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Lee SC, Liou MR, Hsu YH, Wang IN, Lin NS. Trade-off between local replication and long-distance dissemination during experimental evolution of a satellite RNA. Front Microbiol 2023; 14:1139447. [PMID: 37601360 PMCID: PMC10436602 DOI: 10.3389/fmicb.2023.1139447] [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: 01/07/2023] [Accepted: 07/19/2023] [Indexed: 08/22/2023] Open
Abstract
Satellite RNAs (satRNAs) are molecular parasites that depend on their non-homologous helper viruses (HVs) for essential biological functions. While there are multiple molecular and phylogenetic studies on satRNAs, there is no experimental evolution study on how satRNAs may evolve in common infection conditions. In this study, we serially passaged the Bamboo mosaic virus (BaMV) associated-satRNA (satBaMV) under conditions in which satBaMV either coinfects an uninfected host plant, Nicotiana benthamiana, with BaMV or superinfects a transgenic N. benthamiana expressing the full-length BaMV genome. Single-nucleotide polymorphisms (SNPs) of satBaMV populations were analyzed by deep sequencing. Forty-eight SNPs were identified across four different experimental treatments. Most SNPs are treatment-specific, and some are also ephemeral. However, mutations at positions 30, 34, 63, and 82, all located at the 5' untranslated region (UTR), are universal in all treatments. These universal SNPs are configured into several haplotypes and follow different population dynamics. We constructed isogenic satBaMV strains only differing at positions 30 and 82 and conducted competition experiments in protoplasts and host plants. We found that the haplotype that reached high frequency in protoplasts and inoculation leaves also exhibited poor dissemination to systemic leaves and vice versa, thus suggesting an apparent trade-off between local replication and long-distance dissemination. We posit that the trade-off is likely caused by antagonistic pleiotropy at the 5' UTR. Our findings revealed a hitherto under-explored connection between satRNA genome replication and movement within a host plant. The significance of such a connection during satRNA evolution warrants a more thorough investigation.
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Affiliation(s)
- Shu-Chuan Lee
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Ming-Ru Liou
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Yau-Heiu Hsu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Ing-Nang Wang
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
- Department of Biological Sciences, University at Albany, Albany, NY, United States
| | - Na-Sheng Lin
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
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2
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Wang IN, Yeh WB, Lin NS. Phylogeography and Coevolution of Bamboo Mosaic Virus and Its Associated Satellite RNA. Front Microbiol 2017; 8:886. [PMID: 28588562 PMCID: PMC5440514 DOI: 10.3389/fmicb.2017.00886] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 05/02/2017] [Indexed: 11/17/2022] Open
Abstract
Bamboo mosaic virus (BaMV), a plant potexvirus, has been found only in infected bamboo species. It is frequently associated with a large, linear single-stranded satellite RNA (satBaMV) that encodes a non-structural protein. Decades of collecting across a wide geographic area in Asia have accumulated a sizable number of BaMV and satBaMV isolates. In this study, we reconstructed the BaMV phylogeny and satBaMV phylogeny with partial coat protein gene sequences and partial genomic sequences, respectively. The evolutionary relationships allowed us to infer the phylogeography of BaMV and satBaMV on the Asian continent and its outlying islands. The BaMV phylogeny suggests that the BaMV isolates from Taiwan, unsurprisingly, are most likely derived from China. Interestingly, the newly available satBaMV isolates from China were found to be most closely related to the previously established Clade III, which is found in India. The general pattern of clustering along the China/India and Taiwan divide led us to hypothesize that the Taiwan Strait has been a physical barrier to gene flow in the past evolutionary history of both BaMV and satBaMV. Lastly, cophylogeny analyses revealed a complex association pattern between BaMV and satBaMV isolates from China. In general, closely related BaMV sequences tend to carry closely related satBaMV sequences as well; but instances of mismatching with distantly related satBaMV isolates were also found. We hypothesize plausible scenarios of infection and superinfection of bamboo hosts that may be responsible for the observed association pattern. However, a more systematic sampling throughout the geographic distribution of various bamboo species is needed to unambiguously establish the origin, movement, and evolution of BaMV and satBaMV.
