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Guérin C, Roche J, Allard V, Ravel C, Mouzeyar S, Bouzidi MF. Genome-wide analysis, expansion and expression of the NAC family under drought and heat stresses in bread wheat (T. aestivum L.). PLoS One 2019; 14:e0213390. [PMID: 30840709 PMCID: PMC6402696 DOI: 10.1371/journal.pone.0213390] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 02/19/2019] [Indexed: 02/01/2023] Open
Abstract
The NAC family is one of the largest plant-specific transcription factor families, and some of its members are known to play major roles in plant development and response to biotic and abiotic stresses. Here, we inventoried 488 NAC members in bread wheat (Triticum aestivum). Using the recent release of the wheat genome (IWGS RefSeq v1.0), we studied duplication events focusing on genomic regions from 4B-4D-5A chromosomes as an example of the family expansion and neofunctionalization of TaNAC members. Differentially expressed TaNAC genes in organs and in response to abiotic stresses were identified using publicly available RNAseq data. Expression profiling of 23 selected candidate TaNAC genes was studied in leaf and grain from two bread wheat genotypes at two developmental stages in field drought conditions and revealed insights into their specific and/or overlapping expression patterns. This study showed that, of the 23 TaNAC genes, seven have a leaf-specific expression and five have a grain-specific expression. In addition, the grain-specific genes profiles in response to drought depend on the genotype. These genes may be considered as potential candidates for further functional validation and could present an interest for crop improvement programs in response to climate change. Globally, the present study provides new insights into evolution, divergence and functional analysis of NAC gene family in bread wheat.
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Girousse C, Roche J, Guerin C, Le Gouis J, Balzegue S, Mouzeyar S, Bouzidi MF. Coexpression network and phenotypic analysis identify metabolic pathways associated with the effect of warming on grain yield components in wheat. PLoS One 2018; 13:e0199434. [PMID: 29940014 PMCID: PMC6016909 DOI: 10.1371/journal.pone.0199434] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 06/07/2018] [Indexed: 11/18/2022] Open
Abstract
Wheat grains are an important source of human food but current production amounts cannot meet world needs. Environmental conditions such as high temperature (above 30°C) could affect wheat production negatively. Plants from two wheat genotypes have been subjected to two growth temperature regimes. One set has been grown at an optimum daily mean temperature of 19°C while the second set of plants has been subjected to warming at 27°C from two to 13 days after anthesis (daa). While warming did not affect mean grain number per spike, it significantly reduced other yield-related indicators such as grain width, length, volume and maximal cell numbers in the endosperm. Whole genome expression analysis identified 6,258 and 5,220 genes, respectively, whose expression was affected by temperature in the two genotypes. Co-expression analysis using WGCNA (Weighted Gene Coexpression Network Analysis) uncovered modules (groups of co-expressed genes) associated with agronomic traits. In particular, modules enriched in genes related to nutrient reservoir and endopeptidase inhibitor activities were found to be positively associated with cell numbers in the endosperm. A hypothetical model pertaining to the effects of warming on gene expression and growth in wheat grain is proposed. Under moderately high temperature conditions, network analyses suggest a negative effect of the expression of genes related to seed storage proteins and starch biosynthesis on the grain size in wheat.
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Franchel J, Bouzidi MF, Bronner G, Vear F, Nicolas P, Mouzeyar S. Positional cloning of a candidate gene for resistance to the sunflower downy mildew, Plasmopara halstedii race 300. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2013; 126:359-367. [PMID: 23052021 DOI: 10.1007/s00122-012-1984-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Accepted: 09/15/2012] [Indexed: 06/01/2023]
Abstract
The resistance of sunflower to Plasmopara halstedii is conferred by major resistance genes denoted Pl. Previous genetic studies indicated that the majority of these genes are clustered on linkage groups 8 and 13. The Pl6 locus is one of the main clusters to have been identified, and confers resistance to several P. halstedii races. In this study, a map-based cloning strategy was implemented using a large segregating F2 population to establish a fine physical map of this cluster. A marker derived from a bacterial artificial chromosome (BAC) clone was found to be very tightly linked to the gene conferring resistance to race 300, and the corresponding BAC clone was sequenced and annotated. It contains several putative genes including three toll-interleukin receptor-nucleotide binding site-leucine rich repeats (TIR-NBS-LRR) genes. However, only one TIR-NBS-LRR appeared to be expressed, and thus constitutes a candidate gene for resistance to P. halstedii race 300.
