1
|
Chen X, Lu Z, Chen Y, Wu R, Luo Z, Lu Q, Guan N, Chen D. Deletion of the MBP1 Gene, Involved in the Cell Cycle, Affects Respiration and Pseudohyphal Differentiation in Saccharomyces cerevisiae. Microbiol Spectr 2021; 9:e0008821. [PMID: 34346754 PMCID: PMC8552743 DOI: 10.1128/spectrum.00088-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 05/03/2021] [Indexed: 11/20/2022] Open
Abstract
Mbp1p is a component of MBF (MluI cell cycle box binding factor, Mbp1p-Swi6p) and is well known to regulate the G1-S transition of the cell cycle. However, few studies have provided clues regarding its role in fermentation. This work aimed to recognize the function of the MBP1 gene in ethanol fermentation in a wild-type industrial Saccharomyces cerevisiae strain. MBP1 deletion caused an obvious decrease in the final ethanol concentration under oxygen-limited (without agitation), but not under aerobic, conditions (130 rpm). Furthermore, the mbp1Δ strain showed 84% and 35% decreases in respiration intensity under aerobic and oxygen-limited conditions, respectively. These findings indicate that MBP1 plays an important role in responding to variations in oxygen content and is involved in the regulation of respiration and fermentation. Unexpectedly, mbp1Δ also showed pseudohyphal growth, in which cells elongated and remained connected in a multicellular arrangement on yeast extract-peptone-dextrose (YPD) plates. In addition, mbp1Δ showed an increase in cell volume, associated with a decrease in the fraction of budded cells. These results provide more detailed information about the function of MBP1 and suggest some clues to efficiently improve ethanol production by industrially engineered yeast strains. IMPORTANCE Saccharomyces cerevisiae is an especially favorable organism used for ethanol production. However, inhibitors and high osmolarity conferred by fermentation broth, and high concentrations of ethanol as fermentation runs to completion, affect cell growth and ethanol production. Therefore, yeast strains with high performance, such as rapid growth, high tolerance, and high ethanol productivity, are highly desirable. Great efforts have been made to improve their performance by evolutionary engineering, and industrial strains may be a better start than laboratory ones for industrial-scale ethanol production. The significance of our research is uncovering the function of MBP1 in ethanol fermentation in a wild-type industrial S. cerevisiae strain, which may provide clues to engineer better-performance yeast in producing ethanol. Furthermore, the results that lacking MBP1 caused pseudohyphal growth on YPD plates could shed light on the development of xylose-fermenting S. cerevisiae, as using xylose as the sole carbon source also caused pseudohyphal growth.
Collapse
Affiliation(s)
- Xiaoling Chen
- National Engineering Research Center for Non-Food Biorefinery, Guangxi Academy of Sciences, Nanning, Guangxi, People’s Republic of China
| | - Zhilong Lu
- National Engineering Research Center for Non-Food Biorefinery, Guangxi Academy of Sciences, Nanning, Guangxi, People’s Republic of China
| | - Ying Chen
- National Engineering Research Center for Non-Food Biorefinery, Guangxi Academy of Sciences, Nanning, Guangxi, People’s Republic of China
| | - Renzhi Wu
- National Engineering Research Center for Non-Food Biorefinery, Guangxi Academy of Sciences, Nanning, Guangxi, People’s Republic of China
| | - Zhenzhen Luo
- National Engineering Research Center for Non-Food Biorefinery, Guangxi Academy of Sciences, Nanning, Guangxi, People’s Republic of China
| | - Qi Lu
- National Engineering Research Center for Non-Food Biorefinery, Guangxi Academy of Sciences, Nanning, Guangxi, People’s Republic of China
| | - Ni Guan
- National Engineering Research Center for Non-Food Biorefinery, Guangxi Academy of Sciences, Nanning, Guangxi, People’s Republic of China
| | - Dong Chen
- National Engineering Research Center for Non-Food Biorefinery, Guangxi Academy of Sciences, Nanning, Guangxi, People’s Republic of China
| |
Collapse
|
2
|
Bernal M, Yang X, Lisby M, Mazón G. The FANCM family Mph1 helicase localizes to the mitochondria and contributes to mtDNA stability. DNA Repair (Amst) 2019; 82:102684. [DOI: 10.1016/j.dnarep.2019.102684] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 07/31/2019] [Accepted: 08/03/2019] [Indexed: 11/24/2022]
|
3
|
Abstract
Mutations are the root source of genetic variation and underlie the process of evolution. Although the rates at which mutations occur vary considerably between species, little is known about differences within species, or the genetic and molecular basis of these differences. Here, we leveraged the power of the yeast Saccharomyces cerevisiae as a model system to uncover natural genetic variants that underlie variation in mutation rate. We developed a high-throughput fluctuation assay and used it to quantify mutation rates in seven natural yeast isolates and in 1040 segregant progeny from a cross between BY, a laboratory strain, and RM, a wine strain. We observed that mutation rate varies among yeast strains and is heritable (H2 = 0.49). We performed linkage mapping in the segregants and identified four quantitative trait loci underlying mutation rate variation in the cross. We fine-mapped two quantitative trait loci to the underlying causal genes, RAD5 and MKT1, that contribute to mutation rate variation. These genes also underlie sensitivity to the DNA-damaging agents 4NQO and MMS, suggesting a connection between spontaneous mutation rate and mutagen sensitivity.
