Protein-protein interactions during starch biosynthesis

Abstract

Starch biosynthesis requires the ordered assembly of glucose units into amylose and amylopectin from ADP glucose. Whilst amylose has a relatively simple linear structure, the synthesis of amylopectin requires the formation of regular, repeating clusters of glucan chains. These clusters have a 9 nm periodicity and comprise a crystalline, alpha helical region and an amorphous branched region, a unit which is repeated many times over to give rise to blocklets of amylopectin. Although the individual enzymes of starch biosynthesis have been studied extensively, our knowledge of the mechanisms which give rise to this highly ordered structure is limited. There is an increasing body of literature which has demonstrated that several reactions are regulated post-translationally, including via redox modulation, protein-protein interactions and protein phosphorylation. This chapter summarises our current knowledge of these mechanisms and offers a model of how they serve to coordinate the biosynthesis of amylopectin in particular.