Primary Citation of Related Structures: 1JNR, 1JNZ
PubMed Abstract:
The iron-sulfur flavoenzyme adenylylsulfate (adenosine 5'-phosphosulfate, APS) reductase catalyzes reversibly the reduction of APS to sulfite and AMP. The structures of APS reductase from the hyperthermophilic Archaeoglobus fulgidus in the two-electron reduced state and with sulfite bound to FAD are reported at 1 ...
The iron-sulfur flavoenzyme adenylylsulfate (adenosine 5'-phosphosulfate, APS) reductase catalyzes reversibly the reduction of APS to sulfite and AMP. The structures of APS reductase from the hyperthermophilic Archaeoglobus fulgidus in the two-electron reduced state and with sulfite bound to FAD are reported at 1.6- and 2.5- resolution, respectively. The FAD-sulfite adduct was detected after soaking the crystals with APS. This finding and the architecture of the active site strongly suggest that catalysis involves a nucleophilic attack of the N5 atom of reduced FAD on the sulfur atom of APS. In view of the high degree of similarity between APS reductase and fumarate reductase especially with regard to the FAD-binding alpha-subunit, it is proposed that both subunits originate from a common ancestor resembling archaeal APS reductase. The two electrons required for APS reduction are transferred via two [4Fe-4S] clusters from the surface of the protein to FAD. The exceptionally large difference in reduction potential of these clusters (-60 and -500 mV) can be explained by interactions of the clusters with the protein matrix.
Related Citations:
Crystallization and preliminary X-ray analysis of adenylylsulfate reductase from Archaeoglobus fulgidus Roth, A., Fritz, G., Buechert, T., Huber, H., Stetter, K.O., Ermler, U., Kroneck, P.M.H. (2000) Acta Crystallogr D Biol Crystallogr 56: 1673
Organizational Affiliation:
Fachbereich Biologie, Mathematisch-Naturwissenschaftliche Sektion, Universität Konstanz, Fach M665, D-78457 Konstanz, Germany.
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