Abstract Detail

Biochemistry, metabolism, carbon flux

Mehrpooyan, Fatemeh [1], Patterson, Jenelle [1], Tetlow, Ian J. [1], Emes, Michael J. [1].

Regulation of Starch Synthase II, a Key Enzyme of Starch Biosynthesis.

Starch is an important storage carbohydrate in plants, and provides 70% of human caloric intake. Starch is synthesized in plastids (chloroplasts and amyloplasts) through the coordinated activities of starch synthases (SSs), starch branching enzymes (SBEs), and debranching enzymes. These biosynthetic enzymes form functional, multi-enzyme complexes and, in cereals, protein phosphorylation is known to play a role in mediating enzyme complex formation. In maize, the isozyme SSIIa, forms the core of a heteromeric protein complex with SBEIIb and SSI, and is responsible for the localization of this complex between the plastid stroma and starch granule. The activity of this particular protein complex is crucial for normal starch biosynthesis. There are two main aims of the current study: first, to characterize maize SSIIa post-translational regulation in vitro, and second, to determine if SSIIa regulatory mechanisms are universal amongst plant species and plastid types by observing Arabidopsis chloroplastic SSII regulation both in vitro and in planta. The first study will identify the effect of protein phosphorylation on SSIIa catalytic activity and protein complex formation, and to determine which amino acid residues are involved. Putative protein kinase(s) and phosphatases involved in regulating the phosphorylation state of SSIIa, and its interaction with other enzymes, will also be characterized. The second study will focus on the physiological relevance of post-translational regulation of SSII by complementing SSII-null Arabdidopsis mutants with modified SSII sequences using Agrobacterium-mediated transformation. The proposed research will provide new insights into our understanding of the signal transduction system regulating starch biosynthesis in plants. This work is of strategic importance and has the potential to identify novel genes for crop improvement.

1 - University of Guelph, Molecular and Cellular Biology, MCB, Summerlee Science Complex, Guelph, ON, N1G2W1, Canada

Keywords:
Starch Synthase II (SSII)
Arabidopsis
Maize
Starch Biosynthesis.

Presentation Type: Poster:Posters for Topics
Session: P
Location: Hall D/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 5:30 PM
Number: PBC003
Abstract ID:457
Candidate for Awards:None