Biology subjects

Jolivet, N. Y.

Publications and source records attributed to Jolivet, N. Y..

6 recordsLinked to original sources

bioRxiv2026

Mitochondrial inner membrane interactors of Aurora kinase A/AURKA and PHB2 shape organelle metabolic heterogeneity.

Mitochondria support tumor growth by flexibly rewiring their own activity. Yet, how signaling networks organize this metabolic diversity across and within cells remains poorly understood. Here, we uncover a platform of inner mitochondrial membrane proteins that couple Aurora kinase A (AURKA) and the mitophagy receptor Prohibitin-2 (PHB2) to the local control of ATP production and organelle architecture. Using proximity interactomics and live-cell FRET/FLIM microscopy, we identify NDUFA9, ATP5F1A/B, SAMM50, and SLC25A13 as shared AURKA/PHB2 interactors positioned at respiratory chain and cristae-maintaining sites. We show that AURKA overexpression profoundly rewires the interactomes of NDUFA9 and ATP5F1A without disrupting their nanoscale proximity in the inner membrane, and reshapes mitochondrial morphology while preserving these signaling hubs. The AURKA/PHB2-targeting compound HMBB restores NDUFA9 and ATP5F1A interactomes, indicating that these complexes act as key nodes for AURKA-dependent metabolic adaptation at the population level. Finally, single-cell FRET microscopy coupled to super-resolution imaging reveals that SLC25A13 is required to sustain AURKA-induced metabolic heterogeneity within individual cancer cells. Our work links a multifunctional kinase, a mitophagy receptor, and respiratory complexes into a common inner membrane platform that spatially drives mitochondrial heterogeneity, with implications for metabolism-focused anticancer strategies.

cell biology↗

bioRxiv2025

Combining FRET and super-resolution microscopy reveals kinase activation and mitochondrial activity at the nanoscale

Protein kinases are key regulators of intracellular signaling, showing activities in specific subcellular compartments and in micro- or nano-domains. Genetically encoded biosensors based on Forsters Resonance Energy Transfer (FRET) are powerful tools to track kinase dynamics. Yet, they are typically limited by spatial resolution and remain challenging to implement with super-resolution microscopy approaches that require specific fluorophores or optical setups. Aurora kinase A (AURKA), a multifunctional serine/threonine kinase, has recently emerged as a critical regulator of mitochondrial physiology. However, visualising AURKA activation and activity in living cells with sub-diffraction precision remains a challenge. Here, we introduce BioSenSRRF, a versatile approach that combines conventional FRET biosensors with Super-Resolution Radial Fluctuations (SRRF) microscopy. BioSenSRRF requires no modification of existing probes, can be implemented using standard microscopy setups, and is supported by a publicly available ImageJ framework to streamline image processing and data analysis. Using this pipeline, we imaged AURKA activation at mitochondria and its activity in regulating mitochondrial ATP levels. We uncover that AURKA activation and activity are compartmentalised into distinct mitochondrial domains containing the mitochondrial ATP synthase. These subdomains depend on the catalytic activity of AURKA, and they can be altered using previously validated AURKA inhibitors. Finally, we demonstrate that the cancer-associated polymorphism F31I enhances AURKA activation and ATP production on ATP synthase-enriched subdomains, underscoring its pathological relevance. Altogether, BioSenSRRF provides a broadly accessible framework to enhance the spatial resolution of genetically encoded biosensors. This strategy opens new avenues for dissecting the subcellular organisation of protein complexes and their contribution to physiology and disease states.

cell biology↗

bioRxiv2023

Integrin-like adhesin CglD confers traction and stabilizes bacterial focal adhesions involved in myxobacterial gliding motility

AO_SCPLOWBSTRACTC_SCPLOWIntegrins are crucial for eukaryotic cell attachment and motility within the extracellular matrix (ECM) via focal-adhesion formation, with their evolutionary emergence important for the development of multicellularity. Intriguingly, single gliding cells of the predatory deltaproteobacterium Myxococcus xanthus form bacterial focal-adhesion (bFA) sites; therein, helically-trafficked motors become immobilized at anchored locations through Glt apparatus association with cell-surface integrin I-domain-like adhesin CglB. Using traction-force, bead-force, and total internal reflection-fluorescence microscopies combined with biochemical approaches, we herein identify the von Willebrand A domain-containing cell-surface lipoprotein CglD to be a {beta}-integrin-like outer-membrane lipoprotein that functionally associates with and anchors the trans-envelope Glt-CglB gliding apparatus, stabilizing and efficiently anchoring this assembly at bFAs. Calcium dependence governs CglD importance, consistent with its integrated ECM eukaryotic cartilage oligomeric matrix protein domains. CglD thus confers mechanosensory and mechanotransductory capabilities to the gliding apparatus, helping explain bFA-mediated trans-envelope force transduction, from inner-membrane-embedded motors to the cell surface.

