1
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Norppa AJ, Chowdhury I, van Rooijen LE, Ravantti JJ, Snel B, Varjosalo M, Frilander MJ. Distinct functions for the paralogous RBM41 and U11/U12-65K proteins in the minor spliceosome. Nucleic Acids Res 2024; 52:4037-4052. [PMID: 38499487 DOI: 10.1093/nar/gkae070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 01/19/2024] [Accepted: 03/11/2024] [Indexed: 03/20/2024] Open
Abstract
Here, we identify RBM41 as a novel unique protein component of the minor spliceosome. RBM41 has no previously recognized cellular function but has been identified as a paralog of U11/U12-65K, a known unique component of the U11/U12 di-snRNP. Both proteins use their highly similar C-terminal RRMs to bind to 3'-terminal stem-loops in U12 and U6atac snRNAs with comparable affinity. Our BioID data indicate that the unique N-terminal domain of RBM41 is necessary for its association with complexes containing DHX8, an RNA helicase, which in the major spliceosome drives the release of mature mRNA from the spliceosome. Consistently, we show that RBM41 associates with excised U12-type intron lariats, is present in the U12 mono-snRNP, and is enriched in Cajal bodies, together suggesting that RBM41 functions in the post-splicing steps of the minor spliceosome assembly/disassembly cycle. This contrasts with U11/U12-65K, which uses its N-terminal region to interact with U11 snRNP during intron recognition. Finally, while RBM41 knockout cells are viable, they show alterations in U12-type 3' splice site usage. Together, our results highlight the role of the 3'-terminal stem-loop of U12 snRNA as a dynamic binding platform for the U11/U12-65K and RBM41 proteins, which function at distinct stages of the assembly/disassembly cycle.
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Affiliation(s)
- Antto J Norppa
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Iftekhar Chowdhury
- Molecular Systems Biology Research Group and Proteomics Unit, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Laura E van Rooijen
- Theoretical Biology and Bioinformatics, Department of Biology, Faculty of Science, Utrecht University, 3584 CH Utrecht, the Netherlands
| | - Janne J Ravantti
- Molecular and Integrative Biosciences Research Programme, University of Helsinki, Helsinki, Finland
| | - Berend Snel
- Theoretical Biology and Bioinformatics, Department of Biology, Faculty of Science, Utrecht University, 3584 CH Utrecht, the Netherlands
| | - Markku Varjosalo
- Molecular Systems Biology Research Group and Proteomics Unit, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Mikko J Frilander
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
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2
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Laanto E, Ravantti JJ, Sundberg LR. Prophages and Past Prophage-Host Interactions Revealed by CRISPR Spacer Content in a Fish Pathogen. Microorganisms 2020; 8:E1919. [PMID: 33276599 PMCID: PMC7761591 DOI: 10.3390/microorganisms8121919] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 11/26/2020] [Accepted: 11/30/2020] [Indexed: 12/20/2022] Open
Abstract
The role of prophages in the evolution, diversification, or virulence of the fish pathogen Flavobacterium columnare has not been studied thus far. Here, we describe a functional spontaneously inducing prophage fF4 from the F. columnare type strain ATCC 23463, which is not detectable with commonly used prophage search methods. We show that this prophage type has a global distribution and is present in strains isolated from Finland, Thailand, Japan, and North America. The virions of fF4 are myoviruses with contractile tails and infect only bacterial strains originating from Northern Finland. The fF4 resembles transposable phages by similar genome organization and several gene orthologs. Additional bioinformatic analyses reveal several species in the phylum Bacteroidetes that host a similar type of putative prophage, including bacteria that are important animal and human pathogens. Furthermore, a survey of F. columnare Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) spacers indicate a shared evolutionary history between F. columnare strains and the fF4 phage, and another putative prophage in the F. columnare strain ATCC 49512, named p49512. First, CRISPR spacer content from the two CRISPR loci (types II-C and VI-B) of the fF4 lysogen F. columnare ATCC 23463 revealed a phage terminase protein-matching spacer in the VI-B locus. This spacer is also present in two Chinese F. columnare strains. Second, CRISPR analysis revealed four F. columnare strains that contain unique spacers targeting different regions of the putative prophage p49512 in the F. columnare strain ATCC 49512, despite the geographical distance or genomovar of the different strains. This suggests a common ancestry for the F. columnare prophages and different host strains.
