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Mizrahi R, Ostersetzer-Biran O. Mitochondrial RNA Helicases: Key Players in the Regulation of Plant Organellar RNA Splicing and Gene Expression. Int J Mol Sci 2024; 25:5502. [PMID: 38791540 PMCID: PMC11122041 DOI: 10.3390/ijms25105502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 05/06/2024] [Accepted: 05/09/2024] [Indexed: 05/26/2024] Open
Abstract
Mitochondrial genomes of land plants are large and exhibit a complex mode of gene organization and expression, particularly at the post-transcriptional level. The primary organellar transcripts in plants undergo extensive maturation steps, including endo- and/or exo-nucleolytic cleavage, RNA-base modifications (mostly C-to-U deaminations) and both 'cis'- and 'trans'-splicing events. These essential processing steps rely on the activities of a large set of nuclear-encoded factors. RNA helicases serve as key players in RNA metabolism, participating in the regulation of transcription, mRNA processing and translation. They unwind RNA secondary structures and facilitate the formation of ribonucleoprotein complexes crucial for various stages of gene expression. Furthermore, RNA helicases are involved in RNA metabolism by modulating pre-mRNA maturation, transport and degradation processes. These enzymes are, therefore, pivotal in RNA quality-control mechanisms, ensuring the fidelity and efficiency of RNA processing and turnover in plant mitochondria. This review summarizes the significant roles played by helicases in regulating the highly dynamic processes of mitochondrial transcription, RNA processing and translation in plants. We further discuss recent advancements in understanding how dysregulation of mitochondrial RNA helicases affects the splicing of organellar genes, leading to respiratory dysfunctions, and consequently, altered growth, development and physiology of land plants.
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Affiliation(s)
| | - Oren Ostersetzer-Biran
- Department of Plant and Environmental Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus—Givat Ram, Jerusalem 9190401, Israel
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2
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Sayyed A, Chen B, Wang Y, Cao SK, Tan BC. PPR596 Is Required for nad2 Intron Splicing and Complex I Biogenesis in Arabidopsis. Int J Mol Sci 2024; 25:3542. [PMID: 38542518 PMCID: PMC10971677 DOI: 10.3390/ijms25063542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 03/15/2024] [Accepted: 03/16/2024] [Indexed: 04/04/2024] Open
Abstract
Mitochondria are essential organelles that generate energy via oxidative phosphorylation. Plant mitochondrial genome encodes some of the respiratory complex subunits, and these transcripts require accurate processing, including C-to-U RNA editing and intron splicing. Pentatricopeptide repeats (PPR) proteins are involved in various organellar RNA processing events. PPR596, a P-type PPR protein, was previously identified to function in the C-to-U editing of mitochondrial rps3 transcripts in Arabidopsis. Here, we demonstrate that PPR596 functions in the cis-splicing of nad2 intron 3 in mitochondria. Loss of the PPR596 function affects the editing at rps3eU1344SS, impairs nad2 intron 3 splicing and reduces the mitochondrial complex I's assembly and activity, while inducing alternative oxidase (AOX) gene expression. This defect in nad2 intron splicing provides a plausible explanation for the slow growth of the ppr595 mutants. Although a few P-type PPR proteins are involved in RNA C-to-U editing, our results suggest that the primary function of PPR596 is intron splicing.
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Affiliation(s)
| | | | | | | | - Bao-Cai Tan
- Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China; (A.S.); (B.C.); (Y.W.); (S.-K.C.)
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3
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Liu ZX, Zhang S, Zhu HZ, Chen ZH, Yang Y, Li LQ, Lei Y, Liu Y, Li DY, Sun A, Li CP, Tan SQ, Wang GL, Shen JY, Jin S, Gao C, Liu JJG. Hydrolytic endonucleolytic ribozyme (HYER) is programmable for sequence-specific DNA cleavage. Science 2024; 383:eadh4859. [PMID: 38301022 DOI: 10.1126/science.adh4859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 12/27/2023] [Indexed: 02/03/2024]
Abstract
Ribozymes are catalytic RNAs with diverse functions including self-splicing and polymerization. This work aims to discover natural ribozymes that behave as hydrolytic and sequence-specific DNA endonucleases, which could be repurposed as DNA manipulation tools. Focused on bacterial group II-C introns, we found that many systems without intron-encoded protein propagate multiple copies in their resident genomes. These introns, named HYdrolytic Endonucleolytic Ribozymes (HYERs), cleaved RNA, single-stranded DNA, bubbled double-stranded DNA (dsDNA), and plasmids in vitro. HYER1 generated dsDNA breaks in the mammalian genome. Cryo-electron microscopy analysis revealed a homodimer structure for HYER1, where each monomer contains a Mg2+-dependent hydrolysis pocket and captures DNA complementary to the target recognition site (TRS). Rational designs including TRS extension, recruiting sequence insertion, and heterodimerization yielded engineered HYERs showing improved specificity and flexibility for DNA manipulation.
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Affiliation(s)
- Zi-Xian Liu
- Beijing Advanced Innovation Center for Structural Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Shouyue Zhang
- Beijing Advanced Innovation Center for Structural Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Han-Zhou Zhu
- Beijing Advanced Innovation Center for Structural Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Zhi-Hang Chen
- Beijing Advanced Innovation Center for Structural Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yun Yang
- Beijing Advanced Innovation Center for Structural Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Long-Qi Li
- Beijing Advanced Innovation Center for Structural Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yuan Lei
- New Cornerstone Science Laboratory, Center for Genome Editing, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Yun Liu
- Beijing Advanced Innovation Center for Structural Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Dan-Yuan Li
- Beijing Advanced Innovation Center for Structural Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Ao Sun
- Beijing Advanced Innovation Center for Structural Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Cheng-Ping Li
- Beijing Advanced Innovation Center for Structural Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Shun-Qing Tan
- Beijing Advanced Innovation Center for Structural Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Gao-Li Wang
- Beijing Advanced Innovation Center for Structural Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Jie-Yi Shen
- Beijing Advanced Innovation Center for Structural Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Shuai Jin
- New Cornerstone Science Laboratory, Center for Genome Editing, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Caixia Gao
- New Cornerstone Science Laboratory, Center for Genome Editing, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Jun-Jie Gogo Liu
- Beijing Advanced Innovation Center for Structural Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
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4
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Tan Y, Liang J, Lai M, Wan S, Luo X, Li F. Advances in synthetic biology toolboxes paving the way for mechanistic understanding and strain engineering of gut commensal Bacteroides spp. and Clostridium spp. Biotechnol Adv 2023; 69:108272. [PMID: 37844770 DOI: 10.1016/j.biotechadv.2023.108272] [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: 08/13/2023] [Revised: 10/10/2023] [Accepted: 10/13/2023] [Indexed: 10/18/2023]
Abstract
The gut microbiota plays a significant role in influencing human immunity, metabolism, development, and behavior by producing a wide range of metabolites. While there is accumulating data on several microbiota-derived small molecules that contribute to host health and disease, our knowledge regarding the molecular mechanisms underlying metabolite-mediated microbe-host interactions remains limited. This is primarily due to the lack of efficient genetic tools for most commensal bacteria, especially those belonging to the dominant phyla Bacteroides spp. and Clostridium spp., which hinders the application of synthetic biology to these gut commensal bacteria. In this review, we provide an overview of recent advances in synthetic biology tools developed for the two dominant genera, as well as their applications in deciphering the mechanisms of microbe-host interactions mediated by microbiota-derived small molecules. We also discuss the potential biomedical applications of engineering commensal bacteria using these toolboxes. Finally, we share our perspective on the future development of synthetic biology tools for a better understanding of small molecule-mediated microbe-host interactions and their engineering for biomedical purposes.
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Affiliation(s)
- Yang Tan
- Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao C1 Refinery Engineering Research Center, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China; Shandong Energy Institute, Qingdao 266101, China; Qingdao New Energy Shandong Laboratory, Qingdao 266101, China.
| | - Jing Liang
- Center for Synthetic Biochemistry, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Mingchi Lai
- College of Life Sciences, Qingdao Agricultural University, Qingdao 266109, China
| | - Sai Wan
- Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao C1 Refinery Engineering Research Center, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China; Shandong Energy Institute, Qingdao 266101, China; Qingdao New Energy Shandong Laboratory, Qingdao 266101, China
| | - Xiaozhou Luo
- Center for Synthetic Biochemistry, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Fuli Li
- Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao C1 Refinery Engineering Research Center, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China; Shandong Energy Institute, Qingdao 266101, China; Qingdao New Energy Shandong Laboratory, Qingdao 266101, China.
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5
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Wan W, Li D, Li D, Jiao J. Advances in genetic manipulation of Chlamydia trachomatis. Front Immunol 2023; 14:1209879. [PMID: 37449211 PMCID: PMC10337758 DOI: 10.3389/fimmu.2023.1209879] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 06/14/2023] [Indexed: 07/18/2023] Open
Abstract
Chlamydia trachomatis, one species of Chlamydia spp., has the greatest impact on human health and is the main cause of bacterial sexually transmitted diseases and preventable blindness among all Chamydia spp. species. The obligate intracellular parasitism and unique biphasic developmental cycle of C. trachomatis are the main barriers for the development of tools of genetic manipulation. The past decade has witnessed significant gains in genetic manipulation of C. trachomatis, including chemical mutagenesis, group II intron-based targeted gene knockout, fluorescence-reported allelic exchange mutagenesis (FRAEM), CRISPR interference (CRISPRi) and the recently developed transposon mutagenesis. In this review, we discuss the current status of genetic manipulations of C. trachomatis and highlights new challenges in the nascent field of Chlamydia genetics.
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Affiliation(s)
- Weiqiang Wan
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Danni Li
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Dan Li
- Department of Respiratory Medicine, Center for Pathogen Biology and Infectious Diseases, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, The First Hospital of Jilin University, Changchun, China
| | - Jun Jiao
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
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Zumkeller S, Knoop V. Categorizing 161 plant (streptophyte) mitochondrial group II introns into 29 families of related paralogues finds only limited links between intron mobility and intron-borne maturases. BMC Ecol Evol 2023; 23:5. [PMID: 36915058 PMCID: PMC10012718 DOI: 10.1186/s12862-023-02108-y] [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: 09/20/2022] [Accepted: 02/27/2023] [Indexed: 03/14/2023] Open
Abstract
Group II introns are common in the two endosymbiotic organelle genomes of the plant lineage. Chloroplasts harbor 22 positionally conserved group II introns whereas their occurrence in land plant (embryophyte) mitogenomes is highly variable and specific for the seven major clades: liverworts, mosses, hornworts, lycophytes, ferns, gymnosperms and flowering plants. Each plant group features "signature selections" of ca. 20-30 paralogues from a superset of altogether 105 group II introns meantime identified in embryophyte mtDNAs, suggesting massive intron gains and losses along the backbone of plant phylogeny. We report on systematically categorizing plant mitochondrial group II introns into "families", comprising evidently related paralogues at different insertion sites, which may even be more similar than their respective orthologues in phylogenetically distant taxa. Including streptophyte (charophyte) algae extends our sampling to 161 and we sort 104 streptophyte mitochondrial group II introns into 25 core families of related paralogues evidently arising from retrotransposition events. Adding to discoveries of only recently created intron paralogues, hypermobile introns and twintrons, our survey led to further discoveries including previously overlooked "fossil" introns in spacer regions or e.g., in the rps8 pseudogene of lycophytes. Initially excluding intron-borne maturase sequences for family categorization, we added an independent analysis of maturase phylogenies and find a surprising incongruence between intron mobility and the presence of intron-borne maturases. Intriguingly, however, we find that several examples of nuclear splicing factors meantime characterized simultaneously facilitate splicing of independent paralogues now placed into the same intron families. Altogether this suggests that plant group II intron mobility, in contrast to their bacterial counterparts, is not intimately linked to intron-encoded maturases.
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Affiliation(s)
- Simon Zumkeller
- IZMB, Institut für Zelluläre und Molekulare Botanik, Abteilung Molekulare Evolution, Universität Bonn, Kirschallee 1, 53115, Bonn, Germany
| | - Volker Knoop
- IZMB, Institut für Zelluläre und Molekulare Botanik, Abteilung Molekulare Evolution, Universität Bonn, Kirschallee 1, 53115, Bonn, Germany.