Collapse
|
4
|
Activation of Dun1 in response to nuclear DNA instability accounts for the increase in mitochondrial point mutations in Rad27/FEN1 deficient S. cerevisiae. PLoS One 2017; 12:e0180153. [PMID: 28678842 PMCID: PMC5497989 DOI: 10.1371/journal.pone.0180153] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 06/09/2017] [Indexed: 11/25/2022] Open
Abstract
Rad27/FEN1 nuclease that plays important roles in the maintenance of DNA stability in the nucleus has recently been shown to reside in mitochondria. Accordingly, it has been established that Rad27 deficiency causes increased mutagenesis, but decreased microsatellite instability and homologous recombination in mitochondria. Our current analysis of mutations leading to erythromycin resistance indicates that only some of them arise in mitochondrial DNA and that the GC→AT transition is a hallmark of the mitochondrial mutagenesis in rad27 null background. We also show that the mitochondrial mutator phenotype resulting from Rad27 deficiency entirely depends on the DNA damage checkpoint kinase Dun1. DUN1 inactivation suppresses the mitochondrial mutator phenotype caused by Rad27 deficiency and this suppression is eliminated at least in part by subsequent deletion of SML1 encoding a repressor of ribonucleotide reductase. We conclude that Rad27 deficiency causes a mitochondrial mutator phenotype via activation of DNA damage checkpoint kinase Dun1 and that a Dun1-mediated increase of dNTP pools contributes to this phenomenon. These results point to the nuclear DNA instability as the source of mitochondrial mutagenesis. Consistently, we show that mitochondrial mutations occurring more frequently in yeast devoid of Rrm3, a DNA helicase involved in rDNA replication, are also dependent on Dun1. In addition, we have established that overproduction of Exo1, which suppresses DNA damage sensitivity and replication stress in nuclei of Rad27 deficient cells, but does not enter mitochondria, suppresses the mitochondrial mutagenesis. Exo1 overproduction restores also a great part of allelic recombination and microsatellite instability in mitochondria of Rad27 deficient cells. In contrast, the overproduction of Exo1 does not influence mitochondrial direct-repeat mediated deletions in rad27 null background, pointing to this homologous recombination pathway as the direct target of Rad27 activity in mitochondria.