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Affiliation(s)
- Elina Laanto
- Molecular and Integrative Biosciences Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, 00014 Helsinki, Finland;
| | - Janne J. Ravantti
- Molecular and Integrative Biosciences Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, 00014 Helsinki, Finland;
| | - Lotta-Riina Sundberg
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyvaskyla, 40014 Jyvaskyla, Finland;
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3
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Ravantti JJ, Martinez-Castillo A, Abrescia NG. Superimposition of Viral Protein Structures: A Means to Decipher the Phylogenies of Viruses. Viruses 2020; 12:v12101146. [PMID: 33050291 PMCID: PMC7600307 DOI: 10.3390/v12101146] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 10/02/2020] [Accepted: 10/02/2020] [Indexed: 02/07/2023] Open
Abstract
Superimposition of protein structures is key in unravelling structural homology across proteins whose sequence similarity is lost. Structural comparison provides insights into protein function and evolution. Here, we review some of the original findings and thoughts that have led to the current established structure-based phylogeny of viruses: starting from the original observation that the major capsid proteins of plant and animal viruses possess similar folds, to the idea that each virus has an innate “self”. This latter idea fueled the conceptualization of the PRD1-adenovirus lineage whose members possess a major capsid protein (innate “self”) with a double jelly roll fold. Based on this approach, long-range viral evolutionary relationships can be detected allowing the virosphere to be classified in four structure-based lineages. However, this process is not without its challenges or limitations. As an example of these hurdles, we finally touch on the difficulty of establishing structural “self” traits for enveloped viruses showcasing the coronaviruses but also the power of structure-based analysis in the understanding of emerging viruses
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Affiliation(s)
- Janne J. Ravantti
- Molecular and Integrative Biosciences Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, FI-00014 Helsinki, Finland;
| | - Ane Martinez-Castillo
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, 48160 Derio, Spain;
| | - Nicola G.A. Abrescia
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, 48160 Derio, Spain;
- IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Instituto de Salud Carlos III, 28029 Madrid, Spain
- Correspondence: ; Tel.: +34-946572502
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4
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Laanto E, Mäkelä K, Hoikkala V, Ravantti JJ, Sundberg LR. Adapting a Phage to Combat Phage Resistance. Antibiotics (Basel) 2020; 9:E291. [PMID: 32486059 PMCID: PMC7345892 DOI: 10.3390/antibiotics9060291] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 05/27/2020] [Accepted: 05/27/2020] [Indexed: 01/24/2023] Open
Abstract
Phage therapy is becoming a widely recognized alternative for fighting pathogenic bacteria due to increasing antibiotic resistance problems. However, one of the common concerns related to the use of phages is the evolution of bacterial resistance against the phages, putatively disabling the treatment. Experimental adaptation of the phage (phage training) to infect a resistant host has been used to combat this problem. Yet, there is very little information on the trade-offs of phage infectivity and host range. Here we co-cultured a myophage FCV-1 with its host, the fish pathogen Flavobacterium columnare, in lake water and monitored the interaction for a one-month period. Phage resistance was detected within one day of co-culture in the majority of the bacterial isolates (16 out of the 18 co-evolved clones). The primary phage resistance mechanism suggests defense via surface modifications, as the phage numbers rose in the first two days of the experiment and remained stable thereafter. However, one bacterial isolate had acquired a spacer in its CRISPR (Clustered Regularly Interspaced Short Palindromic Repeat)-Cas locus, indicating that also CRISPR-Cas defense was employed in the phage-host interactions. After a week of co-culture, a phage isolate was obtained that was able to infect 18 out of the 32 otherwise resistant clones isolated during the experiment. Phage genome sequencing revealed several mutations in two open reading frames (ORFs) likely to be involved in the regained infectivity of the evolved phage. Their location in the genome suggests that they encode tail genes. Characterization of this evolved phage, however, showed a direct cost for the ability to infect several otherwise resistant clones-adsorption was significantly lower than in the ancestral phage. This work describes a method for adapting the phage to overcome phage resistance in a fish pathogenic system.
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Affiliation(s)
- Elina Laanto
- Faculty of Biological and Environmental Sciences, Molecular and Integrative Biosciences Research Programme, University of Helsinki, 00014 Helsinki, Finland;
- Department of Biological and Environmental Science, Nanoscience Center, University of Jyvaskyla, 40014 Jyvaskyla, Finland; (K.M.); (V.H.); (L.R.S.)
| | - Kati Mäkelä
- Department of Biological and Environmental Science, Nanoscience Center, University of Jyvaskyla, 40014 Jyvaskyla, Finland; (K.M.); (V.H.); (L.R.S.)
| | - Ville Hoikkala
- Department of Biological and Environmental Science, Nanoscience Center, University of Jyvaskyla, 40014 Jyvaskyla, Finland; (K.M.); (V.H.); (L.R.S.)
| | - Janne J. Ravantti
- Faculty of Biological and Environmental Sciences, Molecular and Integrative Biosciences Research Programme, University of Helsinki, 00014 Helsinki, Finland;
| | - Lotta-Riina Sundberg
- Department of Biological and Environmental Science, Nanoscience Center, University of Jyvaskyla, 40014 Jyvaskyla, Finland; (K.M.); (V.H.); (L.R.S.)