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Cui G, Hua D, Zhao X, Zhou J, Yang Y, Huang T, Wang X, Zhao Y, Zhang T, Liao J, Guan Z, Luo P, Chen Z, Qi X, Hong W. A New EBS2b-IBS2b Base Paring (A -8/T -8) Improved the Gene-Targeting Efficiency of Thermotargetron in Escherichia coli. Microbiol Spectr 2023; 11:e0315922. [PMID: 36809044 PMCID: PMC10100991 DOI: 10.1128/spectrum.03159-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 01/21/2023] [Indexed: 02/23/2023] Open
Abstract
Thermophilic group II intron is one type of retrotransposon composed of intron RNA and intron-encoded protein (IEP), which can be utilized in gene targeting by harnessing their novel ribozyme-based DNA integration mechanism termed "retrohoming." It is mediated by a ribonucleoprotein (RNP) complex that contains the excised intron lariat RNA and an IEP with reverse transcriptase (RT) activity. The RNP recognizes targeting sites by exon-binding sequences 2 (EBS2)/intron-binding sequences 2 (IBS2), EBS1/IBS1, and EBS3/IBS3 bases pairing. Previously, we developed the TeI3c/4c intron as a thermophilic gene targeting system-Thermotargetron (TMT). However, we found that the targeting efficiency of TMT varies significantly at different targeting sites, which leads to a relatively low success rate. To further improve the success rate and gene-targeting efficiency of TMT, we constructed a Random Gene-targeting Plasmids Pool (RGPP) to analyze the sequence recognition preference of TMT. A new base pairing, located at the -8 site between EBS2/IBS2 and EBS1/IBS1 (named EBS2b-IBS2b), increased the success rate (2.45- to 5.07-fold) and significantly improved gene-targeting efficiency of TMT. A computer algorithm (TMT 1.0), based on the newly discovered sequence recognition roles, was also developed to facilitate the design of TMT gene-targeting primers. The present work could essentially expand the practicalities of TMT in the genome engineering of heat-tolerance mesophilic and thermophilic bacteria. IMPORTANCE The randomized base pairing in the interval of IBS2 and IBS1 of Tel3c/4c intron (-8 and -7 sites) in Thermotargetron (TMT) results in a low success rate and gene-targeting efficiency in bacteria. In the present work, we constructed a randomized gene-targeting plasmids pool (RGPP) to study whether there is a base preference in target sequences. Among all the successful "retrohoming" targets, we found that a new EBS2b-IBS2b base paring (A-8/T-8) significantly increased TMT's gene-targeting efficiency, and the concept is also applicable to other gene targets in redesigned gene-targeting plasmids pool in E. coli. The improved TMT is a promising tool for the genetic engineering of bacteria and could promote metabolic engineering and synthetic biology research in valuable microbes that recalcitrance for genetic manipulation.
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Affiliation(s)
- Guzhen Cui
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education & Key Laboratory of Medical Molecular Biology of Guizhou Province & Key Laboratory of Microbiology and Parasitology of Education Department of Guizhou, Guizhou Medical University, Guiyang, Guizhou, China
- Joint Laboratory of Helicobacter Pylori and Intestinal Microecology of Affiliated Hospital of Guizhou Medical University
| | - Dengxiong Hua
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education & Key Laboratory of Medical Molecular Biology of Guizhou Province & Key Laboratory of Microbiology and Parasitology of Education Department of Guizhou, Guizhou Medical University, Guiyang, Guizhou, China
- Joint Laboratory of Helicobacter Pylori and Intestinal Microecology of Affiliated Hospital of Guizhou Medical University
| | - Xingxing Zhao
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education & Key Laboratory of Medical Molecular Biology of Guizhou Province & Key Laboratory of Microbiology and Parasitology of Education Department of Guizhou, Guizhou Medical University, Guiyang, Guizhou, China
| | - Jia Zhou
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education & Key Laboratory of Medical Molecular Biology of Guizhou Province & Key Laboratory of Microbiology and Parasitology of Education Department of Guizhou, Guizhou Medical University, Guiyang, Guizhou, China
| | - Ying Yang
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education & Key Laboratory of Medical Molecular Biology of Guizhou Province & Key Laboratory of Microbiology and Parasitology of Education Department of Guizhou, Guizhou Medical University, Guiyang, Guizhou, China
| | - Tingyu Huang
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education & Key Laboratory of Medical Molecular Biology of Guizhou Province & Key Laboratory of Microbiology and Parasitology of Education Department of Guizhou, Guizhou Medical University, Guiyang, Guizhou, China
| | - Xinxin Wang
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education & Key Laboratory of Medical Molecular Biology of Guizhou Province & Key Laboratory of Microbiology and Parasitology of Education Department of Guizhou, Guizhou Medical University, Guiyang, Guizhou, China
- Joint Laboratory of Helicobacter Pylori and Intestinal Microecology of Affiliated Hospital of Guizhou Medical University
| | - Yan Zhao
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education & Key Laboratory of Medical Molecular Biology of Guizhou Province & Key Laboratory of Microbiology and Parasitology of Education Department of Guizhou, Guizhou Medical University, Guiyang, Guizhou, China
| | - Ting Zhang
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education & Key Laboratory of Medical Molecular Biology of Guizhou Province & Key Laboratory of Microbiology and Parasitology of Education Department of Guizhou, Guizhou Medical University, Guiyang, Guizhou, China
| | - Jian Liao
- School/Hospital of Stomatology, Guizhou Medical University, Guiyang, Guizhou, China
| | - Zhizhong Guan
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education & Key Laboratory of Medical Molecular Biology of Guizhou Province & Key Laboratory of Microbiology and Parasitology of Education Department of Guizhou, Guizhou Medical University, Guiyang, Guizhou, China
| | - Peng Luo
- Collaborative Innovation Center for Prevention and Control of Endemic and Ethnic Regional Diseases Co-constructed by the Province and Ministry
| | - Zhenghong Chen
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education & Key Laboratory of Medical Molecular Biology of Guizhou Province & Key Laboratory of Microbiology and Parasitology of Education Department of Guizhou, Guizhou Medical University, Guiyang, Guizhou, China
- Collaborative Innovation Center for Prevention and Control of Endemic and Ethnic Regional Diseases Co-constructed by the Province and Ministry
- Joint Laboratory of Helicobacter Pylori and Intestinal Microecology of Affiliated Hospital of Guizhou Medical University
| | - Xiaolan Qi
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education & Key Laboratory of Medical Molecular Biology of Guizhou Province & Key Laboratory of Microbiology and Parasitology of Education Department of Guizhou, Guizhou Medical University, Guiyang, Guizhou, China
- Collaborative Innovation Center for Prevention and Control of Endemic and Ethnic Regional Diseases Co-constructed by the Province and Ministry
- Joint Laboratory of Helicobacter Pylori and Intestinal Microecology of Affiliated Hospital of Guizhou Medical University
| | - Wei Hong
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education & Key Laboratory of Medical Molecular Biology of Guizhou Province & Key Laboratory of Microbiology and Parasitology of Education Department of Guizhou, Guizhou Medical University, Guiyang, Guizhou, China
- Collaborative Innovation Center for Prevention and Control of Endemic and Ethnic Regional Diseases Co-constructed by the Province and Ministry
- Joint Laboratory of Helicobacter Pylori and Intestinal Microecology of Affiliated Hospital of Guizhou Medical University
- School/Hospital of Stomatology, Guizhou Medical University, Guiyang, Guizhou, China
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Kim S, Eom H, Nandre R, Choi YJ, Lee H, Ryu H, Ro HS. Comparative structural analysis on the mitochondrial DNAs from various strains of Lentinula edodes. Front Microbiol 2022; 13:1034387. [DOI: 10.3389/fmicb.2022.1034387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 11/09/2022] [Indexed: 11/30/2022] Open
Abstract
The evolution of mitochondria through variations in mitochondrial DNA (mtDNA) is one of the intriguing questions in eukaryotic cells. In order to assess the causes of the variations in mitochondria, the mtDNAs of the 21 strains of Lentinula edodes were assembled for this study, and analyzed together with four published mtDNA sequences. The mtDNAs were within the sizes of 117 kb ~ 122 kb. The gene number was observed consistent except for two mtDNAs, which carry a duplicated trnG1-trnG2 unit or a putative gene deletion. The size variation was largely attributed to the number of introns, repeated sequences, transposable elements (TEs), and plasmid-related sequences. Intron loss and gain were found from cox1, rnl, and rns of three mtDNAs. Loss of two introns in cox1 of KY217797.1 reduced its size by 2.7 kb, making it the smallest cox1 gene (8.4 kb) among the cox1s of the 25 mtDNAs, whereas gain of a Group II intron (2.65 kb) and loss of a Group I intron (1.7 kb) in cox1 of MF774813.1 resulted in the longest cox1 (12 kb). In rnl of L. edodes, we discovered four intron insertion consensus sequences which were unique to basidiomycetes but not ascomycetes. Differential incorporation of introns was the primary cause of the rnl size polymorphism. Homing endonucleases (HEGs) were suggestively involved in the mobilization of the introns because all of the introns have HEG genes of the LAGRIDADG or GIY-YIG families with the conserved HEG cleavage sites. TEs contributed to 11.04% of the mtDNA size in average, of which 7.08% was LTR-retrotransposon and 3.96% was DNA transposon, whereas the repeated sequences covered 4.6% of the mtDNA. The repeat numbers were variable in a strain-dependent manner. Both the TEs and repeated sequences were mostly found in the intronic and intergenic regions. Lastly, two major deletions were found in the plasmid-related sequence regions (pol2-pol3 and pol1-atp8) in the five mtDNAs. Particularly, the 6.8 kb-long deletion at pol2-pol3 region made MF774813.1 the shortest mtDNA of all. Our results demonstrate that mtDNA is a dynamic molecule that persistently evolves over a short period of time by insertion/deletion and repetition of DNA segments at the strain level.
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Chung K, Xu L, Chai P, Peng J, Devarkar SC, Pyle AM. Structures of a mobile intron retroelement poised to attack its structured DNA target. Science 2022; 378:627-634. [PMID: 36356138 PMCID: PMC10190682 DOI: 10.1126/science.abq2844] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Group II introns are ribozymes that catalyze their self-excision and function as retroelements that invade DNA. As retrotransposons, group II introns form ribonucleoprotein (RNP) complexes that roam the genome, integrating by reversal of forward splicing. Here we show that retrotransposition is achieved by a tertiary complex between a structurally elaborate ribozyme, its protein mobility factor, and a structured DNA substrate. We solved cryo-electron microscopy structures of an intact group IIC intron-maturase retroelement that was poised for integration into a DNA stem-loop motif. By visualizing the RNP before and after DNA targeting, we show that it is primed for attack and fits perfectly with its DNA target. This study reveals design principles of a prototypical retroelement and reinforces the hypothesis that group II introns are ancient elements of genetic diversification.
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Affiliation(s)
- Kevin Chung
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Ling Xu
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511 USA
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Pengxin Chai
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Junhui Peng
- Laboratory of Evolutionary Genetics and Genomics, The Rockefeller University, New York, NY 10065, USA
| | - Swapnil C. Devarkar
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Anna Marie Pyle
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511 USA
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
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Cao SK, Liu R, Wang M, Sun F, Sayyed A, Shi H, Wang X, Tan BC. The small PPR protein SPR2 interacts with PPR-SMR1 to facilitate the splicing of introns in maize mitochondria. PLANT PHYSIOLOGY 2022; 190:1763-1776. [PMID: 35976145 PMCID: PMC9614438 DOI: 10.1093/plphys/kiac379] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 07/21/2022] [Indexed: 05/31/2023]
Abstract
Splicing of plant mitochondrial introns is facilitated by numerous nucleus-encoded protein factors. Although some splicing factors have been identified in plants, the mechanism underlying mitochondrial intron splicing remains largely unclear. In this study, we identified a small P-type pentatricopeptide repeat (PPR) protein containing merely four PPR repeats, small PPR protein 2 (SPR2), which is required for the splicing of more than half of the introns in maize (Zea mays) mitochondria. Null mutations of Spr2 severely impair the splicing of 15 out of the 22 mitochondrial Group II introns, resulting in substantially decreased mature transcripts, which abolished the assembly and activity of mitochondrial complex I. Consequently, embryogenesis and endosperm development were arrested in the spr2 mutants. Yeast two-hybrid, luciferase complementation imaging, bimolecular fluorescence complementation, and semi-in vivo pull-down analyses indicated that SPR2 interacts with small MutS-related domain protein PPR-SMR1, both of which are required for the splicing of 13 introns. In addition, SPR2 and/or PPR-SMR1 interact with other splicing factors, including PPR proteins EMPTY PERICARP16, PPR14, and chloroplast RNA splicing and ribosome maturation (CRM) protein Zm-mCSF1, which participate in the splicing of specific intron(s) of the 13 introns. These results prompt us to propose that SPR2/PPR-SMR1 serves as the core component of a splicing complex and possibly exerts the splicing function through a dynamic interaction with specific substrate recognizing PPR proteins in mitochondria.
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Affiliation(s)
- Shi-Kai Cao
- Key Laboratory of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China
| | - Rui Liu
- Key Laboratory of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China
- College of Life Science, Yangtze University, Jingzhou 434025, China
| | - Miaodi Wang
- Key Laboratory of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China
| | - Feng Sun
- Key Laboratory of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China
| | - Aqib Sayyed
- Key Laboratory of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China
| | - Hong Shi
- Key Laboratory of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China
| | - Xiaomin Wang
- Key Laboratory of Cell Activities and Stress Adaptations, Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Bao-Cai Tan
- Key Laboratory of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China
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11
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Li Q, Li L, Zhang T, Xiang P, Wu Q, Tu W, Bao Z, Zou L, Chen C. The first two mitochondrial genomes for the genus Ramaria reveal mitochondrial genome evolution of Ramaria and phylogeny of Basidiomycota. IMA Fungus 2022; 13:16. [PMID: 36100951 PMCID: PMC9469536 DOI: 10.1186/s43008-022-00100-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Accepted: 07/12/2022] [Indexed: 11/10/2022] Open
Abstract
In the present study, we assembled and analyzed the mitogenomes of two Ramaria species. The assembled mitogenomes of Ramaria cfr. rubripermanens and R. rubella were circularized, with sizes of 126,497 bp and 143,271 bp, respectively. Comparative mitogenome analysis showed that intron region contributed the most (contribution rate, 43.74%) to the size variations of Ramaria mitogenomes. The genetic contents, gene length, tRNAs, and codon usages of the two Ramaria mitogenomes varied greatly. In addition, the evolutionary rates of different core protein coding genes (PCGs) in Phallomycetidae mitogenomes varied. We detected large-scale gene rearrangements between Phallomycetidae mitogenomes, including gene displacement and tRNA doubling. A total of 4499 bp and 7746 bp aligned fragments were detected between the mitochondrial and nuclear genomes of R. cfr. rubripermanens and R. rubella, respectively, indicating possible gene transferring events. We further found frequent intron loss/gain and potential intron transfer events in Phallomycetidae mitogenomes during the evolution, and the mitogenomes of R. rubella contained a novel intron P44. Phylogenetic analyses using both Bayesian inference (BI) and Maximum Likelihood (ML) methods based on a combined mitochondrial gene dataset obtained an identical and well-supported phylogenetic tree for Basidiomycota, wherein R. cfr. rubripermanens and Turbinellus floccosus are sister species. This study served as the first report on mitogenomes from the genus Ramaria, which provides a basis for understanding the evolution, genetics, and taxonomy of this important fungal group.
