Evidence for horizontal gene transfer of a tetrahydrofuran monooxygenase: Cloning and analysis of a gene cluster for tetrahydrofuran degradation in Rhodococcus sp. YYL

A gene cluster encoding tetrahydrofuran (THF) degrading related enzymes was first isolated from Rhodococcus sp. YYL, a strain of the genus Rhodococcus, which was first reported to degrade tetrahydrofuran, by combination of COnsensus-DEgenerate Hybrid oligonucleotide Primer PCR and thermal asymmetric interlaced PCR. Sequence analysis of the gene cluster revealed 9 open reading frames containing genes encoding aRhodococcus sp. YYL multiple component tetrahydrofuran monooxygenase. The tetrahydrofuran monooxygenase genes had similarities higher than 92% with these inPseudonocardia sp. K1, but had low similarities with other monooxygenase genes using BLAST search in GenBanK. The high specific of tetrahydrofuran monooxygenase genes was further proved by PCR amplification of no product using genomic DNA of other bacteria or even activated sludge as template with primers targeting at the α-subunit of this monooxygenase. Phylogenetic analysis based on amino acid sequences and 16S rDNA strongly suggested that this monooxygenase occurred by horizontal gene transfer. Base composition analysis and the existence of a transposase gene in the gene cluster further proposed that this monooxygenase originated from the genus Rhodococcus and it might be transformed by a transposon between different species.   Key words: Consensus-degenerate hybrid oligonucleotide primer polymerase chain reaction (CODEHOP PCR), thermal asymmetric interlaced PCR (TAIL-PCR), tetrahydrofuran monooxygenase, horizontal gene transfer.