Collapse
|
5
|
Skoneczna A, Kaniak A, Skoneczny M. Genetic instability in budding and fission yeast-sources and mechanisms. FEMS Microbiol Rev 2015; 39:917-67. [PMID: 26109598 PMCID: PMC4608483 DOI: 10.1093/femsre/fuv028] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/26/2015] [Indexed: 12/17/2022] Open
Abstract
Cells are constantly confronted with endogenous and exogenous factors that affect their genomes. Eons of evolution have allowed the cellular mechanisms responsible for preserving the genome to adjust for achieving contradictory objectives: to maintain the genome unchanged and to acquire mutations that allow adaptation to environmental changes. One evolutionary mechanism that has been refined for survival is genetic variation. In this review, we describe the mechanisms responsible for two biological processes: genome maintenance and mutation tolerance involved in generations of genetic variations in mitotic cells of both Saccharomyces cerevisiae and Schizosaccharomyces pombe. These processes encompass mechanisms that ensure the fidelity of replication, DNA lesion sensing and DNA damage response pathways, as well as mechanisms that ensure precision in chromosome segregation during cell division. We discuss various factors that may influence genome stability, such as cellular ploidy, the phase of the cell cycle, transcriptional activity of a particular region of DNA, the proficiency of DNA quality control systems, the metabolic stage of the cell and its respiratory potential, and finally potential exposure to endogenous or environmental stress. The stability of budding and fission yeast genomes is influenced by two contradictory factors: (1) the need to be fully functional, which is ensured through the replication fidelity pathways of nuclear and mitochondrial genomes through sensing and repairing DNA damage, through precise chromosome segregation during cell division; and (2) the need to acquire changes for adaptation to environmental challenges.
Collapse
Affiliation(s)
- Adrianna Skoneczna
- Laboratory of Mutagenesis and DNA Repair, Institute of Biochemistry and Biophysics, Polish Academy of Science, 02-106 Warsaw, Poland
| | - Aneta Kaniak
- Laboratory of Mutagenesis and DNA Repair, Institute of Biochemistry and Biophysics, Polish Academy of Science, 02-106 Warsaw, Poland
| | - Marek Skoneczny
- Department of Genetics, Institute of Biochemistry and Biophysics, Polish Academy of Science, 02-106 Warsaw, Poland
| |
Collapse
|
6
|
Bui VN, Nguyen TTH, Bettarel Y, Nguyen THT, Pham TL, Hoang TY, Nguyen VTT, Nghiem NM, Wölfl S. Genotoxicity of Chemical Compounds Identification and Assessment by Yeast Cells Transformed With GFP Reporter Constructs Regulated by the PLM2 or DIN7 Promoter. Int J Toxicol 2015; 34:31-43. [DOI: 10.1177/1091581814566870] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Yeast cells transformed with high-copy number plasmids comprising a green fluorescent protein (GFP)-encoding gene optimized for yeast under the control of the new DIN7 or PLM2 and the established RNR2 and RAD54 promoters were used to assess the genotoxic potential of chemical compounds. The activity of potential DNA-damaging agents was investigated by genotoxicity assays and by OxoPlate assay in the presence of various test compounds. The fluorescence signal generated by GFP in response to DNA damage was related to the different concentrations of analytes and the analyte-dependent GFP synthesis. The use of distinct DNA damage-inducible promoters presents alternative genotoxicity testing strategies by selective induction of promoters in response to DNA damage. The new DIN7 and PLM2 systems show higher sensitivity than the RNR2 and RAD54 systems in detecting 4-nitroquinoline- N-oxide and actinomycin D. Both DIN7 and PLM2 systems are able to detect camptothecin while RNR2 and RAD54 systems are not. Automated laboratory systems with assay performance on 384-well microplates provide for cost-effective high-throughput screening of DNA-damaging agents, reducing compound consumption to about 53% as compared with existing eukaryotic genotoxicity bioassays.
