InterPro

An operon encoding 4 proteins required for bacterial cellulose biosynthesis (bcs) in Acetobacter xylinus (Gluconacetobacter xylinus) has been isolated via genetic complementation with strains lacking cellulose synthase activity [PMID: 2146681]. Nucleotide sequence analysis showed the cellulose synthase operon to consist of 4 genes, designated bcsA, bcsB, bcsC and bcsD, all of which are required for maximal bacterial cellulose synthesis in A. xylinum.

The calculated molecular mass of the protein encoded by bcsA is 84.4kDa [PMID: 2146681]. Sequence analysis suggests that the gene product is an integral membrane protein with several transmembrane (TM) domains [PMID: 2151718]. It is postulated that the protein is anchored in the membrane at the N-terminal end by a single hydrophobic helix. Two potential N-glycosylation sites are predicted from sequence analysis, consistent with earlier observations that BcsA is a glycoprotein. The function of BcsA is unknown. The sequence shares a high degree of similarity with Escherichia coli YhjO.

Cellulose synthase catalyzes the beta-1,4 polymerisation of glucose residues in the formation of cellulose. In bacteria, the substrate is UDP-glucose. The synthase consists of two subunits (or domains in the frequent cases where it is encoded as a single polypeptide), the catalytic domain modelled here and the regulatory domain (PF03170). The regulatory domain binds the allosteric activator cyclic di-GMP [PMID: 16920715, PMID: 18034161]. The protein is membrane-associated and probably assembles into multimers such that the individual cellulose strands can self-assemble into multi-strand fibrils.