Biology subjects

Fujiyoshi, Y.

Publications and source records attributed to Fujiyoshi, Y..

6 recordsLinked to original sources

bioRxiv2026

De novo design of mini-proteins as specific binders to PACAP-38, a key mediator of migraine

Pituitary adenylate cyclase-activating peptide 38 (PACAP-38) is a vasoactive peptide that is attracting attention as a potential target for next-generation migraine treatments. Antibodies against PACAP-38 have recently shown promising results as a ligand trap medicine in clinical trials. In this study, we investigated the de novo design of miniproteins to evaluate the potential for developing a medium-molecular-weight drug that binds to PACAP-38. Using Bindcraft, we designed binders against PACAP-38 and identified ICLIST-2, a 63-residue peptide with affinity for PACAP-38 (KD = 26.5 nM). Furthermore, by alanine scanning and structural analysis of ICLIST-2, we determined residues that were suitable for further optimization using ProteinMPNN. This resulted in the design of ICLIST-11, which incorporates nine amino acid substitutions relative to ICLIST-2, resulting in a KD of 4.51 nM. Interaction analysis based on a structural model suggested that three mutations in ICLIST-11 may be important for enhancing affinity. Moreover, ICLIST-11 exhibits a Tm value that is 14 {degrees}C higher, and MD simulations suggest that the substitution of three residues with hydrophobic residues (E30F, M31L, and R54W) is one reason for this. In cell-based functional assays, ICLIST-11 demonstrated potent, concentration-dependent neutralizing activity against PACAP-38-induced PAC1R activation (IC50 = 10.6 nM), significantly outperforming the parental ICLIST-2. Taken together, these results provide a framework for protein drug discovery targeting PACAP-38.

bioengineering↗

bioRxiv2025

Structural basis of stepwise G protein activation by a viral chemokine receptor

G protein-coupled receptors (GPCRs) govern diverse cellular responses and are crucial drug targets. However, the sequence of structural events from G protein recognition to GDP release has remained elusive. Here, we leveraged the viral chemokine GPCR US28 to capture multiple activation states of the US28-Gq complex. Using cryo-electron microscopy and an engineered chemokine superagonist, we determined three distinct complex structures, capturing a GDP-bound Encounter state, the nucleotide-free Canonical state, and a putative intermediate bridging the two states, the Transition-to-Canonical state. These structures, along with simulations and functional data, provide high-resolution snapshots of a plausible G protein activation trajectory and support a stepwise conformational model for G protein activation. This activation cascade closely parallels mechanisms proposed for human GPCRs, suggesting a conserved GPCR signaling mechanism.

biophysics↗

bioRxiv2025

Structural Insights into Biased Signaling at Chemokine Receptor CCR7

CC chemokine receptor 7 (CCR7), which orchestrates adaptive immunity, exhibits a phenomenon known as biased agonism. CCL19 induces robust G protein signaling and {beta}-arrestin recruitment, leading to transient signaling. In contrast, CCL21 preferentially activates G protein pathways with minimal arrestin engagement, resulting in sustained signaling and differential functional outcomes. Here, we present the cryo-EM structures of the human CCR7-Gi complex with either CCL19 or CCL21. The structures reveal that while both engage a conserved orthosteric pocket, they adopt markedly distinct binding poses. Notably, the compact 30s loop of CCL21 inserts deeply into the receptors extracellular vestibule, whereas the corresponding loop of CCL19 rests atop extracellular loop 2. Molecular dynamics simulations further reveal that these distinct binding modes induce differential intracellular dynamics, linked to the rotameric state of Y83 at the intracellular end of transmembrane helix 1. We demonstrate that CCL19 stabilizes a flexible conformational ensemble with a highly dynamic helix 8, creating a lateral opening favorable for GPCR kinase engagement. Conversely, CCL21 restricts this flexibility, locking the receptor in a state that precludes kinase interaction while maintaining G protein coupling. Corroborated by functional data, these findings provide key insights into the structural basis of biased agonism at CCR7 and establish a foundation for rational design of pathway-selective immunomodulators. Significance statementChemokine receptor CCR7 directs immune cell migration by activating distinct signaling pathways in response to CCL19 and CCL21, a phenomenon known as biased agonism. The structural basis for this divergence has remained unclear. By combining cryo-electron microscopy with molecular dynamics simulations, we reveal that although both ligands stabilize similar G protein-bound conformations, they drive distinct receptor dynamics. We demonstrate that CCL19 induces a flexible intracellular conformation necessary for recruiting regulatory kinases, whereas CCL21 locks the receptor in a state precluding this interaction. This "dynamic selection" model aligns with functional data and rationalizes a fundamental paradox in chemokine biology, highlighting the critical role of protein dynamics in signal transduction and providing a blueprint for designing precision immunotherapeutics.

