Education
Ph. D. - Plant Physiology and Molecular Biology, Okayama University, 2005
M. Sc. - Plant Nutrition, University of Hanover, 2001
B. Sc. - Plant Sciences, Alemaya University of Agriculture, 1996
Current Research Interests:
Structural-functional analysis of ALMT-type anion transporters that play a role in plant aluminum-resistance
Aluminum-toxicity is a major constraint limiting crop productivity on acid soils that affect over 50% of potentially arable lands worldwide. When the soil pH falls below 5.0 the soluble Al in the soil solution exists predominantly as the toxic trivalent cation Al3+ that can inhibit root growth and functions. As a consequence, plants have developed strategies that enable them cope with toxic Al ions in the soil. The mechanism of Al tolerance that has been most widely documented in plant species involves the release of organic acid anions such as malate, citrate, and oxalate from roots. These organic anions bind the Al3+ in the rhizosphere and minimize their harmful interactions with roots. Two families of membrane transporters, the aluminum activated malate transporter (ALMT) and the multi-drug and toxin compounds extrusion (MATE) families, have been implicated in the release of malate and citrate, respectively, in response to Al3+.
My research focusses on understanding the structure and function of ALMT-type anion transporters by employing multidisciplinary research approaches including molecular, biochemical and biophysical techniques. I am studying the role of amino acid motifs and large protein domains in regulating the transport properties (anion permeation and activation by Al3+) of the ALMT-type proteins from studies involving site-directed mutagenesis and generation of truncated proteins. I am also studying the structural and functional relationships among ALMT-type proteins from wheat, maize and Arabidopsis, which differ in their substrate selectivity and degree of Al3+-sensitivity, by swapping amino- and carboxylic-terminal domains of the ALMT proteins and protein-protein-interaction studies. Furthermore, I am investigating the role of calcium sensors (calcineurin-B-like proteins) and their interacting protein kinases (CIPKs) in Al-stress signaling from studies involving mutant screening and protein-protein interaction in Xenopus oocytes and Arabidopsis. These studies would provide a platform to develop strategies to modify ALMT-type transporters and enhance their ability to confer Al tolerance, and identify those ALMT alleles that are more effective in conferring Al tolerance in crop plants.
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