QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online 3 August 2004
doi: 10.1242/jcs.01200

This Article Summary Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Champion, A. Articles by Henry, Y. Search for Related Content PubMed PubMed Citation Articles by Champion, A. Articles by Henry, Y. Social Bookmarking                         What's this?

AtSGP1, AtSGP2 and MAP4K are nucleolar plant proteins that can complement fission yeast mutants lacking a functional SIN pathway

Antony Champion^1,*,¶, Stefan Jouannic^1,, Stéfanie Guillon¹, Keithanne Mockaitis^1,, Andrea Krapp², Alain Picaud¹, Viesturs Simanis², Martin Kreis¹ and Yves Henry¹

¹ Institut de Biotechnologie des Plantes (IBP), UMR 8618, Bâtiment 630, Université de Paris-Sud, 91405 Orsay Cedex, France
² Cell Cycle Control Laboratory, ISREC, Chemin des Boveresses 155, Epalinges, 1066, Switzerland

View larger version (23K): [in a new window]   Fig. 1. Model of the SIN pathway in S. pombe and homologues from A. thaliana. A parallel is drawn between fission yeast and plants. See text for abbreviations and explanation.

View larger version (22K): [in a new window]   Fig. 2. Protein structure and relationship trees of monomeric G-proteins and MAP4Ks. (A) Comparison of the primary structure of AtSGP proteins with the homologous S. pombe protein. The plant-specific extensions are shown in white. Both identity (bold) and similarity percentages are shown. (B) Phenogram was generated using the Neighbour-Joining algorithm (Saitou and Nei, 1987) and illustrates the evolutionary relatedness of AtSGP1 and AtSGP2 to a representative subset of monomeric GTPases. The subfamily including AtSGP1, AtSGP2, spg1p from S. pombe, Tem1 from S. cerevisiae and GiTem1 from G. intestinalis is boxed. The sequences have been submitted to the EMBL database under the accession numbers AJ238846 (AtSGP1), AJ505743 (AtSGP2), AJ505744 (AtMAP4K1), AJ505745 (AtMAP4K2). (C) Comparison of the primary structures of MAP4K proteins with the homologous S. pombe proteins. The plant-specific extensions are shown in white, the catalytic domains in black. Both identity (bold) and similarity percentages are shown. (D) Schematic representation of the MAP4K groups based on Neighbour-Joining analyses of the catalytic domains. Number of proteins used to build the tree is indicated in brackets after each group of MAP4K.

View larger version (72K): [in a new window]   Fig. 3. Complementation of the S. pombe spg1-B8 and sid1-239 mutants. (A) spg1-B8 mutant cells in inducing conditions transformed with: (1) pREP3ATG, the thiamine-repressible promoter pnmt1 vector at 25°C (permissive temperature), and (2) at 36°C (restrictive temperature); (3) pREP3ATG-AtSGP1 at 36°C; and (4) pREP3ATG-AtSGP2 at 36°C. (B) sid1-239 mutant cells in inducing conditions transformed with: (1) pREP3ATG at 25°C and (2) at 36°C; (3) pREP3ATGBnMAP4K2 at 36°C. Nuclei and septation material were labelled with DAPI and calcofluor, respectively. Representative examples of the septation material are indicated by arrows.

View larger version (57K): [in a new window]   Fig. 4. Effect of the overexpression of AtSGP1, AtSGP2, BnMAP3K1 and BnMAP4K2 on cytokinesis in S. pombe. (A) DAPI calcofluor-stained cells of S. pombe transformed with: (1) pREP3ATG, (2) pREP3ATG-AtSGP1, (3) pREP3ATG-AtSGP2, (4) pREP3ATG-BnMAP3K1 and (5) pREP3ATGBnMAP4K2. (B) Septation index (SI) in cells transformed with: (1) pREP3ATG, (2) pREP3ATG-AtSGP1, (3) pREP3ATG-AtSGP2, (4) pREP3ATG-BnMAP3K1, (5) pREP3ATG-BnMAP4K2 under inducing conditions.

View larger version (38K): [in a new window]   Fig. 5. A. thaliana SIN-related genes expression in various organs (A) and during the cell cycle (B). (A) The abundance of the AtSGP1, AtSGP2, AtMAP3K1, AtMAP3K2, AtMAP4K1 and AtMAP4K2 transcripts was examined in various organs using real-time quantitative PCR. The transcript levels were measured in RNAs extracted from roots (R), rosette leaves (RL), cauline leaves (CL), inflorescence stems (IS), flower buds (FB), mature flowers (MF), siliques (SI) and seedlings (S). Transcript levels are represented as a ratios (R) of the absolute value of the studied gene to the absolute value of the ACT2/ACT8 genes. (B) Analyses of the relative expression levels of AtSGP1, AtSGP2, AtMAP3K1, AtMAP3K2, AtMAP4K1 and AtMAP4K2 during the cell cycle. Cultured A. thaliana cells were arrested at the G1-S phase transition using aphidicolin. After removal of the drug (i.e. time 0), RNA extracts were prepared at the indicated time points and analysed. Accumulation of the G2-M phase-specific genes Cyc1B1;1 and AtMAP3K1, and the S phase-specific gene AtH4 were simultaneously monitored. Transcript levels are represented as ratios (R) of the absolute value of the studied gene to the absolute value of each gene at T0.

View larger version (88K): [in a new window]   Fig. 6. Localisation of plant SIN-related proteins. (A) Interphase cell nuclei stained with DAPI (1) and epifluorescence microscopic image of BnMAP3K1-GFP (2). (B) Confocal fluorescent microscopic images (left) and the corresponding DIC images (right) of: (1) smGFP, (2) BnMAP3K1-GFP, (3) BnMAP3K1-GFP at a higher magnification showing a single nucleus with two nucleoli, (4) AtMAP4K1-GFP, (5) AtMAP4K2-GFP, (6) AtSGP1-GFP, (7) AtSGP2-GFP. Scale bars, 15 mm.

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati

Twitter