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Affiliation(s)
- Ing-Nang Wang
- Department of Biological Sciences, University at Albany, AlbanyNY, United States
| | - Wen-Bin Yeh
- Department of Entomology, National Chung Hsin UniversityTaichung, Taiwan
| | - Na-Sheng Lin
- Institute of Plant and Microbial Biology, Academia SinicaTaipei, Taiwan
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3
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Lin KY, Lin NS. Interfering Satellite RNAs of Bamboo mosaic virus. Front Microbiol 2017; 8:787. [PMID: 28522996 PMCID: PMC5415622 DOI: 10.3389/fmicb.2017.00787] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 04/18/2017] [Indexed: 11/13/2022] Open
Abstract
Satellite RNAs (satRNAs) are sub-viral agents that may interact with their cognate helper virus (HV) and host plant synergistically and/or antagonistically. SatRNAs totally depend on the HV for replication, so satRNAs and HV usually evolve similar secondary or tertiary RNA structures that are recognized by a replication complex, although satRNAs and HV do not share an appreciable sequence homology. The satRNAs of Bamboo mosaic virus (satBaMV), the only satRNAs of the genus Potexvirus, have become one of the models of how satRNAs can modulate HV replication and virus-induced symptoms. In this review, we summarize the molecular mechanisms underlying the interaction of interfering satBaMV and BaMV. Like other satRNAs, satBaMV mimics the secondary structures of 5'- and 3'-untranslated regions (UTRs) of BaMV as a molecular pretender. However, a conserved apical hairpin stem loop (AHSL) in the 5'-UTR of satBaMV was found as the key determinant for downregulating BaMV replication. In particular, two unique nucleotides (C60 and C83) in the AHSL of satBaMVs determine the satBaMV interference ability by competing for the replication machinery. Thus, transgenic plants expressing interfering satBaMV could confer resistance to BaMV, and interfering satBaMV could be used as biological-control agent. Unlike two major anti-viral mechanisms, RNA silencing and salicylic acid-mediated immunity, our findings in plants by in vivo competition assay and RNA deep sequencing suggested replication competition is involved in this transgenic satBaMV-mediated BaMV interference. We propose how a single nucleotide of satBaMV can make a great change in BaMV pathogenicity and the underlying mechanism.
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Affiliation(s)
- Kuan-Yu Lin
- Institute of Plant and Microbial Biology, Academia SinicaTaipei, Taiwan
| | - Na-Sheng Lin
- Institute of Plant and Microbial Biology, Academia SinicaTaipei, Taiwan
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4
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Ashton P, Wu B, D'Angelo J, Grigull J, White KA. Biologically-supported structural model for a viral satellite RNA. Nucleic Acids Res 2015; 43:9965-77. [PMID: 26384416 PMCID: PMC4787747 DOI: 10.1093/nar/gkv917] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 09/04/2015] [Indexed: 01/05/2023] Open
Abstract
Satellite RNAs (satRNAs) are a class of small parasitic RNA replicon that associate with different viruses, including plus-strand RNA viruses. Because satRNAs do not encode a polymerase or capsid subunit, they rely on a companion virus to provide these proteins for their RNA replication and packaging. SatRNAs recruit these and other required factors via their RNA sequences and structures. Here, through a combination of chemical probing analysis of RNA structure, phylogenetic structural comparisons, and viability assays of satRNA mutants in infected cells, the biological importance of a deduced higher-order structure for a 619 nt long tombusvirus satRNA was assessed. Functionally-relevant secondary and tertiary RNA structures were identified throughout the length of the satRNA. Notably, a 3′-terminal segment was found to adopt two mutually-exclusive RNA secondary structures, both of which were required for efficient satRNA accumulation. Accordingly, these alternative conformations likely function as a type of RNA switch. The RNA switch was also found to engage in a required long-range kissing-loop interaction with an upstream sequence. Collectively, these results establish a high level of conformational complexity within this small parasitic RNA and provide a valuable structural framework for detailed mechanistic studies.