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5
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Demina TA, Pietilä MK, Svirskaitė J, Ravantti JJ, Atanasova NS, Bamford DH, Oksanen HM. HCIV-1 and Other Tailless Icosahedral Internal Membrane-Containing Viruses of the Family Sphaerolipoviridae. Viruses 2017; 9:v9020032. [PMID: 28218714 PMCID: PMC5332951 DOI: 10.3390/v9020032] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 01/10/2017] [Accepted: 02/13/2017] [Indexed: 11/16/2022] Open
Abstract
Members of the virus family Sphaerolipoviridae include both archaeal viruses and bacteriophages that possess a tailless icosahedral capsid with an internal membrane. The genera Alpha- and Betasphaerolipovirus comprise viruses that infect halophilic euryarchaea, whereas viruses of thermophilic Thermus bacteria belong to the genus Gammasphaerolipovirus. Both sequence-based and structural clustering of the major capsid proteins and ATPases of sphaerolipoviruses yield three distinct clades corresponding to these three genera. Conserved virion architectural principles observed in sphaerolipoviruses suggest that these viruses belong to the PRD1-adenovirus structural lineage. Here we focus on archaeal alphasphaerolipoviruses and their related putative proviruses. The highest sequence similarities among alphasphaerolipoviruses are observed in the core structural elements of their virions: the two major capsid proteins, the major membrane protein, and a putative packaging ATPase. A recently described tailless icosahedral haloarchaeal virus, Haloarcula californiae icosahedral virus 1 (HCIV-1), has a double-stranded DNA genome and an internal membrane lining the capsid. HCIV-1 shares significant similarities with the other tailless icosahedral internal membrane-containing haloarchaeal viruses of the family Sphaerolipoviridae. The proposal to include a new virus species, Haloarcula virus HCIV1, into the genus Alphasphaerolipovirus was submitted to the International Committee on Taxonomy of Viruses (ICTV) in 2016.
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Affiliation(s)
- Tatiana A Demina
- Department of Biosciences and Institute of Biotechnology, Viikinkaari 9, FIN-00014, University of Helsinki, Helsinki, Finland.
| | - Maija K Pietilä
- Department of Food and Environmental Sciences, Viikinkaari 9, FIN-00014, University of Helsinki, Helsinki, Finland.
| | - Julija Svirskaitė
- Department of Biosciences and Institute of Biotechnology, Viikinkaari 9, FIN-00014, University of Helsinki, Helsinki, Finland.
| | - Janne J Ravantti
- Department of Biosciences and Institute of Biotechnology, Viikinkaari 9, FIN-00014, University of Helsinki, Helsinki, Finland.
| | - Nina S Atanasova
- Department of Biosciences and Institute of Biotechnology, Viikinkaari 9, FIN-00014, University of Helsinki, Helsinki, Finland.
| | - Dennis H Bamford
- Department of Biosciences and Institute of Biotechnology, Viikinkaari 9, FIN-00014, University of Helsinki, Helsinki, Finland.
| | - Hanna M Oksanen
- Department of Biosciences and Institute of Biotechnology, Viikinkaari 9, FIN-00014, University of Helsinki, Helsinki, Finland.
