Western Analysis of Arabidopsis Cellulose Synthase Expression

Open Access
Hammudi, Mustafa Bassam
Area of Honors:
Biochemistry and Molecular Biology
Bachelor of Science
Document Type:
Thesis Supervisors:
  • Ming Tien, Thesis Supervisor
  • Ming Tien, Honors Advisor
  • Teh Hui Kao, Faculty Reader
  • biochemistry
  • arabidopsis
  • cellulose
Cellulose in vascular plants is synthesized by the cellulose synthesis complex (CSC) located in the cell membrane. The Arabidopsis CSC is composed of ten cellulose synthase (CesA) protein isoforms, which, although highly similar, have specialized in the ability to produce the various cell wall types required to make a plant. Primary and secondary cell wall synthesis each require three unique, non-redundant CesA isoforms for CSC assembly and function. CesAs 1, 3, and 6, are required for primary cell wall synthesis, while CesAs 4, 7, and 8 form the CSC for secondary wall cellulose biosynthesis. Our lab has recently answered the long-standing question of CesA stoichiometry within the CSC, leading to the most current CSC model consisting of a hexamer of CesA trimers in a 1:1:1 ratio. This work aims to contribute to the understanding of CesA stoichiometry. The work described herein was integral to the elucidation of an equimolar CesA stoichiometry. I performed quantitative analysis of CesA protein levels along the Arabidopsis stem, which represent a spectrum of development. These results suggest that the elucidated 1:1:1 stoichiometry is fixed throughout the progression from primary to secondary cell wall synthesis. Isoform stoichiometry determination gives a greater understanding of how and when plants produce different CesA proteins and offer insight into the process of cellulose synthesis. This finding was crucial for the interpretation and validation of Tien lab’s determination of an equimolar stoichiometry within a single sample. Additionally, this work aids in mapping CesA protein expression to provide a greater understanding of cellulose synthesis so that one day this process can be manipulated to increase energy yield.