Collapse
Affiliation(s)
- Van Ngoc Bui
- Institute of Biotechnology, Vietnam Academy of Science and Technology (VAST), Hanoi, Vietnam
| | - Thi Thu Huyen Nguyen
- Thai Nguyen University of Sciences, Thai Nguyen University, Thai Nguyen, Hanoi, Vietnam
| | - Yvan Bettarel
- Institute of Research and Development, UMR ECOSYM, Montpellier, France
| | - Thi Hoai Thu Nguyen
- Institute of Biotechnology, Vietnam Academy of Science and Technology (VAST), Hanoi, Vietnam
| | - Thuy Linh Pham
- Institute of Biotechnology, Vietnam Academy of Science and Technology (VAST), Hanoi, Vietnam
| | - Thi Yen Hoang
- Institute of Biotechnology, Vietnam Academy of Science and Technology (VAST), Hanoi, Vietnam
| | - Vu Thanh Thanh Nguyen
- Thai Nguyen University of Sciences, Thai Nguyen University, Thai Nguyen, Hanoi, Vietnam
| | - Ngoc Minh Nghiem
- Institute of Biotechnology, Vietnam Academy of Science and Technology (VAST), Hanoi, Vietnam
| | - Stefan Wölfl
- Institute of Pharmacy and Molecular Biotechnology (IPMB), Heidelberg University, Heidelberg, Germany
| |
Collapse
|
7
|
Mechanism of homologous recombination and implications for aging-related deletions in mitochondrial DNA. Microbiol Mol Biol Rev 2014; 77:476-96. [PMID: 24006472 DOI: 10.1128/mmbr.00007-13] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Homologous recombination is a universal process, conserved from bacteriophage to human, which is important for the repair of double-strand DNA breaks. Recombination in mitochondrial DNA (mtDNA) was documented more than 4 decades ago, but the underlying molecular mechanism has remained elusive. Recent studies have revealed the presence of a Rad52-type recombination system of bacteriophage origin in mitochondria, which operates by a single-strand annealing mechanism independent of the canonical RecA/Rad51-type recombinases. Increasing evidence supports the notion that, like in bacteriophages, mtDNA inheritance is a coordinated interplay between recombination, repair, and replication. These findings could have profound implications for understanding the mechanism of mtDNA inheritance and the generation of mtDNA deletions in aging cells.
Collapse
|
8
|
Ling F, Hori A, Yoshitani A, Niu R, Yoshida M, Shibata T. Din7 and Mhr1 expression levels regulate double-strand-break-induced replication and recombination of mtDNA at ori5 in yeast. Nucleic Acids Res 2013; 41:5799-816. [PMID: 23598996 PMCID: PMC3675488 DOI: 10.1093/nar/gkt273] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The Ntg1 and Mhr1 proteins initiate rolling-circle mitochondrial (mt) DNA replication to achieve homoplasmy, and they also induce homologous recombination to maintain mitochondrial genome integrity. Although replication and recombination profoundly influence mitochondrial inheritance, the regulatory mechanisms that determine the choice between these pathways remain unknown. In Saccharomyces cerevisiae, double-strand breaks (DSBs) introduced by Ntg1 at the mitochondrial replication origin ori5 induce homologous DNA pairing by Mhr1, and reactive oxygen species (ROS) enhance production of DSBs. Here, we show that a mitochondrial nuclease encoded by the nuclear gene DIN7 (DNA damage inducible gene) has 5′-exodeoxyribonuclease activity. Using a small ρ− mtDNA bearing ori5 (hypersuppressive; HS) as a model mtDNA, we revealed that DIN7 is required for ROS-enhanced mtDNA replication and recombination that are both induced at ori5. Din7 overproduction enhanced Mhr1-dependent mtDNA replication and increased the number of residual DSBs at ori5 in HS-ρ− cells and increased deletion mutagenesis at the ori5 region in ρ+ cells. However, simultaneous overproduction of Mhr1 suppressed all of these phenotypes and enhanced homologous recombination. Our results suggest that after homologous pairing, the relative activity levels of Din7 and Mhr1 modulate the preference for replication versus homologous recombination to repair DSBs at ori5.
Collapse
Affiliation(s)
- Feng Ling
- Chemical Genetics Laboratory, RIKEN, Hirosawa 2-1, Wako-shi, Saitama 351-0198, Japan.
| | | | | | | | | | | |
Collapse
|
9
|
Litvinchuk AV, Sokolov SS, Rogov AG, Markova OV, Knorre DA, Severin FF. Mitochondrially-encoded protein Var1 promotes loss of respiratory function in Saccharomyces cerevisiae under stressful conditions. Eur J Cell Biol 2013; 92:169-74. [PMID: 23523087 DOI: 10.1016/j.ejcb.2013.02.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 02/14/2013] [Accepted: 02/22/2013] [Indexed: 02/05/2023] Open
Abstract
Stressed Saccharomyces cerevisiae cells easily lose respiratory function due to deletions in mitochondrial DNA, and this increases their general stress resistance. Is the loss active? We found that erythromycin (an inhibitor of mitochondrial translation) prevents the loss in control cells but not in the ones expressing mitochondrially-encoded protein Var1 in the nucleus. Var1 is a component of mitochondrial ribosomes; it is hydrophilic, positively charged, and prone to aggregation. Addition of DNase altered Var1 content in a preparation of mitochondrial nucleoids. Our data indicate that Var1 physically interacts with mitochondrial DNA and under stress negatively regulates its maintenance.
