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Bhowal P, Roy B, Ganguli S, Igloi GL, Banerjee R. Elucidating the structure-function attributes of a trypanosomal arginyl-tRNA synthetase. Mol Biochem Parasitol 2023; 256:111597. [PMID: 37852416 DOI: 10.1016/j.molbiopara.2023.111597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2023] [Revised: 09/20/2023] [Accepted: 10/10/2023] [Indexed: 10/20/2023]
Abstract
Aminoacyl-tRNA synthetases (aaRSs) are fundamental components of the protein translation machinery. In light of their pivotal role in protein synthesis and structural divergence among species, they have always been considered potential targets for the development of antimicrobial compounds. Arginyl-tRNA synthetase from Trypanosoma cruzi (TcArgRS), the parasite responsible for causing Chagas Disease, contains a 100-amino acid insertion that was found to be completely absent in the human counterpart of similar length, as ascertained from multiple sequence alignment results. Thus, we were prompted to perform a preliminary characterization of TcArgRS using biophysical, biochemical, and bioinformatics tools. We expressed the protein in E. coli and validated its in-vitro enzymatic activity. Additionally, analysis of DTNB kinetics, Circular dichroism (CD) spectra, and ligand-binding studies using intrinsic tryptophan fluorescence measurements aided us to understand some structural features in the absence of available crystal structures. Our study indicates that TcArgRS can discriminate between L-arginine and its analogues. Among the many tested substrates, only L-canavanine and L-thioarginine, a synthetic arginine analogue exhibited notable activation. The binding of various substrates was also determined using in silico methods. This study may provide a viable foundation for studying small compounds that can be targeted against TcArgRS.
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Affiliation(s)
- Pratyasha Bhowal
- Department of Biotechnology and Dr. B. C. Guha Centre for Genetic Engineering and Biotechnology, University of Calcutta, 35, Ballygunge Circular Road, Kolkata 700 019, India
| | - Bappaditya Roy
- Department of Microbiology, The Ohio State University, 318 West 12th Avenue, Columbus, OH 43210, USA; Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA
| | - Sayak Ganguli
- Post Graduate Department of Biotechnology, St. Xavier's College (Autonomous), 30, Park Street, Mullick Bazar, Kolkata 700 016, India.
| | - Gabor L Igloi
- Institute of Biology III, University of Freiburg, Schänzlestr 1, D-79104 Freiburg, Germany
| | - Rajat Banerjee
- Department of Biotechnology and Dr. B. C. Guha Centre for Genetic Engineering and Biotechnology, University of Calcutta, 35, Ballygunge Circular Road, Kolkata 700 019, India.
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2
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Fang G, Yang S, Ruan B, Liu C, Zhang A, Jiang H, Ding S, Tian B, Zhang Y, Jahan N, Zhu L, Zhang G, Dong G, Zhang Q, Zeng D, Guo L, Gao Z, Qian Q. Isolation of TSCD11 Gene for Early Chloroplast Development under High Temperature in Rice. RICE (NEW YORK, N.Y.) 2020; 13:49. [PMID: 32681435 PMCID: PMC7367945 DOI: 10.1186/s12284-020-00411-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Accepted: 07/08/2020] [Indexed: 05/11/2023]
Abstract
BACKGROUND Chloroplasts are essential for photosynthesis and play key roles in plant development. High temperature affects structure of chloroplasts and metabolism in plants. The seryl-tRNA synthetase plays an important role in translation of proteins. Although seryl-tRNA synthetase has been widely studied in microbes and animals, few studies have reported about its role in chloroplast development under high temperature in rice. RESULTS In this study, we isolated a novel temperature-sensitive chlorophyll-deficient 11 (tscd11) mutant by ethyl methane sulfonate (EMS) mutagenesis of japonica variety Wuyujing7. The tscd11 mutant developed albino leaves at the 3-leaf stage under high temperature (35 °C), but had normal green leaves under low temperature (25 °C). Consistent with the albino phenotype, impaired chloroplasts, decreased chlorophyll content and increased ROS accumulation were found in the tscd11 mutant at 35 °C. Fine mapping and DNA sequencing of tscd11 revealed a missense mutation (G to A) in the eighth exon of LOC_Os11g39670 resulted in amino acid change (Glu374 to Lys374). The TSCD11 gene encodes a seryl-tRNA synthetase localized to chloroplast. Complementation test confirmed that the point mutation in TSCD11 is responsible for the phenotype of tscd11. TSCD11 is highly expressed in leaves. Compared with the wild type (WT), mutation in TSCD11 led to significant alteration in expression levels of genes associated with chlorophyll biosynthesis, photosynthesis and chloroplast development under high temperature. CONCLUSIONS TSCD11, encoding a seryl-tRNA synthetase localized to chloroplast, is vital to early chloroplast development at high temperature in rice, which help to further study on the molecular mechanism of chloroplast development under high temperature.