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Affiliation(s)
- Peter Ashton
- Department of Biology, York University, Toronto, Ontario, M3J 1P3 Canada
| | - Baodong Wu
- Department of Biology, York University, Toronto, Ontario, M3J 1P3 Canada
| | - Jessica D'Angelo
- Department of Biology, York University, Toronto, Ontario, M3J 1P3 Canada
| | - Jörg Grigull
- Department of Mathematics and Statistics, York University, Toronto, Ontario, M3J 1P3 Canada
| | - K Andrew White
- Department of Biology, York University, Toronto, Ontario, M3J 1P3 Canada
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5
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Wang IN, Hu CC, Lee CW, Yen SM, Yeh WB, Hsu YH, Lin NS. Genetic diversity and evolution of satellite RNAs associated with the bamboo mosaic virus. PLoS One 2014; 9:e108015. [PMID: 25275532 PMCID: PMC4183488 DOI: 10.1371/journal.pone.0108015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Accepted: 08/20/2014] [Indexed: 02/08/2023] Open
Abstract
Satellite RNAs (satRNAs) are subviral agents that depend on cognate helper viruses for genome replication and encapsidation. Their negative impacts on helper viruses have been exploited to control plant viral diseases. SatBaMV is a commonly found satRNA associated with Bamboo mosaic virus (BaMV) that infects diverse bamboo species in the field. To investigate the genetic diversity and evolution of satRNAs, we examined seven satBaMV populations derived from five bamboo species and cultivars from Taiwan, China, and India and one from the greenhouse. We found 3 distinct clades among the seven populations. Clade I is consisted of all satBaMV isolates, except for those from Dendrocalamus latiflorus in Taiwan and Bambusa vulgaris in India, which belong to Clades II and III, respectively. Interestingly, nucleotide diversity was lower for Clade I than II and III. However, the nucleotide diversity did not seem to depend on bamboo species or geographic location. Our population genetic analyses revealed the presence of excessive low-frequency polymorphic sites, which suggests that the satBaMV population was under purifying selection and/or population expansion. Further analysis of P20, the only satBaMV gene that encodes a non-structural protein involved in the long-distance movement of satBaMV, showed evidence of purifying selection. Taken together, our results suggest that purifying selection against defective P20 protein is responsible at least in part for the evolution of the satBaMV genome.
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Affiliation(s)
- Ing-Nang Wang
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan, Republic of China
- Department of Biological Sciences, University at Albany, Albany, New York, United States of America
| | - Chung-Chi Hu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan, Republic of China
| | - Ching-Wei Lee
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan, Republic of China
| | - Sih-Min Yen
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan, Republic of China
| | - Wen-Bing Yeh
- Department of Entomology, National Chung Hsin University, Taichung, Taiwan, Republic of China
| | - Yau-Heiu Hsu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan, Republic of China
| | - Na-Sheng Lin
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan, Republic of China
- * E-mail:
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Park MR, Seo JK, Kim KH. Viral and nonviral elements in potexvirus replication and movement and in antiviral responses. Adv Virus Res 2013; 87:75-112. [PMID: 23809921 DOI: 10.1016/b978-0-12-407698-3.00003-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In Potato virus X, a member of the genus Potexvirus, special sequences and structures at the 5' and 3' ends of the nontranslated region function as cis-acting elements for viral replication. These elements greatly affect interactions between viral RNAs and those between viral RNAs and host factors. The potexvirus genome encodes five open-reading frames. Viral replicase, which is required for the synthesis of viral RNA, binds viral RNA elements and host factors to form a viral replication complex at the host cellular membrane. The coat protein (CP) and three viral movement proteins (TGB1, TGB2, and TGB3) have critical roles in mediating cell-to-cell viral movement through plasmodesmata by virion formation or by nonvirion ribonucleoprotein (RNP) complex formation with viral movement proteins (TGBs). The RNP complex, like TGB1-CP-viral RNA, is associated with viral replicase and used for immediate reinitiation of viral replication in newly invaded cells. Higher plants have defense mechanisms against potexviruses such as Rx-mediated resistance and RNA silencing. The CP acts as an avirulence effector for plant defense mechanisms, while TGB1 functions as a viral suppressor of RNA silencing, which is the mechanism of innate immune resistance. Here, we describe recent findings concerning the involvement of viral and host factors in potexvirus replication and in antiviral responses to potexvirus infection.
