Abstract:
Genes encoding dioxygenase for acenaphthylene degradation from a transposon Tn5-induced Rhizobium sp. mutant strain D2, which is incapable of acenaphthylene degradation, were identified by Southern hybridization technique using transposon Tn5 fragment as DNA probe. DNA fragment with positive signal was isolated and cloned. The nucleotide sequence adjacent to transposon was sequenced. Comparison of amino acid sequence deduced from 523 bp nucleotide sequence with those in GenBank revealed 69% amino acid sequence homology to alpha subunit of dioxygenase from Xanthobacter polyaromaticivorans strain 127W. DNA-probe was generated from the DNA fragment adjacent to transposon by PCR. The 5.9 kb BamHI-EcoRI positive fragment was cloned into pBluescript KS(+/-) and designated as pDE. The 5.9 kb nucleotide sequence revealed 5 Open Reading Frames (ORFs) in the same transcriptional orientation as following; ORF1 (acnAc) showed 76% homology to alpha subunit of dioxygenase from Xanthobacter sp. 127W; ORF2 (acnAd) showed 60% homology to beta subunit of dioxygenase from Xanthobacter sp. 127W; ORF3 (acnAb) showed 71% homology to ferredoxin of dioxygenase from Xanthobacter sp. 127W; ORF4 (acnB) showed 67% homology to dihydrodiol dehydrogenase from Xanthobacter sp. 127W; ORF5 (acnF), an incomplete ORF, showed 65% homology to aldehyde dehydrogenase from Burkholderia sp. RP007. This study is the first report of genes, acnAbAcAd, encoding dioxygenase for acenaphthylene degradation in Rhizobium sp. CU-A1