The Cryphonectria parasitica mitochondrial rns gene: Plasmid-like elements, introns and homing endonucleases

Monteiro-Vitorello, Cláudia Barros; Hausner, Georg; Searles, Denise B.; Gibb, Ewan A.; Fulbright, D. W.; Bertrand, Helmut

doi:10.1016/j.fgb.2009.07.005

Cited by 25 publications

(22 citation statements)

References 115 publications

(137 reference statements)

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“…Analysis using the BLASTP program (National Center for Biotechnology Information) showed that this particular LHEG is related to that encoded within the mS952 group II intron present in the mt rns gene of C. parasitica (Toor and Zimmerly 2002;Monteiro-Vitorello et al 2009). The LHEase that was expressed in E. coli was 35 kDa, as determined by SDS-PAGE analysis (data not shown).…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, we may be witnessing the evolution of a potentially new combination of mobile element, even though based on currently available data, the LAGLIDADG-type ORFs encoded by group II introns have only a limited distribution, being mostly restricted to mt rDNA of fungi (Toor and Zimmerly 2002;Monteiro-Vitorello et al 2009). This work demonstrates how novel mobile elements can evolve by shuffling components of unrelated, pre-existing mobile genetic units.…”

Section: Resultsmentioning

confidence: 99%

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A group II intron encodes a functional LAGLIDADG homing endonuclease and self-splices under moderate temperature and ionic conditions

Mullineux¹,

Costa²,

Bassi³

et al. 2010

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A group II intron encoding a protein belonging to the LAGLIDADG family of homing endonucleases was identified in the mitochondrial rns gene of the filamentous fungus Leptographium truncatum, and the catalytic activities of both the intron and its encoded protein were characterized. A model of the RNA secondary structure indicates that the intron is a member of the IIB1 subclass and the open reading frame is inserted in ribozyme domain III. In vitro assays carried out with two versions of the intron, one in which the open reading frame was removed and the other in which it was present, demonstrate that both versions of the intron readily self-splice at 37°C and at a concentration of MgCl 2 as low as 6 mM. The open reading frame encodes a functional LAGLIDADG homing endonuclease that cleaves 2 (top strand) and 6 (bottom strand) nucleotides (nt) upstream of the intron insertion site, generating 4 nt 39 OH overhangs. In vitro splicing assays carried out in the absence and presence of the intron-encoded protein indicate that the protein does not enhance intron splicing, and RNA-binding assays show that the protein does not appear to bind to the intron RNA precursor transcript. These findings raise intriguing questions concerning the functional and evolutionary relationships of the two components of this unique composite element.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

A group II intron encodes a functional LAGLIDADG homing endonuclease and self-splices under moderate temperature and ionic conditions

Mullineux¹,

Costa²,

Bassi³

et al. 2010

RNA

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“…S2). As already pointed out by Monteiro-Vitorello et al (2009), the proteins potentially encoded by the SSU788 and SSU952 introns of Cryphonectria parasitica are not closely related. More generally, whereas Mapping of the 59 extremity of gel-extracted linear intron molecules generated by in vitro self-splicing of a Pycnoporellus precursor transcript; the latter was used as a template to generate the sequencing lanes at right with a primer located downstream from the intron 59 extremity.…”

Section: Phylogenetic Relationships Of Mitochondrial Subgroup Iib1 Inmentioning

confidence: 88%

“…All known examples of group II introns encoding proteins completely unrelated to reverse transcriptases also come from mitochondrial genes encoding ribosomal RNA precursor transcripts (Toor and Zimerly 2002;Monteiro-Vitorello et al 2009;Mullineux et al 2010); moreover, these introns belong again to subgroup IIB1, and multiple events of the insertion of an ORF (at least six of them) ( Fig. 5; Supplemental Fig.…”

Section: Endonuclease-mediated Homing and The Loss Of The Lariat Strumentioning

confidence: 99%

“…1). These introns, which happen to belong to the same ribozyme structural subgroup (IIB1) (Michel et al 1989) and are inserted in ribosomal RNA precursor transcripts, exhibit additional remarkable features (Table 1): They all lack the EBS2-IBS2 pairing between the ribozyme and the 59 exon, which is potentially present in most group II introns, and several of them code for a homing endonuclease, rather than a reverse transcriptase (see also Michel and Ferat 1995;Toor and Zimmerly 2002;Monteiro-Vitorello et al 2009). …”

Section: Introductionmentioning

confidence: 99%

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Recurrent insertion of 5′-terminal nucleotides and loss of the branchpoint motif in lineages of group II introns inserted in mitochondrial preribosomal RNAs

Costa²,

Bassi³

et al. 2011

RNA

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A survey of sequence databases revealed 10 instances of subgroup IIB1 mitochondrial ribosomal introns with 1 to 33 additional nucleotides inserted between the 59 exon and the consensus sequence at the intron 59 end. These 10 introns depart further from the IIB1 consensus in their predicted domain VI structure: In contrast to its basal helix and distal GNRA terminal loop, the middle part of domain VI is highly variable and lacks the bulging A that serves as the branchpoint in lariat formation. In vitro experiments using two closely related IIB1 members inserted at the same ribosomal RNA site in the basidiomycete fungi Grifola frondosa and Pycnoporellus fulgens revealed that both ribozymes are capable of efficient self-splicing. However, whereas the Grifola intron was excised predominantly as a lariat, the Pycnoporellus intron, which possesses six additional nucleotides at the 59 end, yielded only linear products, consistent with its predicted domain VI structure. Strikingly, all of the introns with 59 terminal insertions lack the EBS2 exon-binding site. Moreover, several of them are part of the small subset of group II introns that encode potentially functional homing endonucleases of the LAGLIDADG family rather than reverse transcriptases. Such coincidences suggest causal relationships between the shift to DNA-based mobility, the loss of one of the two ribozyme sites for binding the 59 exon, and the exclusive use of hydrolysis to initiate splicing.

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Introns, Mobile Elements, and Plasmids

Hausner

2011

Organelle Genetics

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The Cryphonectria parasitica mitochondrial rns gene: Plasmid-like elements, introns and homing endonucleases

Cited by 25 publications

References 115 publications

A group II intron encodes a functional LAGLIDADG homing endonuclease and self-splices under moderate temperature and ionic conditions

A group II intron encodes a functional LAGLIDADG homing endonuclease and self-splices under moderate temperature and ionic conditions

Recurrent insertion of 5′-terminal nucleotides and loss of the branchpoint motif in lineages of group II introns inserted in mitochondrial preribosomal RNAs

Introns, Mobile Elements, and Plasmids

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