DRL1, a Homolog of the Yeast TOT4/KTI12 Protein, Has a Function in Meristem Activity and Organ Growth in Plants

Abstract

The DEFORMED ROOTS AND LEAVES1 ( DRL1 ) gene is single copy in the Arabidopsis genome, and based on overall amino acid similarity and conservation of functional domains, the DRL1 protein is homologous with yeast TOT4/KTI12. TOT4/ KTI12 associates with Elongator, a multisubunit complex that binds the RNA polymerase II transcription elongation complex. Recessive mutations at the DRL1 locus caused defective organ formation indicative of disorganized shoot, inflorescence, flower, and root meristems. DRL1 is a putative ATP/GTP binding protein; in addition, calmodulin binding activity was demonstrated in vitro for the C terminus of the DRL1 protein. Phenotypic and genetic data position DRL1 relative to regulatory loci for leaf development, in which it acts early. We identified Arabidopsis homologs for the six Elongator components and hypothesize that DRL1 regulates transcription elongation through a putative plant Elongator. Upregulation of the AN-GUSTIFOLIA transcript in the strong drl1-2 allele supports this model.

The elongata mutants identify a functional Elongator complex in plants with a role in cell proliferation during organ growth

“…Mutants elo1, elo2, elo3, elo4͞drl1-4 (12), drl1-2 (code N9360, Nottingham Seed Stock Centre, Nottingham, United Kingdom) (14), and swp1 (16) have been described previously; elo3-3, elo3-4, and elo3-5 (The Plant Chromatin Database available at www.chromdb.org), elo3-2 (FLAGdb͞FST) (17), and SALK insertion lines (Nottingham Seed Stock Centre) are publicly available. Plants were grown as described in ref.…”

“…DRL1 is the ortholog of the yeast KTI12 protein (14), a putative regulator of the Elongator complex (15). Homologs of the six structural components of Elongator are present in the Arabidopsis genome (14). We report that the elo mutations are in genes encoding components of the Elongator complex.…”

“…The elo mutants have a narrow leaf phenotype (12), similar to that of the null mutant drl1-2. Subsequently, elo4 was shown to be allelic to drl1 and was redesignated drl1-4 (14). DRL1 is the ortholog of the yeast KTI12 protein (14), a putative regulator of the Elongator complex (15).…”

“…Subsequently, elo4 was shown to be allelic to drl1 and was redesignated drl1-4 (14). DRL1 is the ortholog of the yeast KTI12 protein (14), a putative regulator of the Elongator complex (15). Homologs of the six structural components of Elongator are present in the Arabidopsis genome (14).…”

TheArabidopsis thalianaHomolog of YeastBRE1Has a Function in Cell Cycle Regulation during Early Leaf and Root Growth

“…The intrinsic leaf size is determined by the number of cells produced by cell division activities during the early stages of primordium formation (Mizukami and Fischer, 2000). A group of genes have been reported to affect leaf shape and size by regulating cell numbers (Mizukami and Fischer, 2000;Nelissen et al, 2003Nelissen et al, , 2005Horiguchi et al, 2005). However, another group of genes affect cell division, leaving organ growth relatively unaffected because of a compensatory effect by cell expansion The yellow to orange color of the circles correspond to the level of significance of the overrepresented GO category from 0.05 and below according to a multiple t test with false discovery rate-corrected P value.…”