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Kahloul S, HajSalah El Beji I, Boulaflous A, Ferchichi A, Kong H, Mouzeyar S, Bouzidi MF. Structural, expression and interaction analysis of rice SKP1-like genes. DNA Res 2012; 20:67-78. [PMID: 23248203 PMCID: PMC3576659 DOI: 10.1093/dnares/dss034] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The degradation of proteins by the 26S proteasome is initiated by protein polyubiquitination mediated by a three-step cascade. The specific ubiquitination of different target proteins is mediated by different classes of E3 ubiquitin ligases, among which the best known are Skp1-Cullin-F-box complexes. Whereas protists, fungi and some vertebrates have a single SKP1 gene, many animal and plant species possess multiple SKP1 homologues. In this paper, we report on the structure, phylogeny and expression of the complete set of rice SKP1 genes (OSKs, Oryza sativa SKP1-like genes). Our analyses indicated that OSK1 and OSK20 belong to a class of SKP1 genes that contain one intron at a conserved position and are highly expressed. In addition, our yeast two-hybrid results revealed that OSK proteins display a differing ability to interact with F-box proteins. However, OSK1 and OSK20 seemed to interact with most of the nine F-box proteins tested. We suggest that rice OSK1 and OSK20 are likely to have functions similar to the Arabidopsis ASK1 and ASK2 genes.
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Bednarek J, Boulaflous A, Girousse C, Ravel C, Tassy C, Barret P, Bouzidi MF, Mouzeyar S. Down-regulation of the TaGW2 gene by RNA interference results in decreased grain size and weight in wheat. JOURNAL OF EXPERIMENTAL BOTANY 2012; 63:5945-55. [PMID: 22996678 DOI: 10.1093/jxb/ers249] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
For important food crops such as wheat and rice, grain yield depends on grain number and size. In rice (Oryza sativa), GW2 was isolated from a major quantitative trait locus for yield and encodes an E3 RING ligase that negatively regulates grain size. Wheat (Triticum aestivum) has TaGW2 homologues in the A, B, and D genomes, and polymorphisms in TaGW2-A were associated with grain width. Here, to investigate TaGW2 function, RNA interference (RNAi) was used to down-regulate TaGW2 transcript levels. Transgenic wheat lines showed significantly decreased grain size-related dimensions compared with controls. Furthermore, TaGW2 knockdown also caused a significant reduction in endosperm cell number. These results indicate that TaGW2 regulates grain size in wheat, possibly by controlling endosperm cell number. Wheat and rice GW2 genes thus seem to have divergent functions, with rice GW2 negatively regulating grain size and TaGW2 positively regulating grain size. Analysis of transcription of TaGW2 homoeologues in developing grains suggested that TaGW2-A and -D act in both the division and late grain-filling phases. Furthermore, biochemical and molecular analyses revealed that TaGW2-A is a functional E3 RING ubiquitin ligase with nucleocytoplasmic subcellular partitioning. A functional nuclear export sequence responsible for TaGW2-A export from the nucleus to the cytosol and retention in the nucleolus was identified. Therefore, these results show that TaGW2 acts in the regulation of grain size and may provide an important tool for enhancement of grain yield.