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Affiliation(s)
- Guonan Fang
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, 310006, China
| | - Shenglong Yang
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, 310006, China
| | - Banpu Ruan
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, 310006, China
| | - Chaolei Liu
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, 310006, China
| | - Anpeng Zhang
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, 310006, China
| | - Hongzhen Jiang
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, 310006, China
| | - Shilin Ding
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, 310006, China
| | - Biao Tian
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, 310006, China
| | - Yu Zhang
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, 310006, China
| | - Noushin Jahan
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, 310006, China
| | - Li Zhu
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, 310006, China
| | - Guangheng Zhang
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, 310006, China
| | - Guojun Dong
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, 310006, China
| | - Qiang Zhang
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, 310006, China
| | - Dali Zeng
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, 310006, China
| | - Longbiao Guo
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, 310006, China
| | - Zhenyu Gao
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, 310006, China.
| | - Qian Qian
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, 310006, China.
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Chakraborty S, Ibba M, Banerjee R. Biophysical characterization Of Alpers encephalopathy associated mutants of human mitochondrial phenylalanyl-tRNA synthetase. IUBMB Life 2019; 71:1141-1149. [PMID: 31241862 DOI: 10.1002/iub.2114] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 06/06/2019] [Indexed: 12/13/2022]
Abstract
Mutations in nucleus-encoded mitochondrial aminoacyl-tRNA synthetases (mitaaRSs) lead to defects in mitochondrial translation affecting the expression and function of 13 subunits of the respiratory chain complex leading to diverse pathological conditions. Mutations in the FARS2 gene encoding human mitochondrial phenylalanyl-tRNA synthetase (HsmitPheRS) have been found to be associated with two different clinical representations, infantile Alpers encephalopathy and spastic paraplegia. Here we have studied three pathogenic mutants (Tyr144Cys, Ile329Thr, and Asp391Val) associated with Alpers encephalopathy to understand how these variants affect the biophysical properties of the enzyme. These mutants have already been reported to have reduced aminoacylation activity. Our study established that the mutants are significantly more thermolabile compared to the wild-type enzyme with reduced solubility in vitro. The presence of aggregation-prone insoluble HsmitPheRS variants could have a detrimental impact on organellar translation, and potentially impact normal mitochondrial function. © 2019 IUBMB Life, 71(8): 1141-1149, 2019 © 2019 IUBMB Life, 71(8):1141-1149, 2019.
