Carbohydrate Molecular Physiology
Dr. Jens Kossmann
New Position: Director of the Institute for Plant Biotechnology, Stellenbosch University, South Africa
The group focused on the use of transgenic plants as tools with which to study the molecular mechanisms involved in starch biosynthesis, cell wall formation, and crop plant phosphate efficiency.
Molecular biology of starch metabolism
Starches, the enigmatic storage polysaccharides of plants, vary in structure both interspecifically and interorganically. Our group uses transgenic plants and ectopic expression of plant genes as tools with which to study starch biosynthesis and structure: cDNAs corresponding to various proteins associated with starch biosynthesis are used both for repressing cognate gene translation in transgenic plants and for cognate gene expression in E. coli. In this way we are able to monitor the effects that the lack of a given protein has on starch metabolism or that the presence of the same protein has upon glycogen metabolism in E. coli.
Starches (glucans and amylopectins) are synthesised via the ADP-glucose pathway by three key enzymes: ADP-glucose pyrophosphorylase, starch synthases, and starch branching enzymes. The randomly branched glucan molecules are then specifically debranched via debranching enzyme to produce amylopectins. Amylopectins are branched in highly ordered clusters and are crystalline in nature, but also contain covalently bound phosphate.
Our group is interested in the functional analysis of starch biosynthetic proteins and in the manipulation of starch structure to broaden its industrial applications. Plant Tec Ltd. was founded in order to pursue such applications.
The group led by Dr. Jens Kossmann was established in feb. 1995 and dissolved in dec. 2000