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Capron D, Mouzeyar S, Boulaflous A, Girousse C, Rustenholz C, Laugier C, Paux E, Bouzidi MF. Transcriptional profile analysis of E3 ligase and hormone-related genes expressed during wheat grain development. BMC PLANT BIOLOGY 2012; 12:35. [PMID: 22416807 PMCID: PMC3405487 DOI: 10.1186/1471-2229-12-35] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Accepted: 03/14/2012] [Indexed: 05/23/2023]
Abstract
BACKGROUND Wheat grains are an important source of food, stock feed and raw materials for industry, but current production levels cannot meet world needs. Elucidation of the molecular mechanisms underlying wheat grain development will contribute valuable information to improving wheat cultivation. One of the most important mechanisms implicated in plant developmental processes is the ubiquitin-proteasome system (UPS). Among the different roles of the UPS, it is clear that it is essential to hormone signaling. In particular, E3 ubiquitin ligases of the UPS have been shown to play critical roles in hormone perception and signal transduction. RESULTS A NimbleGen microarray containing 39,179 UniGenes was used to study the kinetics of gene expression during wheat grain development from the early stages of cell division to the mid-grain filling stage. By comparing 11 consecutive time-points, 9284 differentially expressed genes were identified and annotated during this study. A comparison of the temporal profiles of these genes revealed dynamic transcript accumulation profiles with major reprogramming events that occurred during the time intervals of 80-120 and 220-240°Cdays. The list of the genes expressed differentially during these transitions were identified and annotated. Emphasis was placed on E3 ligase and hormone-related genes. In total, 173 E3 ligase coding genes and 126 hormone-related genes were differentially expressed during the cell division and grain filling stages, with each family displaying a different expression profile. CONCLUSIONS The differential expression of genes involved in the UPS and plant hormone pathways suggests that phytohormones and UPS crosstalk might play a critical role in the wheat grain developmental process. Some E3 ligase and hormone-related genes seem to be up- or down-regulated during the early and late stages of the grain development.
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Radwan O, Bouzidi MF, Mouzeyar S. Molecular characterization of two types of resistance in sunflower to Plasmopara halstedii, the causal agent of downy mildew. PHYTOPATHOLOGY 2011; 101:970-9. [PMID: 21751877 DOI: 10.1094/phyto-06-10-0163] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Depending on host-pathotype combination, two types of sunflower-Plasmopara halstedii incompatibility reactions have previously been identified. Type I resistance can restrict the growth of the pathogen in the basal region of the hypocotyls, whereas type II cannot, thus allowing the pathogen to reach the cotyledons. In type II resistance, a large portion of the hypocotyls is invaded by the pathogen and, subsequently, a hypersensitive reaction (HR) is activated over a long portion of the hypocotyls. Thus, the HR in type II resistance coincides with a higher induction of hsr203j sunflower homologue in comparison with type I resistance, where the HR is activated only in the basal part of hypocotyls. Although the pathogen was not detected in cotyledons of type I resistant plants, semiquantitative polymerase chain reaction confirmed the early abundant growth of the pathogen in cotyledons of susceptible plants by 6 days postinfection (dpi). This was in contrast to scarce growth of the pathogen in cotyledons of type II-resistant plants at a later time point (12 dpi). This suggests that pathogen growth differs according to the host-pathogen combination. To get more information about sunflower downy mildew resistance genes, the full-length cDNAs of RGC151 and RGC203, which segregated with the PlARG gene (resistance type I) and Pl14 gene (resistance type II), were cloned and sequenced. Sequence analyses revealed that RGC151 belongs to the Toll/interleukin-1 receptor (TIR) nucleotide-binding site leucine-rich repeat (NBS-LRR) class whereas RGC203 belongs to class coiled-coil (CC)-NBS-LRR. This study suggests that type II resistance may be controlled by CC-NBS-LRR gene transcripts which are enhanced upon infection by P. halstedii, rather than by the TIR-NBS-LRR genes that might control type I resistance.
