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Literature summary for 1.8.7.1 extracted from

  • Walters, K.A.; Golbeck, J.H.
    Expression, purification and characterization of an active C491G variant of ferredoxin sulfite reductase from Synechococcus elongatus PCC 7942 (2018), Biochim. Biophys. Acta, 1859, 1096-1107 .
    View publication on PubMed
Search for more literature for 1.8.7.1

Cloned(Commentary)

Cloned (Comment) Organism
gene sir, expression from genomic DNA, wild-type FdSiR (FdSiRWT) and a mutant C491G (FdSiRC491G) are cloned from Synechococcus elongatus PCC 7942 and coexpressed with the cysG gene encoding siroheme synthase from Salmonella typhimurium using the pCDFDuet plasmid in Escherichia coli strain BL21(DE3) as His-tagged proteins. Recombinant expression of Synechococcus elongatus PCC 7942 ferredoxin 1 (Fd1) Synechococcus elongatus

Protein Variants

Protein Variants Comment Organism
C491G site-directed mutagenesis, the mutant shows a lower rate of H2S evolution compared to wild-type likely related to its lower cofactor content. The mutagenesis of this Cys residue to a Gly opens an exchangeable coordination site to a corner iron atom that can be chemically rescued by an external thiolate ligand. This ligand can be subsequently displaced by mass action using a dithiol molecular wire to tether two redox active proteins. Application of this technique to tethering Photosystem I to ferredoxin sulfite reductase (FdSiR). UV/Vis absorbance spectra of both FdSiRWT and the FdSiRC491G variant display characteristic peaks at 278, 392 (Soret), 585 (alpha) and 714 nm (charge transfer band), and 278, 394 (Soret), 587 (alpha) and 714 nm (charge transfer band) respectively. Both enzymes in their as-isolated forms display an EPR spectrum characteristic of an S=5/2 high spin heme. When reduced, both enzymes exhibit the signal of a low spin S=1/2 [4Fe-4S]1+ cluster. The FdSiRWT and FdSiRC491G variant both show activity using reduced methyl viologen and Synechococcus elongatus PCC 7942 ferredoxin 1 (Fd1) as electron donors. Based on these results, the FdSIRC491G variant should be a suitable candidate for wiring to Photosystem I Synechococcus elongatus

Metals/Ions

Metals/Ions Comment Organism Structure
Fe2+ in Fe-S centers, determination of non-heme iron content of FdSiR Synechococcus elongatus

Molecular Weight [Da]

Molecular Weight [Da] Molecular Weight Maximum [Da] Comment Organism
70000
-
 about, recombinant enzyme, gel fitration Synechococcus elongatus

Natural Substrates/ Products (Substrates)

Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
hydrogen sulfide + 6 oxidized ferredoxin [iron-sulfur] cluster + 3 H2O Synechococcus elongatus
-
 sulfite + 6 reduced ferredoxin [iron-sulfur] cluster + 6 H+
-
 ?
hydrogen sulfide + 6 oxidized ferredoxin [iron-sulfur] cluster + 3 H2O Synechococcus elongatus FACHB-805
-
 sulfite + 6 reduced ferredoxin [iron-sulfur] cluster + 6 H+
-
 ?
hydrogen sulfide + 6 oxidized ferredoxin [iron-sulfur] cluster + 3 H2O Synechococcus elongatus PCC 7942
-
 sulfite + 6 reduced ferredoxin [iron-sulfur] cluster + 6 H+
-
 ?

Organism

Organism UniProt Comment Textmining
Synechococcus elongatus P30008 i.e. Anacystis nidulans R2
-
Synechococcus elongatus FACHB-805 P30008 i.e. Anacystis nidulans R2
-
Synechococcus elongatus PCC 7942 P30008 i.e. Anacystis nidulans R2
-

Purification (Commentary)

Purification (Comment) Organism
recombinant His-tagged wild-type and mutant enzymes, as well as enzyme CysG, by alternating ultrafiltration and nickel affinity chromatography, followed by anion exchange chromatography, ultrafiltration, and gel filtration Synechococcus elongatus

