Abstract
Mitochondrial fusion requires the sequential merger of four bilayers to two. The outer-membrane solute carrier protein SLC25A46 interacts with both the outer and inner-membrane dynamin family GTPases Mfn1/2 and Opa1. While SLC25A46 levels are known to affect mitochondrial morphology, how SLC25A46 interacts with Mfn1/2 and Opa1 to regulate membrane fusion is not understood. In this study, we use crosslinking mass-spectrometry and AlphaFold 2 modeling to identify interfaces mediating a SLC25A46 interactions with Opa1 and Mfn2. We reveal that the bundle signaling element of Opa1 interacts with SLC25A46, and present evidence of a Mfn2 interaction involving the SLC25A46 cytosolic face. We validate these newly identified interaction interfaces and show that they play a role in mitochondrial network maintenance.
Competing Interest Statement
L.H.C. is an advisor for Stealth Biotherapeutics. The remaining authors declare that there are no competing financial interests.
Footnotes
Revised MS. Reorganized Figures. New Figure 3 Mfn2 data. Statistics for cellular mitochondriall morphology comparisons now included.
Abbreviations and nomenclature
- OMM
- outer mitochondrial membrane
- IMM
- inner mitochondrial membrane
- SLC
- solute carrier family
- SLC25A46
- solute carrier family 25 member A46
- Opa1
- optic atrophy 1
- Mfn1/2
- mitofusin 1/2
- iPSC
- induced pluoripotent stem cells
- BSE
- bundle signaling element
- HR1/2
- heptad repeat 1/2
- ER
- endoplasmic reticulum
- MGD
- minimal GTPase domain
- DDM
- n-Dodecyl-β-D-Maltopyranoside
- GDN
- glyco-diosgenin
- PA
- phosphatidic acid
- TM
- transmembrane segment
- MTS
- mitochondrial targeting sequence
- IMS
- inter-membrane space