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Nadaud I, Girousse C, Debiton C, Chambon C, Bouzidi MF, Martre P, Branlard G. Proteomic and morphological analysis of early stages of wheat grain development. Proteomics 2010; 10:2901-10. [DOI: 10.1002/pmic.200900792] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Bouzidi MF, Parlange F, Nicolas P, Mouzeyar S. Expressed Sequence Tags from the oomycete Plasmopara halstedii, an obligate parasite of the sunflower. BMC Microbiol 2007; 7:110. [PMID: 18062809 PMCID: PMC2242796 DOI: 10.1186/1471-2180-7-110] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2006] [Accepted: 12/06/2007] [Indexed: 11/24/2022] Open
Abstract
Background Sunflower downy mildew is a major disease caused by the obligatory biotrophic oomycete Plasmopara halstedii. Little is known about the molecular mechanisms underlying its pathogenicity. In this study we used a genomics approach to gain a first insight into the transcriptome of P. halstedii. Results To identify genes from the obligatory biotrophic oomycete Plasmopara halstedii that are expressed during infection in sunflower (Helianthus annuus L.) we employed the suppression subtraction hybridization (SSH) method from sunflower seedlings infected by P. halstedii. Using this method and random sequencing of clones, a total of 602 expressed sequence tags (ESTs) corresponding to 230 unique sequence sets were identified. To determine the origin of the unisequences, PCR primers were designed to amplify these gene fragments from genomic DNA isolated either from P. halstedii sporangia or from Helianthus annuus. Only 145 nonredundant ESTs which correspond to a total of 373 ESTs (67.7%) proved to be derived from P. halstedii genes and that are expressed during infection in sunflower. A set of 87 nonredundant sequences were identified as showing matches to sequences deposited in public databases. Nevertheless, about 7% of the ESTs seem to be unique to P. halstedii without any homolog in any public database. Conclusion A summary of the assignment of nonredundant ESTs to functional categories as well as their relative abundance is listed and discussed. Annotation of the ESTs revealed a number of genes that could function in virulence. We provide a first glimpse into the gene content of P. halstedii. These resources should accelerate research on this important pathogen.
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Bouzidi MF, Franchel J, Tao Q, Stormo K, Mraz A, Nicolas P, Mouzeyar S. A sunflower BAC library suitable for PCR screening and physical mapping of targeted genomic regions. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2006; 113:81-9. [PMID: 16783592 DOI: 10.1007/s00122-006-0274-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2005] [Accepted: 03/17/2006] [Indexed: 05/10/2023]
Abstract
A sunflower BAC library consisting of 147,456 clones with an average size of 118 kb has been constructed and characterized. It represents approximately 5x sunflower haploid genome equivalents. The BAC library has been arranged in pools and superpools of DNA allowing screening with various PCR-based markers. Each of the 32 superpools contains 4,608 clones and corresponds to a 36 matrix pools. Thus, the screening of the entire library could be accomplished in less than 80 PCR reactions including positive and negative controls. As a demonstration of the feasibility of the concept, a set of 24 SSR markers covering about 36 cM in the sunflower SSR map (Tang et al. in Theor Appl Genet 105:1124-1136, 2002) have been used to screen the BAC library. About 125 BAC clones have been identified and then organized in 23 contigs by HindIII digestion. The contigs are anchored on the SSR map and thus constitutes a first-generation physical map of this region. The utility of this BAC library as a genomic resource for physical mapping and map-based cloning in sunflower is discussed.
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Radwan O, Mouzeyar S, Venisse JS, Nicolas P, Bouzidi MF. Resistance of sunflower to the biotrophic oomycete Plasmopara halstedii is associated with a delayed hypersensitive response within the hypocotyls. JOURNAL OF EXPERIMENTAL BOTANY 2005; 56:2683-93. [PMID: 16143719 DOI: 10.1093/jxb/eri261] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The biotrophic oomycete Plasmopara halstedii is the causal agent of downy mildew in sunflower. It penetrates the roots of both susceptible and resistant sunflower lines and grows through the hypocotyls towards the upper part of the seedling. RT-PCR analysis has shown that resistance is associated with the activation of a hsr203J-like gene, which is a molecular marker of the hypersensitive reaction in tobacco. Activation of this gene was specifically observed during the incompatible interaction and coincided with cell collapse in the hypocotyls. This HR was also associated with the early and local activation of the NPR1 gene which is a key component in the establishment of the SAR. No such HR or a significant activation of the hsr203J-like gene were observed during the compatible combination. These results suggest that the resistance of sunflower to P. halstedii is associated with an HR which fails to halt the parasite. By contrast, this HR triggers a SAR which takes places in the upper part of the hypocotyls and eventually leads to the arrest of parasite growth. A model describing the resistance of plants to root-infecting oomycetes is proposed.
