The Arabidopsis CAP-D proteins are required for correct chromatin organisation, growth and fertility
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RESEARCH ARTICLE
The Arabidopsis CAP-D proteins are required for correct chromatin organisation, growth and fertility Veit Schubert & Inna Lermontova & Ingo Schubert
Received: 14 January 2013 / Revised: 14 June 2013 / Accepted: 18 June 2013 / Published online: 9 August 2013 # Springer-Verlag Berlin Heidelberg 2013
Abstract In plants as in other eukaryotes, the structural maintenance of chromosome (SMC) protein complexes cohesin, condensin and SMC5/6 are essential for sister chromatid cohesion, chromosome condensation, DNA repair and recombination. The presence of paralogous genes for various components of the different SMC complexes suggests the diversification of their biological functions during the evolution of higher plants. In Arabidopsis thaliana, we identified two candidate genes (Cap-D2 and Cap-D3) which may express conserved proteins presumably associated with condensin. In silico analyses using public databases suggest that both genes are controlled by factors acting in a cell cycle-dependent manner. Cap-D2 is essential because homozygous T-DNA insertion mutants were not viable. The heterozygous mutant showed wild-type growth habit but reduced fertility. For Cap-D3, we selected two homozygous mutants expressing truncated transcripts which are obviously not fully functional. Both mutants show reduced pollen fertility and seed set (one of them also reduced plant vigour), a lower chromatin density and frequent (peri)centromere association in interphase nuclei. Sister chromatid cohesion was impaired compared to wild-type in the cap-D3 mutants but not in the heterozygous cap-D2 mutant. At superresolution (Structured Illumination Microscopy), we found no alteration of chromatin substructure for both cap-D mutants. Chromosome-associated polypeptide (CAP)-D3 and the cohesin subunit SMC3 form similar but positionally nonoverlapping reticulate structures in 2C-16C nuclei, suggesting their importance for interphase chromatin architecture in differentiated nuclei. Thus, we presume that CAP-D proteins are
Electronic supplementary material The online version of this article (doi:10.1007/s00412-013-0424-y) contains supplementary material, which is available to authorized users. V. Schubert (*) : I. Lermontova : I. Schubert Leibniz Institute of Plant Genetics and Crop Plant Research, 06466 Gatersleben, Germany e-mail: [email protected]
required for fertility, growth, chromatin organisation, sister chromatid cohesion and in a process preventing the association of centromeric repeats.
Introduction In plants as in other eukaryotes, the evolutionarily conserved structural maintenance of chromosome (SMC) protein complexes cohesin, condensin and SMC5/6 are involved in such basic biological processes as sister chromatid cohesion, chromosome condensation, DNA repair and recombination (Nasmyth and Haering 2005; Hirano and Hirano 2006; Palecek et al. 2006). In addition, SMC proteins control gene expression and development (Wood et al. 2010; Hirano 2012). The two rod-like structured condensin complexes I and II, iden
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