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Affiliation(s)
- Shruti Chakraborty
- Department of Biotechnology and Dr. B. C. Guha Centre for Genetic Engineering and Biotechnology, University of Calcutta, Kolkata, India
| | - Michael Ibba
- Department of Microbiology, The Ohio State University, Columbus, Ohio
| | - Rajat Banerjee
- Department of Biotechnology and Dr. B. C. Guha Centre for Genetic Engineering and Biotechnology, University of Calcutta, Kolkata, India
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4
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Simon M, Richard EM, Wang X, Shahzad M, Huang VH, Qaiser TA, Potluri P, Mahl SE, Davila A, Nazli S, Hancock S, Yu M, Gargus J, Chang R, Al-sheqaih N, Newman WG, Abdenur J, Starr A, Hegde R, Dorn T, Busch A, Park E, Wu J, Schwenzer H, Flierl A, Florentz C, Sissler M, Khan SN, Li R, Guan MX, Friedman TB, Wu DK, Procaccio V, Riazuddin S, Wallace DC, Ahmed ZM, Huang T, Riazuddin S. Mutations of human NARS2, encoding the mitochondrial asparaginyl-tRNA synthetase, cause nonsyndromic deafness and Leigh syndrome. PLoS Genet 2015; 11:e1005097. [PMID: 25807530 PMCID: PMC4373692 DOI: 10.1371/journal.pgen.1005097] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Accepted: 02/23/2015] [Indexed: 12/31/2022] Open
Abstract
Here we demonstrate association of variants in the mitochondrial asparaginyl-tRNA synthetase NARS2 with human hearing loss and Leigh syndrome. A homozygous missense mutation ([c.637G>T; p.Val213Phe]) is the underlying cause of nonsyndromic hearing loss (DFNB94) and compound heterozygous mutations ([c.969T>A; p.Tyr323*] + [c.1142A>G; p.Asn381Ser]) result in mitochondrial respiratory chain deficiency and Leigh syndrome, which is a neurodegenerative disease characterized by symmetric, bilateral lesions in the basal ganglia, thalamus, and brain stem. The severity of the genetic lesions and their effects on NARS2 protein structure cosegregate with the phenotype. A hypothetical truncated NARS2 protein, secondary to the Leigh syndrome mutation p.Tyr323* is not detectable and p.Asn381Ser further decreases NARS2 protein levels in patient fibroblasts. p.Asn381Ser also disrupts dimerization of NARS2, while the hearing loss p.Val213Phe variant has no effect on NARS2 oligomerization. Additionally we demonstrate decreased steady-state levels of mt-tRNAAsn in fibroblasts from the Leigh syndrome patients. In these cells we show that a decrease in oxygen consumption rates (OCR) and electron transport chain (ETC) activity can be rescued by overexpression of wild type NARS2. However, overexpression of the hearing loss associated p.Val213Phe mutant protein in these fibroblasts cannot complement the OCR and ETC defects. Our findings establish lesions in NARS2 as a new cause for nonsyndromic hearing loss and Leigh syndrome. Mitochondrial respiratory chain (MRC) disease represents a large and heterogeneous group of energy deficiency disorders. Here we report three mutations in NARS2, a mitochondrial asparaginyl-tRNA synthetase, associated with non-syndromic hearing loss (NSHL) and Leigh syndrome in two independent families. Located in the predicted catalytic domain of the protein, missense mutation p.(Val213Phe) results in NSHL (DFNB94) while compound heterozygous mutation (p.Tyr323*; p.Asn381Ser) is leading to Leigh syndrome with auditory neuropathy. In vivo analysis deemed p.Tyr323* mutant protein to be unstable. Co-immunoprecipitation assays show that p.Asn381Ser mutant disrupts the dimerization ability of NARS2. Leigh syndrome patient fibroblasts exhibit a decreased steady-state level of mt-tRNAAsn. In addition, in these cells, the mitochondrial respiratory chain is deficient, including significantly decreased oxygen consumption rates and electron transport chain activities. These functions can be partially restored with over-expression of wild-type NARS2 but not with p.Val213Phe mutant protein. Our study provides new insights into the genes that are necessary for the function of brain and inner ear sensory cells in humans.
