* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Identification of a Cell Cycle-Related Cene, Cyclin, in Nicotiana
Survey
Document related concepts
Protein phosphorylation wikipedia , lookup
Endomembrane system wikipedia , lookup
Cell culture wikipedia , lookup
Cellular differentiation wikipedia , lookup
Extracellular matrix wikipedia , lookup
Signal transduction wikipedia , lookup
Organ-on-a-chip wikipedia , lookup
Programmed cell death wikipedia , lookup
Cell growth wikipedia , lookup
Cytokinesis wikipedia , lookup
Transcript
Plant Physiol. (1995) 108: 425-426 Plant Gene Register Identification of a Cell Cycle-Related Cene, Cyclin, in Nicotiana tabacum (1.) Li-Xian Qin*, Luc Richard, Claudette Perennes, Pierre Gadal, and Catherine Bergounioux lnstitut de Biotechnologie des Plantes, Université Paris-Sud, Bât. 630, Plateau du Moulon, F-91400 Orsay, France (L.-X.Q., C.P., P.G., C.B.); and Département de Biologie Supramoléculaire et Cellulaire, lnstitut Jacques Monod, 2 place jussieu, F-75251 Paris cedex 05, France (L.R.) Among a11 of the proteins known to be involved in the cell cycle, the CDKs are key components in the control of both the G, to S phase and the G, to M phase transitions in a11 eukaryotes (Jacobs, 1992; Nigg, 1993). The kinase activity of CDKs is regulated by subunits called cyclins, which are involved in the modification of the phosphorylation state, the specificity, and the subcellular location of the enzymes. Although these mechanisms are supposed to occur in a11 eukaryotes, the multiplicity and the role of cyclins within plants are comparatively less well documented. Severa1 plant cyclin genes have nevertheless been characterized in various species such as Arabidopsis (Hemerly et al., 1992) and maize (Renaudin et al., 1994).No related gene has been isolated so far in tobacco; therefore, we focused our attention on the isolation of cyclins from Nicotiana tabacum to study cell-cycle regulation in this model plant (Table I). The 1656-bp fragment isolated from a tobacco cell-suspension cDNA library has been identified as a cyclin cDNA with respect to its sequence similarity with other yeast, animal, and plant cyclins yet characterized. This cDNA sequence, named NTCYCl, contains an open reading frame encoding a protein of 447 amino acids. The predicted primary sequence of the NTCYCl gene product shows regions that are conserved among mitotic cyclins. The C terminus contains a putative cyclin box between the amino acid residues Met’” and Trp354,which is known to be involved in binding to and activation of protein kinases of the CDK family (Nugent et al., 1991).Also, the sequence from Met’” to within the cyclin box is similar to the P-box of cyclin B. This consensus motif is necessary for the activation of the protein phosphatase cdc25 underlying activation of the cyclin B-~34‘~‘’ complex during the GJM phase transition (Zheng and Ruderman, 1993). Additional conserved domains are found in the N-terminal part of the sequence outside the cyclin box. The motif RXXLXXXXN specifies the destruction box well characterized in mitotic cyclins. This acts as a signal for the degradation of cyclin at the end of mitosis (Nugent et al., 1991). The mechanism whereby the NTCYCl cyclin might regd a t e kinase activity during cell division in tobacco is not Table 1. Characteristics of a 1656-bp cyclin cDNA sequence from tobacco Organism: Nicotiana tabacum cv Xanthi; cell suspension. Location of Cene: Nuclear genome, chromosome location undetermined. Function: Encodes a cyclin named NTCYC1. Techniques: Cell-suspension cDNA library constructed in AZAPll (Stratagene), dideoxy nucleotide sequencing on both strands. Method of lsolation and Identification: Two degenerate primers, 5’-CTNMMNATYATNCAYMCNTTYYT-3 ’ and 5 ’-CCNC NRTANATYTCYTCRTAYTT-3’, corresponding to the conserved regions of known cyclin homologs within the cyclin boxes were used to amplify a 113-bp PCR fragment from a cDNA obtained by reverse transcription on vegetative bud total RNA. This was subcloned in the Smal site of pUC18, confirmed by sequencing, and used as a probe to screen a cell-suspension cDNA library. presently understood. Animal cells contain at least two classes of mitotic cyclins, the A type and B type, distinct on the basis of their respective consensus sequences. Cyclins A and B have different mitotic functions and are degraded at different times. However, the NTCYCl gene product cannot be assigned unequivocally as A or B type because consensus sequences of both types are partially conserved within NTCYCl. In the cyclin box region, the tobacco cyclin shares 41% sequence identity with the human cyclins of both A and B types. According to Renaudin et al. (1994), plant mitotic cyclins can be more easily classified into three distinct groups conserved among monocotyledonous and dicotyledonous species. Based on amino acid comparison, the homology of up to 46% between the entire primary sequences of NTCYCl and the maize cyclin CycIbZm suggests that the tobacco protein is more closely related to plant cyclins of group I. We are interested in how the expression of the cyclin NTCYCl and other cyclins is regulated during cell division in tobacco to elucidate the cell-cycle molecular machinery. N . tabacum represents one of the plant model systems offering alternative ways to study cell division and its control * Corresponding author; e-mail lrichard8ccr.jussieu.fr; fax 331-69 -33- 64 -23. Abbreviation: CDK, cyclin-dependent kinase. 425 Downloaded from on June 16, 2017 - Published by www.plantphysiol.org Copyright © 1995 American Society of Plant Biologists. All rights reserved. 426 Qin et al. by phytohormones. These include protoplast cultures and cell suspensions that can be synchronized during cell-cycle progression (Nagata et al., 1992). &o, epidermal tobacco tissues may be confined in vitro to produce, selectively, flowers, vegetative buds, roots, or calli in response to exogenous phytohormones (Tran Thanh Van, 1973). Such organogenic potentiality may be used to elucidate the role of cyclins and other cell-cycle regulators during developmental processes. Received October 7, 1994; accepted November 7, 1994. Copyright Clearance Center: 0032-0889/95/108/0425/02. The EMBL accession number for the sequence reported in this article is 237978. LITERATURE ClTED Hemerly A, Bergounioux C, Van Montagu M, Inzé D, Ferreira P (1992)Gene regulating the plant cell cycle: isolation of a mitotic- Plant Physiol. Vol. 108, 1995 like cyclin from Arubidopsis thaliunu. Proc Natl Acad Sci USA 89: 3295-3299 Control Of the 'ycle. Dev Biol l53: l-I.5 Jacobs Nagata T, Nemoto Y, Hasezawa S (1992) Tobacco BY-2 cell line as the HeLa cell in the cell biology of higher plants. Int Rev Cytol 1 3 2 1-30 Nigg EA (1993) Targets of cyclin-dependent protein kinases. Curr Opin Cell Biol 5 187-193 N'gent JHAr Tr HJ'ams Js Conserved structural motifs in cyclins identified by sequence analysis. J Cell Sci 99: 669474 Renaudin J-P, Colasanti J, Rime H, Yuan Z, Sundaresan V (1994) Cloning of four cyclins from maize indicates that higher plants have structurally distinct groups of mitotic cyclins. Proc Natl Acad Sci USA 91: 7375-7379 Tran Thanh Van M (1973)In vitro control de novo flower, bud, root and callus differentiation from excised epidermal tissues. Nature 246 44-45 Zheng X-F,Ruderman JV (1993) Functional analysis of the P box, a domain in cyclin B required for the activation of cdc25. Cell75 155-164 Downloaded from on June 16, 2017 - Published by www.plantphysiol.org Copyright © 1995 American Society of Plant Biologists. All rights reserved.