Components of Coated Vesicles and Nuclear Pore Complexes Share a Common Molecular Architecture

TLDR

Eukaryotic cells possess distinctive internal membrane systems that form elaborate compartments and vesicular trafficking pathways, sequestering chromatin within the nuclear envelope, and the nuclear pore complex mediates macromolecular trafficking across this envelope, yet the evolutionary origin of the nuclear pore complex from organisms lacking analogous transport systems remains unclear. The study aims to structurally analyze the seven proteins of the yNup84/vNup107–160 subcomplex, a core component of the nuclear pore complex. The authors use computational and biochemical methods to perform this structural analysis. The analysis shows that all seven proteins have β‑propeller, α‑solenoid, or mixed folds, revealing close structural similarities to vesicle coating complexes and suggesting a common evolutionary origin for nuclear pore complexes and coated vesicles in an early membrane‑curving module that contributed to modern eukaryotic internal membrane systems.

Abstract

Numerous features distinguish prokaryotes from eukaryotes, chief among which are the distinctive internal membrane systems of eukaryotic cells. These membrane systems form elaborate compartments and vesicular trafficking pathways, and sequester the chromatin within the nuclear envelope. The nuclear pore complex is the portal that specifically mediates macromolecular trafficking across the nuclear envelope. Although it is generally understood that these internal membrane systems evolved from specialized invaginations of the prokaryotic plasma membrane, it is not clear how the nuclear pore complex could have evolved from organisms with no analogous transport system. Here we use computational and biochemical methods to perform a structural analysis of the seven proteins comprising the yNup84/vNup107–160 subcomplex, a core building block of the nuclear pore complex. Our analysis indicates that all seven proteins contain either a β-propeller fold, an α-solenoid fold, or a distinctive arrangement of both, revealing close similarities between the structures comprising the yNup84/vNup107–160 subcomplex and those comprising the major types of vesicle coating complexes that maintain vesicular trafficking pathways. These similarities suggest a common evolutionary origin for nuclear pore complexes and coated vesicles in an early membrane-curving module that led to the formation of the internal membrane systems in modern eukaryotes.