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Affiliation(s)
- Mariella Simon
- Department of Developmental and Cellular Biology, School of Biological Sciences, University of California, Irvine, Irvine, California, United States of America
- CHOC Childrens’, Division of Metabolics, Orange, California, United States of America
| | - Elodie M. Richard
- Department of Otorhinolaryngology Head & Neck Surgery, School of Medicine, University of Maryland, Baltimore, Maryland, United States of America
| | - Xinjian Wang
- Division of Human Genetics, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, United States of America
| | - Mohsin Shahzad
- Department of Otorhinolaryngology Head & Neck Surgery, School of Medicine, University of Maryland, Baltimore, Maryland, United States of America
| | - Vincent H. Huang
- Division of Human Genetics, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, United States of America
| | - Tanveer A. Qaiser
- National Center for Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Prasanth Potluri
- Center for Mitochondrial and Epigenomic Medicine, Children’s Hospital of Philadelphia and Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Sarah E. Mahl
- Division of Pediatric Otolaryngology Head & Neck Surgery, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, United States of America
| | - Antonio Davila
- Smilow Center for Translational Research, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Sabiha Nazli
- National Center for Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Saege Hancock
- Trovagene, San Diego, California, United States of America
| | - Margret Yu
- Marshall B Ketchum University, Fullerton, California, United States of America
| | - Jay Gargus
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, California, United States of America
| | - Richard Chang
- CHOC Childrens’, Division of Metabolics, Orange, California, United States of America
| | - Nada Al-sheqaih
- Manchester Centre for Genomic Medicine, University of Manchester and Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Sciences Centre (MAHSC), Manchester, United Kingdom
| | - William G. Newman
- Manchester Centre for Genomic Medicine, University of Manchester and Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Sciences Centre (MAHSC), Manchester, United Kingdom
| | - Jose Abdenur
- CHOC Childrens’, Division of Metabolics, Orange, California, United States of America
| | - Arnold Starr
- Department of Neurology and Neurobiology, University of California, Irvine, Irvine, California, United States of America
| | - Rashmi Hegde
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, United States of America
| | | | - Anke Busch
- Institute of Molecular Biology, Mainz, Germany
| | - Eddie Park
- Department of Developmental and Cellular Biology, School of Biological Sciences, University of California, Irvine, Irvine, California, United States of America
| | - Jie Wu
- Institute for Genomics and Bioinformatics, University of California, Irvine, Irvine, California, United States of America
| | - Hagen Schwenzer
- Architecture et Réactivité de l’ARN, CNRS, University of Strasbourg, IBMC, Strasbourg, France
| | - Adrian Flierl
- Parkinson’s Institute and Clinical Center, Sunnyvale, California, United States of America
| | - Catherine Florentz
- Architecture et Réactivité de l’ARN, CNRS, University of Strasbourg, IBMC, Strasbourg, France
| | - Marie Sissler
- Architecture et Réactivité de l’ARN, CNRS, University of Strasbourg, IBMC, Strasbourg, France
| | - Shaheen N. Khan
- National Center for Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Ronghua Li
- Division of Human Genetics, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, United States of America
| | - Min-Xin Guan
- Division of Human Genetics, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, United States of America
| | - Thomas B. Friedman
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Doris K. Wu
- Section on Sensory Cell Regeneration and Development, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Vincent Procaccio
- Biochemistry and Genetics Department, UMR CNRS 6214–INSERM U1083, CHU Angers, Angers, France
| | - Sheikh Riazuddin
- Jinnah Hospital Complex, Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan
- University of Lahore, Lahore, Pakistan
- Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Douglas C. Wallace
- Center for Mitochondrial and Epigenomic Medicine, Children’s Hospital of Philadelphia and Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Zubair M. Ahmed
- Department of Otorhinolaryngology Head & Neck Surgery, School of Medicine, University of Maryland, Baltimore, Maryland, United States of America
| | - Taosheng Huang
- Division of Human Genetics, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, United States of America
- * E-mail: (TH); (SR)
| | - Saima Riazuddin
- Department of Otorhinolaryngology Head & Neck Surgery, School of Medicine, University of Maryland, Baltimore, Maryland, United States of America
- * E-mail: (TH); (SR)
