Cryo-EM structure of human class C orphan GPCR GPR179 involved in visual processing.

GPR179, an orphan class C GPCR, is expressed at the dendritic tips of ON-bipolar cells in the retina. It plays a pivotal role in the initial synaptic transmission of visual signals from photoreceptors, and its deficiency is known to be the cause of complete congenital stationary night blindness. Here, we present the cryo-electron microscopy structure of human GPR179.

Identifying a key spot for electron mediator-interaction to tailor CO dehydrogenase's affinity.

Fe‒S cluster-harboring enzymes, such as carbon monoxide dehydrogenases (CODH), employ sophisticated artificial electron mediators like viologens to serve as potent biocatalysts capable of cleaning-up industrial off-gases at stunning reaction rates. Unraveling the interplay between these enzymes and their associated mediators is essential for improving the efficiency of CODHs. Here we show the electron mediator-interaction site on ChCODHs (Ch, Carboxydothermus hydrogenoformans) using a systematic approach that leverages the viologen-reactive characteristics of superficial aromatic residues.

GPCR targeting of E3 ubiquitin ligase MDM2 by inactive β-arrestin.

E3 ubiquitin ligase Mdm2 facilitates β-arrestin ubiquitination, leading to the internalization of G protein-coupled receptors (GPCRs). In this process, β-arrestins bind to Mdm2 and recruit it to the receptor; however, the molecular architecture of the β-arrestin-Mdm2 complex has not been elucidated yet. Here, we identified the β-arrestin-binding region (ABR) on Mdm2 and solved the crystal structure of β-arrestin1 in complex with Mdm2 peptide.

Biochemical Characterization of the Num1-Mdm36 Complex at the Mitochondria-Plasma Membrane Contact Site.

that tethers mitochondria to the plasma membrane and plays a key role in mitochondrial fission. The main components of MECA are Num1 and Mdm36, and it is known that Mdm36 binds to Num1 to enhance mitochondrial tethering. To better understand the biochemical characteristics of the Num1-Mdm36 complex at the molecular level, we purified the coiled-coil domain of Num1, full-length Mdm36, and Num1-Mdm36 complex and identified the oligomeric state and stoichiometric characteristics of the Num1-Mdm36 complex by chemical crosslinking, size-exclusion chromatography coupled with multi-angle light scattering, and isothermal titration calorimetry.

Dissecting the structural features of β-arrestins as multifunctional proteins.

β-arrestins bind active G protein-coupled receptors (GPCRs) and play a crucial role in receptor desensitization and internalization. The classical paradigm of arrestin function has been expanded with the identification of many non-receptor-binding partners, which indicated the multifunctional role of β-arrestins in cellular functions. To elucidate the molecular mechanism of β-arrestin-mediated signaling, the structural features of β-arrestins were investigated using X-ray crystallography and cryogenic electron microscopy (cryo-EM).

Reversible Protein Conjugation on Live Cell Surfaces by Specific Recognition between Coiled-Coil Motifs of Natural Amino Acid Sequences.

In this study, we propose a reversible covalent conjugation method for peptides, proteins, and even live cells based on specific recognition between natural amino acid sequences. Two heptad sequences can specifically recognize each other and induce the formation of a disulfide bond between cysteine residues. We show the covalent bond formation and dissociation between peptides and proteins in cell-free conditions and on the surface of live cells.