Crystallization and preliminary X-ray analysis of a bacterial psychrophilic enzyme, phosphoglycerate kinase

The glycolytic enzyme phosphoglycerate kinase (PGK) from the Antarctic micr oorganism Pseudomonas sp. TACII18 is a cold-adapted enzyme that displays a high specific activity at low temperatures and decreased thermostability re lative to its mesophilic counterpart. Herein, the preliminary crystallizati on and structure solution of psychrophilic PGK in its native form and cocry stallized with 3-phosphoglyceric acid (3-PGA) and the ATP analogue adenylyl imidophosphate (AMP-PNP) is reported. The complexed form of PGK crystalliz ed in 2-3 d at 290 K, whereas the native form of the enzyme required 8-12 m onths. Morphologically, both crystal forms are similar and X-ray diffractio n experiments indicate that the crystals are isomorphous. The crystals diff racted to a resolution of 2.0 Angstrom and belong to the space group P3(2). with unit-cell parameters a = b = 58.5, c = 85.4 Angstrom.