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6
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Mönttinen HA, Ravantti JJ, Poranen MM. Common Structural Core of Three-Dozen Residues Reveals Intersuperfamily Relationships. Mol Biol Evol 2016; 33:1697-710. [DOI: 10.1093/molbev/msw047] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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7
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Jaakkola ST, Pfeiffer F, Ravantti JJ, Guo Q, Liu Y, Chen X, Ma H, Yang C, Oksanen HM, Bamford DH. The complete genome of a viable archaeum isolated from 123-million-year-old rock salt. Environ Microbiol 2016; 18:565-79. [DOI: 10.1111/1462-2920.13130] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 03/02/2015] [Accepted: 03/15/2015] [Indexed: 12/01/2022]
Affiliation(s)
- Salla T. Jaakkola
- Department of Biosciences; Institute of Biotechnology; University of Helsinki; Helsinki Finland
| | - Friedhelm Pfeiffer
- Department of Membrane Biochemistry; Max Planck Institute of Biochemistry; München Germany
| | - Janne J. Ravantti
- Department of Biosciences; Institute of Biotechnology; University of Helsinki; Helsinki Finland
| | - Qinggong Guo
- State Key Laboratory of Virology; College of Life Sciences; Wuhan University; Wuhan China
| | - Ying Liu
- State Key Laboratory of Virology; College of Life Sciences; Wuhan University; Wuhan China
| | - Xiangdong Chen
- State Key Laboratory of Virology; College of Life Sciences; Wuhan University; Wuhan China
| | - Hongling Ma
- State Key Laboratory of Geomechanics and Geotechnical Engineering; Institute of Rock and Soil Mechanics; The Chinese Academy of Science; Wuhan China
| | - Chunhe Yang
- State Key Laboratory of Geomechanics and Geotechnical Engineering; Institute of Rock and Soil Mechanics; The Chinese Academy of Science; Wuhan China
| | - Hanna M. Oksanen
- Department of Biosciences; Institute of Biotechnology; University of Helsinki; Helsinki Finland
| | - Dennis H. Bamford
- Department of Biosciences; Institute of Biotechnology; University of Helsinki; Helsinki Finland
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8
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Laanto E, Bamford JKH, Ravantti JJ, Sundberg LR. The use of phage FCL-2 as an alternative to chemotherapy against columnaris disease in aquaculture. Front Microbiol 2015; 6:829. [PMID: 26347722 PMCID: PMC4541368 DOI: 10.3389/fmicb.2015.00829] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 07/28/2015] [Indexed: 01/21/2023] Open
Abstract
Flavobacterium columnare, the causative agent of columnaris disease in fish, causes millions of dollars of losses in the US channel catfish industry alone, not to mention aquaculture industry worldwide. Novel methods are needed for the control and treatment of bacterial diseases in aquaculture to replace traditionally used chemotherapies. A potential solution could be the use of phages, i.e., bacterial viruses, host-specific and self-enriching particles that can be can easily distributed via water flow. We examined the efficacy of phages to combat columnaris disease. A previously isolated phage, FCL-2, infecting F. columnare, was characterized by sequencing. The 47 142 bp genome of the phage had G + C content of 30.2%, and the closest similarities regarding the structural proteins were found in Cellulophaga phage phiSM. Under controlled experimental conditions, two host fish species, rainbow trout (Oncorhynchus mykiss) and zebrafish (Danio rerio), were used to study the success of phage therapy to prevent F. columnare infections. The survival of both fish species was significantly higher in the presence of the phage. Hundred percent of the zebrafish and 50% of the rainbow trout survived in the phage treatment (survival without phage 0 and 8.3%, respectively). Most importantly, the rainbow trout population was rescued from infection by a single addition of the phage into the water in a flow-through fish tank system. Thus, F. columnare could be used as a model system to test the benefits and risks of phage therapy on a larger scale.
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Affiliation(s)
- Elina Laanto
- Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science, University of JyvaskylaJyvaskyla, Finland
| | - Jaana K. H. Bamford
- Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science, University of JyvaskylaJyvaskyla, Finland
| | - Janne J. Ravantti
- Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science, University of JyvaskylaJyvaskyla, Finland
- Department of Biosciences and Institute of Biotechnology, University of HelsinkiHelsinki, Finland
| | - Lotta-Riina Sundberg
- Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science, University of JyvaskylaJyvaskyla, Finland
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9
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Mäntynen S, Laanto E, Kohvakka A, Poranen MM, Bamford JKH, Ravantti JJ. New enveloped dsRNA phage from freshwater habitat. J Gen Virol 2015; 96:1180-1189. [PMID: 25614591 DOI: 10.1099/vir.0.000063] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 01/15/2015] [Indexed: 12/27/2022] Open
Abstract
Cystoviridae is a family of bacteriophages with a tri-segmented dsRNA genome enclosed in a tri-layered virion structure. Here, we present a new putative member of the Cystoviridae family, bacteriophage ϕNN. ϕNN was isolated from a Finnish lake in contrast to the previously identified cystoviruses, which originate from various legume samples collected in the USA. The nucleotide sequence of the virus reveals a strong genetic similarity (~80 % for the L-segments, ~55 % for the M-segments and ~84 % for the S-segments) to Pseudomonas phage ϕ6, the type member of the virus family. However, the relationship between ϕNN and other cystoviruses is more distant. In general, proteins located in the internal parts of the virion were more conserved than those exposed on the virion surface, a phenomenon previously reported among eukaryotic dsRNA viruses. Structural models of several putative ϕNN proteins propose that cystoviral structures are highly conserved.