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Affiliation(s)
- Qiang Li
- Key Laboratory of Coarse Cereal Processing, Ministry of Agriculture and Rural Affairs, School of Food and Biological Engineering, Chengdu University, Chengdu, Sichuan, People's Republic of China
| | - Lijiao Li
- Key Laboratory of Coarse Cereal Processing, Ministry of Agriculture and Rural Affairs, School of Food and Biological Engineering, Chengdu University, Chengdu, Sichuan, People's Republic of China
| | - Ting Zhang
- Key Laboratory of Coarse Cereal Processing, Ministry of Agriculture and Rural Affairs, School of Food and Biological Engineering, Chengdu University, Chengdu, Sichuan, People's Republic of China
| | - Peng Xiang
- Key Laboratory of Coarse Cereal Processing, Ministry of Agriculture and Rural Affairs, School of Food and Biological Engineering, Chengdu University, Chengdu, Sichuan, People's Republic of China
| | - Qian Wu
- Key Laboratory of Coarse Cereal Processing, Ministry of Agriculture and Rural Affairs, School of Food and Biological Engineering, Chengdu University, Chengdu, Sichuan, People's Republic of China
| | - Wenying Tu
- Key Laboratory of Coarse Cereal Processing, Ministry of Agriculture and Rural Affairs, School of Food and Biological Engineering, Chengdu University, Chengdu, Sichuan, People's Republic of China
| | - Zhijie Bao
- Key Laboratory of Coarse Cereal Processing, Ministry of Agriculture and Rural Affairs, School of Food and Biological Engineering, Chengdu University, Chengdu, Sichuan, People's Republic of China
| | - Liang Zou
- Key Laboratory of Coarse Cereal Processing, Ministry of Agriculture and Rural Affairs, School of Food and Biological Engineering, Chengdu University, Chengdu, Sichuan, People's Republic of China.
| | - Cheng Chen
- Institute of Plant Protection, Sichuan Academy of Agricultural Sciences, Key Laboratory of Integrated Pest Management on Crops in Southwest, Ministry of Agriculture, 20 # Jingjusi Rd, Chengdu, 610066, Sichuan, People's Republic of China.
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12
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Park SH, Kyndt JA, Brown JK. Comparison of Auxenochlorella protothecoides and Chlorella spp. Chloroplast Genomes: Evidence for Endosymbiosis and Horizontal Virus-like Gene Transfer. Life (Basel) 2022; 12:life12030458. [PMID: 35330209 PMCID: PMC8955559 DOI: 10.3390/life12030458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 03/15/2022] [Accepted: 03/16/2022] [Indexed: 12/02/2022] Open
Abstract
Resequencing of the chloroplast genome (cpDNA) of Auxenochlorella protothecoides UTEX 25 was completed (GenBank Accession no. KC631634.1), revealing a genome size of 84,576 base pairs and 30.8% GC content, consistent with features reported for the previously sequenced A. protothecoides 0710, (GenBank Accession no. KC843975). The A. protothecoides UTEX 25 cpDNA encoded 78 predicted open reading frames, 32 tRNAs, and 4 rRNAs, making it smaller and more compact than the cpDNA genome of C. variabilis (124,579 bp) and C. vulgaris (150,613 bp). By comparison, the compact genome size of A. protothecoides was attributable primarily to a lower intergenic sequence content. The cpDNA coding regions of all known Chlorella species were found to be organized in conserved colinear blocks, with some rearrangements. The Auxenochlorella and Chlorella species genome structure and composition were similar, and of particular interest were genes influencing photosynthetic efficiency, i.e., chlorophyll synthesis and photosystem subunit I and II genes, consistent with other biofuel species of interest. Phylogenetic analysis revealed that Prototheca cutis is the closest known A. protothecoides relative, followed by members of the genus Chlorella. The cpDNA of A. protothecoides encodes 37 genes that are highly homologous to representative cyanobacteria species, including rrn16, rrn23, and psbA, corroborating a well-recognized symbiosis. Several putative coding regions were identified that shared high nucleotide sequence identity with virus-like sequences, suggestive of horizontal gene transfer. Despite these predictions, no corresponding transcripts were obtained by RT-PCR amplification, indicating they are unlikely to be expressed in the extant lineage.
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Affiliation(s)
- Sang-Hyuck Park
- School of Plant Sciences, The University of Arizona, Tucson, AZ 85721, USA; (S.-H.P.); (J.K.B.)
- Institute of Cannabis Research, Colorado State University-Pueblo, Pueblo, CO 81001, USA
| | - John A. Kyndt
- College of Science and Technology, Bellevue University, Bellevue, NE 68005, USA
- Correspondence:
| | - Judith K. Brown
- School of Plant Sciences, The University of Arizona, Tucson, AZ 85721, USA; (S.-H.P.); (J.K.B.)
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13
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Prince S, Munoz C, Filion-Bienvenue F, Rioux P, Sarrasin M, Lang BF. Refining Mitochondrial Intron Classification With ERPIN: Identification Based on Conservation of Sequence Plus Secondary Structure Motifs. Front Microbiol 2022; 13:866187. [PMID: 35369492 PMCID: PMC8971849 DOI: 10.3389/fmicb.2022.866187] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Accepted: 02/28/2022] [Indexed: 12/02/2022] Open
Abstract
Mitochondrial genomes—in particular those of fungi—often encode genes with a large number of Group I and Group II introns that are conserved at both the sequence and the RNA structure level. They provide a rich resource for the investigation of intron and gene structure, self- and protein-guided splicing mechanisms, and intron evolution. Yet, the degree of sequence conservation of introns is limited, and the primary sequence differs considerably among the distinct intron sub-groups. It makes intron identification, classification, structural modeling, and the inference of gene models a most challenging and error-prone task—frequently passed on to an “expert” for manual intervention. To reduce the need for manual curation of intron structures and mitochondrial gene models, computational methods using ERPIN sequence profiles were initially developed in 2007. Here we present a refinement of search models and alignments using the now abundant publicly available fungal mtDNA sequences. In addition, we have tested in how far members of the originally proposed sub-groups are clearly distinguished and validated by our computational approach. We confirm clearly distinct mitochondrial Group I sub-groups IA1, IA3, IB3, IC1, IC2, and ID. Yet, IB1, IB2, and IB4 ERPIN models are overlapping substantially in predictions, and are therefore combined and reported as IB. We have further explored the conversion of our ERPIN profiles into covariance models (CM). Current limitations and prospects of the CM approach will be discussed.
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14
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Molina-Sánchez MD, García-Rodríguez FM, Andrés-León E, Toro N. Identification of Group II Intron RmInt1 Binding Sites in a Bacterial Genome. Front Mol Biosci 2022; 9:834020. [PMID: 35281263 PMCID: PMC8914252 DOI: 10.3389/fmolb.2022.834020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Accepted: 02/07/2022] [Indexed: 11/13/2022] Open
Abstract
RmInt1 is a group II intron encoding a reverse transcriptase protein (IEP) lacking the C-terminal endonuclease domain. RmInt1 is an efficient mobile retroelement that predominantly reverse splices into the transient single-stranded DNA at the template for lagging strand DNA synthesis during host replication, a process facilitated by the interaction of the RmInt1 IEP with DnaN at the replication fork. It has been suggested that group II intron ribonucleoprotein particles bind DNA nonspecifically, and then scan for their correct target site. In this study, we investigated RmInt1 binding sites throughout the Sinorhizobium meliloti genome, by chromatin-immunoprecipitation coupled with next-generation sequencing. We found that RmInt1 binding sites cluster around the bidirectional replication origin of each of the three replicons comprising the S. meliloti genome. Our results provide new evidence linking group II intron mobility to host DNA replication.
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Affiliation(s)
- María Dolores Molina-Sánchez
- Structure, Dynamics and Function of Rhizobacterial Genomes, Estación Experimental del Zaidín, Department of Soil Microbiology and Symbiotic Systems, Spanish National Research Council (CSIC), Granada, Spain
| | - Fernando Manuel García-Rodríguez
- Structure, Dynamics and Function of Rhizobacterial Genomes, Estación Experimental del Zaidín, Department of Soil Microbiology and Symbiotic Systems, Spanish National Research Council (CSIC), Granada, Spain
| | - Eduardo Andrés-León
- Bioinformatics Unit, Institute of Parasitology and Biomedicine “López-Neyra” (IPBLN), Spanish National Research Council (CSIC), Granada, Spain
| | - Nicolás Toro
- Structure, Dynamics and Function of Rhizobacterial Genomes, Estación Experimental del Zaidín, Department of Soil Microbiology and Symbiotic Systems, Spanish National Research Council (CSIC), Granada, Spain
- *Correspondence: Nicolás Toro,
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15
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Kim D, Lee J, Cho CH, Kim EJ, Bhattacharya D, Yoon HS. Group II intron and repeat-rich red algal mitochondrial genomes demonstrate the dynamic recent history of autocatalytic RNAs. BMC Biol 2022; 20:2. [PMID: 34996446 PMCID: PMC8742464 DOI: 10.1186/s12915-021-01200-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Accepted: 11/29/2021] [Indexed: 11/10/2022] Open
Abstract
Background Group II introns are mobile genetic elements that can insert at specific target sequences, however, their origins are often challenging to reconstruct because of rapid sequence decay following invasion and spread into different sites. To advance understanding of group II intron spread, we studied the intron-rich mitochondrial genome (mitogenome) in the unicellular red alga, Porphyridium. Results Analysis of mitogenomes in three closely related species in this genus revealed they were 3–6-fold larger in size (56–132 kbp) than in other red algae, that have genomes of size 21–43 kbp. This discrepancy is explained by two factors, group II intron invasion and expansion of repeated sequences in large intergenic regions. Phylogenetic analysis demonstrates that many mitogenome group II intron families are specific to Porphyridium, whereas others are closely related to sequences in fungi and in the red alga-derived plastids of stramenopiles. Network analysis of intron-encoded proteins (IEPs) shows a clear link between plastid and mitochondrial IEPs in distantly related species, with both groups associated with prokaryotic sequences. Conclusion Our analysis of group II introns in Porphyridium mitogenomes demonstrates the dynamic nature of group II intron evolution, strongly supports the lateral movement of group II introns among diverse eukaryotes, and reveals their ability to proliferate, once integrated in mitochondrial DNA. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-021-01200-3.
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Affiliation(s)
- Dongseok Kim
- Department of Biological Sciences, Sungkyunkwan University, Suwon, 16419, South Korea
| | - JunMo Lee
- Department of Oceanography, Kyungpook National University, Daegu, 41566, South Korea
| | - Chung Hyun Cho
- Department of Biological Sciences, Sungkyunkwan University, Suwon, 16419, South Korea
| | - Eun Jeung Kim
- Department of Biological Sciences, Sungkyunkwan University, Suwon, 16419, South Korea
| | - Debashish Bhattacharya
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ, 08901, USA
| | - Hwan Su Yoon
- Department of Biological Sciences, Sungkyunkwan University, Suwon, 16419, South Korea.
