INVOLVEMENT OF AN HETEROTRIMERIC G PROTEIN IN CRYPTOCHROME MEDIATED RESPONSES DURING Arabidopsis SEEDLING DEVELOPMENT

TUDISCA, VANESA; MUSCHIETTI, JORGE; CASAL, JORGE; MAZZELLA, MARÍA AGUSTINA

Pinamar, Prov de Buenos Aires

Congreso; SAIB Sociedad Argentina de Investigacion Bioquimica y Biologia Molecular; 2005

Plants as immotile organisms are able to sense and interpret the light environment adjusting their growth and development, leding to sophisticated light-signaling networks. In Arabidopsis thaliana red light/far red light is perceived by five phytochromes (phyA through phyE), and blue light by two cryptochromes (cry1 and cry2). Arabidopsis has a single gene encoding for the alpha subunit of the heterotrimeric G protein (GPA). Pharmacological studies and experiments with transgenic Arabidopsis overexpressing GPA suggested that the heterotrimeric G protein is involved in red, far red and blue light regulation of Arabidopsis seedling development. However literature is controversial in this regard. Studies using gpa mutants do not support this idea at least for the red light/far red light signaling pathway. Here we combine a biochemical, molecular and genetic approach to analyzed this issue in detail using phyA, phyB, cry1 and cry2 single mutants. The cry1 mutant showed significantly less GTP binding compared to the WT, even in darkness. GPA transcript levels detected by RT-PCR were normal in the cry1 mutant precluding a transcriptional control. To study a translational regulation we are conducting western blots using a G protein antibody. Pull-down experiments, using in vitro synthesized proteins, are used to study interaction between CRY1 and GPA. This study will open new insights in light signal transduction mediated by heterotrimeric G proteins and will contribute to our understanding of plant cell signaling.