Probing the Regulation of CSI1 Through its Phosphorylation

Open Access
- Author:
- Fliegel, Cara
- Area of Honors:
- Biology
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Ying Gu, Thesis Supervisor
Benoit A Dayrat, Thesis Honors Advisor - Keywords:
- Cellulose
Cellulose Synthase Complex
Cellulose Synthase Interactive Protein 1
Phosphorylation
Hypocotyl Length
CSC Velocity
Cellulose Content
Arabidopsis thaliana - Abstract:
- Cellulose, an abundant biopolymer, is of great interest due to its involvement in numerous industrial processes. The correct organization and placement of cellulose, controlled by the cellulose synthase complex (CSC), is vital to cell wall activity. Past studies have discovered that the movement of CSCs along the microtubule is mediated by cellulose synthase interactive protein 1 (CSI1). CSI1 is also responsible for marking the docking site for CSCs-containing vesicles on the plasma membrane and fast recovery of CSCs to the plasma membrane after a stressor. Exploration into CSI1 revealed 11 phosphorylation sites with five localized to the N- terminal. Exploring the function of each phosphorylation site may provide insights into how CSI1 accomplishes three different functions. Therefore, this study explores the phenotypic and subcellular affect CSI1 singular phosphorylation site mutants in Arabidopsis thaliana. Further, investigation focuses on the N-terminal phosphorylation sites looking at doublet and triplet phosphorylation mutants. From this, it was discovered that T37A and T41A mutants affect hypocotyl length in comparison to wildtype measurements. Further, subcellular analysis shows that S33A, T37A, S40A, T41A, T128A, S575A, S1125A, S40A T41A, S40A T42A, T41A T42A, and S40A T41A T42A mutants affects CSC velocity in etiolated hypocotyls. Last, it is shown that S33A, S40A, T128A, S575A, T965A, and S2045A mutants may decrease cellulose content, however further exploration is required. In conclusion, this study establishes the effect of the above listed phosphorylation sites on CSI1 function and proposes further steps for exploration.