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Affiliation(s)
- Mi-Ri Park
- Department of Agricultural Biotechnology, Plant Genomics and Breeding Institute, Seoul National University, Seoul, Republic of Korea
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7
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Lin KY, Hsu YH, Chen HC, Lin NS. Transgenic resistance to Bamboo mosaic virus by expression of interfering satellite RNA. MOLECULAR PLANT PATHOLOGY 2013; 14:693-707. [PMID: 23675895 PMCID: PMC6638707 DOI: 10.1111/mpp.12040] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Plant genetic engineering has broadened the options for plant virus resistance and is mostly based on pathogen-derived resistance. Previously, we have shown that interfering satellite RNA (satRNA) of Bamboo mosaic virus (satBaMV) greatly reduces Bamboo mosaic virus (BaMV) accumulation and BaMV-induced symptoms in co-inoculated plants. Here, we generated a nonviral source of virus-resistant transgenic Nicotiana benthamiana and Arabidopsis thaliana by introducing interfering satBaMV. Asymptomatic transgenic N. benthamiana lines were highly resistant to BaMV virion and viral RNA infection, and the expression of the transgene BSL6 was higher in asymptomatic than mildly symptomatic lines. In addition, BaMV- and satBaMV-specific small RNAs were detectable only after BaMV challenge, and their levels were associated with genomic viral RNA or satRNA levels. By transcriptomic analysis, the salicylic acid (SA) signalling pathway was not induced in satBaMV transgenic A. thaliana in mock conditions, suggesting that two major antiviral mechanisms, RNA silencing and SA-mediated resistance, are not involved directly in transgenic satBaMV-mediated BaMV interference. In contrast, resistance is associated with the level of the interfering satBaMV transgene. We propose satBaMV-mediated BaMV interference in transgenic plants by competition for replicase with BaMV.
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Affiliation(s)
- Kuan-Yu Lin
- Institute of Biotechnology, National Cheng Kung University, Tainan, 701, Taiwan
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8
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Chen HC, Kong LR, Yeh TY, Cheng CP, Hsu YH, Lin NS. The conserved 5' apical hairpin stem loops of bamboo mosaic virus and its satellite RNA contribute to replication competence. Nucleic Acids Res 2012; 40:4641-52. [PMID: 22278884 PMCID: PMC3378871 DOI: 10.1093/nar/gks030] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2011] [Revised: 12/30/2011] [Accepted: 01/05/2012] [Indexed: 11/29/2022] Open
Abstract
Satellite RNAs associated with Bamboo mosaic virus (satBaMVs) depend on BaMV for replication and encapsidation. Certain satBaMVs isolated from natural fields significantly interfere with BaMV replication. The 5' apical hairpin stem loop (AHSL) of satBaMV is the major determinant in interference with BaMV replication. In this study, by in vivo competition assay, we revealed that the sequence and structure of AHSL, along with specific nucleotides (C(60) and C(83)) required for interference with BaMV replication, are also involved in replication competition among satBaMV variants. Moreover, all of the 5' ends of natural BaMV isolates contain the similar AHSLs having conserved nucleotides (C(64) and C(86)) with those of interfering satBaMVs, suggesting their co-evolution. Mutational analyses revealed that C(86) was essential for BaMV replication, and that replacement of C(64) with U reduced replication efficiency. The non-interfering satBaMV interfered with BaMV replication with the BaMV-C64U mutant as helper. These findings suggest that two cytosines at the equivalent positions in the AHSLs of BaMV and satBaMV play a crucial role in replication competence. The downregulation level, which is dependent upon the molar ratio of interfering satBaMV to BaMV, implies that there is competition for limited replication machinery.
