crystallization communications
The bacterial ATP synthase (FOF1) of Escherichia coli has been the prominent model system for genetics, biochemical and more recently single-molecule studies on F-type ATP synthases. With 22 total polypeptide chains (total mass of ∼529 kDa), E. coli FOF1 represents nature's smallest rotary motor, composed of a membrane-embedded proton transporter (FO) and a peripheral catalytic complex (F1). The ATPase activity of isolated F1 is fully expressed by the α3β3γ `core', whereas single δ and subunits are required for structural and functional coupling of E. coli F1 to FO. In contrast to mitochondrial F1-ATPases that have been determined to atomic resolution, the bacterial homologues have proven very difficult to crystallize. In this paper, we describe a biochemical strategy that led us to improve the crystallogenesis of the E. coli F1-ATPase catalytic core. Destabilizing the compact conformation of 's C-terminal domain with a phosphomimetic mutation (S65D) dramatically increased crystallization success and reproducibility, yielding crystals of E. coli F1 that diffract to ∼3.15 Å resolution.