Volume 20 Issue 3, March 2024

Small molecules and drugs are not homogenously distributed across cells, and are instead enriched in distinct subcellular compartments and membraneless biomolecular condensates. A new study lays out the path to identifying chemical features or ‘rationales’ that confer condensate-selective partitioning of small molecules.

Activation of STING-dependent signal transduction results in adaptive immune responses that promote antitumor immunity. A recent study has identified a small-molecule STING agonist that functions by binding to a newly discovered ligandable site to induce high-order STING oligomerization.

Chemically reactive metabolites such as formaldehyde are often toxic and are proposed to react promiscuously with biomolecules. New work shows that some reactive sites on proteins are uniquely sensitive to formaldehyde, leading to functionally important regulation of protein and cell functions.

Developing inhibitors for SH2 domains is challenging due to their shallow pockets and highly charged ligands. Structure-guided drug design has enabled the discovery of a cell-permeable covalent inhibitor of the SOCS2 SH2 domain, a key regulator of cytokine signaling pathways.

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.

The requirement for a protospacer adjacent motif (PAM) is a well-known limitation of the CRISPR–Cas9 system, as it restricts the range of sequences that can be targeted. To address this limitation, we demonstrate a phage-assisted evolution approach for engineering a compact SlugCas9, simplifying its PAM requirement and broadening its DNA targeting scope.

This Review provides an overview of different RNA base editing technologies, including the RNA-targeting platforms and modification effectors, with a focus on the emerging programmable RNA base editors and their potential in correcting pathological mutations.

Condensates have been proposed to create a distinct chemical solvating environment. In vitro condensate screens suggest that condensate chemical environments influence the intracellular distribution of small molecules.

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.

Asymmetric glucose tracers reveal the simultaneous use and unique benefits of parallel glycolytic pathways. Cells possessing both textbook glycolysis and Entner–Doudoroff glycolysis have a selective advantage in dynamic environments.

This study reveals β-arrestin-independent GPCR signaling via the cAMP pathway from endosomes, and it delineates a discrete function of β-arrestin in temporally resolving the endosomal signaling phase as a separate peak of cytoplasmic cAMP.

Through directed evolution, the PAM compatibility of the compact Cas9 variant CjCas9 was increased. Evolved CjCas9 shows higher nuclease activity at canonical and non-canonical sites and enables robust in vivo gene editing from single AAV vectors.

Qi et al. used phage-assisted evolution to optimize SlugCas9, a compact Cas9 nuclease, for NNG PAM recognition and developed a SlugCas9-NNG based adenine base editor for single AAV delivery.

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.

A cell-based phenotypic screen led to the discovery of compounds called NVS-STGs, which bind to the N-terminal domain of STING and act as a molecular glue to induce higher-order oligomerization and activation.

Development of live-cell target engagement approaches to query MEK-bound binary and ternary complexes reveals the distinct pharmacology of clinical MEK inhibitors at specific assemblies composed of MEK, RAF, KSR and 14-3-3.

Peptide epimerization is a common but enigmatic post-translational modification found in antibiotics formed from ribosomally synthesized and post-translationally modified peptides. Now, crystallographic snapshots, spectroscopy and biochemical investigations have provided insight into the mechanism of peptide epimerization catalyzed by radical S-adenosyl-l-methionine epimerases.