Figure 5.

Amino-terminally Truncated forms of IpgC Retain Chaperone Activity for IpaB. Full-length and various truncated forms of IpgC were coexpressed with IpaB^58-357 in recombinant strains of E. coli. Following induction of protein expression, cells were harvested, lysed, and the soluble extracts thereof were subjected to a copurification protocol to assess the ability of IpgC to bind IpaB. SDS-PAGE was used to analyze various protein samples following each step of copurification: M, protein molecular weight standards; E, clarified cellular extract following microfluidization and centrifugation; N, pooled elute following Ni²⁺-Sepharose chromatography; G, pooled fractions of the complex following gel-filtration chromatography. Since IpaB accumulates in inclusion bodies in the absence of IpgC activity[5], and since the untagged IpaB lacks the ability to bind Ni²⁺-NTA Sepharose on its own[20], all four IpgC proteins used in this study maintain chaperone activity.