Choline-binding domain as a novel affinity tag for purification of fusion proteins produced in Pichia pastoris.

The choline-binding domain (ChoBD) of the carboxy-terminal region of the Streptococcus pneumoniae amidase LYTA (C-LYTA) presents a strong affinity for tertiary amines. We report a method for single-step purification of proteins expressed in the methylotrophic yeast Pichia pastoris based on the fusion of C-LYTA to the protein of interest. We show that C-LYTA can be efficiently expressed and secreted in this host. Tagged proteins fused to this binding domain can be purified on inexpensive DEAE matrices. It therefore provides a useful system for the purification of recombinant proteins with high specificity suitable for industrial purposes. Copyright 2001 John Wiley & Sons, Inc.