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Affiliation(s)
- Sari Mäntynen
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
| | - Elina Laanto
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
| | - Annika Kohvakka
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
| | - Minna M Poranen
- Department of Biosciences, University of Helsinki, Helsinki, Finland
| | - Jaana K H Bamford
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
| | - Janne J Ravantti
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland.,Department of Biosciences, University of Helsinki, Helsinki, Finland.,Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
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10
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Mönttinen HAM, Ravantti JJ, Stuart DI, Poranen MM. Automated structural comparisons clarify the phylogeny of the right-hand-shaped polymerases. Mol Biol Evol 2014; 31:2741-52. [PMID: 25063440 DOI: 10.1093/molbev/msu219] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Polymerases are essential for life, being responsible for replication, transcription, and the repair of nucleic acid molecules. Those that share a right-hand-shaped fold and catalytic site structurally similar to the DNA polymerase I of Escherichia coli may catalyze RNA- or DNA-dependent RNA polymerization, reverse transcription, or DNA replication in eukarya, archaea, bacteria, and their viruses. We have applied novel computational methods for structure-based clustering and phylogenetic analyses of this functionally diverse polymerase superfamily, which currently comprises six families. We identified a structural core common to all right-handed polymerases, composed of 57 amino acid residues, harboring two positionally and chemically conserved residues, the catalytic aspartates. The structural conservation within each of the six families is considerable, for example, the structural core shared by family Y DNA polymerases covers over 90% of the polymerase domain of the Sulfolobus solfataricus Dpo4. Our phylogenetic analyses propose an early separation of RNA-dependent polymerases that use primers from those that are primer-independent. Furthermore, the exchange of polymerase genes between viruses and their hosts is evident. Because of this horizontal gene transfer, the phylogeny of polymerases does not always reflect the evolutionary history of the corresponding organisms.
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Affiliation(s)
- Heli A M Mönttinen
- Department of Biosciences, Viikki Biocenter, University of Helsinki, Helsinki, Finland
| | - Janne J Ravantti
- Department of Biosciences, Viikki Biocenter, University of Helsinki, Helsinki, Finland Institute of Biotechnology, Viikki Biocenter, University of Helsinki, Helsinki, Finland
| | - David I Stuart
- Division of Structural Biology and the Oxford Protein Production Facility, The Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom Diamond Light Source Limited, Harwell Science and Innovation Campus, Oxfordshire, United Kingdom
| | - Minna M Poranen
- Department of Biosciences, Viikki Biocenter, University of Helsinki, Helsinki, Finland
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11
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Mönttinen HAM, Ravantti JJ, Poranen MM. Evidence for a non-catalytic ion-binding site in multiple RNA-dependent RNA polymerases. PLoS One 2012; 7:e40581. [PMID: 22792374 PMCID: PMC3394715 DOI: 10.1371/journal.pone.0040581] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Accepted: 06/09/2012] [Indexed: 11/18/2022] Open
Abstract
A high-affinity divalent cation-binding site located proximal to the catalytic center has been identified in several RNA-dependent RNA polymerases (RdRps), but the characteristics of such a site have not been systematically studied. Here, all available polymerase structures that follow the hand-like structural motif were screened for the presence of a divalent cation close to the catalytic site but distinct from catalytic metal ions. Such non-catalytic ions were found in all RNA virus families for which there were high-resolution RdRp structures available. Bound ions were always located in structurally similar locations at an approximate 6-Å distance from the catalytic site. Furthermore, the second aspartate residue in the highly conserved GDD sequence was found to be involved in the coordination of the bound ion in all viral RdRps studied. These results suggest that a non-catalytic ion-binding site is conserved across positive-sense, single-stranded, and double-stranded RNA viruses. Interestingly, a non-catalytic ion was also observed in a similar position in the reverse transcriptase of the human immunodeficiency virus. Moreover, two members of the DNA-dependent DNA polymerase B family displayed an ion at a comparable distance from the catalytic site, but the position was clearly distinct from the non-catalytic ion-binding sites of RdRps.