microbiology↗

bioRxiv2022

Bacterial outer-membrane polysaccharide export (OPX) proteins occupy three structural classes with selective β-barrel porin requirements for polymer secretion

Secretion of high-molecular-weight polysaccharides across the bacterial envelope is ubiquitous as it enhances prokaryotic survival in (a)biotic settings. Such polymers are often assembled by Wzx/Wzy- or ABC transporter-dependent schemes that implicate outer-membrane (OM) polysaccharide export (OPX) proteins in polymer translocation to the cell surface. In the social predatory bacterium Myxococcus xanthus, exopolysaccharide (EPS)-pathway WzaX, major spore coat (MASC)-pathway WzaS, and biosurfactant polysaccharide-pathway WzaB were herein found to be truncated OPX homologues of Escherichia coli Wza lacking OM-spanning -helices. Comparative genomics across all bacteria, complemented with cryo-electron tomography cell- envelope analyses, revealed WzaX/S/B architecture to be the most common amongst three defined OPX-protein structural classes independent of periplasmic thickness. Fold-recognition and deep- learning analyses revealed the conserved M. xanthus proteins MXAN_7418/3226/1916 (encoded adjacent to WzaX/S/B) to be integral OM {beta}-barrels, with structural homology to the poly-N-acetyl-D- glucosamine synthase-dependent pathway porin PgaA. Such porins were identified in bacteria near numerous genes for all three OPX-protein classes. Interior MXAN_7418/3226/1916 {beta}-barrel electrostatics were found to match known properties of their associated polymers. With MXAN_3226 essential for MASC export, and MXAN_7418 absence shown herein to compromise EPS translocation, these data support a novel secretion paradigm for Wzx/Wzy-dependent pathways in which those containing an OPX component that cannot span the OM instead utilize a {beta}-barrel porin to mediate polysaccharide transport across the OM.

microbiology↗

bioRxiv2020

Bacterial glycocalyx integrity drives multicellular swarm biofilm dynamism

Bacterial surface exopolysaccharide (EPS) layers are key determinants of biofilm establishment and maintenance, leading to the formation of higher-order 3D structures conferring numerous survival benefits to a cell community. In addition to a specific EPS glycocalyx, we recently revealed that the social {delta}-proteobacterium Myxococcus xanthus secretes a novel biosurfactant polysaccharide (BPS), with both EPS and BPS polymers required for type IV pilus (T4P)-dependent swarm expansion via spatio-specific biofilm expression profiles. Thus the synergy between EPS and BPS secretion somehow modulates the multicellular lifecycle of M. xanthus. Herein, we demonstrate that BPS secretion functionally-activates the EPS glycocalyx via its destabilization, fundamentally altering the characteristics of the cell surface. This impacts motility behaviours at the single-cell level as well as the aggregative capacity of cells in groups via EPS fibril formation and T4P assembly. These changes modulate structuration of swarm biofilms via cell layering, likely contributing to the formation of internal swarm polysaccharide architecture. Together, these data reveal the manner by which the interplay between two secreted polymers induces single-cell changes that modulate swarm biofilm communities.

microbiology↗

bioRxiv2020

CglB adhesins secreted at bacterial focal adhesions mediate gliding motility

AO_SCPLOWBSTRACTC_SCPLOWThe predatory deltaproteobacterium Myxococcus xanthus uses a helically-trafficked motor at bacterial focal adhesion (bFA) sites to power gliding motility. Using TIRF and force microscopy, we herein identify the integrin I-domain-like outer-membrane (OM) lipoprotein CglB as an essential substratum-coupling protein of the gliding motility complex. Similar to most known OM lipoproteins, CglB is anchored on the periplasmic side of the OM and thus a mechanism must exist to secrete it to the cell surface in order for it to interact with the underlying substratum. We reveal this process to be mediated by a predicted OM {beta}-barrel structure of the gliding complex. This OM platform was found to regulate the conformational activation and secretion of CglB across the OM. These data suggest that the gliding complex promotes surface exposure of CglB at bFAs, thus explaining the manner by which forces exerted by inner-membrane motors are transduced across the cell envelope to the substratum; they also uncover a novel protein secretion mechanism, highlighting the ubiquitous connection between secretion and bacterial motility.

microbiology↗