Isolation of an Active Catalytic Core of Streptococcus downei MFe28 GTF-I Glucosyltransferase

Truncated variants of GTF-I from Streptococcus downei MFe28 were purified by means of a histidine tag. Sequential deletions showed that the C-terminal domain was not directly involved in the catalytic process but was required for primer activation. A fully active catalytic core of only 100 kDa was isolated.