An unusual tandem‐domain rhodanese harbouring two active sites identified in Desulfitobacterium hafniense

• Published in: The FEBS journal Vol. 279; no. 15; pp. 2754 - 2767
• Main Authors: Prat, Laure, Maillard, Julien, Rohrbach‐Brandt, Emmanuelle, Holliger, Christof
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-08-2012
• Subjects: Amino Acid Sequence; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Catalytic Domain - genetics; Desulfitobacterium; Desulfitobacterium - enzymology; Desulfitobacterium - genetics; Genes, Bacterial; Molecular Sequence Data; Multigene Family; Operon; Protein Structure, Tertiary; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Sequence Homology, Amino Acid; sulfide; Sulfur - metabolism; sulfur‐transferase; tandem‐domain rhodanese; Thiosulfate Sulfurtransferase - chemistry; Thiosulfate Sulfurtransferase - genetics; Thiosulfate Sulfurtransferase - metabolism
• ISSN: 1742-464X; 1742-4658
• DOI: 10.1111/j.1742-4658.2012.08660.x

The rhodanese protein domain is common throughout all kingdoms of life and is characterized by an active site cysteine residue that is able to bind sulfane sulfur and catalyse sulfur transfer. No unique function has been attributed to rhodanese‐domain‐containing proteins, most probably because of their diversity at both the level of sequence and protein domain architecture. In this study, we investigated the biochemical properties of an unusual rhodanese protein, PhsE, from Desulfitobacterium hafniense strain TCE1 which we have previously shown to be massively expressed under anaerobic respiration with tetrachloroethene. The peculiarity of the PhsE protein is its domain architecture which is constituted of two rhodanese domains each with an active site cysteine. The N‐terminal rhodanese domain is preceded by a lipoprotein signal peptide anchoring PhsE on the outside of the cytoplasmic membrane. In vitro sulfur‐transferase activity of recombinant PhsE variants was measured for both domains contrasting with other tandem‐domain rhodaneses in which usually only the C‐terminal domain has been found to be active. The genetic context of phsE shows that it is part of a six‐gene operon displaying homology with gene clusters encoding respiratory molybdoenzymes of the PhsA/PsrA family, possibly involved in the reduction of sulfur compounds. Our data suggest, however, that the presence of sulfide in the medium is responsible for the high expression of PhsE in Desulfitobacterium, where it could play a role in the sulfur homeostasis of the cell.
Rhodanese proteins are characterized by active site cysteines able to catalyze sulfur transfer. We report on the genetic and biochemical characterization of an unusual tandem‐domain rhodanese, PhsE, from Desulfitobacterium hafniense: PhsE is lipoprotein facing the outside of the cell, presents two catalytically active sites, and is encoded within an operon belonging to the molybdoenzymes family