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Proc Natl Acad Sci U S A. 2018 Apr 10;115(15):E3578-E3587. doi: 10.1073/pnas.1800182115. Epub 2018 Mar 26.

CSI1, PATROL1, and exocyst complex cooperate in delivery of cellulose synthase complexes to the plasma membrane.

Zhu X1, Li S1, Pan S2,3, Xin X1, Gu Y4.

Author information

1
Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802.
2
W. M. Keck Proteomics Laboratory, Institute for Integrative Genome Biology, University of California, Riverside, CA 92521.
3
Department of Botany and Plant Sciences, University of California, Riverside, CA 92521.
4
Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802; yug13@psu.edu.

Abstract

Cellulose synthesis occurs exclusively at the plasma membrane by cellulose synthase complexes (CSCs). Therefore, delivery of CSCs to discrete sites at the plasma membrane is critical for cellulose synthesis. Despite their significance, the delivery of CSCs is poorly understood. Here we used proteomics approaches, functional genetics, and live cell imaging to show that the de novo secretion of CSCs is mediated by cooperation among cellulose synthase interactive 1 (CSI1), the plant-specific protein PATROL1, and exocyst complex in Arabidopsis thaliana We propose that CSI1 plays a role in marking the docking site, which allows CSCs-containing vesicles access to the plasma membrane through its interaction with microtubules. PATROL1 assists in exocytosis by its interaction with multiple components, including CSI1, CSCs, and exocyst subunits. Both PATROL1 and the exocyst complex determine the rate of delivery of CSCs to the plasma membrane. By monitoring the exocyst complex, PATROL1, CSI1, and CSCs dynamics in real time, we present a timeline of events for exocytosis of CSCs. Our findings provide unique insights into the evolution of exocytosis in eukaryotes.

KEYWORDS:

cellulose synthase complex; exocyst complex; exocytosis; microtubule; plasma membrane

PMID:
29581258
PMCID:
PMC5899483
DOI:
10.1073/pnas.1800182115
[Indexed for MEDLINE]
Free PMC Article

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