Catalytic Activity of the Archetype from Group 4 of the FTR-like Ferredoxin:Thioredoxin Reductase Family Is Regulated by Unique = 7/2 and = 1/2 [4Fe-4S] Clusters.

Thioredoxin reductases (TrxR) activate thioredoxins (Trx) that regulate the activity of diverse target proteins essential to prokaryotic and eukaryotic life. However, very little is understood of TrxR/Trx systems and redox control in methanogenic microbes from the domain (methanogens), for which genomes are abundant with annotations for ferredoxin:thioredoxin reductases [Fdx/thioredoxin reductase (FTR)] from group 4 of the widespread FTR-like family. Only two from the FTR-like family are characterized: the plant-type FTR from group 1 and FDR from group 6.

Identification and characterization of the low molecular mass ferredoxins involved in central metabolism in Heliomicrobium modesticaldum.

The homodimeric Type I reaction center (RC) from Heliomicrobium modesticaldum lacks the PsaC subunit found in Photosystem I and instead uses the interpolypeptide [4Fe-4S] cluster F as the terminal electron acceptor. Our goal was to identify which of the small mobile dicluster ferredoxins encoded by the H. modesticaldum genome are capable of accepting electrons from the heliobacterial RC (HbRC) and pyruvate:ferredoxin oxidoreductase (PFOR), a key metabolic enzyme.

Structure and function of an unusual flavodoxin from the domain .

Flavodoxins, electron transfer proteins essential for diverse metabolisms in microbes from the domain , are extensively characterized. Remarkably, although genomic annotations of flavodoxins are widespread in microbes from the domain , none have been isolated and characterized. Herein is described the structural, biochemical, and physiological characterization of an unusual flavodoxin (FldA) from , an acetate-utilizing methane-producing microbe of the domain In contrast to all flavodoxins, FldA is homodimeric, markedly less acidic, and stabilizes an anionic semiquinone.

Designing a modified clostridial 2[4Fe-4S] ferredoxin as a redox coupler to directly link photosystem I with a Pt nanoparticle.

A methodology previously developed in our laboratory utilized an aliphatic hydrocarbon terminated by thiol groups to tether two redox proteins, i.e., the [4Fe-4S] cluster F of photosystem I (PS I) and the distal [4Fe-4S] cluster of a [FeFe]-hydrogenase, to create a biohybrid dihydrogen-generating complex.

Expression, purification and characterization of an active C491G variant of ferredoxin sulfite reductase from Synechococcus elongatus PCC 7942.

Recently developed molecular wire technology takes advantage of [4Fe-4S] clusters that are ligated by at least one surface exposed Cys residue. 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.

Toward a mechanistic and physiological understanding of a ferredoxin:disulfide reductase from the domains Archaea and Bacteria.

Disulfide reductases reduce other proteins and are critically important for cellular redox signaling and homeostasis. is a methane-producing microbe from the domain Archaea that produces a ferredoxin:disulfide reductase (FDR) for which the crystal structure has been reported, yet its biochemical mechanism and physiological substrates are unknown. FDR and the extensively characterized plant-type ferredoxin:thioredoxin reductase (FTR) belong to a distinct class of disulfide reductases that contain a unique active-site [4Fe-4S] cluster.

Tetratricopeptide repeat protein protects photosystem I from oxidative disruption during assembly.

A Chlamydomonas reinhardtii mutant lacking CGL71, a thylakoid membrane protein previously shown to be involved in photosystem I (PSI) accumulation, exhibited photosensitivity and highly reduced abundance of PSI under photoheterotrophic conditions. Remarkably, the PSI content of this mutant declined to nearly undetectable levels under dark, oxic conditions, demonstrating that reduced PSI accumulation in the mutant is not strictly the result of photodamage. Furthermore, PSI returns to nearly wild-type levels when the O2 concentration in the medium is lowered.