Seminars Archive

Structural and Functional Studies on Plant Metallothioneins and Heterotrimeric G-Proteins

Abstract
Our work focuses on structural and functional analyses of two families of proteins that are involved in responses in plants to stress conditions. These are metallothioneins and heterotrimeric G-proteins Metallothioneins (MTs) are a large family of proteins with small molecular mass, large cystein content and high capacity to bind essential as well as toxic metals. MTs participate in metal homeostasis and responses to heavy metal toxicity. Heterotrimeric G-proteins, on the other hand, mediate transmission of signals from G-protein coupled receptors to cell interior and activate a variety of signaling pathways. They are involved in responses to light and drought stress and play a role in plant growth. Both families of proteins are present in organisms from yeast to mammals and plants, and although extensive structural studies have helped to clarify their mechanisms of function in mammalian systems, detailed structural information is lacking for the plant proteins. We cloned, expressed and purified a type I metallothionein from durum wheat and subunits of G-proteins from Arabidopsis thaliana, and investigated their structural features and function using several biophysical and in vivo techniques. Results of our work using circular dichroism spectropolarimetry, dynamic light scattering and small angle X-ray scattering will be presented together with biochemical analyses and gene expression studies to develop models for mechanisms of function for these proteins in plants. In the last part of this talk a brief description of the new synchrotron radiation facility SESAME (Synchrotron light for Experimental Science and Applications in the Middle East), that is being built in Jordan, and some of the scientific projects that are being developed in this context will be presented. This work was supported by bilateral TUBITAK-Julich grants TBAG-U-34 (101T177), TBAG-U-157 (105T535) and by Sabanci University Internal Research Fund Project No. IACF08-00514. Organizers: S. Onesti, G. Paolucci.