biophysics↗

bioRxiv2019

Crystal structure of a human plasma membrane phospholipid flippase

ATP11C, a member of P4-ATPase flippase, exclusively translocates phosphatidylserine from the outer to the inner leaflets of the plasma membrane, and maintains the asymmetric distribution of phosphatidylserine in the living cell. However, the mechanisms by which ATP11C translocates phosphatidylserine remain elusive. Here we show the crystal structures of a human plasma membrane flippase, ATP11C-CDC50A complex, in an outward-open E2P conformation. Two phosphatidylserine molecules are in a conduit that continues from the cell surface to the occlusion site in the middle of the membrane. Mutations in either of the phosphotidylserine binding sites or along the pathway between significantly impairs specific ATPase and transport activities. We propose a model for phosphatidylserine translocation from the outer to the inner leaflet of the plasma membrane.

biochemistry↗

bioRxiv2019

A native prokaryotic voltage-dependent calcium channel with a novel selectivity filter sequence

Voltage-dependent Ca2+ channels (Cavs) are indispensable for coupling action potentials with Ca2+ signaling in living organisms. The structure of Cavs is similar to that of voltage-dependent Na+ channels (Navs). It is known that prokaryotic Navs can obtain Ca2+ selectivity by negative charge mutations of the selectivity filter, but native prokaryotic Cavs had not yet been identified.\n\nHere, we report the first identification of a native prokaryotic Cav, CavMr, and its relative, NavPp. Although CavMr contains a smaller number of negatively charged residues in the selectivity filter than artificial prokaryotic Cavs, CavMr exhibits high Ca2+ selectivity. In contrast, NavPp, which has similar filter sequence to artificial Cavs, mainly allows Na+ to permeate. Interestingly, a NavPp mutant whose selectivity filter was replaced with that of CavMr exhibits high Ca2+ selectivity. Mutational analyses revealed that the glycine residue of the CavMr selectivity filter is a determinant for Ca2+ selectivity. This glycine residue is well conserved among subdomains I and III of eukaryotic Cavs.\n\nThese findings provide new insight into the Ca2+ selectivity mechanism conserved from prokaryotes to eukaryotes.

biophysics↗

bioRxiv2019

A single K+-binding site in the crystal structure of the gastric proton pump

The gastric proton pump (H+,K+-ATPase), a P-type ATPase responsible for gastric acidification, mediates electro-neutral exchange of H+ and K+ coupled with ATP hydrolysis, but with an as yet undetermined transport stoichiometry. Here we show crystal structures at a resolution of 2.5 [A] of the pump in the E2-P transition state, in which the counter-transporting cation is occluded. We found a single K+ bound to the cation-binding site of H+,K+-ATPase, indicating an exchange of 1H+/1K+ per hydrolysis of one ATP molecule. This fulfils the energy requirement for the generation of a six pH unit gradient across the membrane. The structural basis of K+recognition is resolved, supported by molecular dynamics simulations, and this establishes how H+,K+-ATPase overcomes the energetic challenge to generate an H+ gradient of more than a million-fold - the highest cation gradient known in any mammalian tissue - across the membrane.

biochemistry↗