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Affiliation(s)
| | - Janne J. Ravantti
- Department of Biosciences, University of Helsinki, Helsinki, Finland
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Minna M. Poranen
- Department of Biosciences, University of Helsinki, Helsinki, Finland
- * E-mail:
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12
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Verbeeren J, Niemelä EH, Turunen JJ, Will CL, Ravantti JJ, Lührmann R, Frilander MJ. An ancient mechanism for splicing control: U11 snRNP as an activator of alternative splicing. Mol Cell 2010; 37:821-33. [PMID: 20347424 DOI: 10.1016/j.molcel.2010.02.014] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2009] [Revised: 11/03/2009] [Accepted: 12/23/2009] [Indexed: 12/15/2022]
Abstract
Alternative pre-mRNA splicing is typically regulated by specific protein factors that recognize unique sequence elements in pre-mRNA and affect, directly or indirectly, nearby splice site usage. We show that 5' splice site sequences (5'ss) of U12-type introns, when repeated in tandem, form a U11 snRNP-binding splicing enhancer, USSE. Binding of U11 to the USSE regulates alternative splicing of U2-type introns by activating an upstream 3'ss. The U12-type 5'ss-like sequences within the USSE have a regulatory role and do not function as splicing donors. USSEs, present both in animal and plant genes encoding the U11/U12 di-snRNP-specific 48K and 65K proteins, create sensitive switches that respond to intracellular levels of functional U11 snRNP and alter the stability of 48K and 65K mRNAs. We conclude that U11 functions not only in 5'ss recognition in constitutive splicing, but also as an activator of U2-dependent alternative splicing and as a regulator of the U12-dependent spliceosome.
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Affiliation(s)
- Jens Verbeeren
- Institute of Biotechnology, University of Helsinki, Helsinki FIN-00014, Finland
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13
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Abstract
Background Geminiviruses (family Geminiviridae) are small single-stranded (ss) DNA viruses infecting plants. Their virion morphology is unique in the known viral world – two incomplete T = 1 icosahedra are joined together to form twinned particles. Geminiviruses utilize a rolling-circle mode to replicate their genomes. A limited sequence similarity between the three conserved motifs of the rolling-circle replication initiation proteins (RCR Reps) of geminiviruses and plasmids of Gram-positive bacteria allowed Koonin and Ilyina to propose that geminiviruses descend from bacterial replicons. Results Phylogenetic and clustering analyses of various RCR Reps suggest that Rep proteins of geminiviruses share a most recent common ancestor with Reps encoded on plasmids of phytoplasmas, parasitic wall-less bacteria replicating both in plant and insect cells and therefore occupying a common ecological niche with geminiviruses. Capsid protein of Satellite tobacco necrosis virus was found to be the best template for homology-based structural modeling of the geminiviral capsid protein. Good stereochemical quality of the generated models indicates that the geminiviral capsid protein shares the same structural fold, the viral jelly-roll, with the vast majority of icosahedral plant-infecting ssRNA viruses. Conclusion We propose a plasmid-to-virus transition scenario, where a phytoplasmal plasmid acquired a capsid-coding gene from a plant RNA virus to give rise to the ancestor of geminiviruses.
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Affiliation(s)
- Mart Krupovic
- Department of Biological and Environmental Sciences and Institute of Biotechnology, Biocenter 2, PO Box 56 (Viikinkaari 5), FIN-00014 University of Helsinki, Helsinki, Finland.
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14
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Sarin LP, Poranen MM, Lehti NM, Ravantti JJ, Koivunen MRL, Aalto AP, van Dijk AA, Stuart DI, Grimes JM, Bamford DH. Insights into the pre-initiation events of bacteriophage phi 6 RNA-dependent RNA polymerase: towards the assembly of a productive binary complex. Nucleic Acids Res 2009; 37:1182-92. [PMID: 19129226 PMCID: PMC2651803 DOI: 10.1093/nar/gkn1035] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The RNA-dependent RNA polymerase (RdRP) of double-stranded RNA (dsRNA) viruses performs both RNA replication and transcription. In order to initiate RNA polymerization, viral RdRPs must be able to interact with the incoming 3′ terminus of the template and position it, so that a productive binary complex is formed. Structural studies have revealed that RdRPs of dsRNA viruses that lack helicases have electrostatically charged areas on the polymerase surface, which might facilitate such interactions. In this study, structure-based mutagenesis, enzymatic assays and molecular mapping of bacteriophage φ6 RdRP and its RNA were used to elucidate the roles of the negatively charged plough area on the polymerase surface, of the rim of the template tunnel and of the template specificity pocket that is key in the formation of the productive RNA-polymerase binary complex. The positively charged rim of the template tunnel has a significant role in the engagement of highly structured ssRNA molecules, whereas specific interactions further down in the template tunnel promote ssRNA entry to the catalytic site. Hence, we show that by aiding the formation of a stable binary complex with optimized RNA templates, the overall polymerization activity of the φ6 RdRP can be greatly enhanced.
