The function of putative bacterial vitamin K-dependent carboxylases (VKDCs) has so far been uncertain. Now, Micklefield and co-workers show that a bacterial VKDC orthologue is involved in the biosynthesis of the antibiotic malonomycin, generating an unusual malonic acid moiety that is essential for its biological activity.

Mitochondrial protein synthesis requires charging a mitochondrial tRNA with its amino acid. Here, the authors describe pathogenic variants in the GatCAB protein complex genes required for the generation of glutaminyl-mt-tRNA^Gln, that impairs mitochondrial translation and presents with cardiomyopathy.

Modifying the non-ribosomal peptide synthase (NRPS)/polyketide synthase (PKS) pathway to generate novel non-ribosomal peptides often results in a loss of productivity. Here the authors use evolutionary alignments of NRPS/PKS gene clusters to guide rational design of complexes that can produce novel lactones.

Catabolizing lignin-derived aromatic compounds requires an aryl-O-demethylation step. Here the authors present the structures of GcoA and GcoB, a cytochrome P450-reductase pair that catalyzes aryl-O-demethylations and show that GcoA displays broad substrate specificity, which is of interest for biotechnology applications.