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16
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Mudziwapasi R, Mufandaedza J, Jomane FN, Songwe F, Ndudzo A, Nyamusamba RP, Takombwa AR, Mahla MG, Pullen J, Mlambo SS, Mahuni C, Mufandaedza E, Shoko R. Unlocking the potential of synthetic biology for improving livelihoods in sub-Saharan Africa. ALL LIFE 2022. [DOI: 10.1080/26895293.2021.2014986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Affiliation(s)
- Reagan Mudziwapasi
- Department of Crop and Soil Sciences, Faculty of Agricultural Sciences, Lupane State University, Lupane, Zimbabwe
| | | | - Fortune N. Jomane
- Department of Animal Science and Rangeland Management, Faculty of Agricultural Sciences, Lupane State University, Lupane, Zimbabwe
| | - Fanuel Songwe
- Department of Biosciences and Biotechnology, Faculty of Science and Technology, Midlands State University, Gweru, Zimbabwe
| | - Abigarl Ndudzo
- Department of Crop and Soil Sciences, Faculty of Agricultural Sciences, Lupane State University, Lupane, Zimbabwe
| | - Rutendo P. Nyamusamba
- Department of Crop and Soil Sciences, Faculty of Agricultural Sciences, Lupane State University, Lupane, Zimbabwe
| | | | - Melinda G. Mahla
- Department of Crop and Soil Sciences, Faculty of Agricultural Sciences, Lupane State University, Lupane, Zimbabwe
| | - Jessica Pullen
- Department of Crop and Soil Sciences, Faculty of Agricultural Sciences, Lupane State University, Lupane, Zimbabwe
| | - Sibonani S. Mlambo
- Department of Biotechnology, Faculty of Agriculture, Chinhoyi University of Technology, Chinhoyi, Zimbabwe
| | | | - Edward Mufandaedza
- Department of Environmental Sciences, Faculty of Agricultural Sciences, Lupane State University, Lupane, Zimbabwe
| | - Ryman Shoko
- Department of Biology, Faculty of Agriculture, Chinhoyi University of Technology, Chinhoyi, Zimbabwe
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17
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Wang Y, Wen F, Hong X, Li Z, Mi Y, Zhao B. Comparative chloroplast genome analyses of Paraboea (Gesneriaceae): Insights into adaptive evolution and phylogenetic analysis. FRONTIERS IN PLANT SCIENCE 2022; 13:1019831. [PMID: 36275537 PMCID: PMC9581172 DOI: 10.3389/fpls.2022.1019831] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 09/16/2022] [Indexed: 05/22/2023]
Abstract
Paraboea (Gesneriaceae) distributed in the karst areas of South and Southwest China and Southeast Asia, is an ideal genus to study the phylogeny and adaptive evolution of karst plants. In this study, the complete chloroplast genomes of twelve Paraboea species were sequenced and analyzed. Twelve chloroplast genomes ranged in size from 153166 to 154245 bp. Each chloroplast genome had a typical quartile structure, and relatively conserved type and number of gene components, including 131 genes which are composed of 87 protein coding genes, 36 transfer RNAs and 8 ribosomal RNAs. A total of 600 simple sequence repeats and 389 non-overlapped sequence repeats were obtained from the twelve Paraboea chloroplast genomes. We found ten divergent regions (trnH-GUG-psbA, trnM-CAU, trnC-GCA, atpF-atpH, ycf1, trnK-UUU-rps16, rps15, petL, trnS-GCU-trnR-UCU and psaJ-rpl33) among the 12 Paraboea species to be potential molecular markers. In the phylogenetic tree of 31 Gesneriaceae plants including twelve Paraboea species, all Paraboea species clustered in a clade and confirmed the monophyly of Paraboea. Nine genes with positive selection sites were detected, most of which were related to photosynthesis and protein synthesis, and might played crucial roles in the adaptability of Paraboea to diverse karst environments. These findings are valuable for further study of the phylogeny and karst adaptability of Gesneriaceae plants.
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Affiliation(s)
- Yifei Wang
- Department of Pharmacognosy, Guilin Medical University, Guilin, China
- Department of Pharmacy, Guilin Medical University, Guilin, China
| | - Fang Wen
- Guangxi Key Laboratory of Plant Conservation and Restoration Ecology in Karst Terrain, Guangxi Institute of Botany, Guangxi Zhuang Autonomous Region and Chinese Academy of Sciences, Guilin, China
| | - Xin Hong
- Anhui Provincial Engineering Laboratory of Wetland Ecosystem Protection and Restoration, School of Resources and Environmental Engineering, Anhui University, Hefei, China
- Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
| | - Zhenglong Li
- Anhui Provincial Engineering Laboratory of Wetland Ecosystem Protection and Restoration, School of Resources and Environmental Engineering, Anhui University, Hefei, China
- Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
| | - Yaolei Mi
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China
- *Correspondence: Bo Zhao, ; Yaolei Mi,
| | - Bo Zhao
- Department of Pharmacognosy, Guilin Medical University, Guilin, China
- Department of Pharmacy, Guilin Medical University, Guilin, China
- Guangxi Key Laboratory of Plant Conservation and Restoration Ecology in Karst Terrain, Guangxi Institute of Botany, Guangxi Zhuang Autonomous Region and Chinese Academy of Sciences, Guilin, China
- *Correspondence: Bo Zhao, ; Yaolei Mi,
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18
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Wang X, Wang J, Li S, Lu C, Sui N. An overview of RNA splicing and functioning of splicing factors in land plant chloroplasts. RNA Biol 2022; 19:897-907. [PMID: 35811474 PMCID: PMC9275481 DOI: 10.1080/15476286.2022.2096801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
RNA splicing refers to a process by which introns of a pre-mRNA are excised and the exons at both ends are joined together. Chloroplast introns are inherently self-splicing ribozymes, but over time, they have lost self-splicing ability due to the degeneration of intronic elements. Thus, the splicing of chloroplast introns relies heavily on nuclear-encoded splicing factors, which belong to diverse protein families. Different splicing factors and their shared intron targets are supposed to form ribonucleoprotein particles (RNPs) to facilitate intron splicing. As characterized in a previous review, around 14 chloroplast intron splicing factors were identified until 2010. However, only a few genetic and biochemical evidence has shown that these splicing factors are required for the splicing of one or several introns. The roles of splicing factors are generally believed to facilitate intron folding; however, the precise role of each protein in RNA splicing remains ambiguous. This may be because the precise binding site of most of these splicing factors remains unexplored. In the last decade, several new splicing factors have been identified. Also, several splicing factors were found to bind to specific sequences within introns, which enhanced the understanding of splicing factors. Here, we summarize recent progress on the splicing factors in land plant chloroplasts and discuss their possible roles in chloroplast RNA splicing based on previous studies.
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Affiliation(s)
- Xuemei Wang
- Shandong Provincial Key Laboratory of Plant Stress, College of Life Sciences, Shandong Normal University, Jinan, Western Shandong, China
| | - Jingyi Wang
- Shandong Provincial Key Laboratory of Plant Stress, College of Life Sciences, Shandong Normal University, Jinan, Western Shandong, China
| | - Simin Li
- Shandong Provincial Key Laboratory of Plant Stress, College of Life Sciences, Shandong Normal University, Jinan, Western Shandong, China
| | - Congming Lu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, Western Shandong, China
| | - Na Sui
- Shandong Provincial Key Laboratory of Plant Stress, College of Life Sciences, Shandong Normal University, Jinan, Western Shandong, China
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19
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Liu T, Pyle AM. Discovery of highly reactive self-splicing group II introns within the mitochondrial genomes of human pathogenic fungi. Nucleic Acids Res 2021; 49:12422-12432. [PMID: 34850132 PMCID: PMC8643640 DOI: 10.1093/nar/gkab1077] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 09/27/2021] [Accepted: 10/20/2021] [Indexed: 11/25/2022] Open
Abstract
Fungal pathogens represent an expanding global health threat for which treatment options are limited. Self-splicing group II introns have emerged as promising drug targets, but their development has been limited by a lack of information on their distribution and architecture in pathogenic fungi. To meet this challenge, we developed a bioinformatic workflow for scanning sequence data to identify unique RNA structural signatures within group II introns. Using this approach, we discovered a set of ubiquitous introns within thermally dimorphic fungi (genera of Blastomyces, Coccidioides and Histoplasma). These introns are the most biochemically reactive group II introns ever reported, and they self-splice rapidly under near-physiological conditions without protein cofactors. Moreover, we demonstrated the small molecule targetability of these introns by showing that they can be inhibited by the FDA-approved drug mitoxantrone in vitro. Taken together, our results highlight the utility of structure-based informatic searches for identifying riboregulatory elements in pathogens, revealing a striking diversity of reactive self-splicing introns with great promise as antifungal drug targets.
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Affiliation(s)
- Tianshuo Liu
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, 06520, USA
| | - Anna M Pyle
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, 06520, USA.,Department of Chemistry, Yale University, New Haven, CT, 06520, USA.,Howard Hughes Medical Institute, Yale University, New Haven, CT, 06520, USA
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20
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Thompson SRL, Lee DK, Lachance MA, Smith DR. Mutational Effects of Mobile Introns on the Mitochondrial Genomes of Metschnikowia Yeasts. Front Genet 2021; 12:785218. [PMID: 34804133 PMCID: PMC8601654 DOI: 10.3389/fgene.2021.785218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 10/19/2021] [Indexed: 11/25/2022] Open
Abstract
It has been argued that DNA repair by homologous recombination in the context of endonuclease-mediated cleavage can cause mutations. To better understand this phenomenon, we examined homologous recombination following endonuclease cleavage in a native genomic context: the movement of self-splicing introns in the mitochondrial genomes of Metschnikowia yeasts. Self-splicing mitochondrial introns are mobile elements, which can copy and paste themselves at specific insertion sites in mitochondrial DNA using a homing endonuclease in conjunction with homologous recombination. Here, we explore the mutational effects of self-splicing introns by comparing sequence variation within the intron-rich cox1 and cob genes from 71 strains (belonging to 40 species) from the yeast genus Metschnikowia. We observed a higher density of single nucleotide polymorphisms around self-splicing-intron insertion sites. Given what is currently known about the movement of organelle introns, it is likely that their mutational effects result from the high binding affinity of endonucleases and their interference with repair machinery during homologous recombination (or, alternatively, via gene conversion occurring during the intron insertion process). These findings suggest that there are fitness costs to harbouring self-splicing, mobile introns and will help us better understand the risks associated with modern biotechnologies that use endonuclease-mediated homologous recombination, such as CRISPR-Cas9 gene editing.
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Affiliation(s)
- Scout R L Thompson
- Department of Biology, University of Western Ontario, London, ON, Canada
| | - Dong Kyung Lee
- Department of Biology, University of Western Ontario, London, ON, Canada
| | | | - David Roy Smith
- Department of Biology, University of Western Ontario, London, ON, Canada
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21
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González-Delgado A, Mestre MR, Martínez-Abarca F, Toro N. Prokaryotic reverse transcriptases: from retroelements to specialized defense systems. FEMS Microbiol Rev 2021; 45:fuab025. [PMID: 33983378 PMCID: PMC8632793 DOI: 10.1093/femsre/fuab025] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 05/07/2021] [Indexed: 12/30/2022] Open
Abstract
Reverse transcriptases (RTs) catalyze the polymerization of DNA from an RNA template. These enzymes were first discovered in RNA tumor viruses in 1970, but it was not until 1989 that they were found in prokaryotes as a key component of retrons. Apart from RTs encoded by the 'selfish' mobile retroelements known as group II introns, prokaryotic RTs are extraordinarily diverse, but their function has remained elusive. However, recent studies have revealed that different lineages of prokaryotic RTs, including retrons, those associated with CRISPR-Cas systems, Abi-like RTs and other yet uncharacterized RTs, are key components of different lines of defense against phages and other mobile genetic elements. Prokaryotic RTs participate in various antiviral strategies, including abortive infection (Abi), in which the infected cell is induced to commit suicide to protect the host population, adaptive immunity, in which a memory of previous infection is used to build an efficient defense, and other as yet unidentified mechanisms. These prokaryotic enzymes are attracting considerable attention, both for use in cutting-edge technologies, such as genome editing, and as an emerging research topic. In this review, we discuss what is known about prokaryotic RTs, and the exciting evidence for their domestication from retroelements to create specialized defense systems.
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Affiliation(s)
- Alejandro González-Delgado
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, C/ Profesor Albareda 1, 18008 Granada, Spain
| | - Mario Rodríguez Mestre
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, C/ Profesor Albareda 1, 18008 Granada, Spain
- Department of Biochemistry, Universidad Autónoma de Madrid and Instituto de Investigaciones Biomédicas “Alberto Sols”, CSIC-UAM, Madrid, Spain
| | - Francisco Martínez-Abarca
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, C/ Profesor Albareda 1, 18008 Granada, Spain
| | - Nicolás Toro
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, C/ Profesor Albareda 1, 18008 Granada, Spain
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22
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Viviani A, Ventimiglia M, Fambrini M, Vangelisti A, Mascagni F, Pugliesi C, Usai G. Impact of transposable elements on the evolution of complex living systems and their epigenetic control. Biosystems 2021; 210:104566. [PMID: 34718084 DOI: 10.1016/j.biosystems.2021.104566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 10/21/2021] [Accepted: 10/21/2021] [Indexed: 10/20/2022]
Abstract
Transposable elements (TEs) contribute to genomic innovations, as well as genome instability, across a wide variety of species. Popular designations such as 'selfish DNA' and 'junk DNA,' common in the 1980s, may be either inaccurate or misleading, while a more enlightened view of the TE-host relationship covers a range from parasitism to mutualism. Both plant and animal hosts have evolved epigenetic mechanisms to reduce the impact of TEs, both by directly silencing them and by reducing their ability to transpose in the genome. However, TEs have also been co-opted by both plant and animal genomes to perform a variety of physiological functions, ranging from TE-derived proteins acting directly in normal biological functions to innovations in transcription factor activity and also influencing gene expression. Their presence, in fact, can affect a range of features at genome, phenotype, and population levels. The impact TEs have had on evolution is multifaceted, and many aspects still remain unexplored. In this review, the epigenetic control of TEs is contextualized according to the evolution of complex living systems.
