4.D.3.1.6
Core cellulose synthase complex, BcsA/BcsB (Morgan et al. 2013; Omadjela et al. 2013).  BcsA (YhjO) is an 10 - 12 TMS protein with 4 N-terminal TMSs, the glycosyl transferase domain and 4 C-terminal TMSs.  It is believed to both synthesize the glycosyl linkages and transport the polysaccharide across the membrane (Römling and Galperin 2015).  BcsB (YhjN) is a cellulose synthase regulator, a cyclic diGMP binding protein, with two TMSs at the N- and C-termini and the bulk of the protein in the periplasm.  BcsC (TC# 1.B.55.3.1) is the outer membrane porin for the export of cellulose with an N-terminal α-TMS, a large N-terminal hydrophylic domain, and a C-terminal β-barrel domain.  Two other proteins, an endoglucanase, BscZ or YhjM, and a diguanylate cyclase, YedQ (TC# 9.B.34.1.4) may play roles in cellulose biosynthesis (Imai et al. 2014).  Cellulose is a component of the bacterial extracellular matrix (Zogaj et al. 2001) and plays roles in biofilm formation and cell adhesion (Hu et al. 2015).