bims-nucpor 2023-08-20 papers

Issue of 2023‒08‒20
two papers selected by
Sara Mingu, Johannes Gutenberg University

Sci Rep. 2023 08 16. 13(1): 13327

Particle fusion of super-resolution data reveals the unit structure of Nup96 in Nuclear Pore Complex.

Wenxiu Wang, Arjen Jakobi, Yu-Le Wu, Jonas Ries, Sjoerd Stallinga, Bernd Rieger.

Single molecule localization microscopy offers resolution nearly down to the molecular level with specific molecular labelling, and is thereby a promising tool for structural biology. In practice, however, the actual value to this field is limited primarily by incomplete fluorescent labelling of the structure. This missing information can be completed by merging information from many structurally identical particles in a particle fusion approach similar to cryo-EM single-particle analysis. In this paper, we present a data analysis of particle fusion results of fluorescently labelled Nup96 nucleoporins in the Nuclear Pore Complex to show that Nup96 occurs in a spatial arrangement of two rings of 8 units with two Nup96 copies per unit giving a total of 32 Nup96 copies per pore. We use Artificial Intelligence assisted modeling in Alphafold to extend the existing cryo-EM model of Nup96 to accurately pinpoint the positions of the fluorescent labels and show the accuracy of the match between fluorescent and cryo-EM data to be better than 3 nm in-plane and 5 nm out-of-plane.

DOI: https://doi.org/10.1038/s41598-023-39829-5

Nat Cell Biol. 2023 Aug 17.

Lipid saturation controls nuclear envelope function.

Anete Romanauska, Alwin Köhler.

The nuclear envelope (NE) is a spherical double membrane with elastic properties. How NE shape and elasticity are regulated by lipid chemistry is unknown. Here we discover lipid acyl chain unsaturation as essential for NE and nuclear pore complex (NPC) architecture and function. Increased lipid saturation rigidifies the NE and the endoplasmic reticulum into planar, polygonal membranes, which are fracture prone. These membranes exhibit a micron-scale segregation of lipids into ordered and disordered phases, excluding NPCs from the ordered phase. Balanced lipid saturation is required for NPC integrity, pore membrane curvature and nucleocytoplasmic transport. Oxygen deprivation amplifies the impact of saturated lipids, causing NE rigidification and rupture. Conversely, lipid droplets buffer saturated lipids to preserve NE architecture. Our study uncovers a fundamental link between lipid acyl chain structure and the integrity of the cell nucleus with implications for nuclear membrane malfunction in ischaemic tissues.

DOI: https://doi.org/10.1038/s41556-023-01207-8