Cellulose biosynthesis: Exciting times for a difficult field of study

The past few decades have witnessed exciting progress in studies on the bio synthesis of cellulose. In the bacterium Acetobacter xylinum, discovery of the activator of the cellulose synthase, cyclic diguanylic acid, opened the way for obtaining high rates of in vitro synthesis of cellulose. This, in turn, led to purification of the cellulose synthase and for the cloning of genes that encode the catalytic subunit and other proteins that bind the ac tivator and regulate its synthesis and degradation, or that control secreti on and crystallization of the microfibrils. In higher plants, a family of g enes has been discovered that show interesting similarities and differences from the gene in bacteria that encodes the catalytic subunit of the syntha se. Genetic evidence now supports the concept that members of this family e ncode the catalytic subunit in these organisms, with various members showin g tissue-specific expression. Although the cellulose synthase has not yet b een purified to homogeneity from plants, recent progress in this area sugge sts that this will soon be accomplished.