Metallocofactor assembly for [FeFe]-hydrogenases.

Hydrogenases are a potential source of environmentally benign bioenergy, using complex cofactors to catalyze the reversible reduction of protons to form hydrogen. The most active subclass, the [FeFe]-hydrogenases, is dependent on a metallocofactor, the H cluster, that consists of a two iron subcluster ([2Fe]) bridging to a classical cubane cluster ([4Fe-4S]). The ligands coordinating to the diiron subcluster include an azadithiolate, three carbon monoxides, and two cyanides.

The PqqD homologous domain of the radical SAM enzyme ThnB is required for thioether bond formation during thurincin H maturation.

Thurincin H is a 31-residue, ribosomally synthesized bacteriocin originating from the thn operon of Bacillus thuringiensis SF361. It is the only known sactipeptide carrying four thioether bridges between four cysteines and the α-carbons of a serine, an asparagine and two threonine residues. By analysis of the thn operon and use of in vitro studies we now reveal that ThnB is a radical S-adenosylmethionine (SAM) enzyme containing two [4Fe-4S] clusters.

Copper prevents amyloid-β(1-42) from forming amyloid fibrils under near-physiological conditions in vitro.

The aggregation and deposition of amyloid-β((1-42) )(Aβ(42)) in the brain is implicated in the aetiology of Alzheimer's disease (AD). While the mechanism underlying its deposition in vivo is unknown its precipitation in vitro is influenced by metal ions. For example, Aβ(42) is known to bind copper, Cu(II), in vitro and binding results in aggregation of the peptide.

Two [4Fe-4S] clusters containing radical SAM enzyme SkfB catalyze thioether bond formation during the maturation of the sporulation killing factor.

The sporulation killing factor (SKF) is a 26-residue ribosomally assembled and posttranslationally modified sactipeptide. It is produced by Bacillus subtilis 168 and plays a key role in its sporulation. Like all sactipeptides, SKF contains a thioether bond, which links the cysteine residue Cys4 with the α-carbon of the methionine residue Met12.