Comparative "Golgi" Proteome Study of Lolium multiflorum and Populus trichocarpa.

Kristina Ford,Vaibhav Srivastava,Monika Doblin,Antony Bacic,Tony Chin,Vincent Bulone,Wei Zeng

doi:10.3390/proteomes4030023

Abstract

The Golgi apparatus (GA) is a crucial organelle in the biosynthesis of non-cellulosic polysaccharides, glycoproteins and proteoglycans that are primarily destined for secretion to the cell surface (plasma membrane, cell wall and apoplast). Only a small proportion of the proteins involved in these processes have been identified in plants, with the majority of their functions still unknown. The availability of a GA proteome would greatly assist plant biochemists, cell and molecular biologists in determining the precise function of the cell wall-related proteins. There has been some progress towards defining the GA proteome in the model plant system Arabidopsis thaliana, yet in commercially important species, such as either the cereals or woody species there has been relatively less progress. In this study, we applied discontinuous sucrose gradient centrifugation to partially enrich GA from suspension cell cultures (SCCs) and combined this with stable isotope labelling (iTRAQ) to determine protein sub-cellular locations. Results from a representative grass species, Italian ryegrass (Lolium multiflorum) and a dicot species, black cottonwood (Populus trichocarpa) are compared. The results confirm that membrane fractionation approaches that provide effective GA-enriched fractions for proteomic analyses in Arabidopsis are much less effective in the species examined here and highlight the complexity of the GA, both within and between species.

Highlights

The Golgi apparatus (GA) is the cell’s “engine room” for glycosylation and plays an important role in the biosynthesis of non-cellulosic polysaccharides, glycoproteins and proteoglycans, the major macromolecular components of the plant cell surface
Seven-day-old L. multiflorum and P. trichocarpa suspension cell cultures (SCCs) were used for protein extraction
There were 79 proteins identified with a predicted signal peptide, indicating that they are destined for delivery to post-Golgi membrane compartments downstream in GA-Enriched from

Summary

Introduction

The Golgi apparatus (GA) is the cell’s “engine room” for glycosylation and plays an important role in the biosynthesis of non-cellulosic polysaccharides, glycoproteins and proteoglycans, the major macromolecular components of the plant cell surface. The GA is vital for plant growth and development, as well as for responses to abiotic and biotic stress [1] It is an important component of a very dynamic membranous secretory pathway, which contributes significantly to the challenges of defining the GA proteome [2]. While a number of proteins are resident to the GA, many are transiently associated with the organelle and exert their function elsewhere in the cell. This is the case for all proteins that transit through the GA during secretion to their final destination at either the vacuole or the cell surface. The similarity of the structural properties of the GA and ER makes them difficult to separate

Methods

Findings

Discussion

Conclusion