A non-linear system patterns Rab5 GTPase on the membrane

Cezanne, Alice; Lauer, J.; Solomatina, Anastasia I.; Sbalzarini, Ivo F.; Zerial, Marino

doi:10.7554/elife.54434

Cited by 34 publications

(42 citation statements)

References 70 publications

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“…Consistent with the organelle-specific roles of Rab5a on early endosomes 14,56,57 and Rab1 in autophagy 30,58,59 , we found that Rab5a preferentially activates complex II over complex I, and Rab1a activates only complex I. The cryo-ET structure shows that the VPS15 WD40 and SGD domains, as well as the VPS34 C2 helical insertion (C2HH), make interactions with Rab5a (Fig.…”

Section: Discussionsupporting

confidence: 82%

“…Cryo-ET enabled us to visualise the molecular organisation of Rab5a-GTP/ complex II assembly on membranes. The dynamic mode of complex II membrane attachment allows the activated VPS34 kinase to survey the membrane for available substrate and generate local enrichment of PI3P that enables patterning of tightly organised Rab-containing domains 14 that ultimately determine organellar identity.…”

Section: Discussionmentioning

confidence: 99%

“…Rab5 is indispensable at early endosomes 12 , where it has a role in the activation of VPS34 13 . PI3P positively regulates the activity of Rab5 by recruiting it to membranes through a positive feedback loop with its GEF/ effector complex, Rabex5/Rabaptin5 14 . Human VPS34 forms two heterotetrameric core complexes known as complexes I and II 15 .…”

mentioning

confidence: 99%

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Structural basis for VPS34 kinase activation by Rab1 and Rab5 on membranes

et al. 2021

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The lipid phosphatidylinositol-3-phosphate (PI3P) is a regulator of two fundamental but distinct cellular processes, endocytosis and autophagy, so its generation needs to be under precise temporal and spatial control. PI3P is generated by two complexes that both contain the lipid kinase VPS34: complex II on endosomes (VPS34/VPS15/Beclin 1/UVRAG), and complex I on autophagosomes (VPS34/VPS15/Beclin 1/ATG14L). The endosomal GTPase Rab5 binds complex II, but the mechanism of VPS34 activation by Rab5 has remained elusive, and no GTPase is known to bind complex I. Here we show that Rab5a–GTP recruits endocytic complex II to membranes and activates it by binding between the VPS34 C2 and VPS15 WD40 domains. Electron cryotomography of complex II on Rab5a-decorated vesicles shows that the VPS34 kinase domain is released from inhibition by VPS15 and hovers over the lipid bilayer, poised for catalysis. We also show that the GTPase Rab1a, which is known to be involved in autophagy, recruits and activates the autophagy-specific complex I, but not complex II. Both Rabs bind to the same VPS34 interface but in a manner unique for each. These findings reveal how VPS34 complexes are activated on membranes by specific Rab GTPases and how they are recruited to unique cellular locations.

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Section: Discussionsupporting

confidence: 82%

Section: Discussionmentioning

confidence: 99%

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Structural basis for VPS34 kinase activation by Rab1 and Rab5 on membranes

et al. 2021

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“…Relaxing this condition by reversing the GTPase:GEF ratio produced multiple coexisting mesa patterns, despite the reaction kinetics remaining the same. These modeling results are in good agreement with the results of [63] that, for the first time in any known system, succeeded in the in vitro reconstitution of the GTPase pattern formation using only a minimal set of recombinant proteins and lipid-coated beads. This remarkable effort produced multiple mesa-type spots of Rab5-GTP that stably coexisted during the duration of experiment.…”

Section: Implications For Cellular Morphogenesissupporting

confidence: 87%

Compete or Coexist? Why the Same Mechanisms of Symmetry Breaking Can Yield Distinct Outcomes

Goryachev

Leda

2020

Cells

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Cellular morphogenesis is governed by the prepattern based on the symmetry-breaking emergence of dense protein clusters. Thus, a cluster of active GTPase Cdc42 marks the site of nascent bud in the baker’s yeast. An important biological question is which mechanisms control the number of pattern maxima (spots) and, thus, the number of nascent cellular structures. Distinct flavors of theoretical models seem to suggest different predictions. While the classical Turing scenario leads to an array of stably coexisting multiple structures, mass-conserved models predict formation of a single spot that emerges via the greedy competition between the pattern maxima for the common molecular resources. Both the outcome and the kinetics of this competition are of significant biological importance but remained poorly explored. Recent theoretical analyses largely addressed these questions, but their results have not yet been fully appreciated by the broad biological community. Keeping mathematical apparatus and jargon to the minimum, we review the main conclusions of these analyses with their biological implications in mind. Focusing on the specific example of pattern formation by small GTPases, we speculate on the features of the patterning mechanisms that bypass competition and favor formation of multiple coexisting structures and contrast them with those of the mechanisms that harness competition to form unique cellular structures.

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“…This is to actively recruit Rab7a to the maturing endosome, which is necessary for the convergence phase of Rab5 maturation. Formation of the initial Rab5 domains in the convergence phase might be spontaneous and GTP dependent, as found in cell-free studies ( Cezanne et al, 2020 ). Our FRAP experiments showed a gradual increase of the relative Rab5-immobile fraction, also indicating a GTP-dependent organization of Rab5-positive domains during convergence.…”

Section: Discussionmentioning

confidence: 69%

De novo formation of early endosomes during Rab5-to-Rab7a transition

Skjeldal

Haugen

Mateus

et al. 2021

Journal of Cell Science

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Rab5 and Rab7a are the main determinants of early and late endosomes and are important regulators of endosomal progression. The transport from early endosomes to late endosome seems to be regulated through an endosomal maturation switch where Rab5 is gradually exchanged with Rab7a on the same endosome. Here we provide new insight into the mechanism of endosomal maturation where we have discovered a stepwise Rab5 detachment, sequentially regulated by Rab7a. The initial detachment of Rab5 is Rab7a independent and demonstrate a diffusion-like exchange between cytosol and endosomal membrane, and a second phase where Rab5 converges into specific domains that detaches as a Rab5 indigenous endosome. Consequently, we show that early endosomal maturation regulated through the Rab5 to Rab7a switch induce the formation of new fully functional rab5 positive early endosomes. Progression through a stepwise early endosomal maturation regulates the direction of the transport and concomitantly regulates the homeostasis of early endosomes.

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A non-linear system patterns Rab5 GTPase on the membrane

Cited by 34 publications

References 70 publications

Structural basis for VPS34 kinase activation by Rab1 and Rab5 on membranes

Structural basis for VPS34 kinase activation by Rab1 and Rab5 on membranes

Compete or Coexist? Why the Same Mechanisms of Symmetry Breaking Can Yield Distinct Outcomes

De novo formation of early endosomes during Rab5-to-Rab7a transition

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