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Affiliation(s)
- Ambra Viviani
- Department of Agriculture, Food and Environment (DAFE), University of Pisa, Via del Borghetto, 80-56124, Pisa, Italy
| | - Maria Ventimiglia
- Department of Agriculture, Food and Environment (DAFE), University of Pisa, Via del Borghetto, 80-56124, Pisa, Italy
| | - Marco Fambrini
- Department of Agriculture, Food and Environment (DAFE), University of Pisa, Via del Borghetto, 80-56124, Pisa, Italy
| | - Alberto Vangelisti
- Department of Agriculture, Food and Environment (DAFE), University of Pisa, Via del Borghetto, 80-56124, Pisa, Italy
| | - Flavia Mascagni
- Department of Agriculture, Food and Environment (DAFE), University of Pisa, Via del Borghetto, 80-56124, Pisa, Italy
| | - Claudio Pugliesi
- Department of Agriculture, Food and Environment (DAFE), University of Pisa, Via del Borghetto, 80-56124, Pisa, Italy.
| | - Gabriele Usai
- Department of Agriculture, Food and Environment (DAFE), University of Pisa, Via del Borghetto, 80-56124, Pisa, Italy
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Kim H, Yang JH, Bustamante DE, Calderon MS, Mansilla A, Maggs CA, Hansen GI, Yoon HS. Organelle Genome Variation in the Red Algal Genus Ahnfeltia (Florideophyceae). Front Genet 2021; 12:724734. [PMID: 34646303 PMCID: PMC8503264 DOI: 10.3389/fgene.2021.724734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 09/09/2021] [Indexed: 11/13/2022] Open
Abstract
The agarophyte Ahnfeltia (Ahnfeltiales, Rhodophyta) is a globally widespread genus with 11 accepted species names. Two of the most widespread species in this genus, A. plicata and A. fastigiata, may have diverged genetically due to past geographic changes and subsequent geographic isolation. To investigate this genomic and genetic diversity, we generated new plastid (ptDNAs) and mitochondrial genomes (mtDNAs) of these Ahnfeltia species from four different regions (A. plicata - Chile and UK and A. fastigiata - Korea and Oregon). Two architecture variations were found in the Ahnfeltia genomes: in ptDNA of A. fastigiata Oregon, the hypothetical pseudogene region was translocated, likely due to recombination with palindromic repeats or a gene transfer from a red algal plasmid. In mtDNA of A. fastigiata Korea, the composition of the group II intronic ORFs was distinct from others suggesting different scenarios of gain and loss of group II intronic ORFs. These features resulted in genome size differences between the two species. Overall gene contents of organelle genomes of Ahnfeltia were conserved. Phylogenetic analysis using concatenated genes from ptDNAs and mtDNAs supported the monophyly of the Ahnfeltiophycidae. The most probable individual gene trees showed that the Ahnfeltia populations were genetically diversified. These trees, the cox1 haplotype network, and a dN/dS analysis all supported the theory that these Ahnfeltia populations have diversified genetically in accordance with geographic distribution.
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Affiliation(s)
- Hocheol Kim
- Department of Biological Sciences, Sungkyunkwan University, Suwon, South Korea
| | - Ji Hyun Yang
- Department of Biological Sciences, Sungkyunkwan University, Suwon, South Korea
| | - Danilo E Bustamante
- Instituto de Investigación para el Desarrollo Sustentable de Ceja de Selva (INDES-CES), Universidad Nacional Toribio Rodríguez de Mendoza, Chachapoyas, Peru
| | - Martha S Calderon
- Laboratorio de Macroalgas Antárticas y Subantárticas, Universidad de Magallanes, Punta Arenas, Chile
| | - Andres Mansilla
- Laboratorio de Macroalgas Antárticas y Subantárticas, Universidad de Magallanes, Punta Arenas, Chile
| | - Christine A Maggs
- School of Biological Sciences, Queen's University Belfast, Belfast, United Kingdom
| | - Gayle I Hansen
- Marine Algal Biodiversity Research, Newport, OR, United States
| | - Hwan Su Yoon
- Department of Biological Sciences, Sungkyunkwan University, Suwon, South Korea
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Wang M, Li K, Li Y, Mi L, Hu Z, Guo S, Song CP, Duan Z. An Exon Skipping in CRS1 Is Associated with Perturbed Chloroplast Development in Maize. Int J Mol Sci 2021; 22:ijms221910668. [PMID: 34639010 PMCID: PMC8508894 DOI: 10.3390/ijms221910668] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 09/20/2021] [Accepted: 09/27/2021] [Indexed: 02/07/2023] Open
Abstract
Chloroplasts of higher plants are semi-autonomous organelles that perform photosynthesis and produce hormones and metabolites. They play crucial roles in plant growth and development. Although many seedling-lethal nuclear genes or regulators required for chloroplast development have been characterized, the understanding of chloroplast development is still limited. Using a genetic screen, we isolated a mutant named ell1, with etiolated leaves and a seedling-lethal phenotype. Analysis by BN-PAGE and transmission electron microscopy revealed drastic morphological defects of chloroplasts in ell1 mutants. Genetic mapping of the mutant gene revealed a single mutation (G-to-A) at the 5′ splice site of intron 5 in CRS1, resulting in an exon skipping in CRS1, indicating that this mutation in CRS1 is responsible for the observed phenotype, which was further confirmed by genetic analysis. The incorrectly spliced CRS1 failed to mediate the splicing of atpF intron. Moreover, the quantitative analysis suggested that ZmCRS1 may participate in chloroplast transcription to regulate the development of chloroplast. Taken together, these findings improve our understanding of the ZmCRS1 protein and shed new light on the regulation of chloroplast development in maize.
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25
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Mukhopadhyay J, Hausner G. Organellar Introns in Fungi, Algae, and Plants. Cells 2021; 10:cells10082001. [PMID: 34440770 PMCID: PMC8393795 DOI: 10.3390/cells10082001] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/31/2021] [Accepted: 08/05/2021] [Indexed: 12/16/2022] Open
Abstract
Introns are ubiquitous in eukaryotic genomes and have long been considered as ‘junk RNA’ but the huge energy expenditure in their transcription, removal, and degradation indicate that they may have functional significance and can offer evolutionary advantages. In fungi, plants and algae introns make a significant contribution to the size of the organellar genomes. Organellar introns are classified as catalytic self-splicing introns that can be categorized as either Group I or Group II introns. There are some biases, with Group I introns being more frequently encountered in fungal mitochondrial genomes, whereas among plants Group II introns dominate within the mitochondrial and chloroplast genomes. Organellar introns can encode a variety of proteins, such as maturases, homing endonucleases, reverse transcriptases, and, in some cases, ribosomal proteins, along with other novel open reading frames. Although organellar introns are viewed to be ribozymes, they do interact with various intron- or nuclear genome-encoded protein factors that assist in the intron RNA to fold into competent splicing structures, or facilitate the turn-over of intron RNAs to prevent reverse splicing. Organellar introns are also known to be involved in non-canonical splicing, such as backsplicing and trans-splicing which can result in novel splicing products or, in some instances, compensate for the fragmentation of genes by recombination events. In organellar genomes, Group I and II introns may exist in nested intronic arrangements, such as introns within introns, referred to as twintrons, where splicing of the external intron may be dependent on splicing of the internal intron. These nested or complex introns, with two or three-component intron modules, are being explored as platforms for alternative splicing and their possible function as molecular switches for modulating gene expression which could be potentially applied towards heterologous gene expression. This review explores recent findings on organellar Group I and II introns, focusing on splicing and mobility mechanisms aided by associated intron/nuclear encoded proteins and their potential roles in organellar gene expression and cross talk between nuclear and organellar genomes. Potential application for these types of elements in biotechnology are also discussed.
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MESH Headings
- Evolution, Molecular
- Gene Expression Regulation, Fungal
- Gene Expression Regulation, Plant
- Genome, Fungal
- Genome, Plant
- Introns
- Organelles/genetics
- Organelles/metabolism
- RNA Splicing
- RNA Stability
- RNA, Algal/genetics
- RNA, Algal/metabolism
- RNA, Fungal/genetics
- RNA, Fungal/metabolism
- RNA, Plant/genetics
- RNA, Plant/metabolism
- RNA, Untranslated/genetics
- RNA, Untranslated/metabolism
- Transcription, Genetic
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Comparative Chloroplast Genomes of Four Lycoris Species (Amaryllidaceae) Provides New Insight into Interspecific Relationship and Phylogeny. BIOLOGY 2021; 10:biology10080715. [PMID: 34439948 PMCID: PMC8389210 DOI: 10.3390/biology10080715] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 07/23/2021] [Indexed: 11/16/2022]
Abstract
The genus Lycoris (Amaryllidaceae) consists of about 20 species, which is endemic to East Asia. Although the Lycoris species is of great horticultural and medical importance, challenges in accurate species identification persist due to frequent natural hybridization and large-scale intraspecific variation. In this study, we sequenced chloroplast genomes of four Lycoris species and retrieved seven published chloroplast (cp) genome sequences in this genus for comparative genomic and phylogenetic analyses. The cp genomes of these four newly sequenced species were found to be 158,405-158,498 bp with the same GC content of 37.8%. The structure of the genomes exhibited the typical quadripartite structure with conserved gene order and content. A total of 113 genes (20 duplicated) were identified, including 79 protein-coding genes (PCGs), 30 tRNAs, and 4 rRNAs. Phylogenetic analysis showed that the 11 species were clustered into three main groups, and L. sprengeri locate at the base of Lycoriss. The L. radiata was suggested to be the female donor of the L. incarnata, L. shaanxiensis, and L. squamigera. The L. straminea and L. houdyshelii may be derived from L. anhuiensis, L. chinensis, or L. longituba. These results could not only offer a genome-scale platform for identification and utilization of Lycoris but also provide a phylogenomic framework for future studies in this genus.
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RNA-Targeting Splicing Modifiers: Drug Development and Screening Assays. Molecules 2021; 26:molecules26082263. [PMID: 33919699 PMCID: PMC8070285 DOI: 10.3390/molecules26082263] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 04/05/2021] [Accepted: 04/09/2021] [Indexed: 02/06/2023] Open
Abstract
RNA splicing is an essential step in producing mature messenger RNA (mRNA) and other RNA species. Harnessing RNA splicing modifiers as a new pharmacological modality is promising for the treatment of diseases caused by aberrant splicing. This drug modality can be used for infectious diseases by disrupting the splicing of essential pathogenic genes. Several antisense oligonucleotide splicing modifiers were approved by the U.S. Food and Drug Administration (FDA) for the treatment of spinal muscular atrophy (SMA) and Duchenne muscular dystrophy (DMD). Recently, a small-molecule splicing modifier, risdiplam, was also approved for the treatment of SMA, highlighting small molecules as important warheads in the arsenal for regulating RNA splicing. The cellular targets of these approved drugs are all mRNA precursors (pre-mRNAs) in human cells. The development of novel RNA-targeting splicing modifiers can not only expand the scope of drug targets to include many previously considered “undruggable” genes but also enrich the chemical-genetic toolbox for basic biomedical research. In this review, we summarized known splicing modifiers, screening methods for novel splicing modifiers, and the chemical space occupied by the small-molecule splicing modifiers.
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28
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Dreher TW, Davis EW, Mueller RS, Otten TG. Comparative genomics of the ADA clade within the Nostocales. HARMFUL ALGAE 2021; 104:102037. [PMID: 34023075 DOI: 10.1016/j.hal.2021.102037] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 04/14/2021] [Accepted: 04/23/2021] [Indexed: 06/12/2023]
Abstract
The ADA clade of Nostocales cyanobacteria, a group that is prominent in current harmful algal bloom events, now includes over 40 genome sequences with the recent addition of sixteen novel sequenced genomes (Dreher et al., Harmful Algae, 2021). Fourteen genomes are complete (closed), enabling highly detailed assessments of gene content and genome architecture. ADA genomes contain 5 rRNA operons, genes expected to support a photoautotrophic and diazotrophic lifestyle, and a varied array of genes for the synthesis of bioactive secondary metabolites. Genes for the production of the taste-and-odor compound geosmin and the four major classes of cyanotoxins - anatoxin-a, cylindrospermopsin, microcystin and saxitoxin - are represented in members of the ADA clade. Notably, the gene array for the synthesis of cylindrospermopsin by Dolichospermum sp. DET69 was located on a plasmid, raising the possibility of facile horizontal transmission. However, genes supporting independent conjugative transfer of this plasmid are lacking. Further, analysis of genomic loci containing this and other cyanotoxin gene arrays shows evidence that these arrays have long-term stability and do not appear to be genomic islands easily capable of horizontal transmission to other cells. There is considerable diversity in the gene complements of individual ADA genomes, including the variable presence of physiologically important genes: genomes in three species-level subclades lack the gas vesicle genes that facilitate a planktonic lifestyle, and, surprisingly, the genome of Cuspidothrix issatschenkoi CHARLIE-1, a reported diazotroph, lacks the genes for nitrogen fixation. Notably, phylogenetically related genomes possess limited synteny, indicating a prominent role for chromosome rearrangements during ADA strain evolution. The genomes contain abundant insertion sequences and repetitive transposase genes, which could be the main drivers of genome rearrangement through active transposition and homologous recombination. No prophages were found, and no evidence of viral infection was observed in the bloom population samples from which the genomes discussed here were derived. Phages thus seem to have a limited influence on ADA evolution.
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Affiliation(s)
- Theo W Dreher
- Department of Microbiology, Oregon State University, Corvallis, Oregon 97331 USA; Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon 97331 USA.
| | - Edward W Davis
- Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon 97331 USA
| | - Ryan S Mueller
- Department of Microbiology, Oregon State University, Corvallis, Oregon 97331 USA
| | - Timothy G Otten
- Department of Microbiology, Oregon State University, Corvallis, Oregon 97331 USA.
