Speaker: Ying Gu, Pennsylvania State University Department of Biochemistry and Molecular Biology associate professor

Title: "The deceptively simple glucan chain and a complicated cellulose synthase complex"

Abstract: Cellulose is a deceptively simple b-1,4 linked glucose polymer. It is the most abundant biopolymer on earth and is an economically important source of food, paper, textiles, and biofuel. As a critical component of plant cell wall, cellulose organization is important for anisotropic cell growth. Despite its economical and biological significance, the regulation of cellulose biosynthesis is far from being fully understood. Cellulose is synthesized at the plasma membrane by cellulose synthase complexes (CSCs). Our lab has revealed new elements of regulation of the cellulose synthesis machinery, including proteins that control cellulose synthase delivery, guidance, and removal from the cell surface. By a combination of proteomic, live-cell imaging, and genetic approaches, we revealed that the de novo secretion of CSCs is mediated by cooperation among cellulose synthase interacting protein 1 (CSI1), exocyst complex, and a plant-specific protein PATROL1 in Arabidopsis thaliana. Upon delivery of CSCs to the plasma membrane, they synthesize cellulose microfibrils in a direction mirroring the underlying cortical microtubule in a CSI1-dependent manner. The retrieval of CSCs from the PM depends on clathrin-mediated endocytosis by two separate complexes: Adaptor complex (AP2) and TPLATE/TSET complex. Cellulose synthase complexes represent cargo proteins that are not present in yeast and mammalian cells. Therefore, plants offer unique opportunities to characterize the function of endocytosis and exocytosis that may provide insights into the evolution of protein trafficking in eukaryotes.  

Host: Michelle Guo, GDCB adjunct assistant professor

Gu Lab: http://www.gulilab.org/

March 29, 2022, GDCB Seminar flyer