Purification and characterization of a membrane-bound enzyme complex from the sulfate-reducing archaeon Archaeoglobus fulgidus related to heterodisulfide reductase from methanogenic archaea

A Post-Genomic View of the Ecophysiology, Catabolism and Biotechnological Relevance of Sulphate-Reducing Prokaryotes

“…DsrK is homologous to the HdrD catalytic subunit that binds a special [4Fe-4S] 3+ centre, which is the centre responsible for heterodisulphide reduction . This characteristic FeS centre was also detected in A. fulgidus and D. desulfuricans DsrK (Mander et al, 2002;Pires et al, 2006). A cysteine-rich domain (also referred to as the CCG domain) contains the conserved sequence CX n CCGX m CXXC that binds the [4Fe-4S] 3+ centre (Hamann et al, 2007).…”

“…The identification of the electron donors to these two terminal reductases has been a long-standing question in the SRP field, whose elucidation is essential for the understanding of SRP bioenergetics. Two membrane complexes, the QmoABC complex (Pires et al, 2003) and the DsrMKJOP complex (Mander, Duin, Linder, Stetter, & Hedderich, 2002;Pires et al, 2006) (Tables 2 and 3), are conserved across SRP , and there is compelling evidence for their involvement in the electron transfer to AprBA and DsrAB/ DsrC, respectively (Grein et al, 2013;Ramos et al, 2012;Pereira, 2008). These complexes are characteristic of microorganisms that dissimilate sulphur compounds, being present also in many SOB where, unlike SRP, more than one possible pathway for oxidation of a given sulphur compound exists (Frigaard & Dahl, 2009).…”

“…The DsrMKJOP complex is the second conserved membrane complex of SRP (Grein et al, 2013;Mander et al, 2002;Pereira et al, 2007Pereira et al, , 2011Pires et al, 2006). In many Gram-positive SRP (and also C. maquilingensis and T. tenax), only the cytoplasmic-facing dsrMK genes are present, suggesting that this is the minimally functional module ( Junier et al, 2010;Pereira et al, 2011).…”

“…The main exception to this is the genus Desulfosporosinus (Pester, Brambilla, et al, 2012), members of which have a complete set of dsrMKJOP genes, and curiously have several copies of the dsrJ gene, in contrast to other SRP. The Dsr complex was first isolated from the archaeon A. fulgidus (where it was named Hme for Hdr-like menaquinol-oxidizing enzyme) (Mander et al, 2002), and later from D. desulfuricans ATCC 27774 (Pires et al, 2006). The Dsr complex comprises two periplasmic subunits (the membrane-anchored trihaem cytochrome c DsrJ (Grein, Venceslau, et al, 2010;Pires et al, 2006) and the Fe-S protein DsrP), two membrane proteins (the dihaem cytochrome b DsrM and DsrP) and a cytoplasmic protein (the Fe-S protein DsrK).…”

A variant System I for cytochrome c biogenesis in archaea and some bacteria has a novel CcmE and no CcmH

“…(i) Each archaeon containing this unusual cysteine form of CcmE contains the gene for at least one probable c-type cytochrome (see below). Some cytochromes c from these archaea have been purified or studied biochemically [18][19][20][21], so must have been handled by a functional biogenesis apparatus. (ii) No other known cytochrome c maturation proteins are present in these archaeal genomes.…”