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Affiliation(s)
- Hsin-Chuan Chen
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei and Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Lih-Ren Kong
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei and Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Ting-Yu Yeh
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei and Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Chi-Ping Cheng
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei and Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Yau-Heiu Hsu
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei and Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Na-Sheng Lin
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei and Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
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9
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Lin KY, Cheng CP, Chang BCH, Wang WC, Huang YW, Lee YS, Huang HD, Hsu YH, Lin NS. Global analyses of small interfering RNAs derived from Bamboo mosaic virus and its associated satellite RNAs in different plants. PLoS One 2010; 5:e11928. [PMID: 20689857 PMCID: PMC2914070 DOI: 10.1371/journal.pone.0011928] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2009] [Accepted: 07/08/2010] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Satellite RNAs (satRNAs), virus parasites, are exclusively associated with plant virus infection and have attracted much interest over the last 3 decades. Upon virus infection, virus-specific small interfering RNAs (vsiRNAs) are produced by dicer-like (DCL) endoribonucleases for anti-viral defense. The composition of vsiRNAs has been studied extensively; however, studies of satRNA-derived siRNAs (satsiRNAs) or siRNA profiles after satRNA co-infection are limited. Here, we report on the small RNA profiles associated with infection with Bamboo mosaic virus (BaMV) and its two satellite RNAs (satBaMVs) in Nicotiana benthamiana and Arabidopsis thaliana. METHODOLOGY/PRINCIPAL FINDINGS Leaves of N. benthamiana or A. thaliana inoculated with water, BaMV alone or co-inoculated with interfering or noninterfering satBaMV were collected for RNA extraction, then large-scale Solexa sequencing. Up to about 20% of total siRNAs as BaMV-specific siRNAs were accumulated in highly susceptible N. benthamiana leaves inoculated with BaMV alone or co-inoculated with noninterfering satBaMV; however, only about 0.1% of vsiRNAs were produced in plants co-infected with interfering satBaMV. The abundant region of siRNA distribution along BaMV and satBaMV genomes differed by host but not by co-infection with satBaMV. Most of the BaMV and satBaMV siRNAs were 21 or 22 nt, of both (+) and (-) polarities; however, a higher proportion of 22-nt BaMV and satBaMV siRNAs were generated in N. benthamiana than in A. thaliana. Furthermore, the proportion of non-viral 24-nt siRNAs was greatly increased in N. benthamiana after virus infection. CONCLUSIONS/SIGNIFICANCE The overall composition of vsiRNAs and satsiRNAs in the infected plants reflect the combined action of virus, satRNA and different DCLs in host plants. Our findings suggest that the structure and/or sequence demands of various DCLs in different hosts may result in differential susceptibility to the same virus. DCL2 producing 24-nt siRNAs under biotic stresses may play a vital role in the antiviral mechanism in N. benthamiana.
