Expression of Giardia duodenalis beta-tubulin as a soluble protein in Escherichia coli

The beta -tubulin gene of the parasitic protozoan Giardia dia duodenalis ha s been expressed for the first time using a novel and direct method. The pr otein was expressed in both soluble and insoluble forms in an Escherichia c oli-based expression system. The level of expression was found to be affect ed by several variables including the incubation temperature, length of tim e for which expression was carried out, and the E. coli culture volume. The protein expression system contributed no additional amino acids to the fin al fusion protein and the polyhistidine fusion sequence was easily removed from the beta -tubulin protein using a specific enterokinase enzyme. The ex pression system also provided a means of preparing a soluble protein and pu rifying it by a relatively straightforward affinity chromatography method t o give a very high level of protein purity. This makes the protein suitable for a number of applications for characterization including beta -tubulin antibody assays, alpha-/beta -tubulin-binding regions, and beta -tubulin fo lding intermediates. (C) 2001 Academic Press.