Functionality of the uncharacterized carboxyl terminus of the HD-Zip proteins

ARCE AL; RAINERI J; CABELLO JV; CHAN RL

San Miguel de Tucumán

Congreso; XLV Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2009

SAIB

Título: FUNCTIONALITY OF THE UNCHARACTERIZED CARBOXYL-TERMINUS OF HD-ZIP I PROTEINS. Autores: Arce, Agustín Lucas; Raineri, Jésica; Cabello, Julieta Virginia; Chan, Raquel Lía Lugar de trabajo: Laboratorio de Biotecnología Vegetal, IAL, Ciudad Universitaria, 3000 Santa Fe Transcription factors exert their function essentially via protein-DNA and protein-protein interactions. For this purpose, they present different domains and motives. The HD-Zip family of transcription factors is characterized by the presence of a homeodomain DNA binding domain (HD) associatedwith a dimerization domain, the leucine zipper (Zip).The subfamily I of HD-Zip proteins has been extensively characterized from a physiological and biochemical point of view. Although the members analyzed bind preferentially the same DNA sequence; their overexpression in Arabidopsis under the 35SCaMV promoter resulted in transgenic plants with significantly differential phenotypes.The alignment of the sequences of a sunflower HD-Zip I protein and its homologous in other species showed that there is a high degree of conservation in the uncharacterized C-terminus. Similar results were obtained when a more extensive analysis of this region was performed with HD-Zip I members from Arabidopsis, rice and other species.Arabidopsis plants expressing this complete sunflower protein share a similar phenotype with plants expressing a chimerical fusion of the C-terminus of this protein to the HD-Zip domain of the HAHB4 HD-Zip I protein, specially when grown in sucrose or ACC.These results strongly suggest that this poorly studied region has an important role in the function of HD-Zip I proteins