title: Self-clearance mechanism of mitochondrial E3 ligase MARCH5 contributes to mitochondria quality control.
abstract: MARCH5, a mitochondrial E3 ubiquitin ligase, controls mitochondrial dynamics proteins and misfolded proteins, and has been proposed to play a role in mitochondria quality control. However, it remains unclear how mutant MARCH5 found in cancer tissues is removed from cells. Here, we show that mutation in the MARCH5 ligase domain increased its half-life fourfold, resulting in a drastic increase in its protein level. Abnormal accumulation of the E3 ligase-defective MARCH5 mutants MARCH5(H43W) and MARCH5(C65/68S) was diminished by overexpression of active MARCH5(WT) ; the mutant proteins were degraded through the ubiquitin-proteasome pathway. Coimmunoprecipitation revealed that MARCH5 forms homodimers, and that substitution of Gly to Leu at the first putative GxxxG dimerization motif, but not the second, resulted in a loss of dimeric interaction. Moreover, overexpression of the dimerization-defective mutant MARCH5(4GL) could not decrease the level of accumulated MARCH5(H43W) , suggesting that dimerization of MARCH5 is necessary for self-clearance. Abnormal accumulation of MARCH5(H43W) and mitochondrial hyperfusion led to NF-ĸB activation, which was suppressed by overexpression of MARCH5(WT) . Together, the data reveal a self-protective mechanism involving MARCH5, which can target its own dysfunctional mutant for degradation in order to maintain mitochondrial homeostasis.
authors.affiliation: Department of Biochemistry, Ajou University School of Medicine, Suwon, Korea.
authors.forename: Song-Hee
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Department of Biochemistry, Ajou University School of Medicine, Suwon, Korea.
authors.forename: Yong-Yea
authors.initials: YY
authors.lastname: Park
authors.affiliation: Department of Biochemistry, Ajou University School of Medicine, Suwon, Korea.|Department of Biomedical Sciences, Graduate School of Ajou University, Suwon, Korea.
authors.forename: Young-Suk
authors.initials: YS
authors.lastname: Yoo
authors.affiliation: Department of Biochemistry, Ajou University School of Medicine, Suwon, Korea.|Department of Biomedical Sciences, Graduate School of Ajou University, Suwon, Korea.
authors.forename: Hyeseong
authors.initials: H
authors.lastname: Cho
mesh_terms: D020816:Amino Acid Motifs; D057809:HEK293 Cells; D006207:Half-Life; D006367:HeLa Cells; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D009154:Mutation; D016328:NF-kappa B / Q000378:metabolism; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D059748:Proteolysis; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: D008565:Membrane Proteins; D016328:NF-kappa B; C515578:MARCHF5 protein, human; D044767:Ubiquitin-Protein Ligases
keywords: E3 ubiquitin ligase; MARCH5; mitochondria; quality control; self-clearance