Crystallization of acetate kinase from Methanosarcina thermophila and prediction of its fold

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Abstract
The unique biochemical properties of acetate kinase present a classic conundrum in the study of the mechanism of enzyme‐catalyzed phosphoryl transfer. Large, single crystals of acetate kinase from Methanosarcina thermophila were grown from a solution of ammonium sulfate in the presence of ATP. The crystals diffract to beyond 1.7 Å resolution. Analysis of X‐ray data from the crystals is consistent with a space group of C2 and unit cell dimensions a = 181 Å, b = 67 Å, c = 83 Å, β = 103°. Diffraction data have been collected from the crystals at 110 and 277 K. Data collected at 277 K extend to lower resolution, but are more reproducible. The orientation of a noncrystallographic twofold axis of symmetry has been determined. Based on an analysis of the predicted amino acid sequences of acetate kinase from several organisms, we hypothesize that acetate kinase is a member of the sugar kinase/actin/hsp70 structural family.