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Affiliation(s)
- Kuan-Yu Lin
- Institute of Biotechnology, National Cheng Kung University, Tainan, Taiwan
| | - Chi-Ping Cheng
- Department of Life Science, Tzu Chi University, Hualien, Taiwan
| | | | - Wei-Chi Wang
- Institute of Bioinformatics and Systems Biology, National Chiao Tung University, Hsin-Chu, Taiwan
| | - Ying-Wen Huang
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Yun-Shien Lee
- Department of Biotechnology, Ming Chuan University, Taoyuan, Taiwan
| | - Hsien-Da Huang
- Institute of Bioinformatics and Systems Biology, National Chiao Tung University, Hsin-Chu, Taiwan
- Department of Biological Science and Technology, National Chiao Tung University, Hsin-Chu, Taiwan
| | - Yau-Heiu Hsu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Na-Sheng Lin
- Institute of Biotechnology, National Cheng Kung University, Tainan, Taiwan
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
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10
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Satellite RNAs and Satellite Viruses of Plants. Viruses 2009; 1:1325-50. [PMID: 21994595 PMCID: PMC3185516 DOI: 10.3390/v1031325] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2009] [Revised: 12/07/2009] [Accepted: 12/07/2009] [Indexed: 12/24/2022] Open
Abstract
The view that satellite RNAs (satRNAs) and satellite viruses are purely molecular parasites of their cognate helper viruses has changed. The molecular mechanisms underlying the synergistic and/or antagonistic interactions among satRNAs/satellite viruses, helper viruses, and host plants are beginning to be comprehended. This review aims to summarize the recent achievements in basic and practical research, with special emphasis on the involvement of RNA silencing mechanisms in the pathogenicity, population dynamics, and, possibly, the origin(s) of these subviral agents. With further research following current trends, the comprehensive understanding of satRNAs and satellite viruses could lead to new insights into the trilateral interactions among host plants, viruses, and satellites.
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11
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Chen SC, Desprez A, Olsthoorn RCL. Structural homology between bamboo mosaic virus and its satellite RNAs in the 5'untranslated region. J Gen Virol 2009; 91:782-7. [PMID: 19906937 DOI: 10.1099/vir.0.015941-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
A structural element was identified in the 5'-proximal sequence of the bamboo mosaic virus (BaMV) RNA. Mutational analysis of the hairpin showed that disruptions of the secondary structure or substitutions of the loop sequences resulted in reduced accumulation of BaMV genomic RNA. Phylogenetic analysis further suggested the presence of structural homologues of this hairpin in all other potexviruses. In addition, remarkable structural homology was discovered between the BaMV hairpin and a stem-loop in the 5'untranslated region of satellite RNAs responsible for attenuation of BaMV in co-infected plants. The role of this homology in the helper-satellite interaction is discussed.
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Affiliation(s)
- Shih-Cheng Chen
- Leiden Institute of Chemistry, Department of Molecular Genetics, 2300 RA Leiden, The Netherlands
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12
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Huang YW, Hu CC, Lin CA, Liu YP, Tsai CH, Lin NS, Hsu YH. Structural and functional analyses of the 3' untranslated region of Bamboo mosaic virus satellite RNA. Virology 2009; 386:139-53. [PMID: 19201437 DOI: 10.1016/j.virol.2009.01.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2008] [Revised: 11/16/2008] [Accepted: 01/10/2009] [Indexed: 12/29/2022]
Abstract
The 3'-untranslated region (UTR) of RNA genomes of viruses and satellite RNAs plays essential roles in viral replication and transcription. The structural features of the 3'-UTR of the satellite RNA of Bamboo mosaic virus (satBaMV) involved in its replication were analyzed in this study. By the use of enzymatic probing, the secondary structure of satBaMV 3'-UTR was confirmed to comprise two small stem-loops (SLA and SLB), one large stem-loop (SLC), and a poly(A) tail of mainly 75-200 adenylate residues, which is similar to those on the genomic RNA of the helper virus, BaMV. Five sets of mutants of satBaMV were constructed to analyze the biological functions of the structural elements of the 3'-UTR. The data revealed that both the polyadenylation signal and poly(A) tail are required for satBaMV RNA replication. The structural conservation of SLA, SLB, and SLC is also important for efficient satBaMV accumulation, whereas the nucleotides in these regions may also possess sequence-specific functions. In contrast to the requirement for the accumulation of BaMV genomic RNA, mutations in the conserved hexanucleotide (ACCUAA) in the loop region of SLC had limited effect on the accumulation of satBaMV RNA. In addition, replacing the 5'-, 3'-UTR, or both regions of satBaMV by those of BaMV greatly decreased the accumulation of satBaMV RNA. Taken together, these data indicate that satBaMV might have adopted a 3'-UTR structure similar to that of BaMV but may have evolved distinct features for its efficient replication.
