INTERRING COMMUNICATION IS DISRUPTED IN THE GROEL MUTANT ARG13-]GLY, ALA126-]VAL WITH KNOWN CRYSTAL-STRUCTURE

The crystal structures of the chaperonin GroEL Arg13 --> Gly; Ala126 - -> Val double mutant, without and in complex with ATP gamma S, have be en determined at atomic resolution. Here, we show that the double muta tion Arg13 --> Gly; Ala126 --> Val disrupts negative co-operativity be tween GroEL rings, with respect to ATP, but has little effect on the p ositive co-operativity within each ring. Our results help to explain w hy the double mutation facilitated the crystallization of GroEL and wh y breaking of dyad symmetry between rings is not observed in crystal s tructures of this mutant. Our results may also help to explain why the observed structural differences between the GroEL double mutant and i ts ATP gamma S-bound form are small. (C) 1996 Academic Press Limited