Cellulose biosynthesis is one of the most important biochemical processes in plant biology. Despite this, and the great commercial importance of cellulose, we still know very little about the molecular mechanisms responsible for cellulose biosynthesis.
Cellulose is the most common organic substance in nature. It is found in the cell walls in a large number of organisms, plant cells representing the largest source. We use cells from trees (different species of poplars) and microorganisms (Gluconoacetobacter and Oomycetes species) to decipher the molecular mechanisms of the polymerisation, crystallization and self-assembly of cellulose microfibrils with other cell wall components.
This fundamental information will help to understand the natural process of wall formation to facilitate fiber engineering and the design of biomimetic materials. Modern and powerful biochemical and biophysical methods are used for the characterization of the proteins involved in cellulose biosynthesis. To unravel the catalytic mechanisms and roles of the newly discovered enzymes in cell wall biosynthesis, the research program combines plant biotechnology with mechanistic and structural enzymology.
Enzyme technology can be used to modify plant fibers for a number of industrial applications. In addition to microbial enzymes, plants produce enzymes that can be used to tailor wood and fiber properties. Lignin biosynthesis is already relatively well understood, but progress on cell wall carbohydrate biosynthesis has been slower. We have used genomic approaches to identify over 200 genes involved in wood formation in hybrid aspen. In addition to putative cellulose synthases, these genes encode e.g. cellulases and other glycoside hydrolases, a pectin methylesterase (PME), xyloglucan endo-transglycosylases (XET), different carbohydrate-binding modules and expansins.
The XET-technology – a method inspired by nature
Combining chemistry and enzymology the XET- technology can create a lot of exciting new properties on cellulose fiber surfaces. For instance, paper that is stronger, catches bio-molecules, is fireproof or water-repellent.
The XET-technology is based on many years of profound studies of the structure and enzymology of wood and cellulose, carried out at KTH in close collaboration with Umeå Plant Science Center.
– Using gene technology and genomics, we now have a deeper knowledge about the plant cell enzymes participating in the wood formation process and how these enzymes work. Based on this knowledge a biotechnical tool has been developed that, among other things, can be applied to modify fibers in the forest industry, says Harry Brumer, Assoc. Prof at KTH Glycoscience.
The method is based on a plant polymer, xyloglucan, which binds strongly to the plant cell wall cellulose. By using a plant enzyme, called “XET”, different chemical functions can be attached to the polymer. The modified xyloglucan then binds at the cellulose fiber surface, bringing with it the new chemistry. The advantage of the method is that specific surface properties can be created without disturbing the strength properties of cellulose.
Read more about the XET-technology:
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|Interview XET-technology, KTH&Co nr3/06 (på svenska)||Interview with Prof. Tuula Teeri, Assoc. Prof. Harry Brumer and PhD-student Fredrika Gullfot||1244 Kb||09/07/09 17:33|