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Sonbol S, Siam R. The association of group IIB intron with integrons in hypersaline environments. Mob DNA 2021; 12:8. [PMID: 33648565 PMCID: PMC7923331 DOI: 10.1186/s13100-021-00234-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2020] [Accepted: 01/27/2021] [Indexed: 11/25/2022] Open
Abstract
Background Group II introns are mobile genetic elements used as efficient gene targeting tools. They function as both ribozymes and retroelements. Group IIC introns are the only class reported so far to be associated with integrons. In order to identify group II introns linked with integrons and CALINS (cluster of attC sites lacking a neighboring integron integrase) within halophiles, we mined for integrons in 28 assembled metagenomes from hypersaline environments and publically available 104 halophilic genomes using Integron Finder followed by blast search for group II intron reverse transcriptases (RT)s. Results We report the presence of different group II introns associated with integrons and integron-related sequences denoted by UHB.F1, UHB.I2, H.ha.F1 and H.ha.F2. The first two were identified within putative integrons in the metagenome of Tanatar-5 hypersaline soda lake, belonging to IIC and IIB intron classes, respectively at which the first was a truncated intron. Other truncated introns H.ha.F1 and H.ha.F2 were also detected in a CALIN within the extreme halophile Halorhodospira halochloris, both belonging to group IIB introns. The intron-encoded proteins (IEP) s identified within group IIB introns belonged to different classes: CL1 class in UHB.I2 and bacterial class E in H.ha.Fa1 and H.ha.F2. A newly identified insertion sequence (ISHahl1) of IS200/605 superfamily was also identified adjacent to H. halochloris CALIN. Finally, an abundance of toxin-antitoxin (TA) systems was observed within the identified integrons. Conclusion So far, this is the first investigation of group II introns within integrons in halophilic genomes and metagenomes from hypersaline environments. We report the presence of group IIB introns associated with integrons or CALINs. This study provides the basis for understanding the role of group IIB introns in the evolution of halophiles and their potential biotechnological role. Supplementary Information The online version contains supplementary material available at 10.1186/s13100-021-00234-2.
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Affiliation(s)
- Sarah Sonbol
- Biology Department and the Graduate Program of Biotechnology, School of Sciences and Engineering, the American University in Cairo, New Cairo, Cairo, 11835, Egypt
| | - Rania Siam
- Biology Department and the Graduate Program of Biotechnology, School of Sciences and Engineering, the American University in Cairo, New Cairo, Cairo, 11835, Egypt. .,University of Medicine and Health Sciences, Basseterre, Saint Kitts and Nevis.
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Feiz L, Asakura Y, Mao L, Strickler SR, Fei Z, Rojas M, Barkan A, Stern DB. CFM1, a member of the CRM-domain protein family, functions in chloroplast group II intron splicing in Setaria viridis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 105:639-648. [PMID: 33140462 DOI: 10.1111/tpj.15060] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 08/27/2020] [Accepted: 10/19/2020] [Indexed: 06/11/2023]
Abstract
The chloroplast RNA splicing and ribosome maturation (CRM) domain is a RNA-binding domain found in a plant-specific protein family whose characterized members play essential roles in splicing group I and group II introns in mitochondria and chloroplasts. Together, these proteins are required for splicing of the majority of the approximately 20 chloroplast introns in land plants. Here, we provide evidence from Setaria viridis and maize that an uncharacterized member of this family, CRM Family Member1 (CFM1), promotes the splicing of most of the introns that had not previously been shown to require a CRM domain protein. A Setaria mutant expressing mutated CFM1 was strongly disrupted in the splicing of three chloroplast tRNAs: trnI, trnV and trnA. Analyses by RNA gel blot and polysome association suggest that the tRNA deficiencies lead to compromised chloroplast protein synthesis and the observed whole-plant chlorotic phenotypes. Co-immunoprecipitation data demonstrate that the maize CFM1 ortholog is bound to introns whose splicing is disrupted in the cfm1 mutant. With these results, CRM domain proteins have been shown to promote the splicing of all but two of the introns found in angiosperm chloroplast genomes.
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Affiliation(s)
- Leila Feiz
- Boyce Thompson Institute for Plant Research, Ithaca, NY, 14853, USA
| | - Yukari Asakura
- Institute of Molecular Biology, University of Oregon, Eugene, OR, 97403, USA
| | - Linyong Mao
- Boyce Thompson Institute for Plant Research, Ithaca, NY, 14853, USA
| | | | - Zhangjun Fei
- Boyce Thompson Institute for Plant Research, Ithaca, NY, 14853, USA
| | - Margarita Rojas
- Institute of Molecular Biology, University of Oregon, Eugene, OR, 97403, USA
| | - Alice Barkan
- Institute of Molecular Biology, University of Oregon, Eugene, OR, 97403, USA
| | - David B Stern
- Boyce Thompson Institute for Plant Research, Ithaca, NY, 14853, USA
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Chen W, Cui Y, Wang Z, Chen R, He C, Liu Y, Du X, Liu Y, Fu J, Wang G, Wang J, Gu R. Nuclear-Encoded Maturase Protein 3 Is Required for the Splicing of Various Group II Introns in Mitochondria during Maize (Zea mays L.) Seed Development. ACTA ACUST UNITED AC 2021; 62:293-305. [DOI: 10.1093/pcp/pcaa161] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 12/05/2020] [Indexed: 11/12/2022]
Abstract
Abstract
Splicing of plant organellar group II introns from precursor-RNA transcripts requires the assistance of nuclear-encoded splicing factors. Maturase (nMAT) is one such factor, as its three homologs (nMAT1, 2 and 4) have been identified as being required for the splicing of various mitochondrial introns in Arabidopsis. However, the function of nMAT in maize (Zea mays L.) is unknown. In this study, we identified a seed development mutant, empty pericarp 2441 (emp2441) from maize, which showed severely arrested embryogenesis and endosperm development. Positional cloning and transgenic complementation assays revealed that Emp2441 encodes a maturase-related protein, ZmnMAT3. ZmnMAT3 is highly expressed during seed development and its protein locates to the mitochondria. The loss of function of ZmnMAT3 resulted in the reduced splicing efficiency of various mitochondrial group II introns, particularly of the trans-splicing of nad1 introns 1, 3 and 4, which consequently abolished the transcript of nad1 and severely impaired the assembly and activity of mitochondrial complex I. Moreover, the Zmnmat3 mutant showed defective mitochondrial structure and exhibited expression and activity of alternative oxidases. These results indicate that ZmnMAT3 is essential for mitochondrial complex I assembly during kernel development in maize.
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Affiliation(s)
- Weiwei Chen
- Center of Seed Science and Technology, Beijing Innovation Center for Seed Technology (MOA), Beijing Key Laboratory of Crop Genetic Improvement, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Yu Cui
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Zheyuan Wang
- Center of Seed Science and Technology, Beijing Innovation Center for Seed Technology (MOA), Beijing Key Laboratory of Crop Genetic Improvement, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China
| | - Rongrong Chen
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Cheng He
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Yan Liu
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Xuemei Du
- Center of Seed Science and Technology, Beijing Innovation Center for Seed Technology (MOA), Beijing Key Laboratory of Crop Genetic Improvement, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China
| | - Yunjun Liu
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Junjie Fu
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Guoying Wang
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Jianhua Wang
- Center of Seed Science and Technology, Beijing Innovation Center for Seed Technology (MOA), Beijing Key Laboratory of Crop Genetic Improvement, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China
| | - Riliang Gu
- Center of Seed Science and Technology, Beijing Innovation Center for Seed Technology (MOA), Beijing Key Laboratory of Crop Genetic Improvement, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China
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32
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Mestre MR, González-Delgado A, Gutiérrez-Rus LI, Martínez-Abarca F, Toro N. Systematic prediction of genes functionally associated with bacterial retrons and classification of the encoded tripartite systems. Nucleic Acids Res 2021; 48:12632-12647. [PMID: 33275130 PMCID: PMC7736814 DOI: 10.1093/nar/gkaa1149] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 11/05/2020] [Accepted: 11/10/2020] [Indexed: 02/06/2023] Open
Abstract
Bacterial retrons consist of a reverse transcriptase (RT) and a contiguous non-coding RNA (ncRNA) gene. One third of annotated retrons carry additional open reading frames (ORFs), the contribution and significance of which in retron biology remains to be determined. In this study we developed a computational pipeline for the systematic prediction of genes specifically associated with retron RTs based on a previously reported large dataset representative of the diversity of prokaryotic RTs. We found that retrons generally comprise a tripartite system composed of the ncRNA, the RT and an additional protein or RT-fused domain with diverse enzymatic functions. These retron systems are highly modular, and their components have coevolved to different extents. Based on the additional module, we classified retrons into 13 types, some of which include additional variants. Our findings provide a basis for future studies on the biological function of retrons and for expanding their biotechnological applications.
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Affiliation(s)
- Mario Rodríguez Mestre
- Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Profesor Albareda 1, 18008 Granada, Spain
| | - Alejandro González-Delgado
- Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Profesor Albareda 1, 18008 Granada, Spain
| | - Luis I Gutiérrez-Rus
- Departamento de Química Física. Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain
| | - Francisco Martínez-Abarca
- Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Profesor Albareda 1, 18008 Granada, Spain
| | - Nicolás Toro
- Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Profesor Albareda 1, 18008 Granada, Spain
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Skuza L, Filip E, Szućko I, Bocianowski J. SPInDel Analysis of the Non-Coding Regions of cpDNA as a More Useful Tool for the Identification of Rye (Poaceae: Secale) Species. Int J Mol Sci 2020; 21:ijms21249421. [PMID: 33321948 PMCID: PMC7762986 DOI: 10.3390/ijms21249421] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Revised: 12/07/2020] [Accepted: 12/08/2020] [Indexed: 01/09/2023] Open
Abstract
Secale is a small but very diverse genus from the tribe Triticeae (family Poaceae), which includes annual, perennial, self-pollinating and open-pollinating, cultivated, weedy and wild species of various phenotypes. Despite its high economic importance, classification of this genus, comprising 3–8 species, is inconsistent. This has resulted in significantly reduced progress in the breeding of rye which could be enriched with functional traits derived from wild rye species. Our previous research has suggested the utility of non-coding sequences of chloroplast and mitochondrial DNA in studies on closely related species of the genus Secale. Here we applied the SPInDel (Species Identification by Insertions/Deletions) approach, which targets hypervariable genomic regions containing multiple insertions/deletions (indels) and exhibiting extensive length variability. We analysed a total of 140 and 210 non-coding sequences from cpDNA and mtDNA, respectively. The resulting data highlight regions which may represent useful molecular markers with respect to closely related species of the genus Secale, however, we found the chloroplast genome to be more informative. These molecular markers include non-coding regions of chloroplast DNA: atpB-rbcL and trnT-trnL and non-coding regions of mitochondrial DNA: nad1B-nad1C and rrn5/rrn18. Our results demonstrate the utility of the SPInDel concept for the characterisation of Secale species.
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Affiliation(s)
- Lidia Skuza
- Institute of Biology, University of Szczecin, 13 Wąska, 71-415 Szczecin, Poland; (E.F.); (I.S.)
- The Centre for Molecular Biology and Biotechnology, University of Szczecin, 13 Wąska, 71-415 Szczecin, Poland
- Correspondence:
| | - Ewa Filip
- Institute of Biology, University of Szczecin, 13 Wąska, 71-415 Szczecin, Poland; (E.F.); (I.S.)
- The Centre for Molecular Biology and Biotechnology, University of Szczecin, 13 Wąska, 71-415 Szczecin, Poland
| | - Izabela Szućko
- Institute of Biology, University of Szczecin, 13 Wąska, 71-415 Szczecin, Poland; (E.F.); (I.S.)
- The Centre for Molecular Biology and Biotechnology, University of Szczecin, 13 Wąska, 71-415 Szczecin, Poland
| | - Jan Bocianowski
- Department of Mathematical and Statistical Methods, Faculty of Agronomy and Bioengineering, Poznań University of Life Sciences, 28 Wojska Polskiego, 60-637 Poznań, Poland;
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Ichinose M, Ishimaru A, Sugita C, Nakajima K, Kawaguchi Y, Sugita M. Two Novel PLS-Class Pentatricopeptide Repeat Proteins Are Involved in the Group II Intron Splicing of Mitochondrial Transcripts in the Moss Physcomitrella patens. PLANT & CELL PHYSIOLOGY 2020; 61:1687-1698. [PMID: 32525534 DOI: 10.1093/pcp/pcaa070] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Accepted: 05/16/2020] [Indexed: 06/11/2023]
Abstract
Pentatricopeptide repeat (PPR) proteins are RNA-binding proteins that function in posttranscriptional regulation as gene-specific regulators of RNA metabolism in plant organelles. Plant PPR proteins are divided into four classes: P, PLS, E and DYW. The E- and DYW-class proteins are mainly implicated in RNA editing, whereas most of the P-class proteins predominantly participate in RNA cleavage, splicing and stabilization. In contrast, the functions of PLS-class proteins still remain obscure. Here, we report the function of PLS-class PpPPR_31 and PpPPR_9 in Physcomitrella patens. The knockout (KO) mutants of PpPPR_31 and PpPPR_9 exhibited slower protonema growth compared to the wild type. The PpPPR_31 KO mutants showed a considerable reduction in the splicing of nad5 intron 3 and atp9 intron 1. The PpPPR_9 KO mutants displayed severely reduced splicing of cox1 intron 3. An RNA electrophoresis mobility shift assay showed that the recombinant PpPPR_31 protein bound to the 5' region of nad5 exon 4 and the bulged A region in domain VI of atp9 group II intron 1 while the recombinant PpPPR_9 bound to the translated region of ORF622 in cox1 intron 3. These results suggest that a certain set of PLS-class PPR proteins may influence the splicing efficiency of mitochondrial group II introns.