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
hydrogen sulfide + 6 oxidized ferredoxin I [iron-sulfur] cluster + 3 H2O
-
 Synechococcus elongatus sulfite + 6 reduced ferredoxin I [iron-sulfur] cluster + 6 H+
-
 ?
hydrogen sulfide + 6 oxidized ferredoxin I [iron-sulfur] cluster + 3 H2O
-
 Synechococcus elongatus FACHB-805 sulfite + 6 reduced ferredoxin I [iron-sulfur] cluster + 6 H+
-
 ?
hydrogen sulfide + 6 oxidized ferredoxin I [iron-sulfur] cluster + 3 H2O
-
 Synechococcus elongatus PCC 7942 sulfite + 6 reduced ferredoxin I [iron-sulfur] cluster + 6 H+
-
 ?
hydrogen sulfide + 6 oxidized ferredoxin [iron-sulfur] cluster + 3 H2O
-
 Synechococcus elongatus sulfite + 6 reduced ferredoxin [iron-sulfur] cluster + 6 H+
-
 ?
hydrogen sulfide + 6 oxidized ferredoxin [iron-sulfur] cluster + 3 H2O
-
 Synechococcus elongatus FACHB-805 sulfite + 6 reduced ferredoxin [iron-sulfur] cluster + 6 H+
-
 ?
hydrogen sulfide + 6 oxidized ferredoxin [iron-sulfur] cluster + 3 H2O
-
 Synechococcus elongatus PCC 7942 sulfite + 6 reduced ferredoxin [iron-sulfur] cluster + 6 H+
-
 ?
hydrogen sulfide + 6 oxidized methyl viologen [iron-sulfur] cluster + 3 H2O
-
 Synechococcus elongatus sulfite + 6 reduced methyl viologen [iron-sulfur] cluster + 6 H+
-
 ?
hydrogen sulfide + 6 oxidized methyl viologen [iron-sulfur] cluster + 3 H2O
-
 Synechococcus elongatus FACHB-805 sulfite + 6 reduced methyl viologen [iron-sulfur] cluster + 6 H+
-
 ?
hydrogen sulfide + 6 oxidized methyl viologen [iron-sulfur] cluster + 3 H2O
-
 Synechococcus elongatus PCC 7942 sulfite + 6 reduced methyl viologen [iron-sulfur] cluster + 6 H+
-
 ?

Subunits

Subunits Comment Organism
monomer 1 * 70000, about, recombinant enzyme, SDS-PAGE Synechococcus elongatus

Synonyms

Synonyms Comment Organism
FdSiR
-
 Synechococcus elongatus
ferredoxin sulfite reductase
-
 Synechococcus elongatus
SIR
-
 Synechococcus elongatus

Temperature Optimum [°C]

Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
22
-
 assay at room temperature Synechococcus elongatus

pH Optimum

pH Optimum Minimum pH Optimum Maximum Comment Organism
7
-
 assay at Synechococcus elongatus

Cofactor

Cofactor Comment Organism Structure
Fe-S center the enzyme contains a [4Fe-4S]2+/1+ cluster and a siroheme active site Synechococcus elongatus
methyl viologen artificial cofactor Synechococcus elongatus

General Information

General Information Comment Organism
evolution the common feature of both assimilatory and dissimilatory sulfite reductases is that they share a highly conserved domain C-X5-C-n-C-X3-C for binding the siroheme and the [4Fe-4S] cluster. In addition to these two class of sulfite reductases there exists a third class of assimilatory sulfite reductase found in a number of strictly anaerobic bacteria, cf. EC 1.8.1.2 and EC 1.8.99.5 Synechococcus elongatus
malfunction wild-type FdSiR and mutant FdSiRC491G in the presence of the artificial electron donor methyl viologen are both able to reduce sulfite to H2S, but the detected lower rate of H2S evolution for mutant FdSiRC491G is likely related to its lower cofactor content Synechococcus elongatus
additional information the enzyme contains a [4Fe-4S]2+/1+ cluster and a siroheme active site Synechococcus elongatus
physiological function ferredoxin sulfite reductase (FdSiR) catalyzes the six-electron reduction of sulfite to hydrogen sulfite and nitrite to ammonia Synechococcus elongatus