Identification of transcription factors that interact with the Arabidopsis COX5b-1 promoter

COMELLI RN, HONG JC, GONZÁLEZ DH

San Miguel de Tucumán, Argentina

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

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB)

Arabidopsis thaliana nuclear gene COX5b-1 (At3g15640) encodes an isoform of the zinc binding subunit 5b of mitochondrial cytochrome c oxidase. A promoter region located between nucleotides -333 and -259 was analyzed previously using plants transformed with different promoter fragments fused to gus reporter gene. This region is required for expression in vegetative tissues and contains elements with the core sequence ATCATT and distalB-like sequences (CCACTTG). These sequences bind different sets of proteins present in plant nuclear extracts and participate in induction by sucrose (ATCATT) and abscisic acid (distalB) of the COX5b-1 promoter. In this work, a yeast one-hybrid screen was performed to identify Arabidopsis transcription factors that interact with this promoter region. Results obtained with both HIS3 and lacZ reporter genes showing that two transcription factors from the HD-Zip and MYB families are more efficient transactivators in the yeast one-hybrid assay. Binding properties in vitro was also analysed using proteins as a fusion with GST from Schistosoma japonicum and purified by affinity chromatography. EMSAs indicated that both proteins recognize the ATCATT core since binding was abolished upon mutation of this element while mutation of the distalB-like sequences did not affect the interaction.