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Affiliation(s)
- Mizuho Ichinose
- Center for Gene Research, Nagoya University, Nagoya, 464-8602 Japan
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Nagoya, 464-8601 Japan
- Faculty of Agriculture, Kyushu University, Fukuoka, 819-0395 Japan
| | - Airi Ishimaru
- Center for Gene Research, Nagoya University, Nagoya, 464-8602 Japan
| | - Chieko Sugita
- Center for Gene Research, Nagoya University, Nagoya, 464-8602 Japan
| | - Kensaku Nakajima
- Center for Gene Research, Nagoya University, Nagoya, 464-8602 Japan
| | | | - Mamoru Sugita
- Center for Gene Research, Nagoya University, Nagoya, 464-8602 Japan
- Graduate School of Information Science, Nagoya University, Nagoya, 464-8601 Japan
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Liu R, Cao SK, Sayyed A, Xu C, Sun F, Wang X, Tan BC. The Mitochondrial Pentatricopeptide Repeat Protein PPR18 Is Required for the cis-Splicing of nad4 Intron 1 and Essential to Seed Development in Maize. Int J Mol Sci 2020; 21:ijms21114047. [PMID: 32516991 PMCID: PMC7312232 DOI: 10.3390/ijms21114047] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 05/30/2020] [Accepted: 06/02/2020] [Indexed: 11/16/2022] Open
Abstract
Pentatricopeptide repeat (PPR) protein comprises a large family, participating in various aspects of organellar RNA metabolism in land plants. There are approximately 600 PPR proteins in maize, but the functions of many PPR proteins remain unknown. In this study, we defined the function of PPR18 in the cis-splicing of nad4 intron 1 in mitochondria and seed development in maize. Loss function of PPR18 seriously impairs embryo and endosperm development, resulting in the empty pericarp (emp) phenotype in maize. PPR18 encodes a mitochondrion-targeted P-type PPR protein with 18 PPR motifs. Transcripts analysis indicated that the splicing of nad4 intron 1 is impaired in the ppr18 mutant, resulting in the absence of nad4 transcript, leading to severely reduced assembly and activity of mitochondrial complex I and dramatically reduced respiration rate. These results demonstrate that PPR18 is required for the cis-splicing of nad4 intron 1 in mitochondria, and critical to complex I assembly and seed development in maize.
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Affiliation(s)
- Rui Liu
- Key Laboratory of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China; (R.L.); (S.-K.C.); (A.S.); (C.X.); (F.S.)
| | - Shi-Kai Cao
- Key Laboratory of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China; (R.L.); (S.-K.C.); (A.S.); (C.X.); (F.S.)
| | - Aqib Sayyed
- Key Laboratory of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China; (R.L.); (S.-K.C.); (A.S.); (C.X.); (F.S.)
| | - Chunhui Xu
- Key Laboratory of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China; (R.L.); (S.-K.C.); (A.S.); (C.X.); (F.S.)
| | - Feng Sun
- Key Laboratory of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China; (R.L.); (S.-K.C.); (A.S.); (C.X.); (F.S.)
| | - Xiaomin Wang
- Key Laboratory of Cell Activities and Stress Adaptations, Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou 730000, China;
| | - Bao-Cai Tan
- Key Laboratory of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China; (R.L.); (S.-K.C.); (A.S.); (C.X.); (F.S.)
- Correspondence:
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Smathers CM, Robart AR. Transitions between the steps of forward and reverse splicing of group IIC introns. RNA (NEW YORK, N.Y.) 2020; 26:664-673. [PMID: 32127385 PMCID: PMC7161350 DOI: 10.1261/rna.075044.120] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 02/27/2020] [Indexed: 06/10/2023]
Abstract
Group II introns are mobile genetic elements that perform both self-splicing and intron mobility reactions. These ribozymes are comprised of a catalytic RNA core that binds to an intron-encoded protein (IEP) to form a ribonucleoprotein (RNP) complex. Splicing proceeds through two competing reactions: hydrolysis or branching. Group IIC intron ribozymes have a minimal RNA architecture, and splice almost exclusively through hydrolysis in ribozyme reactions. Addition of the IEP allows the splicing reaction to form branched lariat RNPs capable of intron mobility. Here we examine ribozyme splicing, IEP-dependent splicing, and mobility reactions of a group IIC intron from the thermophilic bacterium Thermoanerobacter italicus (Ta.it.I1). We show that Ta.it.I1 is highly active for ribozyme activity, forming linear hydrolytic intron products. Addition of purified IEP switches activity to the canonical lariat forming splicing reaction. We demonstrate that the Ta.it.I1 group IIC intron coordinates the progression of the forward splicing reaction through a π-π' interaction between intron domains II and VI. We further show that branched splicing is supported in the absence of the IEP when the π-π' interaction is mutated. We also investigated the regulation of the two steps of reverse splicing during intron mobility into DNA substrates. Using a fluorescent mobility assay that simultaneously visualizes all steps of intron integration into DNA, we show that completion of reverse splicing is tightly coupled to cDNA synthesis regardless of mutation of the π-π' interaction.
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Affiliation(s)
- Claire M Smathers
- Department of Biochemistry, West Virginia University, Morgantown, West Virginia 20506, USA
| | - Aaron R Robart
- Department of Biochemistry, West Virginia University, Morgantown, West Virginia 20506, USA
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Abstract
Ever since its discovery, the double-stranded DNA contained in the mitochondria of eukaryotes has fascinated researchers because of its bacterial endosymbiotic origin, crucial role in encoding subunits of the respiratory complexes, compact nature, and specific inheritance mechanisms. In the last few years, high-throughput sequencing techniques have accelerated the sequencing of mitochondrial genomes (mitogenomes) and uncovered the great diversity of organizations, gene contents, and modes of replication and transcription found in living eukaryotes. Some early divergent lineages of unicellular eukaryotes retain certain synteny and gene content resembling those observed in the genomes of alphaproteobacteria (the inferred closest living group of mitochondria), whereas others adapted to anaerobic environments have drastically reduced or even lost the mitogenome. In the three main multicellular lineages of eukaryotes, mitogenomes have pursued diverse evolutionary trajectories in which different types of molecules (circular versus linear and single versus multipartite), gene structures (with or without self-splicing introns), gene contents, gene orders, genetic codes, and transfer RNA editing mechanisms have been selected. Whereas animals have evolved a rather compact mitochondrial genome between 11 and 50 Kb in length with a highly conserved gene content in bilaterians, plants exhibit large mitochondrial genomes of 66 Kb to 11.3 Mb with large intergenic repetitions prone to recombination, and fungal mitogenomes have intermediate sizes of 12 to 236 Kb.
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Affiliation(s)
- Rafael Zardoya
- Departamento de Biodiversidad y Biología Evolutiva, Museo Nacional de Ciencias Naturales (MNCN-CSIC), Madrid, Spain
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Comprehensive genomic analyses with 115 plastomes from algae to seed plants: structure, gene contents, GC contents, and introns. Genes Genomics 2020; 42:553-570. [PMID: 32200544 DOI: 10.1007/s13258-020-00923-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 03/09/2020] [Indexed: 02/08/2023]
Abstract
BACKGROUND Chloroplasts are a common character in plants. The chloroplasts in each plant lineage have shaped their own genomes, plastomes, by structural changes and transferring many genes to nuclear genomes during plant evolution. Some plastid genes have introns that are mostly group II introns. OBJECTIVE This study aimed to get genomic and evolutionary insights on the plastomes from green algae to flowering plants. METHODS Plastomes of 115 species from green algae, bryophytes, pteridophytes (spore bearing vascular plants), gymnosperms, and angiosperms were mined from NCBI organelle genome database. Plastome structure, gene contents and GC contents were analyzed by the in-house developed Phyton code. Intronic features including presence/absence, length, intron phases were analyzed by manually in the annotated information in NCBI. RESULTS The canonical quadripartite structures were retained in most plastomes except of a few plastomes that had lost an invert repeat (IR). Expansion or reduction or deletion of IRs resulted in the length variation of the plastomes. The number of protein coding genes ranged from 40 to 92 with an average 79.43 ± 5.84 per plastome and gene losses were apparent in specific lineages. The number of trn genes ranged from 13 to 33 with an average 21.19 ± 2.42 per plastome. Ribosomal RNA genes, rrn, were located in the IRs so that they were present in a duplicate except of the species that had lost one of the IR. GC contents were variable from 24.9 to 51.0% with an average 38.21 ± 3.27%, indicating bias to high AT contents. Plastid introns were present in 18 protein coding genes, six trn genes, and one rrn gene. Intron losses occurred among the orthologous genes in different plant lineages. The plastid introns were long compared with the nuclear introns, which might be related with the spliceosome nuclear introns and self-splicing group II plastid introns. The trnK-UUU intron contained the maturase encoding matK gene except in the chlorophyte algae and monilophyte ferns in which the trnK-UUU was lost, but matK retained. There were many annotation artefacts in the intron positions in the NCBI database. In the analysis of intron phases, phase 0 introns were more frequent than those of phase 2 and 3 introns. Phase polymorphism was observed in the introns of clpP which was derived from nucleotide insertion. Plastid trn introns were long compared to the archaeal or eukaryotic nuclear tRNA introns. Of the six plastid trn introns, one was at the D loop and other five were at the anticodon loop. The insertion sites were conserved among the trn genes in archaea, eukaryotic nuclear and plastid tRNA genes. CONCLUSIONS Current study refurbrished the previous findings of structural variations, gene contents, and GC contents of the chloroplast genomes from green algae to flowering plants. The study also included some noble findings and discussions on the plastome introns including their length variations and phase variation. We also presented and corrected some false annotations on the introns in protein coding and tRNA genes in the genome database, which might be confirmed by the chloroplast transcriptome analysis in the future.
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Abstract
The past 10 years have been revolutionary for clostridial genetics. The rise of next-generation sequencing led to the availability of annotated whole-genome sequences of the important pathogenic clostridia: Clostridium perfringens, Clostridioides (Clostridium) difficile, and Clostridium botulinum, but also Paeniclostridium (Clostridium) sordellii and Clostridium tetani. These sequences were a prerequisite for the development of functional, sophisticated genetic tools for the pathogenic clostridia. A breakthrough came in the early 2000s with the development of TargeTron-based technologies specific for the clostridia, such as ClosTron, an insertional gene inactivation tool. The following years saw a plethora of new technologies being developed, mostly for C. difficile, but also for other members of the genus, including C. perfringens. A range of tools is now available, allowing researchers to precisely delete genes, change single nucleotides in the genome, complement deletions, integrate novel DNA into genomes, or overexpress genes. There are tools for forward genetics, including an inducible transposon mutagenesis system for C. difficile. As the latest addition to the tool kit, clustered regularly interspaced short palindromic repeat (CRISPR)-Cas9 technologies have also been adopted for the construction of single and multiple gene deletions in C. difficile. This article summarizes the key genetic technologies available to manipulate, study, and understand the pathogenic clostridia.
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Yang YZ, Ding S, Wang Y, Wang HC, Liu XY, Sun F, Xu C, Liu B, Tan BC. PPR20 Is Required for the cis-Splicing of Mitochondrial nad2 Intron 3 and Seed Development in Maize. PLANT & CELL PHYSIOLOGY 2020; 61:370-380. [PMID: 31670803 DOI: 10.1093/pcp/pcz204] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 10/22/2019] [Indexed: 05/02/2023]
Abstract
Pentatricopeptide repeat (PPR) proteins are helical repeat RNA-binding proteins that function in RNA processing by conferring sequence-specific RNA-binding activity. Owing to the lethality of PPR mutants, functions of many PPR proteins remain obscure. In this study, we report the function of PPR20 in intron splicing in mitochondria and its role in maize seed development. PPR20 is a P-type PPR protein targeted to mitochondria. The ppr20 mutants display slow embryo and endosperm development. Null mutation of PPR20 severely reduces the cis-splicing of mitochondrial nad2 intron 3, resulting in reduction in the assembly and activity of mitochondrial complex I. The ppr20-35 allele with a Mu insertion in the N-terminal region shows a much weaker phenotype. Molecular analyses revealed that the mutant produces a truncated transcript, coding for PPR20ΔN120 lacking the N-terminal 120 amino acids. Subcellular localization revealed that PPR20ΔN120:GFP is able to target to mitochondria as well, suggesting the sequence diversity of the mitochondrial targeting peptides. Another mutant zm_mterf15 was also found to be impaired in the splicing of mitochondrial nad2 intron 3. Further analyses are required to identify the exact function of PPR20 and Zm_mTERF15 in the splicing of nad2 intron 3.
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Affiliation(s)
- Yan-Zhuo Yang
- Key Lab of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China
| | - Shuo Ding
- Key Lab of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China
| | - Yong Wang
- Key Lab of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China
| | - Hong-Chun Wang
- Key Lab of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China
| | - Xin-Yuan Liu
- Key Lab of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China
| | - Feng Sun
- Key Lab of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China
| | - Chunhui Xu
- Key Lab of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China
| | - Baohui Liu
- School of Life Sciences, Guangzhou University, Guangzhou 510006, China
| | - Bao-Cai Tan
- Key Lab of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China
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Dujon B. Mitochondrial genetics revisited. Yeast 2020; 37:191-205. [DOI: 10.1002/yea.3445] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 10/05/2019] [Accepted: 10/08/2019] [Indexed: 12/17/2022] Open
Affiliation(s)
- Bernard Dujon
- Department Genomes and GeneticsInstitut Pasteur Paris France
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Abstract
Clostridia are a group of Gram-positive anaerobic bacteria of medical and industrial importance for which limited genetic methods are available. Here, we demonstrate an approach to make large genomic deletions and insertions in the model Clostridium phytofermentans by combining designed group II introns (targetrons) and Cre recombinase. We apply these methods to delete a 50-gene prophage island by programming targetrons to position markerless lox66 and lox71 sites, which mediate deletion of the intervening 39-kb DNA region using Cre recombinase. Gene expression and growth of the deletion strain showed that the prophage genes contribute to fitness on nonpreferred carbon sources. We also inserted an inducible fluorescent reporter gene into a neutral genomic site by recombination-mediated cassette exchange (RMCE) between genomic and plasmid-based tandem lox sites bearing heterospecific spacers to prevent intracassette recombination. These approaches generally enable facile markerless genome engineering in clostridia to study their genome structure and regulation.IMPORTANCE Clostridia are anaerobic bacteria with important roles in intestinal and soil microbiomes. The inability to experimentally modify the genomes of clostridia has limited their study and application in biotechnology. Here, we developed a targetron-recombinase system to efficiently make large targeted genomic deletions and insertions using the model Clostridium phytofermentans We applied this approach to reveal the importance of a prophage to host fitness and introduce an inducible reporter by recombination-mediated cassette exchange.
