The cellulose synthase gene of Dictyostelium

Cellulose is a major component of the extracellular matrices formed during development of the social amoeba, Dictyostelium discoideum. We isolated ins ertional mutants that failed to accumulate cellulose and had no cellulose s ynthase activity at any stage of development. Development proceeded normall y in the null mutants up to the beginning of stalk formation, at which poin t the culminating structures collapsed onto themselves, then proceeded to a ttempt culmination again. No spores or stalk cells were ever made in the mu tants, with all cells eventually lysing. The predicted product of the disru pted gene (dcsA) showed significant similarity to the catalytic subunit of cellulose synthases found in bacteria, Enzyme activity and normal developme nt were recovered in strains transformed with a construct expressing the in tact dcsA gene. Growing amoebae carrying the construct accumulated the prot ein product of dcsA, but did not make cellulose until they had developed fo r at least in hr, These studies show directly that the product of dcsA is n ecessary, but not sufficient, for synthesis of cellulose.