Hydrolytic effects of scaffolding proteins CbpB and CbpC on crystalline cellulose mediated by the major cellulolytic complex from Clostridium cellulovorans

• The scaffolding protein, CbpB and CbpC bind cell surface of C. cellulovorans.
• The CbpB and CbpC complex leads to increase crystalline cellulose hydrolysis.
• The mixture of CbpB and CbpC complex with CbpA complex induces to synergy effect.
• CbpC complex efficient hydrolyze released substrate after CbpA complex degradation.

The role of the scaffolding proteins, cellulose binding protein B and C (CbpB and CbpC, respectively) were identified in cellulolytic complex (cellulosome) of Clostridium cellulovorans for efficient degradation of cellulose. Recombinant CbpB and CbpC directly anchored to the cell surface of C. cellulovorans. In addition, CbpB and CbpC showed increased hydrolytic activity on crystalline cellulose incubated with exoglucanase S (ExgS) and endoglucanase Z (EngZ) compared with the activity of free enzymes. Moreover, the results showed synergistic effects of crystalline cellulose hydrolytic activity (1.8- to 2.2-fold) when CbpB and CbpC complex with ExgS and EngZ are incubated with cellulolytic complex containing mini-CbpA. The results suggest C. cellulovorans critically uses CbpB and CbpC, which can directly anchor cells for the hydrolysis of cellulosic material with the major cellulosome complex.