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García-Rodríguez FM, Neira JL, Marcia M, Molina-Sánchez MD, Toro N. A group II intron-encoded protein interacts with the cellular replicative machinery through the β-sliding clamp. Nucleic Acids Res 2019; 47:7605-7617. [PMID: 31127285 PMCID: PMC6698660 DOI: 10.1093/nar/gkz468] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 05/14/2019] [Accepted: 05/16/2019] [Indexed: 12/15/2022] Open
Abstract
Group II introns are self-splicing mobile genetic retroelements. The spliced intron RNA and the intron-encoded protein (IEP) form ribonucleoprotein particles (RNPs) that recognize and invade specific DNA target sites. The IEP is a reverse transcriptase/maturase that may bear a C-terminal endonuclease domain enabling the RNP to cleave the target DNA strand to prime reverse transcription. However, some mobile introns, such as RmInt1, lack the En domain but nevertheless retrohome efficiently to transient single-stranded DNA target sites at a DNA replication fork. Their mobility is associated with host DNA replication, and they use the nascent lagging strand as a primer for reverse transcription. We searched for proteins that interact with RmInt1 RNPs and direct these RNPs to the DNA replication fork. Co-immunoprecipitation assays suggested that DnaN (the β-sliding clamp), a component of DNA polymerase III, interacts with the protein component of the RmInt1 RNP. Pulldown assays, far-western blots and biolayer interferometry supported this interaction. Peptide binding assays also identified a putative DnaN-interacting motif in the RmInt1 IEP structurally conserved in group II intron IEPs. Our results suggest that intron RNP interacts with the β-sliding clamp of the DNA replication machinery, favouring reverse splicing into the transient ssDNA at DNA replication forks.
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Affiliation(s)
- Fernando M García-Rodríguez
- Structure, Dynamics and Function of Rhizobacterial Genomes (Grupo de Ecología Genética de la Rizosfera), Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/Profesor Albareda 1, 18008 Granada, Spain
| | - José L Neira
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, 03202 Elche (Alicante), Spain.,Instituto de Biocomputación y Física de Sistemas Complejos, Joint Units IQFR-CSIC-BIFI, and GBsC-CSIC-BIFI, Universidad de Zaragoza, 50009 Zaragoza
| | - Marco Marcia
- European Molecular Biology Laboratory (EMBL), Grenoble Outstation, 71 Avenue des Martyrs, Grenoble 38042, France
| | - María D Molina-Sánchez
- Structure, Dynamics and Function of Rhizobacterial Genomes (Grupo de Ecología Genética de la Rizosfera), Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/Profesor Albareda 1, 18008 Granada, Spain
| | - Nicolás Toro
- Structure, Dynamics and Function of Rhizobacterial Genomes (Grupo de Ecología Genética de la Rizosfera), Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/Profesor Albareda 1, 18008 Granada, Spain
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Gitsels A, Sanders N, Vanrompay D. Chlamydial Infection From Outside to Inside. Front Microbiol 2019; 10:2329. [PMID: 31649655 PMCID: PMC6795091 DOI: 10.3389/fmicb.2019.02329] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 09/24/2019] [Indexed: 12/16/2022] Open
Abstract
Chlamydia are obligate intracellular bacteria, characterized by a unique biphasic developmental cycle. Specific interactions with the host cell are crucial for the bacteria’s survival and amplification because of the reduced chlamydial genome. At the start of infection, pathogen-host interactions are set in place in order for Chlamydia to enter the host cell and reach the nutrient-rich peri-Golgi region. Once intracellular localization is established, interactions with organelles and pathways of the host cell enable the necessary hijacking of host-derived nutrients. Detailed information on the aforementioned processes will increase our understanding on the intracellular pathogenesis of chlamydiae and hence might lead to new strategies to battle chlamydial infection. This review summarizes how chlamydiae generate their intracellular niche in the host cell, acquire host-derived nutrients in order to enable their growth and finally exit the host cell in order to infect new cells. Moreover, the evolution in the development of molecular genetic tools, necessary for studying the chlamydial infection biology in more depth, is discussed in great detail.
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Affiliation(s)
- Arlieke Gitsels
- Laboratory for Immunology and Animal Biotechnology, Department of Animal Sciences and Aquatic Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Niek Sanders
- Laboratory of Gene Therapy, Department of Nutrition, Genetics and Ethology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Daisy Vanrompay
- Laboratory for Immunology and Animal Biotechnology, Department of Animal Sciences and Aquatic Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
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Velázquez E, Lorenzo VD, Al-Ramahi Y. Recombination-Independent Genome Editing through CRISPR/Cas9-Enhanced TargeTron Delivery. ACS Synth Biol 2019; 8:2186-2193. [PMID: 31419111 DOI: 10.1021/acssynbio.9b00293] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Group II introns were developed some time ago as tools for the construction of knockout mutants in a wide range of organisms, ranging from Gram-positive and Gram-negative bacteria to human cells. Utilizing these introns is advantageous because they are independent of the host's DNA recombination machinery, they can carry heterologous sequences (and thus be used as vehicles for gene delivery), and they can be easily retargeted for subsequent insertions of additional genes at the user's will. Alas, the use of this platform has been limited, as insertion efficiencies greatly change depending on the target sites and cannot be predicted a priori. Moreover, the ability of introns to perform their own splicing and integration is compromised when they carry foreign sequences. To overcome these limitations, we merged the group II intron-based TargeTron system with CRISPR/Cas9 counterselection. To this end, we first engineered a new group-II intron by replacing the retrotransposition-activated selectable marker (RAM) with ura3 and retargeting it to a new site in the lacZ gene of E. coli. Then, we showed that directing CRISPR/Cas9 toward the wild-type sequences dramatically increased the chances of finding clones that integrated the retrointron into the target lacZ sequence. The CRISPR-Cas9 counterselection strategy presented herein thus overcomes a major limitation that has prevented the use of group II introns as devices for gene delivery and genome editing at large in a recombination-independent fashion.
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Affiliation(s)
- Elena Velázquez
- Systems Biology Program, Centro Nacional de Biotecnología-CSIC, Campus de Cantoblanco, Madrid, 28049, Spain
| | - Víctor de Lorenzo
- Systems Biology Program, Centro Nacional de Biotecnología-CSIC, Campus de Cantoblanco, Madrid, 28049, Spain
| | - Yamal Al-Ramahi
- Systems Biology Program, Centro Nacional de Biotecnología-CSIC, Campus de Cantoblanco, Madrid, 28049, Spain
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Smathers CM, Robart AR. The mechanism of splicing as told by group II introns: Ancestors of the spliceosome. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2019; 1862:194390. [PMID: 31202783 DOI: 10.1016/j.bbagrm.2019.06.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 06/10/2019] [Indexed: 12/31/2022]
Abstract
Spliceosomal introns and self-splicing group II introns share a common mechanism of intron splicing where two sequential transesterification reactions remove intron lariats and ligate exons. The recent revolution in cryo-electron microscopy (cryo-EM) has allowed visualization of the spliceosome's ribozyme core. Comparison of these cryo-EM structures to recent group II intron crystal structures presents an opportunity to draw parallels between the RNA active site, substrate positioning, and product formation in these two model systems of intron splicing. In addition to shared RNA architectural features, structural similarity between group II intron encoded proteins (IEPs) and the integral spliceosomal protein Prp8 further support a shared catalytic core. These mechanistic and structural similarities support the long-held assertion that group II introns and the eukaryotic spliceosome have a common evolutionary origin. In this review, we discuss how recent structural insights into group II introns and the spliceosome facilitate the chemistry of splicing, highlight similarities between the two systems, and discuss their likely evolutionary connections. This article is part of a Special Issue entitled: RNA structure and splicing regulation edited by Francisco Baralle, Ravindra Singh and Stefan Stamm.
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Affiliation(s)
- Claire M Smathers
- Department of Biochemistry, West Virginia University, Morgantown, WV, United States of America
| | - Aaron R Robart
- Department of Biochemistry, West Virginia University, Morgantown, WV, United States of America.
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Abstract
Introduction of CRISPR/Cas9 methods (clustered regularly interspaced short palindromic repeats, CRISPR-associated protein 9) have led to a huge surge in the use of precision genome editing for research applications. Translational medical efforts are likewise rapidly progressing, and Phase I clinical trials using these techniques have already started. As with any new technology that is applied to medical therapeutics, risks must be carefully defined and steps taken to mitigate side effects wherever possible. Effective methods are now available that permit identification of off-target cleavage events, a major class of potential side effects seen in mammalian genome editing. Off-target prediction algorithms are improving and have utility, but are insufficient to use alone. Empiric methods to define the off-target profile must also be used. Once defined, the frequency of off-target cleavage can be minimized using methods that limit the duration of exposure of the genome to the active genome editing complex, for example, using the ribonucleoprotein (RNP) approach. In addition, Cas9 mutants have been developed that markedly reduce the rate of off-target cleavage compared to the wild-type enzyme. Use of these new tools should become standard practice for medical applications.
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Villarreal LP, Witzany G. That is life: communicating RNA networks from viruses and cells in continuous interaction. Ann N Y Acad Sci 2019; 1447:5-20. [PMID: 30865312 DOI: 10.1111/nyas.14040] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 01/13/2019] [Accepted: 01/31/2019] [Indexed: 02/06/2023]
Abstract
All the conserved detailed results of evolution stored in DNA must be read, transcribed, and translated via an RNA-mediated process. This is required for the development and growth of each individual cell. Thus, all known living organisms fundamentally depend on these RNA-mediated processes. In most cases, they are interconnected with other RNAs and their associated protein complexes and function in a strictly coordinated hierarchy of temporal and spatial steps (i.e., an RNA network). Clearly, all cellular life as we know it could not function without these key agents of DNA replication, namely rRNA, tRNA, and mRNA. Thus, any definition of life that lacks RNA functions and their networks misses an essential requirement for RNA agents that inherently regulate and coordinate (communicate to) cells, tissues, organs, and organisms. The precellular evolution of RNAs occurred at the core of the emergence of cellular life and the question remained of how both precellular and cellular levels are interconnected historically and functionally. RNA networks and RNA communication can interconnect these levels. With the reemergence of virology in evolution, it became clear that communicating viruses and subviral infectious genetic parasites are bridging these two levels by invading, integrating, coadapting, exapting, and recombining constituent parts in host genomes for cellular requirements in gene regulation and coordination aims. Therefore, a 21st century understanding of life is of an inherently social process based on communicating RNA networks, in which viruses and cells continuously interact.
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Affiliation(s)
- Luis P Villarreal
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California
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Skuza L, Szućko I, Filip E, Strzała T. Genetic diversity and relationship between cultivated, weedy and wild rye species as revealed by chloroplast and mitochondrial DNA non-coding regions analysis. PLoS One 2019; 14:e0213023. [PMID: 30811487 PMCID: PMC6392296 DOI: 10.1371/journal.pone.0213023] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 02/13/2019] [Indexed: 11/18/2022] Open
Abstract
The genus Secale is small but very diverse. Despite the high economic importance, phylogenetic relationships of rye species have not been fully determined, and they are extremely important for the process of breeding of new cultivars that can be enriched with functional traits derived from wild rye species. The study analyzed the degree of relationship of 35 accessions of the genus Secale, representing 13 most often distinguished species and subspecies, originating from various seed collections in the world, based on the analysis of non-coding regions of the chloroplast (cpDNA) and mitochondrial genome (mtDNA), widely used in phylogenetic and population plant studies, because of a higher rate of evolution than the coding regions. There was no clear genetic structure between different species and subspecies, which may indicated the introgression between these taxa. The obtained data confirmed that S. vavilovii was very similar to S. cereale, which confirmed the assumption that they might share a common ancestor. The results also confirmed the divergence of S. sylvestre from other species and subspecies of rye. Areas that may be useful molecular markers in studies on closely related species of the genus Secale were also indicated.
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Affiliation(s)
- Lidia Skuza
- Department of Molecular Biology and Cytology, The Institute for Research on Biodiversity, Faculty of Biology, University of Szczecin, Szczecin, Poland
- The Centre for Molecular Biology and Biotechnology, Faculty of Biology, University of Szczecin, Szczecin, Poland
- * E-mail:
| | - Izabela Szućko
- Department of Molecular Biology and Cytology, The Institute for Research on Biodiversity, Faculty of Biology, University of Szczecin, Szczecin, Poland
- The Centre for Molecular Biology and Biotechnology, Faculty of Biology, University of Szczecin, Szczecin, Poland
| | - Ewa Filip
- Department of Molecular Biology and Cytology, The Institute for Research on Biodiversity, Faculty of Biology, University of Szczecin, Szczecin, Poland
- The Centre for Molecular Biology and Biotechnology, Faculty of Biology, University of Szczecin, Szczecin, Poland
| | - Tomasz Strzała
- Department of Genetics, Faculty of Biology and Animal Science, Wrocław University of Environmental and Life Sciences, Wrocław, Poland
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