In silico Approaches Provide New Insights into the Structural and Functional Organization of Different Plant AGPases

Starch constitutes upto 80% of the daily human calorific intake which is the major carbohydrate reserve in plant storage tissues. ADP-glucose pyrophosphorylase (AGPase) has been engineered successfully in several occasion for increasing starch yield in several plants. It is a heterotetrameric enzyme (two small and two large subunit) in plants and is the first rate limiting enzyme in starch biosynthesis. Understanding the role of specific amino acids or motifs responsible for allosteric regulation and catalytic mechanisms has provided enormous potential for AGPase manipulation. In this study, various small and large subunits of AGPase were considered for a comparative sequence, structure and functional analysis. In absence of atomic resolution structure of the heterotetrameric structure of AGPase, we modeled the structure of both the subunits of the selected plant species and a detailedstructural comparisonwas done. Key amino acid residues and particular motif involved in substrate and regulator binding was highlighted the important structural aspects of AGPase is shown.