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Radwan O, Mouzeyar S, Nicolas P, Bouzidi MF. Induction of a sunflower CC-NBS-LRR resistance gene analogue during incompatible interaction with Plasmopara halstedii. JOURNAL OF EXPERIMENTAL BOTANY 2005; 56:567-575. [PMID: 15545294 DOI: 10.1093/jxb/eri030] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Downy mildew caused by Plasmopara halstedii is one of the main diseases causing economic losses in cultivated sunflower. Resistance in this host is conferred by major genes denoted Pl. The inbred sunflower line QIR8, which contains the Pl8 locus and is resistant to all known downy mildew races, was used to isolate a full-length resistance gene analogue (RGA) belonging to the CC-NBC-LRR class of plant resistance genes. The genetically incompatible combination involving downy mildew races 300 and sunflower line QIR8 was characterized by a hypersensitive-like reaction. Semi-quantitative RT-PCR analysis showed that the transcript of Ha-NTIR11g RGA was specifically induced during the incompatible reaction. The transcript was induced approximately 3 d post-infection (dpi), and then decreased by 9 dpi. The high level of transcriptional expression of this RGA coincides with a transcript accumulation of the hsr203J gene which is a marker of the hypersensitive reaction. Treatment with signalling molecules, including salicylic acid and methyl jasmonate, did not activate transcription of the Ha-NTIR11g gene, indicating that Ha-NTIR11g expression is not regulated by defence signalling pathways triggered by these molecules. Ha-NTIR11g was not induced by treatment with hydrogen peroxide or wounding. These results suggest that Ha-NTIR11g RGA may play a critical role in protecting sunflower cells against P. halstedii. The transcript accumulation of R gene-mediated signalling components was also examined.
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Radwan O, Bouzidi MF, Nicolas P, Mouzeyar S. Development of PCR markers for the Pl5/Pl8 locus for resistance to Plasmopara halstedii in sunflower, Helianthus annuus L. from complete CC-NBS-LRR sequences. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2004; 109:176-85. [PMID: 15007505 DOI: 10.1007/s00122-004-1613-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2003] [Accepted: 01/28/2004] [Indexed: 05/20/2023]
Abstract
Sunflower downy mildew, caused by Plasmopara halstedii, is one of the major diseases of this crop. Development of elite sunflower lines resistant to different races of this oomycete seems to be the most efficient method to limit downy mildew damage. At least two different gene clusters conferring resistance to different races of P. halstedii have been described. In this work we report the cloning and mapping of two full-length resistance gene analogs (RGA) belonging to the CC-NBC-LRR class of plant resistance genes. The two sequences were then used to develop 14 sequence tagged sites (STS) within the Pl5/Pl8 locus conferring resistance to a wide range of P. halstedii races. These STSs will be useful in marker-assisted selection programs.
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Radwan O, Bouzidi MF, Vear F, Philippon J, De Labrouhe DT, Nicolas P, Mouzeyar S. Identification of non-TIR-NBS-LRR markers linked to the Pl5/ Pl8 locus for resistance to downy mildew in sunflower. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2003; 106:1438-1446. [PMID: 12750787 DOI: 10.1007/s00122-003-1196-1] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2002] [Accepted: 11/11/2002] [Indexed: 05/24/2023]
Abstract
The resistance of sunflower, Helianthus annuus L., to downy mildew, caused by Plasmopara halstedii, is conferred by major genes denoted by Pl. Using degenerate and specific primers, 16 different resistance gene analogs (RGAs) have been cloned and sequenced. Sequence comparison and Southern-blot analysis distinguished six classes of RGA. Two of these classes correspond to TIR-NBS-LRR sequences while the remaining four classes correspond to the non-TIR-NBS-LRR type of resistance genes. The genetic mapping of these RGAs on two segregating F2 populations showed that the non-TIR-NBS-LRR RGAs are clustered and linked to the Pl5/ Pl8 locus for resistance to downy mildew in sunflower. These and other results indicate that different Pl loci conferring resistance to the same pathogen races may contain different sequences.
