TY - JOUR
T1 - Dual role of a GTPase conformational switch for membrane fusion by mitofusin ubiquitylation
AU - Schuster, Ramona
AU - Anton, Vincent
AU - Simões, Tânia
AU - Altin, Selver
AU - den Brave, Fabian
AU - Hermanns, Thomas
AU - Hospenthal, Manuela
AU - Komander, David
AU - Dittmar, Gunnar
AU - Jürgen Dohmen, R.
AU - Escobar-Henriques, Mafalda
N1 - Funding Information:
We would like to thank T Sommer for the Cdc48 and Ubc6 antibodies; S Claypool for the Psd1 antibody; B Westermann for the plasmids pYX142-mtGFP; pYX113-mtGFP and pYX113-mtRFP; J Shaw for pRS415-3xMyc-Fzo1; K Tanaka for the Ubiquitin plasmid and corresponding K48R mutant variant; A Buchberger for the GAL1-CDC48 plasmid; I Woiwode for help with the purification of USP21; and A Taly for the computational models to bacterial dynamin-like protein of Fzo1. We are grateful to T Tatsuta for critical reading of the manuscript and to G Praefcke for stimulating discussions. This work was supported by grants of the Deutsche Forschungsgemeinschaft (ES338/3-1, Collaborative Research Center 1218 TP A03; to M Escobar-Henriques), the Center for Molecular Medicine Cologne (CAP14, to M Escobar-Henriques), was funded under the Institutional Strategy of the University of Cologne within the German Excellence Initiative (ZUK 81/1, to M Escobar-Henriques), and benefited from funds of the Faculty of Mathematics and Natural Sciences, attributed to M Escobar-Henriques.
Publisher Copyright:
© 2020 Rockefeller University Press. All rights reserved.
PY - 2020
Y1 - 2020
N2 - Mitochondria are essential organelles whose function is upheld by their dynamic nature. This plasticity is mediated by large dynamin-related GTPases, called mitofusins in the case of fusion between two mitochondrial outer membranes. Fusion requires ubiquitylation, attached to K398 in the yeast mitofusin Fzo1, occurring in atypical and conserved forms. Here, modelling located ubiquitylation to α4 of the GTPase domain, a critical helix in Ras-mediated events. Structure-driven analysis revealed a dual role of K398. First, it is required for GTP-dependent dynamic changes of α4. Indeed, mutations designed to restore the conformational switch, in the absence of K398, rescued wild-type-like ubiquitylation on Fzo1 and allowed fusion. Second, K398 is needed for Fzo1 recognition by the pro-fusion factors Cdc48 and Ubp2. Finally, the atypical ubiquitylation pattern is stringently required bilaterally on both involved mitochondria. In contrast, exchange of the conserved pattern with conventional ubiquitin chains was not sufficient for fusion. In sum, α4 lysines from both small and large GTPases could generally have an electrostatic function for membrane interaction, followed by posttranslational modifications, thus driving membrane fusion events.
AB - Mitochondria are essential organelles whose function is upheld by their dynamic nature. This plasticity is mediated by large dynamin-related GTPases, called mitofusins in the case of fusion between two mitochondrial outer membranes. Fusion requires ubiquitylation, attached to K398 in the yeast mitofusin Fzo1, occurring in atypical and conserved forms. Here, modelling located ubiquitylation to α4 of the GTPase domain, a critical helix in Ras-mediated events. Structure-driven analysis revealed a dual role of K398. First, it is required for GTP-dependent dynamic changes of α4. Indeed, mutations designed to restore the conformational switch, in the absence of K398, rescued wild-type-like ubiquitylation on Fzo1 and allowed fusion. Second, K398 is needed for Fzo1 recognition by the pro-fusion factors Cdc48 and Ubp2. Finally, the atypical ubiquitylation pattern is stringently required bilaterally on both involved mitochondria. In contrast, exchange of the conserved pattern with conventional ubiquitin chains was not sufficient for fusion. In sum, α4 lysines from both small and large GTPases could generally have an electrostatic function for membrane interaction, followed by posttranslational modifications, thus driving membrane fusion events.
UR - http://www.scopus.com/inward/record.url?scp=85077132006&partnerID=8YFLogxK
U2 - 10.26508/lsa.201900476
DO - 10.26508/lsa.201900476
M3 - Article
C2 - 31857350
AN - SCOPUS:85077132006
SN - 2575-1077
VL - 3
JO - Life Science Alliance
JF - Life Science Alliance
IS - 1
M1 - e201900476
ER -