Collapse
Affiliation(s)
- Alexandra V Litvinchuk
- Faculty of Bioengineering and Bioinformatics, Moscow State University, Vorobyevy Gory 1, Moscow, Russia
| | | | | | | | | | | |
Collapse
|
10
|
Abstract
Yeast exonuclease 5 is encoded by the YBR163w (DEM1) gene, and this gene has been renamed EXO5. It is distantly related to the Escherichia coli RecB exonuclease class. Exo5 is localized to the mitochondria, and EXO5 deletions or nuclease-defective EXO5 mutants invariably yield petites, amplifying either the ori3 or ori5 region of the mitochondrial genome. These petites remain unstable and undergo continuous rearrangement. The mitochondrial phenotype of exo5Delta strains suggests an essential role for the enzyme in DNA replication and recombination. No nuclear phenotype associated with EXO5 deletions has been detected. Exo5 is a monomeric 5' exonuclease that releases dinucleotides as products. It is specific for single-stranded DNA and does not hydrolyze RNA. However, Exo5 has the capacity to slide across 5' double-stranded DNA or 5' RNA sequences and resumes cutting two nucleotides downstream of the double-stranded-to-single-stranded junction or RNA-to-DNA junction, respectively.
Collapse
|
11
|
Kaniak A, Dzierzbicki P, Rogowska AT, Malc E, Fikus M, Ciesla Z. Msh1p counteracts oxidative lesion-induced instability of mtDNA and stimulates mitochondrial recombination in Saccharomyces cerevisiae. DNA Repair (Amst) 2009; 8:318-29. [DOI: 10.1016/j.dnarep.2008.11.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Revised: 11/02/2008] [Accepted: 11/05/2008] [Indexed: 01/01/2023]
|
12
|
Miyakawa I, Fujimura R, Kadowaki Y. Use of the nuc1 null mutant for analysis of yeast mitochondrial nucleoids. J GEN APPL MICROBIOL 2009; 54:317-25. [PMID: 19164874 DOI: 10.2323/jgam.54.317] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Mitochondrial DNA (mtDNA) of the yeast Saccharomyces cerevisiae is organized to form mitochondrial nucleoids (mt-nucleoids) by association with specific proteins. The sensitivity of DNA-protein complexes to nuclease digestion is a useful means for examining DNA packaging and organization. However, the mt-nucleoids isolated from wild-type cells of S. cerevisiae demonstrated a significant amount of endogenous nuclease activity. In order to minimize the nuclease activity associated with the isolated mt-nucleoids, we isolated the mt-nucleoids from a mutant strain that lacked the mitochondrial nuclease, Nuc1p. In this manner, we succeeded in isolating mt-nucleoids that showed a low level of the nuclease activity. Micrococcal nuclease treatment of these mt-nucleoids led to the continuous digestion of mtDNA in the presence of Ca(2+) ions. MtDNA in the mt-nucleoids also showed the continuous digestion pattern when treated with DNase II. These results suggest that mtDNA in the mt-nucleoids is protected from nuclease digestion by association with proteins, but the organization of the mtDNA-protein complexes is different from that of nuclear chromatin, in which the unit of DNA packaging is regularly repeated.
Collapse
Affiliation(s)
- Isamu Miyakawa
- Department of Physics, Biology, and Informatics, Faculty of Science, Yamaguchi University, Japan.
| | | | | |
Collapse
|
13
|
Pham TK, Wright PC. The Proteomic Response of Saccharomyces cerevisiae in Very High Glucose Conditions with Amino Acid Supplementation. J Proteome Res 2008; 7:4766-74. [DOI: 10.1021/pr800331s] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Trong Khoa Pham
- Biological and Environmental Systems Group, Department of Chemical and Process Engineering, The University of Sheffield, Mappin Street, Sheffield S1 3JD, United Kingdom
| | - Phillip C. Wright
- Biological and Environmental Systems Group, Department of Chemical and Process Engineering, The University of Sheffield, Mappin Street, Sheffield S1 3JD, United Kingdom
| |
Collapse
|
14
|
The yeast checkpoint kinase Dun1 downregulates DIN7 in the absence of DNA damage. Biosci Biotechnol Biochem 2008; 72:1630-4. [PMID: 18540090 DOI: 10.1271/bbb.80114] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Yeast DIN7 is a DNA damage-inducible gene. Its expression is increased in the absence of Dun1, a DNA damage checkpoint kinase. We identified a DIN7 promoter region responsible for Dun1-mediated downregulation and found that DIN7 expression was not further increased in response to hydroxyurea in Deltadun1 cells. Thus DIN7 repression by Dun1 can be released upon DNA damage.
