Original Article
Hop, an Active Mutator-like Element in the Genome of the Fungus Fusarium oxysporum

Authors: Chalvet F.¹; Grimaldi C.¹; Kaper F.¹; Langin T.¹; Daboussi M-J.^{1, 2}

Source: Molecular Biology and Evolution, Volume 20, Number 8, August 2003 , pp. 1362-1375(14)

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Abstract:

A new type of active DNA transposon has been identified in the genome of Fusarium oxysporum by its transposition into the niaD target gene. Two insertions within the final exon, in opposite orientations at the same nucleotide site, have been characterized. These elements, called Hop, are 3,299 bp long, with perfect terminal inverted repeats (TIRs) of 99 bp. The sequencing of genomic copies reveals a 9-bp target site duplication and no apparent sequence specificity at the insertion sites. The sequencing of a cDNA indicates that Hop does not contain an intron and encodes a putative transposase of 836 amino acids. The structural features (length, TIRs size, and 9-bp duplication), together with the presence of conserved domains in the transposase, strongly suggest that Hop is a Mutator-like element (MULE). Hop is thus the first active member of this family found beyond plants. The high rate of excision observed indicates that Hop is very active and thus represents a promising efficient tagging system for the isolation of fungal genes. The distribution of Hop elements within the Fusarium genus revealed that they are present in different species, suggesting that related elements could be present in other fungal genomes. In fact, Hop-related sequences have been identified in the survey of the entire genome sequence of three other ascomycetes, Magnaporthe grisea, Neurospora crassa, and Aspergillus fumigatus.

Keywords: Fusarium oxysporum; transposable element; mutator; plant pathogen

Document Type: Original article

Affiliations: 1: Institut de Ge´ne´tique et Microbiologie, Universite´ Paris-Sud, Orsay Cedex, France 2: E-mail: daboussi@igmors.u-psud.fr.

Publication date: 2003-08-01

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Molecular Biology and Evolution publishes research at the interface between molecular and evolutionary biology. The journal publishes investigations of molecular evolutionary patterns and processes, tests of evolutionary hypotheses that use molecular data, and studies that use molecular evolutionary information to address questions about biological function at all levels of organization.