Biology subjects

Rivier-Cordey, A.-S.

Publications and source records attributed to Rivier-Cordey, A.-S..

4 recordsLinked to original sources

bioRxiv2026

Adaptor interactions trigger Pan1 self-assembly during clathrin-mediated endocytosis in budding yeast

Clathrin-mediated endocytosis requires the coordinated assembly of a highly dynamic protein network that couples membrane remodeling to actin-driven force generation. The essential budding yeast protein, Pan1, scaffolds the endocytic protein network by linking adaptor proteins, and other coat components, and actin assembly regulators. How Pan1 coordinates all these different proteins in space and time is not well understood. We show that Pan1 undergoes biomolecular condensation. Elevated Pan1 expression induced the formation of condensates that exhibited partial rapid molecular exchange, temperature-dependent reversibility, and sensitivity to disruption of weak hydrophobic interactions. The Pan1 assemblies are compositionally selective, preferentially enriching late-stage endocytic factors while excluding early adaptor proteins. Truncation analysis demonstrated that condensation depends on cooperative contributions from intrinsically disordered regions, the EH2 domain, and the oligomerization module, whereas a C-terminal region negatively regulates condensation. Deletion of Pan1 regions promoting its self-assembly perturbed Pan1 assembly and function at endocytic sites. Disruption of interactions between Pan1 and endocytic adaptors did not alter the dynamics of endocytic events but instead reduced the number of endocytic events marked by Pan1 and caused the formation of ectopic Pan1 condensates. This indicates that adaptor-mediated interactions spatially constrain Pan1 localization by seeding Pan1 assembly at endocytic sites. Our findings support a model in which adaptor proteins seed Pan1 assembly at the endocytic sites while multivalent interactions drive Pan1 self-assembly to build the higher-order molecular network of the late endocytic coat.

cell biology↗

bioRxiv2026

A switch in clathrin turnover controls endocytic coat size and organisation

Endocytosis internalises nutrients, regulates extracellular signals, and recycles membrane components. Clathrin polymerises into a coat that shapes the endocytic vesicle from the plasma membrane. However, the role of clathrins dynamic assembly in the endocytic process remains unclear. We show, using two-colour fluorescence recovery after photobleaching assays in yeast, that the clathrin coat turns over rapidly in the early phase of endocytosis, dependent on the auxilin Swa2 and its ATPase. In the late phase the turnover is stopped by the coat protein Sla1. Regulated clathrin turnover is critical for the timing of endocytic progression and for controlling coat size. In the absence of this dynamic regulation the endocytic coats become abnormally large, resulting in the failure of the final actin-driven vesicle budding. These findings reveal that, in addition to its classic structural function, the dynamic properties of the clathrin lattice are critical for both the temporal and mechanical aspects of endocytosis.

cell biology↗

bioRxiv2025

Evolutionarily diverged on-switch for actin assembly in fungal endocytosis

Clathrin-mediated endocytosis is a conserved eukaryotic trafficking process where an Arp2/3 complex nucleated branched actin network provides force for vesicle formation. The mechanisms that initiate endocytic actin assembly are incompletely understood. In the fission yeast, Schizosaccharomyces pombe, actin assembly is initiated by Dip1, an Arp2/3 activator. In the budding yeast, Saccharomyces cerevisiae, the initiation of actin assembly has remained a mystery. Here we show that S. cerevisiae Ldb17, the homolog of Dip1, functions as an on-switch for endocytic actin assembly. Unexpectedly, the regulation of Ldb17 is more complicated than that of constitutively active Dip1. Ldb17 is controlled by a coat protein, Sla1, via separate recruitment and activation steps. This regulation was likely lost in the S. pombe lineage and this simplification may be related to other changes in actin assembly between these species. Our findings add a key missing piece in the understanding of endocytosis in S. cerevisiae and reveal an intriguing evolutionary tinkering of the actin on-switch.

cell biology↗

bioRxiv2024

An evolutionary cell biology perspective into the diverging mechanisms of clathrin-mediated endocytosis in dikarya fungi

Clathrin-mediated endocytosis is an ancient eukaryotic trafficking pathway, which transports plasma membrane and associated cargo into the cell and is involved in numerous cell- and tissue-level processes. Cargo selection and clathrin-coated vesicle formation is mediated by over 60 proteins that assemble in a regular and sequential manner at the plasma membrane. Decades of endocytosis studies have followed the tenet that uncovering the conserved core molecular mechanisms is sufficient to understand a cellular process. However, this approach also revealed a number of cell type or species-related variations that challenge a universal conserved, core mechanism. In this paper, we refocus on the endocytic diversity to understand how evolution shapes endocytic mechanisms. We define a comparative evolutionary cell biology approach that uses dikarya fungi as a model clade and live-cell fluorescence microscopy to study endocytosis dynamics in three species: Saccharomyces cerevisiae, Schizosaccharomyces pombe and Ustilago maydis. Our results quantitatively define several phenotypic differences between the species. We uncover several differences that impact the endocytic early phase, the protein assembly order, actin regulation, membrane invagination and scission. These findings demonstrate a mosaic evolution of endocytic traits, suggest ancestral states and direction of changes. We also investigate the phenotypic plasticity and robustness against environmental conditions. Lastly, we demonstrate that relatively minor evolutionary changes can majorly impact endocytic phenotypes. These studies force an appreciation of endocytic variation as not auxiliary, but vital to mechanistic understanding of this conserved cellular pathway.

cell biology↗