Cloning of cellulose synthase genes from Acetobacter xylinum JCM 7664: implication of a novel set of cellulose synthase genes

Three sets of cellulose synthase genes were cloned from a cellulose-producing bacterium Acetobacter xylinum JCM 7664. One set of genes (bcsAI/bcsBI/bcsCI/bcsDI) were highly conserved with the well-established type I genes in other strains of A. xylinum, while the other two (bcsABII-A, bcsABII-B) were homologous to the known type II (acsAII). Unexpectedly, they were immediately followed by a gene cluster of bcsX/bcsY/bcsCII/ORF569, likely forming an operon. Western blotting demonstrated that the BcsY protein accumulated in cells. Since BcsY showed striking similarities to a number of membrane-bound transacylases, it was hypothesized that the type II cellulose synthase produces acylated cellulose, which might be anchored on the cytoplasmic membrane. An insertion sequence of IS1380-type was found just upstream of the one type II gene (bcsABII-B), suggestive of nonfunctioning.