cellulase and dichlobanil

Cellulose synthesis in plants requires beta-1,4-glucan chain initiation, elongation, and termination. The process of chain elongation is likely to be distinct from the process of chain initiation. We demonstrate that a CesA glucosyltransferase initiates glucan polymerization by using sitosterol-beta-glucoside (SG) as primer. Cotton fiber membranes synthesize sitosterol-cellodextrins (SCDs) from SG and uridine 5'-diphosphate-glucose (UDP-Glc) under conditions that also favor cellulose synthesis. The cellulase encoded by the Korrigan (Kor) gene, required for cellulose synthesis in plants, may function to cleave SG from the growing polymer chain.

Topics: Arabidopsis Proteins; Calcium; Cell Wall; Cellobiose; Cellulase; Cellulose; Dextrins; Egtazic Acid; Glucans; Glucose; Glucosyltransferases; Gossypium; Herbicides; Membrane Proteins; Nitriles; Recombinant Proteins; Sitosterols; Uridine Diphosphate Glucose; Yeasts

The biochemical analysis of cellulose biosynthesis by plants has been a difficult problem due to the lack of a reliable assay procedure for cellulose synthase activity. Recently, the celA1 gene was cloned from cotton fiber, and this gene was identified from the rsw1 mutant of Arabidopsis as a catalytic subunit of cellulose synthase (Arioli et al. 1998). The cloning of these genes enables us to obtain specific antibodies against cellulose synthase. A highly specific antibody against celA1 protein was prepared and used to detect the protein from microsomal fraction of tobacco BY-2 cells. The quantity of celA1 protein in microsomal fraction of normal BY-2 cells was under the detection limit, although they contained a large quantity of cellulose. In contrast, cells habituated to 1 microM DCB (a specific inhibitor of cellulose biosynthesis) produced 1/10 of cellulose content of the normal cells, but had much more celA1 protein than the normal cells. The amount of polysaccharides in the EDTA-soluble fraction was relatively increased in habituated cells. The results suggest that celA1 protein is stabilized upon DCB binding and that the crystallization of cellulose microfibrils is inhibited simultaneously.

Topics: Amino Acid Sequence; Blotting, Western; Cell Line; Cell Wall; Cellulase; Cellulose; Molecular Sequence Data; Nicotiana; Nitriles; Plants, Toxic; Sequence Homology, Amino Acid