Cloning, expression, purification, crystallization and preliminary X-ray diffraction analysis of 2-keto-3-deoxy-6-phosphogluconate aldolase from Zymomonas mobilis ZM4

Abstract

Zymomonas mobilis ZM4 is an organism optimized for ethanol production which uses the Entner-Doudoroff (ED) pathway for the breakdown of glucose. The key enzyme in this process is 2-keto-3-deoxy-6-phosphogluconate (KDPG) aldolase, which produces glyceraldehyde 3-phosphate and pyruvate. In order to provide a molecular background for the KDPG aldolase from this ethanologenic organism (zmKDPG aldolase), the ZMO0997 gene of Z. mobilis ZM4 coding for zmKDPG aldolase was cloned and expressed and the purified protein was crystallized from 25%(w/v) polyethylene glycol 3350 and 0.1 M bis-tris pH 5.5. Diffraction data were collected to 1.8 A resolution using synchrotron radiation. The crystal belonged to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 63.7, b = 83.0, c = 117.2 A. A trimeric zmKDPG aldolase molecule was present in the asymmetric unit, resulting in a crystal volume per unit protein weight of 2.40 A3 Da-1 and a solvent content of 48%.