title: Biochemical Evidence for a Nuclear Modifier Allele (A10S) in TRMU (Methylaminomethyl-2-thiouridylate-methyltransferase) Related to Mitochondrial tRNA Modification in the Phenotypic Manifestation of Deafness-associated 12S rRNA Mutation.
abstract: Nuclear modifier gene(s) was proposed to modulate the phenotypic expression of mitochondrial DNA mutation(s). Our previous investigations revealed that a nuclear modifier allele (A10S) in TRMU (methylaminomethyl-2-thiouridylate-methyltransferase) related to tRNA modification interacts with 12S rRNA 1555A→G mutation to cause deafness. The A10S mutation resided at a highly conserved residue of the N-terminal sequence. It was hypothesized that the A10S mutation altered the structure and function of TRMU, thereby causing mitochondrial dysfunction. Using molecular dynamics simulations, we showed that the A10S mutation introduced the Ser10dynamic electrostatic interaction with the Lys106residue of helix 4 within the catalytic domain of TRMU. The Western blotting analysis displayed the reduced levels of TRMU in mutant cells carrying the A10S mutation. The thermal shift assay revealed theTmvalue of mutant TRMU protein, lower than that of the wild-type counterpart. The A10S mutation caused marked decreases in 2-thiouridine modification of U34 of tRNALys, tRNAGluand tRNAGlnHowever, the A10S mutation mildly increased the aminoacylated efficiency of tRNAs. The altered 2-thiouridine modification worsened the impairment of mitochondrial translation associated with the m.1555A→G mutation. The defective translation resulted in the reduced activities of mitochondrial respiration chains. The respiratory deficiency caused the reduction of mitochondrial ATP production and elevated the production of reactive oxidative species. As a result, mutated TRMU worsened mitochondrial dysfunctions associated with m.1555A→G mutation, exceeding the threshold for expressing a deafness phenotype. Our findings provided new insights into the pathophysiology of maternally inherited deafness that was manifested by interaction between mtDNA mutation and nuclear modifier gene.
authors.affiliation: From the Division of Medical Genetics and Genomics, Zhejiang Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China.|the Institute of Genetics and.
authors.forename: Feilong
authors.initials: F
authors.lastname: Meng
authors.affiliation: From the Division of Medical Genetics and Genomics, Zhejiang Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China.|the Institute of Genetics and.
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Cang
authors.affiliation: the Institute of Genetics and.|the Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229.
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Peng
authors.affiliation: the Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia 30307.
authors.forename: Ronghua
authors.initials: R
authors.lastname: Li
authors.affiliation: the Institute of Genetics and.
authors.forename: Zhengyue
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: the Institute of Genetics and.
authors.forename: Fushan
authors.initials: F
authors.lastname: Li
authors.affiliation: the Institute of Genetics and.
authors.forename: Qingqing
authors.initials: Q
authors.lastname: Fan
authors.affiliation: the Ahmanson Department of Pediatrics, Cedars-Sinai Medical Center, UCLA School of Medicine, Los Angeles, California 90095, and.
authors.forename: Anna S
authors.initials: AS
authors.lastname: Guan
authors.affiliation: the Ahmanson Department of Pediatrics, Cedars-Sinai Medical Center, UCLA School of Medicine, Los Angeles, California 90095, and.
authors.forename: Nathan
authors.initials: N
authors.lastname: Fischel-Ghosian
authors.affiliation: the Institute of Genetics and zhaoxiaoli@zju.edu.cn.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Zhao
authors.affiliation: From the Division of Medical Genetics and Genomics, Zhejiang Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China, gminxin88@zju.edu.cn.|the Institute of Genetics and.|the Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University, Hangzhou, Zhejiang 310058, China.|the Joining Institute of Genetics and Genomic Medicine between Zhejiang University and University of Toronto, Hangzhou, Zhejiang 310058, China.
authors.forename: Min-Xin
authors.initials: MX
authors.lastname: Guan
mesh_terms: D000483:Alleles; D049148:Aminoacylation; D003638:Deafness / Q000235:genetics*; D004795:Enzyme Stability; D005470:Fluorometry; D006801:Humans; D008928:Mitochondria / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D056004:Molecular Dynamics Simulation; D009154:Mutation; D010641:Phenotype; D012335:RNA, Ribosomal / Q000235:genetics*; D012343:RNA, Transfer / Q000378:metabolism*; D012359:tRNA Methyltransferases / Q000235:genetics / Q000378:metabolism*
chemical_list: D024101:Mitochondrial Proteins; D012335:RNA, Ribosomal; C075526:RNA, ribosomal, 12S; D012343:RNA, Transfer; D012359:tRNA Methyltransferases; C496706:TRMU protein, human
keywords: hearing; mitochondrial DNA (mtDNA); mitochondrial disease; molecular modeling; oxygen radicals; post-translational modification (PTM); respiration; ribosomal ribonucleic acid (rRNA) (ribosomal RNA); transfer RNA (tRNA); translation