Asp52 in Combination with Asp398 Plays a Critical Role in ATP Hydrolysis of Chaperonin GroEL [Protein Synthesis and Degradation]

September 8th, 2014 by Koike-Takeshita, A., Mitsuoka, K., Taguchi, H.

The Escherichia coli chaperonin GroEL is a double-ring chaperone that assists in protein folding with the aid of GroES and ATP. Asp398 in GroEL is known as one of the critical residues on ATP hydrolysis because GroEL(D398A) mutant is deficient in ATP hydrolysis (< 2% of the wild type) but not in ATP binding. In the archaeal Group II chaperonin, another aspartate residue, Asp52 in corresponding E. coli GroEL, in addition to Asp398, is also important for ATP hydrolysis. Then we investigated the role of Asp52 in GroEL, and found that ATPase activity of GroEL(D52A) and GroEL(D52A/D398A) mutants were ~20% and < 1% of wild type GroEL, respectively, indicating that Asp-52 in E. coli GroEL is also involved in the ATP hydrolysis. GroEL(D52A/D398A) formed a symmetric football-shaped GroEL-GroES complex in the presence of ATP, confirming again the importance of the symmetric complex during GroEL ATPase cycle. Notably, the symmetric complex of GroEL(D52A/D398A) was extremely stable, with a half-time of ~150 h (~6 days), providing a good model to characterize the football-shaped complex.