Comparative analysis of Mutator -like transposases in sugarcane

Abstract

The maize Mutator ( Mu) system has been described as the most active and mutagenic plant transposon so far discovered. Mu -like elements (MULEs) are widespread among plants, and many and diverse variants can coexist in a particular genome. The autonomous regulatory element MuDR contains two genes: mudrA encodes the transposase, while the function of the mudrB gene product remains unknown. Although mudrA -like sequences are ubiquitous in plants, mudrB seems to be restricted to the genus Zea. In the SUCEST (the Brazilian Sugarcane EST Sequencing Project) database, several mudrA -like cDNAs have been identified, suggesting the presence of a transcriptionally active Mu system in sugarcane. Phylogenetic studies have revealed the presence in plants of four classes of mudrA -like sequences, which arose prior to the monocot/eudicot split. At least three of the four classes are also found in the progenitors of the sugarcane hybrid (Saccharum spp.), Saccharum officinarum and S. spontaneum. The frequency of putatively functional transposase ORFs varies among the classes, as revealed at both cDNA and genomic levels. The predicted products of some sugarcane mudrA -like transcripts contain both a DNA-binding domain and a transposase catalytic-site motif, supporting the idea that an active Mu system exists in this hybrid genome.

Sequence diversity and copy number variation of Mutator-like transposases in wheat

“…Two other Mutator-related elements, Trap (Comelli et al 1999) and Jittery (Xu et al 2004), have been identified in maize. Mutator-like transposases were divided into four classes in sugarcane, rice and Arabidopsis (Rossi et al 2004). Nucleotide sequences of the conserved transposase region from MuDR, Trap, Jittery and representative clones, TE165, TE109, TE266 and TE148, from each of the four MULE classes of sugarcane were used as queries in the homology search.…”

“…Bootstrap values higher than 50% for 1000 replications are shown at the nodes. Classification into classes followed Rossi et al (2004). MuDR, Jittery and Trap are from maize and OsMu4-2 (Asakura et al 2002) is from rice.…”

“…MuDR, Jittery and Trap are from maize and OsMu4-2 (Asakura et al 2002) is from rice. Sequences denoted with TE are from sugarcane (Rossi et al 2004) and sequences designated MoTU were isolated from T. urartu. Details of other sequences identified in the genera Triticum and Aegilops by blastn and tblastx searches are described in Table 2. genome.…”

O sistema Mutator em cana-de-açúcar: uma análise comparativa com arroz

“…Já o outro gene, mudrB, codifica para a proteína MURB cuja função ainda não está esclarecida. Embora em milho MURB seja necessária para ocorrer transposição, o gene mudrB tem sido identificado apenas em elementos das espécies do gênero Zea (Lisch et al 2001, Rossi et al 2004. A figura 2 esquematiza a estrutura de MuDR apresentando a organização dos genes mudrA e mudrB e as TIRs.…”

“…6). Estes resultados sugerem que a existência destes clados é anterior à divergência entre mono e dicotiledôneas há mais de 150 milhões de anos (Rossi et al 2004). Dada a sua função, as transposases possuem um domínio de ligação ao DNA conservado, CX2CX4HX4(ou 6)C (onde X é qualquer aminoácido), na extremidade C terminal.…”