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Affiliation(s)
- L Peter Sarin
- Institute of Biotechnology and Department of Biological and Environmental Sciences, University of Helsinki, Biocenter 2, Helsinki, Finland
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15
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Ruokoranta TM, Grahn AM, Ravantti JJ, Poranen MM, Bamford DH. Complete genome sequence of the broad host range single-stranded RNA phage PRR1 places it in the Levivirus genus with characteristics shared with Alloleviviruses. J Virol 2006; 80:9326-30. [PMID: 16940544 PMCID: PMC1563911 DOI: 10.1128/jvi.01005-06] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Single-stranded RNA (ssRNA) bacteriophages of the family Leviviridae infect gram-negative bacteria. They are restricted to a single host genus. Phage PRR1 is an exception, having a broad host range due to the promiscuity of the receptor encoded by the IncP plasmid. Here we report the complete genome sequence of PRR1. Three proteins homologous with those of other ssRNA phages, i.e., maturation, coat, and replicase proteins, were identified. A fourth protein has a lysis function. Comparison of PRR1 with other members of the Leviviridae family places PRR1 in the genus Levivirus with some characteristics more similar to those of members of the genus Allolevivirus.
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Affiliation(s)
- Tanja M Ruokoranta
- Department of Biological and Environmental Sciences, Institute of Biotechnology, Viikki Biocenter 2, P.O. Box 56 (Viikinkaari 5), FIN-00014 University of Helsinki, Finland
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16
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Poranen MM, Ravantti JJ, Grahn AM, Gupta R, Auvinen P, Bamford DH. Global changes in cellular gene expression during bacteriophage PRD1 infection. J Virol 2006; 80:8081-8. [PMID: 16873264 PMCID: PMC1563795 DOI: 10.1128/jvi.00065-06] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Virus-induced changes in cellular gene expression and host physiology have been studied extensively. Still, there are only a few analyses covering the entire viral replication cycle and whole-host gene pool expression at the resolution of a single gene. Here we report changes in Escherichia coli gene expression during bacteriophage PRD1 infection using microarray technology. Relative mRNA levels were systematically measured for over 99% of the host open reading frames throughout the infection cycle. Although drastic modifications could be detected in the expression of individual genes, global changes at the whole-genome level were moderate. Notably, the majority of virus-induced changes took place only after the synthesis of virion components, indicating that there is no major reprogramming of the host during early infection. The most highly induced genes encoded chaparones and other stress-inducible proteins.
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Affiliation(s)
- Minna M Poranen
- Institute of Biotechnology, Viikki Biocenter, P.O. Box 56 (Viikinkaari 5), 00014 University of Helsinki, Helsinki, Finland
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17
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Saren AM, Ravantti JJ, Benson SD, Burnett RM, Paulin L, Bamford DH, Bamford JKH. A snapshot of viral evolution from genome analysis of the tectiviridae family. J Mol Biol 2005; 350:427-40. [PMID: 15946683 DOI: 10.1016/j.jmb.2005.04.059] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2004] [Revised: 04/22/2005] [Accepted: 04/26/2005] [Indexed: 10/25/2022]
Abstract
The origin, evolution and relationships of viruses are all fascinating topics. Current thinking in these areas is strongly influenced by the tailed double-stranded (ds) DNA bacteriophages. These viruses have mosaic genomes produced by genetic exchange and so new natural isolates are quite dissimilar to each other, and to laboratory strains. Consequently, they are not amenable to study by current tools for phylogenetic analysis. Less attention has been paid to the Tectiviridae family, which embraces icosahedral dsDNA bacterial viruses with an internal lipid membrane. It includes viruses, such as PRD1, that infect Gram-negative bacteria, as well as viruses like Bam35 with Gram-positive hosts. Although PRD1 and Bam35 have closely related virion morphology and genome organization, they have no detectable sequence similarity. There is strong evidence that the Bam35 coat protein has the "double-barrel trimer" arrangement of PRD1 that was first observed in adenovirus and is predicted to occur in other viruses with large facets. It is very likely that a single ancestral virus gave rise to this very large group of viruses. The unprecedented degree of conservation recently observed for two Bam35-like tectiviruses made it important to investigate those infecting Gram-negative bacteria. The DNA sequences for six PRD1-like isolates (PRD1, PR3, PR4, PR5, L17, PR772) have now been determined. Remarkably, these bacteriophages, isolated at distinctly different dates and global locations, have almost identical genomes. The discovery of almost invariant genomes for the two main Tectiviridae groups contrasts sharply with the situation in the tailed dsDNA bacteriophages. Notably, it permits a sequence analysis of the isolates revealing that the tectiviral proteins can be dissected into a slowly evolving group descended from the ancestor, the viral self, and a more rapidly changing group reflecting interactions with the host.
