Overproduction, Purification and Characterization of the Cellulose‐Binding Domain of the Erwinia Chrysanthemi Secreted Endoglucanase EGZ

EGZ is the major endoglucanase secreted by Erwinia chrysanthemi. Functional characterization indicates that it is made of a catalytic N-terminal domain linked to a C-terminal cellulose-binding domain (CBD) by a Ser/Thr-rich linker. A chimeric plasmid, in which the CBD-encoding region was fused downstream of the ompA signal sequence, was constructed and introduced into Escherichia coli. This allowed for the production of processed and disulfide-bonded CBD, mostly recovered from the culture supernatant of E. coli. One-dimensional NMR analysis of the purified CBD reveals that it folds into a well-structured domain. Moreover, comparison with the one-dimensional NMR analysis of full-length EGZ strongly suggests that the CBD folds autonomously, providing experimental support for the existence of domains of EGZ.