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A small ferredoxin (Shethna protein II) of Azotobacter vinelandii can provide protection from O₂ stress that may be crucial for the maintenance of recombinant nitrogenase in food crops.

Biological nitrogen fixation requires low-potential electrons from ferredoxin or flavodoxin. Here the authors show how the soil diazotroph Azotobacter vinelandii employs the NADH:ferredoxin oxidoreductase RNF1 complex to lower the midpoint potential of the electron from NADH to reduce ferredoxin.

The covalent linkage of hemes to cytochromes c requires a maturation machinery. Here, the authors provide mechanistic insights into how the heme translocase complex CcmABCD flops a heme group, driven by ATP hydrolysis, and delivers it to the chaperone CcmE.

Nitrogenases are of high interest due to their ability to form NH₄⁺ by reduction of atmospheric dinitrogen. However, the detailed architecture of the Fe-only isoform remained unknown. Now, a high-resolution crystal structure of Fe-nitrogenase is solved, deepening the understanding of nitrogenase catalysis.

Cryo-electron microscopy structures of the bacterial protein machinery that is involved in the production and function of nitrous oxide provide insight into the assembly pathway of this enzyme and the mechanisms of copper transport.

The structure of the heme lyase CcmF, an integral membrane protein, reveals a cavity opening toward the extracellular side to receive heme groups from the chaperone CcmE and a surface groove for guiding the substrate protein during heme attachment.

The [Mo:7Fe:9S:C] iron-molybdenum cofactor (FeMoco) of nitrogenase is a large metal cluster with an important role in biological nitrogen fixation. Here, the authors use spatially resolved refinement of the anomalous scattering contributions of the iron atoms to determine the resting-state electron distribution of FeMoco.

The structure of vanadium nitrogenase reveals key differences from its counterpart molybdenum nitrogenase, particularly in the way it ligands its FeV cofactor, that help to explain the basis for the unique properties of these two nitrogenases.

The involvement of the sirtuin family of lysine deacylases in disease, metabolism and ageing makes them promising pharmaceutical targets. Rumpf et al.present structures of human Sirt2 in complex with two highly selective drug-like inhibitors, and show that they act by rearranging the enzyme’s active site.

Wang et al. report on an inhibitor of the lysine methyltransferase KMT9 with cellular activity. The inhibitor blocks proliferation of androgen-resistant prostate cancer cells, opening therapeutics avenues to treat this type of cancer.

An alternative nitrogenase enzyme that only utilizes iron as its cofactor is shown to reduce carbon dioxide while actively fixing dinitrogen, so that it simultaneously produces ammonium, hydrogen and methane.

Here, the authors characterize selenium and sulphur incorporated FeMo cofactors of the catalytic MoFe protein component from Azotobacter vinelandii under turnover conditions using EPR.

Respiratory complex I plays a central role in cellular energy metabolism coupling NADH oxidation to proton translocation. Here, the authors report the structure of the electron input part of Aquifex aeolicus complex I at up to 1.8 Å resolution with bound substrates in the reduced and oxidized states.

In plants, plasma membrane topologies are predominantly driven by the cell wall. In this study, the authors demonstrate that remorin proteins can take over these functions at specialized, unwalled plasma membranes such as infection droplets associated with symbiotic infection threads.

KMT9, a new histone lysine methyltransferase targeting H4K12, is enriched at promoters of genes encoding molecules involved in the cell cycle and controls the growth of androgen receptor–dependent and castration- and enzalutamide-resistant prostate cancer cells and xenograft tumors.

Methylation of the lysine demethylase KDM1A and the recognition of this modification by the chromodomain helicase CHD1 control androgen-dependent gene transcription and TMPRSS2-ERG gene fusion, a common translocation event in prostate cancer.

Sulfite-reducing microbes couple the reduction of sulfite to the generation of a proton motive force that sustains organismic growth; here, two X-ray crystal structures are solved of MccA, a c-type cytochrome enzyme with eight haem groups that catalyses the six-electron reduction of sulfite to sulfide at a novel haem–copper active site.