FIG. 4.

DnaB intein activity and AIP-I purification. (A) A DHFR protein fusion was used to test DnaB activity. Plasmids pDnaB8, pDnaB8-DHFR, and pET22-bsDHFR were expressed in strain AH394 with or without IPTG induction as indicated. Overexpressed bands corresponding to intein-CBD, DHFR-intein-CBD, and DHFR are shown. (B) Samples of an iAIP-I purification were separated by SDS-PAGE and probed with CBD antibody (shown on top). Gel lanes are as follows: SM, size marker; Un, uninduced; Ind, induced; FT-1, early flowthrough sample; FT-2, late flowthrough sample; resin, chitin resin.