyorgyey J, Feher A, Brown S, Kondorosi A, Kondorosi E (2000) Cell cycle function of a Medicago sativa A2-type cyclin interacting with a PSTAIRE-type cyclin-dependent kinase and a retinoblastoma protein. Plant J 23: 73–83[CrossRef][Web of Science][Medline] Stals H, Inzé D (2001) When plant cells decide to divide. Trends Plant Sci 6: 359–364[CrossRef][Web of Science][Medline]
Swaminathan K, Yang Y, Grotz N, Campisi L, Jack T
(2000) An enhancer trap line associated with a D-class cyclin
gene in Arabidopsis. Plant Physiol
124:
1658–1667 Umeda M, Iwamoto N, Umeda-Hara C, Yamaguchi M, Hashimoto J, Uchimiya H (1999a) Molecular characterization of mitotic cyclins in rice plants. Mol Gen Genet 262: 230–238[CrossRef][Medline]
Umeda M, Umeda-Hara C, Uchimiya H (2000) A
cyclin-dependent kinase-activating kinase regulates differentiation of root
initial cells in Arabidopsis. Proc Natl Acad Sci USA
97:
13396–13400
Umeda M, Umeda-Hara C, Yamaguchi M, Hashimoto J, Uchimiya H
(1999b) Differential expression of genes for cyclin-dependent
protein kinases in rice plants. Plant Physiol
119:
31–40
Vandepoele K, Raes J, De Veylder L, Rouzé P, Rombauts S,
Inzé D (2002) Genome-wide analysis of core cell cycle
genes in Arabidopsis. Plant Cell
14:
903–916 Yamaguchi M, Fabian T, Sauter M, Bhalerao RP, Schrader J, Sandberg G, Umeda M, Uchimiya H (2000) Activation of CDK-activating kinase is dependent on interaction with H-type cyclins in plants. Plant J 24: 11–20[CrossRef][Web of Science][Medline] Yamaguchi M, Umeda M, Uchimiya H (1998) A rice homolog of Cdk7/MO15 phosphorylates both cyclin-dependent protein kinases and the carboxy-terminal domain of RNA polymerase II. Plant J 16: 613–619[CrossRef][Web of Science][Medline] This article has been cited by other articles:
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ABSTRACT
RESULTS
-Galactosidase activity of yeast
cells grown on a minimal medium was observed by the colony filter assay.
T (Pharmacia, Piscataway, NJ). GST fusion proteins were
expressed in Escherichia coli and purified with glutathione Sepharose
(Amersham Pharmacia Biotech, Piscataway, NJ) as described previously
(Yamaguchi et al., 1998
