ISSN:
1433-4909
Keywords:
Key words Dissimilatory sulfite reductase
;
Archaeoglobus profundus
;
Desulfotomaculum thermocisternum
;
Sequence analysis
;
Phylogenetic analysis
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The genes encoding the α- and β-subunits of dissimilatory sulfite reductase, dsrAB, from the hyper-thermophilic archaeon Archaeoglobus profundus and the thermophilic gram-positive bacterium Desulfotomaculum thermocisternum were cloned and sequenced. The dsrAB genes are contiguous, and most probably comprise an operon also including a dsrD homolog, a conserved gene of unknown function located downstream of dsrAB in all four sulfate reducers so far sequenced. Sequence comparison confirms that dissimilatory sulfite reductase, Dsr, is a highly conserved enzyme. A phylogenetic analysis using the available Dsr sequences, including Dsr-like proteins from nonsulfate reducers, suggests a paralogous origin of the α- and β-subunits. Furthermore, the Dsr from sulfate reducers forms a separate cluster, with Dsr from the bacterial sulfate reducers Desulfotomaculum thermocisternum and Desulfovibrio vulgaris branching together, next to Dsr from Archaeoglobus profundus and Archaeoglobus fulgidus. Based on an alignment with the assimilatory sulfite reductase from Escherichia coli, the amino acid residues involved in binding of sulfite, siroheme, and [Fe4S4]-clusters have been tentatively identified, which is consistent with the binding of two sirohemes and four [Fe4S4]-clusters per α2β2 structure. The evolution of Dsr and the structural basis for the binding of substrate and cofactors are discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s007920050100
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