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Castiglione A, Guaran V, Astolfi L, Orioli E, Zeri G, Gemmati D, Bovo R, Montaldi A, Alghisi A, Martini A. Karyotype-phenotype correlation in partial trisomies of the short arm of chromosome 6: a family case report and review of the literature. Cytogenet Genome Res 2013; 141:243-59. [PMID: 23942271 DOI: 10.1159/000353846] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/02/2013] [Indexed: 11/19/2022] Open
Abstract
The first child (proband) of nonconsanguineous Caucasian parents underwent genetic investigation because she was affected with congenital choanal atresia, heart defects and kidney hyposplasia with mild transient renal insufficiency. The direct DNA sequencing after PCR of the CHD7 gene, which is thought to be responsible for approximately 60-70% of the cases of CHARGE syndrome/association, found no mutations. The cytogenetic analysis (standard GTG banding karyotype) revealed the presence of extrachromosomal material on 10q. The chromosome analysis was completed with array CGH (30 kb resolution), MLPA and FISH, which allowed the identification of three 6p regions (6p.25.3p23 × 3): 2 of these regions are normally located on chromosome 6, and the third region is translocated to the long arm of chromosome 10. The same chromosomal rearrangement was subsequently found in the father, who was affected with congenital ptosis and progressive hearing loss, and in the proband's sister, the second child, who presented at birth with choanal atresia and congenital heart defects. The mutated karyotypes, which were directly inherited, are thought to be responsible for a variable phenotype, including craniofacial dysmorphisms, choanal atresia, congenital ptosis, sensorineural hearing loss, heart defects, developmental delay, and renal dysfunction. Nevertheless, to achieve a complete audiological assessment of the father, he underwent further investigation that revealed an increased level of the coagulation factor XIII (300% increased activity), fluctuating levels of fibrin D-dimer degradation products (from 296 to 1,587 ng/ml) and a homoplasmic mitochondrial DNA mutation: T961G in the MTRNR1 (12S rRNA) gene. He was made a candidate for cochlear implantation. Preoperative high-resolution computed tomography and magnetic resonance imaging of the temporal bone revealed the presence of an Arnold-Chiari malformation type I. To the best of our knowledge, this study is the second report on partial 6p trisomy that involves the 10q terminal region. Furthermore, we report the first case of documented Arnold-Chiari malformation type I and increased factor XIII activity associated with 6p trisomy. We present a comprehensive report of the familial cases and an exhaustive literature review.
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Affiliation(s)
- A Castiglione
- Department of Neurosciences, Complex Operative Unit of Otorhinolaryngology and Otosurgery, Padua University Hospital, Padua, Italy
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Santos-Cortez RLP, Lee K, Azeem Z, Antonellis PJ, Pollock LM, Khan S, Andrade-Elizondo PB, Chiu I, Adams MD, Basit S, Smith JD, Nickerson DA, McDermott BM, Ahmad W, Leal SM. Mutations in KARS, encoding lysyl-tRNA synthetase, cause autosomal-recessive nonsyndromic hearing impairment DFNB89. Am J Hum Genet 2013; 93:132-40. [PMID: 23768514 DOI: 10.1016/j.ajhg.2013.05.018] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 05/02/2013] [Accepted: 05/20/2013] [Indexed: 01/27/2023] Open
Abstract
Previously, DFNB89, a locus associated with autosomal-recessive nonsyndromic hearing impairment (ARNSHI), was mapped to chromosomal region 16q21-q23.2 in three unrelated, consanguineous Pakistani families. Through whole-exome sequencing of a hearing-impaired individual from each family, missense mutations were identified at highly conserved residues of lysyl-tRNA synthetase (KARS): the c.1129G>A (p.Asp377Asn) variant was found in one family, and the c.517T>C (p.Tyr173His) variant was found in the other two families. Both variants were predicted to be damaging by multiple bioinformatics tools. The two variants both segregated with the nonsyndromic-hearing-impairment phenotype within the three families, and neither mutation was identified in ethnically matched controls or within variant databases. Individuals homozygous for KARS mutations had symmetric, severe hearing impairment across all frequencies but did not show evidence of auditory or limb neuropathy. It has been demonstrated that KARS is expressed in hair cells of zebrafish, chickens, and mice. Moreover, KARS has strong localization to the spiral ligament region of the cochlea, as well as to Deiters' cells, the sulcus epithelium, the basilar membrane, and the surface of the spiral limbus. It is hypothesized that KARS variants affect aminoacylation in inner-ear cells by interfering with binding activity to tRNA or p38 and with tetramer formation. The identification of rare KARS variants in ARNSHI-affected families defines a gene that is associated with ARNSHI.
