Utilization of glucan phosphatase Starch Excess4 to enhance in-vitro starch degradation

Starch is one of the most attractive natural polymers because of its biodegradability, abundance, and renewability. However, the inert nature and semicrystalline structure of native starch granules make starch essentially unusable for most industrial applications without further processing. Therefore, starch is additionally modified via physical, chemical, and biotechnological methods to increase processability and function. Starch obtained from corn, rice, wheat, potato, and cassava, serves as the main resource for the majority of starch-based products. However, much of our understanding of starch metabolism is coming from Arabidopsis thaliana transitory starch metabolism. More systematic studies are needed to understand starch turnover in different species and organs of biotechnologically important species. Reversible starch phosphorylation is essential for efficient starch degradation and SEX4 is a key enzyme in this process. We employed biochemical and functional analyses to study SEX4 from agronomically important crops. Taken together, our findings provide an in depth understanding of SEX4 dephosphorylation of agronomically important plants and green algae species and provide compelling evidence of how SEX4 can be utilized to enhance native starch degradation. © FASEB.