Enhancement of chaperone activity of M. leprae HSP18 induced by ATP and its non-hydrolysable analog, ATP-γS.

Thermal aggregation of 0.06 mg/ml CS at 43°C (panel A) and DTT-induced aggregation of 0.05 mg/ml lysozyme at 37°C (panel B) in the absence or presence of different HSP18 preparations. Trace 1:Client protein (CP) alone; Trace 2: CP + 1 mM ATP; Trace 3: CP + 1 mM ATP-γS; Trace 4: CP+ HSP18; Trace 5: CP + HSP18 preincubated with 1 mM ATP; Trace 6: CP + HSP18 preincubated with 1 mM ATP-γS. Each data point is the average of triplicate measurements. Panels C and D represents the percent protection ability of different HSP18 preparations against CS and lysozyme aggregation. The chaperone:client protein ratio was 1:1 (w/w) for CS and lysozyme aggregation assays. Data are the means ± standard deviation from triplicate measurements. **p< 0.005 and ***p<0.0005.