RESUMEN
The ANGUSTIFOLIA (AN) gene is required for leaf hair (trichome) branching and is also involved in polarized expansion underlying organ shape. Here we show that the AN gene encodes a C-terminal binding proteins/brefeldin A ADP-ribosylated substrates (CtBP/BARS) related protein. AN is expressed at low levels in all organs and the AN protein is localized in the cytoplasm. In an mutant trichomes, the organization of the actin cytoskeleton is normal but the distribution of microtubules is aberrant. A role of AN in the control of the microtubule cytoskeleton is further supported by the finding that AN genetically and physically interacts with ZWICHEL, a kinesin motor molecule involved in trichome branching. Our data suggest that CtBP/BARS-like protein function in plants is directly associated with the microtubule cytoskeleton.
Asunto(s)
Proteínas de Arabidopsis/fisiología , Proteínas de Unión al ADN/fisiología , Microtúbulos/fisiología , Proteínas de Plantas/fisiología , Proteínas Represoras/fisiología , Factores de Transcripción , Oxidorreductasas de Alcohol , Secuencia de Aminoácidos , Animales , Proteínas de Arabidopsis/clasificación , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Unión a Calmodulina/genética , Proteínas de Unión a Calmodulina/metabolismo , Proteínas Portadoras , Clonación Molecular , Secuencia Conservada , Citoesqueleto/metabolismo , Citoesqueleto/fisiología , Proteínas de Unión al ADN/clasificación , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Evolución Molecular , Expresión Génica , Genes de Plantas , Líquido Intracelular/metabolismo , Microtúbulos/metabolismo , Datos de Secuencia Molecular , Morfogénesis , Mutagénesis , Fosfoproteínas , Proteínas de Plantas/clasificación , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Proteínas Represoras/clasificación , Proteínas Represoras/genética , Proteínas Represoras/metabolismo , Análisis de Secuencia de ADN , Homología de Secuencia de AminoácidoRESUMEN
Plants often respond to pathogens by sacrificing cells at the infection site. This type of programmed cell death is mimicked by the constitutive pathogene response5 (cpr5) mutant in Arabidopsis in the absence of pathogens, suggesting a role for CPR5 in programmed cell death control. The analysis of the cellular phenotypes of two T-DNA-tagged cpr5 alleles revealed an additional role for CPR5 in the regulation of endoreduplication and cell division. In cpr5 mutant trichomes, endoreduplication cycles stop after two rounds instead of four, and trichome cells have fewer branches than normal. Eventually, cpr5 trichomes die, the nucleus disintegrates, and the cell collapses. Similarly, leaf growth stops earlier than in wild-type, and, frequently, regions displaying spontaneous cell death are observed. The cloning of the CPR5 gene revealed a novel putative transmembrane protein with a cytosolic domain containing a nuclear-targeting sequence. The dual role of CPR5 in cell proliferation and cell death control suggests a regulatory link between these two processes.