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

A group of anaerobic microorganisms use sulfate as the terminal electron acceptor for energy conservation. The process of sulfate reduction involves several enzymatic steps. One of them is the conversion of adenylyl sulfate (adenosine-5'-phosphosulfate) to sulfite, catalyzed by adenylylsulfate reductase. This enzyme is composed of a FAD-containing alpha-subunit and a beta-subunit harbouring two [4Fe-4S] clusters. Adenylylsulfate reductase was isolated from Archaeoglobus fulgidus under anaerobic conditions and crystallized using the hanging-drop vapour-diffusion method using PEG 4000 as precipitant. The crystals grew in space group P2(1)2(1)2(1), with unit-cell parameters a = 72.4, b = 113.2, c = 194.0 A. The asymmetric unit probably contains two alphabeta units. The crystals diffract beyond 2 A resolution and are suitable for X-ray structure analysis.