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Poyau A, Buchet K, Bouzidi MF, Zabot MT, Echenne B, Yao J, Shoubridge EA, Godinot C. Missense mutations in SURF1 associated with deficient cytochrome c oxidase assembly in Leigh syndrome patients. Hum Genet 2000; 106:194-205. [PMID: 10746561 DOI: 10.1007/s004390051028] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
We have studied the fibroblasts of three patients suffering from Leigh syndrome associated with cytochrome c oxidase deficiency (LS-COX-). Their mitochondrial DNA was functional and all nuclear COX subunits had a normal sequence. The expression of transcripts encoding mitochondrial and nuclear COX subunits was normal or slightly increased. Similarly, the OXA1 transcript coding for a protein involved in COX assembly was increased. However, several COX-protein subunits were severely depressed, indicating deficient COX assembly. Surf1, a factor involved in COX biogenesis, was recently reported as mutated in LS-COX- patients, all mutations predicting a truncated protein. Sequence analysis of SURF1 gene in our three patients revealed seven heterozygous mutations, six of which were new : an insertion, a nonsense mutation, a splicing mutation of intron 7 in addition to three missense mutations. The mutation G385 A (Gly124-->Glu) changes a Gly that is strictly conserved in Surfl homologs of 12 species. The substitution G618 C (Asp202-->His), changing an Asp that is conserved only in mammals, appears to be a polymorphism. The mutation T751 C changes Ile246 to Thr, a position at which a hydrophobic amino acid is conserved in all eukaryotic and some bacterial species. Replacing Ile246 by Thr disrupts a predicted beta sheet structure present in all higher eukaryotes. COX activity could be restored in fibroblasts of the three patients by complementation with a retroviral vector containing normal SURF1 cDNA. These mutations identify domains essential to Surf1 protein structure and/or function.
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Bouzidi MF, Poyau A, Godinot C. Co-existence of high levels of a cytochrome b mutation and of a tandem 200 bp duplication in the D-loop of muscle human mitochondrial DNA. Hum Mol Genet 1998; 7:385-91. [PMID: 9466994 DOI: 10.1093/hmg/7.3.385] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Previous studies have suggested that some patients with large-scale mitochondrial DNA (mtDNA) deletions also presented a heteroplasmic 260 bp tandem duplication in the mtDNA D-loop region. Such duplications were observed not only in patients with mitochondrial pathology but also in aged subjects. However, the percentage of duplicated mtDNA did not exceed a few per cent of the total mtDNA, except in one example where it reached 30%. We report here another type of 200 bp duplication in the mtDNA D-loop region that, instead of being associated with a large-scale deletion, is correlated to the presence of a point mutation in the cytochrome b gene. The 200 bp duplication concerned up to 95% of the total mtDNA of some muscle mitochondria and was absent from the patient lymphocyte DNA. The percentages of the 200 bp duplication and that of the cytochrome b mutation were relatively close in whole muscle as well as in single muscle fibres, suggesting a correlation between the mutation and the duplication. This duplication could also be detected by PCR in two other patients with mitochondrial disorders but without known deletion or mtDNA mutation. These data suggest that the accumulation of these small duplications in the mtDNA D-loop could be indicative of the presence of other defects of the mtDNA which would damage the respiratory chain function. These deficiencies would induce the generation of small duplications in the D-loop.