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Affiliation(s)
- Ari-Matti Saren
- Institute of Biotechnology, University of Helsinki, PO Box 56 (Viikinkaari 4), FIN-00014 Helsinki, Finland
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18
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Bamford DH, Ravantti JJ, Rönnholm G, Laurinavicius S, Kukkaro P, Dyall-Smith M, Somerharju P, Kalkkinen N, Bamford JKH. Constituents of SH1, a novel lipid-containing virus infecting the halophilic euryarchaeon Haloarcula hispanica. J Virol 2005; 79:9097-107. [PMID: 15994804 PMCID: PMC1168735 DOI: 10.1128/jvi.79.14.9097-9107.2005] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Recent studies have indicated that a number of bacterial and eukaryotic viruses that share a common architectural principle are related, leading to the proposal of an early common ancestor. A prediction of this model would be the discovery of similar viruses that infect archaeal hosts. Our main interest lies in icosahedral double-stranded DNA (dsDNA) viruses with an internal membrane, and we now extend our studies to include viruses infecting archaeal hosts. While the number of sequenced archaeal viruses is increasing, very little sequence similarity has been detected between bacterial and eukaryotic viruses. In this investigation we rigorously show that SH1, an icosahedral dsDNA virus infecting Haloarcula hispanica, possesses lipid structural components that are selectively acquired from the host pool. We also determined the sequence of the 31-kb SH1 genome and positively identified genes for 11 structural proteins, with putative identification of three additional proteins. The SH1 genome is unique and, except for a few open reading frames, shows no detectable similarity to other published sequences, but the overall structure of the SH1 virion and its linear genome with inverted terminal repeats is reminiscent of lipid-containing dsDNA bacteriophages like PRD1.
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Affiliation(s)
- Dennis H Bamford
- Department of Biological and Environmental Sciences, P.O. Box 56 (Viikinkaari 5), University of Helsinki, FIN-00014 Helsinki, Finland.
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Ravantti JJ, Gaidelyte A, Bamford DH, Bamford JKH. Comparative analysis of bacterial viruses Bam35, infecting a gram-positive host, and PRD1, infecting gram-negative hosts, demonstrates a viral lineage. Virology 2003; 313:401-14. [PMID: 12954208 DOI: 10.1016/s0042-6822(03)00295-2] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Extra- and intracellular viruses in the biosphere outnumber their cellular hosts by at least one order of magnitude. How is this enormous domain of viruses organized? Sampling of the virosphere has been scarce and focused on viruses infecting humans, cultivated plants, and animals as well as those infecting well-studied bacteria. It has been relatively easy to cluster closely related viruses based on their genome sequences. However, it has been impossible to establish long-range evolutionary relationships as sequence homology diminishes. Recent advances in the evaluation of virus architecture by high-resolution structural analysis and elucidation of viral functions have allowed new opportunities for establishment of possible long-range phylogenic relationships-virus lineages. Here, we use a genomic approach to investigate a proposed virus lineage formed by bacteriophage PRD1, infecting gram-negative bacteria, and human adenovirus. The new member of this proposed lineage, bacteriophage Bam35, is morphologically indistinguishable from PRD1. It infects gram-positive hosts that evolutionarily separated from gram-negative bacteria more than one billion years ago. For example, it can be inferred from structural analysis of the coat protein sequence that the fold is very similar to that of PRD1. This and other observations made here support the idea that a common early ancestor for Bam35, PRD1, and adenoviruses existed.
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Affiliation(s)
- Janne J Ravantti
- Department of Computer Science, P.O. Box 26, (Teollisuuskatu 23), 00014 University of Helsinki, Helsinki, Finland
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20
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Abstract
Results of electron microscopy-based three-dimensional reconstructions of macromolecules or their complexes are usually stored as density maps. Each point ("voxel") in the map represents a density value and one approach for studying details of the map is to display an isosurface enclosing areas of interest. We have taken a data mining approach not only focusing on the areas of immediate interest but determining all possible separate entities ("blobs") from a density map. After the entire density map is analyzed with our mining program BLOBBER, properties of all detected blobs can be browsed and sets of blobs can be visualized using our VIZBLOB program. Since BLOBBER analyzes density maps using only density information and relates it to spatial relationships, BLOBBER can be used to analyze symmetrical or asymmetrical density maps from any source. To test our program we have analyzed published bacteriophage PRD1 reconstructions. We identified various structural details ranging from individual proteins to major complexes such as the whole capsid shell and more elaborate details of possible connections between membrane interfaces. This approach can also be a useful preprocessing tool for visualizing reconstructions.
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Affiliation(s)
- J J Ravantti
- Department of Computer Science, University of Helsinki, Helsinki, 00014, Finland
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