Biology subjects

Senju, Y.

Publications and source records attributed to Senju, Y..

4 recordsLinked to original sources

bioRxiv2025

Redeployment of Archaeal ESCRT Systems Reveals Conserved Mechanisms Underlying Eukaryotic Complexity

Eukaryotic ESCRT complexes remodel membranes at the plasma membrane and internal compartments, yet how these systems evolved from prokaryotic precursors functioning at the cellular membrane remains unresolved. Here, we show that ESCRT-II, ESCRT-III, VPS4, and ubiquitin from Candidatus Prometheoarchaeum syntrophicum (MK-D1), an Asgard archaeon closely related to eukaryotes, are recruited to canonical ESCRT sites in human cells, including centrosomes, midbodies, nuclear envelopes, endosomes despite the absence of these structures from MK-D1 morphology. In addition to MK-D1 ESCRT II recruitment at these regions, MK-D1 ESCRT-III and VPS4 form ring assemblies at midbodies and target reforming nuclear envelope regions. Futhermore, expression of MK-D1 ESCRT modules enhances efficiency of viral budding in human cells. These findings provide direct experimental evidence that archaeal ESCRT modules integrate into diverse eukaryotic structures, supporting a model in which ancestral membrane-remodeling systems were redeployed during eukaryogenesis to organize novel internal architectures.

evolutionary biology↗

bioRxiv2023

The role of location propagation for translocon complex relocation during eukaryogenesis

In all domains of life, the translationally-active ribosome-translocon complex inserts nascent transmembrane proteins into, and processes and transports signal peptide-containing proteins across, membranes1,2. Eukaryotic translocons are anchored in the endoplasmic reticulum, while the prokaryotic complexes reside in cell membranes. DNA sequence analyses indicate that the eukaryotic Sec61/OST/TRAP translocon is inherited from an Asgard archaea ancestor3,4. However, the mechanism for translocon migration from a peripheral membrane to an internal cellular compartment (the proto-endoplasmic reticulum) during eukaryogenesis is unknown. Here we show that Asgard and eukaryotic ribosome-translocon complexes are intercompatible. We find that fluorescently-tagged Asgard translocon proteins from Candidatus Prometheoarchaeum syntrophicum strain MK-D15, a Lokiarchaeon confirmed to contain no internal cellular membranes, are targeted to the eukaryotic endoplasmic reticulum on ectopic expression. Our data demonstrate that the location of existing ribosome-translocon complexes, at the protein level, determines the future placement of yet to be translated translocon subunits. This principle predicts that during eukaryogenesis, under positive selection pressure, the relocation of a few translocon complexes to the proto-endoplasmic reticulum will have propagated the new translocon location, leading to their loss from the cell membrane.

evolutionary biology↗

bioRxiv2022

Activated I-BAR IRSp53 clustering controls the formation of VASP-actin-based membrane protrusions

Filopodia are actin-rich membrane protrusions essential for cell morphogenesis, motility, and cancer invasion. How cells control filopodia initiation on the plasma membrane remains elusive. We performed experiments in cellulo, in vitro and in silico to unravel the mechanism of filopodia initiation driven by the membrane curvature sensor IRSp53. We showed that full-length IRSp53 self-assembles into clusters on membranes depending on PIP2. Using well-controlled in vitro reconstitution systems, we demonstrated that IRSp53 clusters recruit the actin polymerase VASP to assemble actin filaments locally on membranes, leading to the generation of actin-filled membrane protrusions reminiscent of filopodia. By pulling membrane nanotubes from live cells, we observed that IRSp53 can only be enriched and trigger actin assembly in nanotubes at highly dynamic membrane regions. Our work supports a regulation mechanism of IRSp53 in its attributes of curvature sensation and partner recruitment to ensure a precise spatial-temporal control of filopodia initiation.

biophysics↗

bioRxiv2018

Ezrin enrichment on curved membranes requires a specific conformation or interaction with a curvature-sensitive partner

One challenge in current cell biology is to decipher the biophysical mechanisms governing protein enrichment on curved membranes and the resulting membrane deformation. The ERM protein ezrin is abundant and associated with cellular membranes that are flat or with positive or negative curvatures. Using in vitro and cell biology approaches, we assess mechanisms of ezrins enrichment on curved membranes. We evidence that ezrin (ezrinWT) and its phosphomimetic mutant T567D (ezrinTD) do not deform membranes but self-assemble anti-parallelly, zipping adjacent membranes. EzrinTDs specific conformation reduces intermolecular ezrin interactions, allows binding to actin filaments, and promotes ezrin binding to positively curved membranes. While neither ezrinTD nor ezrinWT senses negative membrane curvature alone, we demonstrate that interacting with curvature sensors I-BAR-domain proteins facilitates ezrin enrichment in negatively curved membrane protrusions. Overall, our work reveals new mechanisms, specific conformation or binding to a curvature sensor partner, for targeting curvature insensitive proteins to curved membranes.

biophysics↗