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Affiliation(s)
- Ying-Wen Huang
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 40227, Taiwan, ROC
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13
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Huang YW, Hu CC, Lin NS, Tsai CH, Hsu YH. In vitro replication of Bamboo mosaic virus satellite RNA. Virus Res 2008; 136:98-106. [PMID: 18538884 DOI: 10.1016/j.virusres.2008.04.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2007] [Revised: 04/13/2008] [Accepted: 04/28/2008] [Indexed: 01/17/2023]
Abstract
An in vitro system was applied to analyze the replication of a satellite RNA of Bamboo mosaic virus (BaMV), designated satBaMV RNA, using solubilized membrane-bound RNA-dependent RNA polymerase (RdRp) complexes isolated from BaMV-infected Nicotiana benthamiana. After removal of endogenous templates, the RdRp complexes of BaMV catalyzed RNA synthesis upon the addition of the full-length positive (+)- or negative (-)-strand satBaMV RNA transcripts used as templates. Both (+)- and (-)-satBaMV RNA products were detected when only the (+)-satBaMV RNA was used as a template in the in vitro RdRp assays, which further demonstrated the capability of the RdRp preparation to complete the replication cycles of satBaMV RNAs. In addition, use of 5' rapid amplification of cDNA ends and DNA sequencing showed that the BaMV RdRp preparation could specifically recognize the promoter sequences in the (-)-satBaMV RNA for accurate initiation of (+)-satBaMV RNA synthesis. The results suggested that the same enzyme complexes could be used for the replication of both BaMV genomic and satBaMV RNAs. The soluble and template-dependent RdRp could be further used in mechanistic studies, such as those analyzing the cis-elements and candidate host factors required for satBaMV RNA replication in vitro.
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Affiliation(s)
- Ying-Wen Huang
- Graduate Institute of Biotechnology, National Chung Hsing University, 250 Kuokuang Road, Taichung 40227, Taiwan, ROC
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14
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Kinetics of polynucleotide phosphorylase: comparison of enzymes from Streptomyces and Escherichia coli and effects of nucleoside diphosphates. J Bacteriol 2007; 190:98-106. [PMID: 17965156 DOI: 10.1128/jb.00327-07] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We examined the activity of polynucleotide phosphorylase (PNPase) from Streptomyces coelicolor, Streptomyces antibioticus, and Escherichia coli in phosphorolysis using substrates derived from the rpsO-pnp operon of S. coelicolor. The Streptomyces and E. coli enzymes were both able to digest a substrate with a 3' single-stranded tail although E. coli PNPase was more effective in digesting this substrate than were the Streptomyces enzymes. The kcat for the E. coli enzyme was ca. twofold higher than that observed with the S. coelicolor enzyme. S. coelicolor PNPase was more effective than its E. coli counterpart in digesting a substrate possessing a 3' stem-loop structure, and the Km for the E. coli enzyme was ca. twice that of the S. coelicolor enzyme. Electrophoretic mobility shift assays revealed an increased affinity of S. coelicolor PNPase for the substrate possessing a 3' stem-loop structure compared with the E. coli enzyme. We observed an effect of nucleoside diphosphates on the activity of the S. coelicolor PNPase but not the E. coli enzyme. In the presence of a mixture of 20 microM ADP, CDP, GDP, and UDP, the Km for the phosphorolysis of the substrate with the 3' stem-loop was some fivefold lower than the value observed in the absence of nucleoside diphosphates. No effect of nucleoside diphosphates on the phosphorolytic activity of E. coli PNPase was observed. To our knowledge, this is the first demonstration of an effect of nucleoside diphosphates, the normal substrates for polymerization by PNPase, on the phosphorolytic activity of that enzyme.
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