07 Jul 2016
A collaboration between Dr Piers Hemsley at the University of Dundee / The James Hutton Institute and Professor Simon Turner at the University of Manchester has revealed an entirely new mechanism regulating the synthesis of cellulose in plants.
Cellulose is the most abundant biopolymer on the planet, with about 1.5 x 1012 tonnes being produced annually by photosynthetic organisms, and forms the major component of the plant cell wall. Much of what we regard as the body of a plant is made from cellulose and it provides structure, support and protection for the plant. Cellulose is one of the most widely used natural resources, best known in the form of wood, cotton and paper and is also the starting point for many industrial polymers and products such as rayon/viscose, cellophane and nitrocellulose. It forms the cornerstone of emerging green nanotechnologies and is an important component of pharmaceutical drug delivery systems. Cellulose is the main combustible and fermentable component of plants and is therefore the most important factor in biofuel production. Manipulating and understanding cellulose biosynthesis to improve biofuel and industrial feedstock output from crop plants while maintaining food yields and decreasing environmental impact is an important goal of plant science research. This will be of even greater importance in the future as demand increases for improved food production to cope with expanding global populations.
The study has identified that cellulose synthases, the integral membrane enzymes that “spin” cellulose fibres from glucose, are all modified by the covalent attachment of a fatty acid. This modification, termed S-acylation or palmitoylation, is thought to be a major regulator of membrane protein function affecting protein shape, activity, localisation within the cell and which other proteins they can interact with. In the absence of cellulose synthase S-acylation the study found that plants were unable to make cellulose, indicating a critical requirement for S-acylation in cellulose synthesis. Cellulose synthases form large complexes containing 18 individual cellulose synthase enzymes and every subunit must be S-acylated for function. This finding indicates that the cellulose synthase complex is the most heavily S-acylated complex ever described and the degree of S-acylation is likely to have profound effects on the membrane environment surrounding the cellulose synthase complex.
The results of this work are published in Science (8th July 2016, Vol 353, Issue 6294) and the research was supported by the BBSRC.