Controlled interactions between macromolecules are fundamental regulatory layers. Hijacking these circuits via proximity-inducing small molecules offers many therapeutic opportunities. The organizers, Georg Winter and Cristina Mayor-Ruiz, report on the latest trends in this emerging field discussed at the 39th IRB-BioMed Conference in Barcelona.

DNA-encoded libraries are a powerful tool to identify novel chemical inducers of proximity such as targeted protein degraders, even without a known binder for the target protein.

Cells contain compartments composed of phase-separated protein condensates. We find that these condensates have a unique chemical microenvironment that enriches amphipathic metabolites such as phospholipids. Therefore, condensates are mixtures of proteins, nucleic acids and specific metabolites. The presence of phospholipids and other amphipathic metabolites might enable condensates to facilitate specific metabolic reactions.

Genetically encoded tools to manipulate redox metabolism are in high demand for investigating the underlying mechanism of cofactor imbalances in mammalian systems. A new tool enables the induction and interrogation of NADH reductive stress.

A workflow integrating tools from bioinformatics, structural biology and synthetic biology has been developed that enables the rapid design of pili-enabled living materials. This approach allows mining of pili-producing nonpathogenic chassis, understanding of the pili structure and assembly, and engineering of pili-enabled living materials in a systematic and sequential manner.

Efforts to rationally engineer nonribosomal peptide synthetase (NRPS) enzymes have focused on making individual modifications. Here the authors describe a targeted random engineering approach that uses thousands of NRPS domains amplified from the soil metagenome for mass substitution experiments.

Oxygen sensitivity hampers applications of metal-dependent CO₂ reductases. Here, Oliveira et al. describe how an allosteric disulfide bond controls the activity of a CO₂ reductase, preventing its physiological reduction during transient O₂ exposure and allowing aerobic handling of the enzyme.

Cui et al. developed LAUNCHER, a single-component switch using potyviral protease, which offers a high signal-to-noise ratio for precise payload release, enabling versatile cellular applications and enhanced synthetic circuit performance.

Here, the authors describe the mechanistic flexibility and substrate promiscuity of the apramycin resistance enzyme ApmA. They identify additional clinical drugs susceptible to modification through a molecular mechanism that diverges from other enzymes within the left-handed β-helix superfamily.

Dumelie et al. asked whether biomolecular phase-separated condensates can establish microenvironments with distinct metabolomes and found that amphipathic lipids are highly enriched in these microenvironments and influence the properties of the condensates.