FIG. 4.

Protection from proteolytic cleavage of the DNase by Im9. The lux induction assay was used to show that Im9-complexed YZ25 was not cleaved (A), whereas Im9-free YZ25 was cleaved by EK after binding to BtuB (B). The luminescence of cultures of E. coli DPD1718 treated with oxidized YZ25/Im9 (A) or free YZ25 (B), followed by EK treatment for 30 min (⧫) or 60 min (▴), and then immediately reduced with 1 mM DTT was compared to that of E. coli DPD1718 treated with oxidized YZ25/Im9 or free YZ25 without EK treatment but reduced with 1 mM DTT after 30 min (▪) or 60 min (×). The luminescence of E. coli DPD1718 cells treated with oxidized YZ25/Im9 (A) or YZ25 (B) and then trypsin treatment for 30 min, followed by reduction with 1 mM DTT (+), and cells with no addition (−) is shown. Arrows indicate the addition of DTT at 30 and 60 min, respectively.