Reverse Transcriptase Activities in Mycelial Fungi

Fassbender, S.; Kück, Ulrich

doi:10.1007/978-3-662-10364-7_15

Cited by 7 publications

(4 citation statements)

References 106 publications

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“…Class I elements transpose via an RNA intermediate employing a reverse transcriptase. (21) By contrast, most class II elements transpose at the DNA level by excision from a donor site and reintegration elsewhere in the genome. Approximately one-half of all identified fungal transposons belong to class I (Table 1).…”

Section: Structure and Function Of Transposable Elementsmentioning

confidence: 99%

Transposons in filamentous fungi-facts and perspectives

1998

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Transposons are ubiquitous genetic elements discovered so far in all investigated prokaryotes and eukaryotes. In remarkable contrast to all other genes, transposable elements are able to move to new locations within their host genomes. Transposition of transposons into coding sequences and their initiation of chromosome rearrangements have tremendous impact on gene expression and genome evolution. While transposons have long been known in bacteria, plants, and animals, only in recent years has there been a significant increase in the number of transposable elements discovered in filamentous fungi. Like those of other eukaryotes, each fungal transposable element is either of class I or of class II. While class I elements transpose by a RNA intermediate and employ reverse transcriptases, class II elements transpose directly at the DNA level. We present structural and functional features for such transposons that have been identified so far in filamentous fungi. Emphasis is given to specific advantages or unique features when fungal systems are used to study transposable elements, e.g., the evolutionary impact of transposons in coenocytic organisms and possible experimental approaches toward horizontal gene transfer. Finally, we focus on the potential of transposons for tagging and identifying fungal genes.

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Section: Structure and Function Of Transposable Elementsmentioning

confidence: 99%

Transposons in filamentous fungi-facts and perspectives

1998

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“…Retrotransposons are divided into two subgroups, elements with and without long terminal repeats (Flavell 1995). Class I elements have been found in several fungal species (Fassbender and KuÈ ck 1995;Daboussi 1996), and such elements with long terminal repeats, named Foret1 and skippy, have been identi®ed in F. oxysporum (Julien et al 1992;Anaya and Roncero 1995).…”

Section: Introductionmentioning

confidence: 99%

“…Two major strategies have been used to identify class II transposons in fungi: the characterization of dispersed repetitive sequences and the molecular analysis of spontaneous mutants (Fassbender and KuÈ ck 1995;Daboussi 1996). We have previously selected four repetitive DNA clones, named FOLR1 to FOLR4, from a genomic library of strain MAFF305118 of F. oxysporum f. sp.…”

Section: Introductionmentioning

confidence: 99%

Tfo1: an Ac -like transposon from the plant pathogenic fungus Fusarium oxysporum

Okuda

Ikeda

Namiki³

et al. 1998

Mol Gen Genet

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A transposable element from a plant pathogenic fungus, Fusarium oxrysporum, was isolated and characterized. Four clones carrying moderately repetitive DNA were selected from a genomic library of the strain MAFF305118 of F. oxysporum f. sp. lagenariae, which causes wilt of bottle gourd. One the four clones was found to include a transposable element, which we have named Tfo1. This element is 2763 bp in size and appears to contain a long ORF that can encode a polypeptide of 777 amino acids. The amino acid sequence shows significant similarity to transposases from the hAT family of transposons, such as the maize transposon Activator (Ac). The element has 15-bp terminal inverted repeats and causes an 8-bp target site duplication upon insertion, as expected for an hAT-family transposon. Northern analysis detected a transcript, which hybridized to the putative transposase-encoding region of Tfo1. The size of this transcript (about 2.3 kb) corresponds to that of the ORF. A Southern analysis using pulsed-field gel electrophoresis showed that multiple chromosomal bands carry Tfo1 elements. PCR amplification of the Tfo1 elements with a 15-base inverted repeat primer produced a single DNA fragment of about 2.8 kb in all bottle gourd-infecting strains used. The element was found in multiple copies in the genome of all these strains and also in strains from other formae speciales tested. The sequence similarity of the Tfo1 element to other transposons, together with its transcriptional expression and genomic distribution, strongly suggests that Tfo1 is a member of the hAT transposon family.

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“…30 Often, scenarios for retroprocessing are postulated without knowledge of the RTs involved. Group II introns are in fact the predominant RT encoded in mitochondrial and chloroplast genomes, along with RTs of mitochondrial retroplasmids 31,32 and occasional free-standing RT ORFs of unknown function. 33 Based on sequences present in Genbank (November 2001), bacterial group II intron RTs now outnumber bacterial retron RTs by a factor of 1.5, and are found in a considerably wider range of host species (24 versus 8; L. Dai & S.Z., unpublished observation).…”

Section: Discussionmentioning

confidence: 99%