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Affiliation(s)
- Regie Lyn P Santos-Cortez
- Center for Statistical Genetics, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
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7
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Pathogenic mutations causing LBSL affect mitochondrial aspartyl-tRNA synthetase in diverse ways. Biochem J 2013; 450:345-50. [PMID: 23216004 DOI: 10.1042/bj20121564] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The autosomal recessive white matter disorder LBSL (leukoencephalopathy with brain stem and spinal cord involvement and lactate elevation) is caused by mutations in DARS2, coding for mtAspRS (mitochondrial aspartyl-tRNA synthetase). Generally, patients are compound heterozygous for mutations in DARS2. Many different mutations have been identified in patients, including several missense mutations. In the present study, we have examined the effects of missense mutations found in LBSL patients on the expression, enzyme activity, localization and dimerization of mtAspRS, which is important for understanding the cellular defect underlying the pathogenesis of the disease. Nine different missense mutations were analysed and were shown to have various effects on mtAspRS properties. Several mutations have a direct effect on the catalytic activity of the enzyme; others have an effect on protein expression or dimerization. Most mutations have a clear impact on at least one of the properties of mtAspRS studied, probably resulting in a small contribution of the missense variants to the mitochondrial aspartylation activity in the cell.
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8
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Choudhury A, Banerjee R. The N-terminal fragment of Acanthamoeba polyphaga
mimivirus tyrosyl-tRNA synthetase (TyrRSapm
) is a monomer in solution. FEBS Lett 2013; 587:590-9. [DOI: 10.1016/j.febslet.2013.01.048] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Revised: 01/21/2013] [Accepted: 01/22/2013] [Indexed: 01/14/2023]
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9
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Elo JM, Yadavalli SS, Euro L, Isohanni P, Götz A, Carroll CJ, Valanne L, Alkuraya FS, Uusimaa J, Paetau A, Caruso EM, Pihko H, Ibba M, Tyynismaa H, Suomalainen A. Mitochondrial phenylalanyl-tRNA synthetase mutations underlie fatal infantile Alpers encephalopathy. Hum Mol Genet 2012; 21:4521-9. [PMID: 22833457 DOI: 10.1093/hmg/dds294] [Citation(s) in RCA: 122] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Next-generation sequencing has turned out to be a powerful tool to uncover genetic basis of childhood mitochondrial disorders. We utilized whole-exome analysis and discovered novel compound heterozygous mutations in FARS2 (mitochondrial phenylalanyl transfer RNA synthetase), encoding the mitochondrial phenylalanyl transfer RNA (tRNA) synthetase (mtPheRS) in two patients with fatal epileptic mitochondrial encephalopathy. The mutations affected highly conserved amino acids, p.I329T and p.D391V. Recently, a homozygous FARS2 variant p.Y144C was reported in a Saudi girl with mitochondrial encephalopathy, but the pathogenic role of the variant remained open. Clinical features, including postnatal onset, catastrophic epilepsy, lactic acidemia, early lethality and neuroimaging findings of the patients with FARS2 variants, resembled each other closely, and neuropathology was consistent with Alpers syndrome. Our structural analysis of mtPheRS predicted that p.I329T weakened ATP binding in the aminoacylation domain, and in vitro studies with recombinant mutant protein showed decreased affinity of this variant to ATP. Furthermore, p.D391V and p.Y144C were predicted to disrupt synthetase function by interrupting the rotation of the tRNA anticodon stem-binding domain from a closed to an open form. In vitro characterization indicated reduced affinity of p.D391V mutant protein to phenylalanine, whereas p.Y144C disrupted tRNA binding. The stability of p.I329T and p.D391V mutants in a refolding assay was impaired. Our results imply that the three FARS2 mutations directly impair aminoacylation function and stability of mtPheRS, leading to a decrease in overall tRNA charging capacity. This study establishes a new genetic cause of infantile mitochondrial Alpers encephalopathy and reports a new mitochondrial aminoacyl-tRNA synthetase as a cause of mitochondrial disease.
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Affiliation(s)
- Jenni M Elo
- Research Programs Unit, Molecular Neurology, Biomedicum-Helsinki, University of Helsinki, 00290 Helsinki, Finland
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