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Bouzidi MF, Carrier H, Godinot C. Antimycin resistance and ubiquinol cytochrome c reductase instability associated with a human cytochrome b mutation. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1317:199-209. [PMID: 8988236 DOI: 10.1016/s0925-4439(96)00055-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Progressive exercise intolerance was associated with a decreased maximal rate of ubiquinol cytochrome c reductase (complex III) activity in the muscle mitochondria of the studied patient and with a thirty five-fold increase in the I50 for antimycin A. In contrast, myxothiazol sensitivity was not altered. Complex III activity was stable at 37 degrees C, but progressively decreased at 4 degrees C. An heteroplasmic G to A mutation at position 15615 of the mitochondrial DNA, resulting in the replacement of the highly conserved Gly290 in cytochrome b by Asp, was identified. Histochemical studies showed increased cytochrome oxidase and succinate dehydrogenase activities under the sarcolemma of type I fibres. After partial extraction of mitochondria from the muscle, the residual pellet contained a lower percentage of the mutation than did whole muscle, suggesting that the percentage of mutation is higher in the most readily extracted mitochondria, most probably present under the sarcolemma. In the current 8 transmembrane helix model of cytochrome b, Gly290 lies at the end of the sixth transmembrane helix, facing the intermembrane space and close to the presumed sites of interaction between cytochrome b, the iron-sulfur protein and the 9.5 kDa protein. Since immunoblotting experiments showed a relative decrease in the proportions of these three subunits in the patient's mitochondria compared with the other complex III subunits, it is probable that the complex III instability and the relative decrease in these subunits are related to the mutation. The relationship between the decrease in the apparent affinity for antimycin A and the instability of complex III are discussed.
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Bouzidi MF, Enjolras N, Carrier H, Vial C, Lopez-Mediavilla C, Burt-Pichat B, Couthon F, Godinot C. Variations of muscle mitochondrial creatine kinase activity in mitochondrial diseases. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1316:61-70. [PMID: 8672552 DOI: 10.1016/0925-4439(95)00126-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Mitochondrial creatine kinase (mtCK) activity has been measured in the mitochondria isolated from the muscle of 69 patients suspected of mitochondrial diseases. The isolated mitochondria did not contain significant amounts of the muscle isoform of creatine kinase, as checked by an immunoassay performed after electrophoretic separation of the various isoforms. Hence, the enzyme assay reliably represented the mtCK activity. Therefore, a simple measurement of CK activity in isolated mitochondria permitted the measurement of mtCK activity. An absence of mtCK activity in muscle was never observed. The lowest activities were not associated to defined mitochondrial diseases linked to defects of respiratory chain complexes or to defects of citric cycle enzymes. On the contrary, mtCK activity was significantly increased in the muscle of patients exhibiting ragged red fibers. This increase was generally associated to an increase of citrate synthase activity. Since ragged-red fibers and elevated mtCK activities were generally not found in children younger than 3 years, even in cases of characteristic oxidative phosphorylation deficiency, it is suggested that the increase in mtCK activity as well as the appearance of ragged-red fibers are not the first events which occur during the evolution of mitochondrial diseases but would rather be long-term secondary processes which slowly develop in deficient mitochondria.
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Bouzidi MF, Schägger H, Collombet JM, Carrier H, Flocard F, Quard S, Mousson B, Godinot C. Decreased expression of ubiquinol-cytochrome c reductase subunits in patients exhibiting mitochondrial myopathy with progressive exercise intolerance. Neuromuscul Disord 1993; 3:599-604. [PMID: 8186719 DOI: 10.1016/0960-8966(93)90123-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The expression of mitochondrial proteins of two patients suffering from myopathy with progressive exercise intolerance and exhibiting a deficiency in the enzymatic activity of complex III (ubiquinol-cytochrome c reductase) has been analyzed by immunological titration. In both patients, the Fe-S protein, the cytochrome b and the 9.5 kDa protein were decreased while the expression of the other complex III subunits were close to normal values. This data indicates that, in some mitochondrial myopathies, proteins of the respiratory chain complexes can be accumulated in mitochondria without being integrated into a functional complex. This may be explained either by a lack of control of the coordination between the synthesis of subunits of mitochondrial and nuclear origin or by a difference in the degradation rate of the various subunits which are not properly assembled.
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