Crystallization and preliminary X-ray analysis of adenylylsulfate reductase from Archaeoglobus fulgidus

A group of anaerobic microorganisms use sulfate as the terminal electron ac ceptor for energy conservation. The process of sulfate reduction involves s everal enzymatic steps. One of them is the conversion of adenylyl sulfate ( adenosine-5'-phosphosulfate) to sulfite, catalyzed by adenylylsulfate reduc tase. This enzyme is composed of a FAD-containing alpha -subunit and a beta -subunit harbouring two [4Fe-4S] clusters. Adenylylsulfate reductase was i solated from Archaeoglobus fulgidus under anaerobic conditions and crystall ized using the hanging-drop vapour-diffusion method using PEG 4000 as preci pitant. The crystals grew in space group P2(1)2(1)2(1), with unit-cell para meters a = 72.4, b = 113.2, c = 194.0 Angstrom. The asymmetric unit probabl y contains two alpha beta units. The crystals diffract beyond 2 Angstrom re solution and are suitable for X-ray structure analysis.