title: Structural basis for the phosphorylation of FUNDC1 LIR as a molecular switch of mitophagy.
abstract: Mitophagy is a fundamental process that determines mitochondrial quality and homeostasis. Several mitophagy receptors, including the newly identified FUNDC1, mediate selective removal of damaged or superfluous mitochondria through their specific interaction with LC3. However, the precise mechanism by which this interaction is regulated to initiate mitophagy is not understood. Here, we report the solution structure of LC3 in complex with a peptide containing the FUNDC1 LC3-interacting region (LIR) motif. The structure reveals a noncanonical LC3-LIR binding conformation, in which the third LIR residue (Val20) is also inserted into the hydrophobic pocket of LC3, together with the conserved residues Tyr18 and Leu21. This enables Tyr18 to be positioned near Asp19 of LC3, and thus phosphorylation of Tyr18 significantly weakens the binding affinity due to electrostatic repulsion. Functional analysis revealed that mitochondrial targeting of the LIR-containing cytosolic portion of FUNDC1 is necessary and sufficient to initiate mitophagy when Tyr18 is unphosphorylated, even in the absence of mitochondrial fragmentation. Thus, we demonstrated that phosphorylation of Tyr18 of FUNDC1 serves as a molecular switch for mitophagy. This may represent a novel target for therapeutic intervention.
authors.affiliation: a Beijing Nuclear Magnetic Resonance Center, College of Chemistry and Molecular Engineering, School of Life Sciences, Peking University , Beijing , China.
authors.forename: Yao
authors.initials: Y
authors.lastname: Kuang
authors.affiliation: b State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Protein Science, College of Life Sciences, Nankai University , Tianjin , China.
authors.forename: Kaili
authors.initials: K
authors.lastname: Ma
authors.affiliation: b State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Protein Science, College of Life Sciences, Nankai University , Tianjin , China.
authors.forename: Changqian
authors.initials: C
authors.lastname: Zhou
authors.affiliation: a Beijing Nuclear Magnetic Resonance Center, College of Chemistry and Molecular Engineering, School of Life Sciences, Peking University , Beijing , China.
authors.forename: Pengfei
authors.initials: P
authors.lastname: Ding
authors.affiliation: b State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Protein Science, College of Life Sciences, Nankai University , Tianjin , China.
authors.forename: Yushan
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: b State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Protein Science, College of Life Sciences, Nankai University , Tianjin , China.|c State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Zoology, Chinese Academy of Sciences , Beijing , China.
authors.forename: Quan
authors.initials: Q
authors.lastname: Chen
authors.affiliation: a Beijing Nuclear Magnetic Resonance Center, College of Chemistry and Molecular Engineering, School of Life Sciences, Peking University , Beijing , China.
authors.forename: Bin
authors.initials: B
authors.lastname: Xia
mesh_terms: D020816:Amino Acid Motifs; D003600:Cytosol / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism*; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000737:chemistry* / Q000378:metabolism*; D063306:Mitophagy; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D013329:Structure-Activity Relationship
chemical_list: C571016:FUNDC1 protein, human; C477012:MAP1LC3A protein, human; D008565:Membrane Proteins; D008869:Microtubule-Associated Proteins; D024101:Mitochondrial Proteins; D010455:Peptides; D019000:Phosphotyrosine
keywords: FUNDC1; LC3; LIR; NMR; mitophagy; phosphorylation