title: Molecular dissection of a putative iron reductase from Desulfotomaculum reducens MI-1.
abstract: Desulfotomaculum reducens MI-1 is a Firmicute strain capable of reducing a variety of heavy metal ions and has a great potential in heavy metal bioremediation. We recently identified Dred_2421 as a potential iron reductase through proteomic study of D. reducens. The current study examines its iron-reduction mechanism. Dred_2421, like its close homolog from Escherichia coli (2, 4-dienoyl-CoA reductase), has an FMN-binding N-terminal domain (NTD), an FAD-binding C-terminal domain (CTD), and a 4Fe-4S cluster between the two domains. To understand the mechanism of the iron-reduction activity and the role of each domain, we generated a series of variants for each domain and investigated their iron-reduction activity. Our results suggest that CTD is the main contributor of the iron-reduction activity, and that NTD and the 4Fe-4S cluster are not directly involved in such activity. This study provides a mechanistic understanding of the iron-reductase activity of Dred_2421 and may also help to elucidate other physiological activities this enzyme may have.
authors.affiliation: Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Li
authors.affiliation: Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.
authors.forename: David D
authors.initials: DD
authors.lastname: Kim
authors.affiliation: Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Ornella D
authors.initials: OD
authors.lastname: Nelson
authors.affiliation: Department of Microbiology, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Anne E
authors.initials: AE
authors.lastname: Otwell
authors.affiliation: School of Civil and Environmental Engineering, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Ruth E
authors.initials: RE
authors.lastname: Richardson
authors.affiliation: Pacific Northwest National Laboratory, Richland, WA 99354, USA.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Callister
authors.affiliation: Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA; Howard Hughes Medical Institute, USA. Electronic address: hl379@cornell.edu.
authors.forename: Hening
authors.initials: H
authors.lastname: Lin
mesh_terms: D045859:Desulfotomaculum / Q000201:enzymology*; D038181:FMN Reductase / Q000235:genetics / Q000378:metabolism*
chemical_list: D038181:FMN Reductase; C023903:ferric citrate iron reductase
keywords: Desulfotomaculum; Iron reduction; NADH; NADH:Flavin oxidoreductase; Old yellow enzymes; pfam00724