Genetics, Mechanism, and Regulation of Cellulose Synthesis in A. tumefaciens

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Incubation of Agrobacterium tumefaciens with host cells results in synthesis by the bacteria of cellulose fibrils. These fibrils serve to anchor the bacteria firmly to the host cell surface. Using transposon mutants which are unable to synthesize cellulose, the genes required for cellulose synthesis are being identified and characterized. The subcellular localization of these gene products and the steps involved in cellulose synthesis are being determined and the regulation of bacterial cellulose synthesis by the presence of host cells examined. Although there is some information available on the mechanism of cellulose synthesis, there is little knowledge of the genes and gene products involved in its synthesis in any organism. In addition, cellulose synthesis in A. tumefaciens is an interesting example of the regulation of the synthesis of an exopolysaccharide involved in bacterial adhesion by the presence of the host cells to which the bacteria bind. Cellulose is the most abundant polymer in the cell walls of higher plants and is of enormous importance globally. Other organisms (besides higher plants) are also capable of synthesizing cellulose and are more amendable to biochemical and molecular manipulation. The plant pathogen, Agrobacterium tumefaciens, synthesizes cellulose which appears to play an important role in its interaction with its host. There is very little information available about the mechanism of cellulose synthesis in any system and almost nothing is known of the genes involved or their regulation. A. tumefaciens provides a good system in which to examine the mechanisms and genes required for cellulose synthesis not only in this organism, but higher plants as well.