Biology subjects

Kise, Y.

Publications and source records attributed to Kise, Y..

2 recordsLinked to original sources

bioRxiv2023

Structure of full-length ERGIC-53 in complex with MCFD2 for cargo transport

ERGIC-53 is a cargo receptor that promotes the transport of certain subsets of newly synthesized secretory proteins and membrane proteins from the endoplasmic reticulum (ER) to the Golgi apparatus (GA)1,2. Despite numerous structural and functional studies since its identification, the overall architecture and mechanism of action of this cargo receptor in its full-length form remain unclear. Here we present cryo-electron microscopy (cryo-EM) structures of full-length ERGIC-53 in complex with its functional partner MCFD2. These structures, in combination with SEC-MALS/SAXS analysis, reveal that ERGIC-53 exists as a homotetramer, not a homohexamer as previously suggested, and comprises a four-leaf clover-like head structure and a long stalk composed of three sets of four-helix coiled-coil followed by a transmembrane (TM) domain. The tetrameric head of ERGIC-53 consists of the vertically assembled carbohydrate recognition domains and the central four-helix coiled-coil. 3D variability analysis visualizes the globally flexible motion of the long stalk and local plasticity of the head region. Notably, MCFD2 has been found to possess a Zn2+ binding site in its N-terminal lid, which appears to modulate cargo binding. Altogether, unique mechanisms of regulated cargo capture and release by ERGIC-53 via the stalk bending and metal binding are proposed.

biochemistry↗

bioRxiv2023

Structural basis for lysophosphatidylserine recognition by GPR34

GPR34 is a recently identified G-protein coupled receptor, which has an immunomodulatory role and recognizes lysophosphatidylserine (LysoPS) as a putative ligand. Here, we report cryo-electron microscopy structures of human GPR34-Gi complex bound with either the LysoPS analogue S3E-LysoPS, which contains an ethoxy group at the sn-1 position, or M1, a derivative of S3E-LysoPS in which oleic acid is substituted with a metabolically stable aromatic fatty acid surrogate. In both structures, the ligand-binding pocket is laterally open toward the membrane, allowing lateral entry of lipidic agonists into the cavity. The amine and carboxylate groups of the serine moiety are recognized by the charged residue cluster, and the aromatic fatty acid surrogate of M1 forms stable hydrophobic interactions with the cavity, thus acting as a superagonist. Molecular dynamics simulations further account for the LysoPS-regioselectivity of GPR34. Thus, using a series of structural and physiological experiments, we provide evidence that chemically unstable 2-acyl LysoPS is the physiological ligand for GPR34, suggesting its short signal duration. Overall, we anticipate the present structures will pave the way for development of novel anticancer drugs that specifically target GPR34.

biochemistry↗