Purification of AatAF after expression in E. coli BL21. The internal part of aatA encoding the passenger domain of AatA was cloned into pET32a(+) leading to the expression of the 64-kDa fusion protein AatAF. BL21 cells were incubated in LB at 37°C without (lane 1) or with (lane 3) addition of IPTG. Proteins of total extracts (lane 1 and 3) and of eluates of the purified AatAF (lane 4) were separated on an SDS-PAGE and stained with coomassie. TE: total extract, -: without IPTG, +: with IPTG; M: protein marker.