Fusion to an Endoglucanase Allows Alkaline Phosphatase to Bind to Cellulose

Endoglucanase CenA of Cellulomonas fimi comprises an N-terminal cellulose-binding domain and a C-terminal catalytic domain joined together by a sequence of 23 proline and threonine residues (the Pro-Thr box). The domains function independently when separated by proteolysis. TnphoA has been used to generate cenA'-'phoA fusions. CenA'-'PhoA fusion polypeptides which contain the entire cellulose-binding domain of CenA bind to cellulose, allowing their purification from periplasmic extracts in a single, facile step. This result has implications for purification or immobilisation of chimeric proteins on a cheap cellulose matrix.