[4Fe‐4S]2+ cluster assembly in human cytosol requires both a [2Fe‐2S] cluster chaperone being able to donate two [2Fe‐2S]2+ clusters and an electron donor providing two electrons to reductively couple the two [2Fe‐2S]2+ clusters into a [4Fe‐4S]2+ cluster. The mechanism through which the cytosolic [4Fe‐4S]2+ cluster assembly works is still not defined. Here, we show that a hetero‐tetrameric complex formed by two molecules of cluster‐reduced [2Fe‐2S]+2‐anamorsin and one molecule of dimeric cluster‐oxidized [2Fe‐2S]2+2‐GLRX32 orchestrates the assembly of a [4Fe‐4S]2+ cluster on the N‐terminal cluster binding site of the cytosolic protein NUBP1. We demonstrate that the hetero‐tetrameric complex is able to synergically provide two [2Fe‐2S]2+ clusters from GLRX3 and two electrons from anamorsin for the assembly of the [4Fe‐4S]2+ cluster on the N‐terminal cluster binding site of NUBP1. We also showed that only one of the two [2Fe‐2S] clusters bound to anamorsin, that is, that bound to the CX8CX2CXC motif, provides the electrons required to form the [4Fe‐4S]2+ cluster. Our study contributes to the molecular understanding of the mechanism of [4Fe‐4S] protein biogenesis in the cytosol.

Alzheimer’s disease (AD) is a severe multifactorial neurodegenerative disorder characterized by a progressive loss of neurons in the brain. Despite research efforts, the pathogenesis and mechanism of AD progression are not yet completely understood. There are only a few symptomatic drugs approved for the treatment of AD. The multifactorial character of AD suggests that it is important to develop molecules able to target the numerous pathological mechanisms associated with the disease. Thus, in the context of the worldwide recognized interest of multifunctional ligand therapy, we report herein the synthesis, characterization, physicochemical and biological evaluation of a set of five (1a–e) new ferulic acid-based hybrid compounds, namely feroyl-benzyloxyamidic derivatives enclosing different substituent groups, as potential anti-Alzheimer’s disease agents. These hybrids can keep both the radical scavenging activity and metal chelation capacity of the naturally occurring ferulic acid scaffold, presenting also good/mild capacity for inhibition of self-Aβ aggregation and fairly good inhibition of Cu-induced Aβ aggregation. The predicted pharmacokinetic properties point towards good absorption, comparable to known oral drugs.

Multiple mitochondrial dysfunctions syndrome type 2 with hyperglycinemia (MMDS2) is a severe disorder of mitochondrial energy metabolism, associated with biallelic mutations in the gene encoding for BOLA3, a protein with a not yet completely understood role in iron-sulfur (Fe-S) cluster biogenesis, but essential for the maturation of mitochondrial [4Fe-4S] proteins. To better understand the role of BOLA3 in MMDS2, we have investigated the impact of the p.His96Arg (c.287A > G) point mutation, which involves a highly conserved residue, previously identified as a [2Fe-2S] cluster ligand in the BOLA3-[2Fe-2S]-GLRX5 heterocomplex, on the structural and functional properties of BOLA3 protein. The His96Arg mutation has been associated with a severe MMDS2 phenotype, characterized by defects in the activity of mitochondrial respiratory complexes and lipoic acid-dependent enzymes. Size exclusion chromatography, NMR, UV-visible, circular dichroism, and EPR spectroscopy characterization have shown that the His96Arg mutation does not impair the interaction of BOLA3 with its protein partner GLRX5, but leads to the formation of an aberrant BOLA3-[2Fe-2S]-GLRX5 heterocomplex, that is not functional anymore in the assembly of a [4Fe-4S] cluster on NFU1. These results allowed us to rationalize the severe phenotype observed in MMDS2 caused by His96Arg mutation.

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