Collapse
|
15
|
Cheng X, Dunaway S, Ivessa AS. The role of Pif1p, a DNA helicase in Saccharomyces cerevisiae, in maintaining mitochondrial DNA. Mitochondrion 2006; 7:211-22. [PMID: 17257907 DOI: 10.1016/j.mito.2006.11.023] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2006] [Revised: 11/22/2006] [Accepted: 11/27/2006] [Indexed: 11/19/2022]
Abstract
Mitochondrial DNA (mtDNA) is highly susceptible to oxidative and chemically induced damage, and these insults lead to a number of diseases. In Saccharomyces cerevisiae, the DNA helicase Pif1p is localized to the nucleus and mitochondria. We show that pif1 mutant cells are sensitive to ethidium bromide-induced damage and this mtDNA is prone to fragmentation. We also show that Pif1p associates with mtDNA. In pif1 mutant cells, mtDNA breaks at specific sites that exhibit Pif1-dependent recombination. We conclude that Pif1p participates in the protection from double-stranded (ds) DNA breaks or alternatively in the repair process of dsDNA breaks in mtDNA.
Collapse
Affiliation(s)
- Xin Cheng
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, 185 South Orange Avenue, Newark, NJ 07101-1709, USA
| | | | | |
Collapse
|
16
|
Laquel-Robert P, Sellem CH, Sainsard-Chanet A, Castroviejo M. Identification and biochemical analysis of a mitochondrial endonuclease of Podospora anserina related to curved-DNA binding proteins. Biochim Biophys Acta Gen Subj 2006; 1770:527-42. [PMID: 17188431 DOI: 10.1016/j.bbagen.2006.10.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2006] [Revised: 09/07/2006] [Accepted: 10/03/2006] [Indexed: 11/16/2022]
Abstract
We purified and characterized previously from Podospora anserina mitochondria an endonuclease, active on single-stranded, double-stranded and flap DNA, with RNAse H activity, named P49 according to the major 49 kDa band observed on SDS-PAGE. Edman sequencing allowed us to identify the corresponding gene called nuc49. Here we report the properties of the (His)-tagged NUC49 protein expressed in E. coli. We show that this protein does exhibit an endonuclease activity on plasmid DNA, circular recessed and flap M13 substrate with short protruding single strand. However, in contrast to the mt endonuclease purified fraction it does not present RNase H activity and does not cleave linear flap substrate. The activity differences between the protein expressed in E. coli and the mitochondrial endonuclease fraction previously described are discussed. NUC49 presents a strong homology with the S. pombe CDB4 curved DNA binding protein which belongs to a large family including the human cell cycle protein PA2G4 and is able to bind curved DNA. The results constitute the first description of a mitochondrial endonuclease activity associated to this family of proliferation associated homologous proteins. The function of this endonuclease either in recombination, repair or mt DNA rearrangements remains to be determined.
Collapse
Affiliation(s)
- Patricia Laquel-Robert
- CNRS UMR 5097- Université Victor Segalen Bordeaux 2, 146 rue Léo Saignat, 33076 Bordeaux cedex, France.
| | | | | | | |
Collapse
|
17
|
Graziewicz MA, Longley MJ, Copeland WC. DNA polymerase gamma in mitochondrial DNA replication and repair. Chem Rev 2006; 106:383-405. [PMID: 16464011 DOI: 10.1021/cr040463d] [Citation(s) in RCA: 206] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Maria A Graziewicz
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA
| | | | | |
Collapse
|
18
|
Mookerjee SA, Sia EA. Overlapping contributions of Msh1p and putative recombination proteins Cce1p, Din7p, and Mhr1p in large-scale recombination and genome sorting events in the mitochondrial genome of Saccharomyces cerevisiae. Mutat Res 2006; 595:91-106. [PMID: 16337661 DOI: 10.1016/j.mrfmmm.2005.10.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2005] [Revised: 09/22/2005] [Accepted: 10/20/2005] [Indexed: 05/05/2023]
Abstract
The mechanisms that govern mutation avoidance in the mitochondrial genome, though believed to be numerous, are poorly understood. The identification of individual genes has implicated mismatch repair and several recombination pathways in maintaining the fidelity and structural stability of mitochondrial DNA. However, the majority of genes in these pathways have not been identified and the interactions between different pathways have not been extensively studied. Additionally, the multicopy presence of the mitochondrial genome affects the occurrence and persistence of mutant phenotypes, making mitochondrial DNA transmission and sorting important factors affecting mutation accumulation. We present new evidence that the putative recombination genes CCE1, DIN7, and MHR1 have overlapping function with the mismatch repair homolog MSH1 in point mutation avoidance and suppression of aberrant recombination events. In addition, we demonstrate a novel role for Msh1p in mtDNA transmission, a role not predicted by studies of its nuclear homologs.
Collapse
Affiliation(s)
- Shona A Mookerjee
- Department of Biology, University of Rochester, Rochester, NY 14627-0211, USA
| | | |
Collapse
|
19
|
Phadnis N, Sia RA, Sia EA. Analysis of repeat-mediated deletions in the mitochondrial genome of Saccharomyces cerevisiae. Genetics 2005; 171:1549-59. [PMID: 16157666 PMCID: PMC1456083 DOI: 10.1534/genetics.105.047092] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2005] [Accepted: 08/26/2005] [Indexed: 11/18/2022] Open
Abstract
Mitochondrial DNA deletions and point mutations accumulate in an age-dependent manner in mammals. The mitochondrial genome in aging humans often displays a 4977-bp deletion flanked by short direct repeats. Additionally, direct repeats flank two-thirds of the reported mitochondrial DNA deletions. The mechanism by which these deletions arise is unknown, but direct-repeat-mediated deletions involving polymerase slippage, homologous recombination, and nonhomologous end joining have been proposed. We have developed a genetic reporter to measure the rate at which direct-repeat-mediated deletions arise in the mitochondrial genome of Saccharomyces cerevisiae. Here we analyze the effect of repeat size and heterology between repeats on the rate of deletions. We find that the dependence on homology for repeat-mediated deletions is linear down to 33 bp. Heterology between repeats does not affect the deletion rate substantially. Analysis of recombination products suggests that the deletions are produced by at least two different pathways, one that generates only deletions and one that appears to generate both deletions and reciprocal products of recombination. We discuss how this reporter may be used to identify the proteins in yeast that have an impact on the generation of direct-repeat-mediated deletions.
Collapse
Affiliation(s)
- Naina Phadnis
- Department of Biological Sciences, University of Rochester, Rochester, NY 14627, USA
| | | | | |
Collapse
|
20
|
Larsen NB, Rasmussen M, Rasmussen LJ. Nuclear and mitochondrial DNA repair: similar pathways? Mitochondrion 2005; 5:89-108. [PMID: 16050976 DOI: 10.1016/j.mito.2005.02.002] [Citation(s) in RCA: 209] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2004] [Revised: 01/31/2005] [Accepted: 02/03/2005] [Indexed: 02/08/2023]
Abstract
Mitochondrial DNA (mtDNA) alterations are implicated in a broad range of human diseases and alterations of the mitochondrial genome are assumed to be a result of its high susceptibility to oxidative damage and its limited DNA repair compared to nuclear DNA (nDNA). Characterization of DNA repair mechanisms has generally focused on these processes in nDNA but increasing interest and research effort have contributed to our knowledge of the mechanisms underlying DNA repair in mitochondria. In this review, we make comparisons between nDNA and mtDNA repair pathways and propose a model for how these pathways interact in mitochondria.
Collapse
Affiliation(s)
- Nicolai Balle Larsen
- Department of Life Sciences and Chemistry, Roskilde University, Universitetsvej 1, 4000 Roskilde, Denmark
| | | | | |
Collapse
|