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A Restriction Map of Naphthalene Catabolic Plasmid pWW60-1 and the Location of Some of Its Catabolic Genes

1986; Microbiology Society; Volume: 132; Issue: 10 Linguagem: Inglês

10.1099/00221287-132-10-2919

1465-2080

Patricia A. Cane, Peter A. Williams,

Bacterial Genetics and Biotechnology

SUMMARY: A restriction map for the 87 kbp IncP9 naphthalene catabolic plasmid pWW60-1 is presented. Transposon mutants were obtained using direct Tn5 insertion or using an indirect method involving the intermediate formation of unstable cointegrates between RP4 and pWW60-1. Insertions which affected expression of the early enzymes of the pathway (naphthalene to salicylate) were separated from inserts which affected expression of salicylate hydroxylase (nahG) or catechol 2,3-oxygenase (nahH). nahABC were cloned on a contiguous region of the plasmid on either a 6.9 kbp HindIII fragment (HE) or a 5.7 kbp XhoI fragment (XD). nahGH were cloned on a region situated about 30 kbp from nahABC on an XhoI fragment (XC), but nahH was only expressed on the corresponding but smaller XhoI fragments from two derivative plasmids of pWW60-1 with a deletion in that region. The detailed restriction map of nahH shows no similarities with the restriction maps of the genes for catechol 2,3-oxygenases from TOL plasmids, although the cloned gene did hybridize with genes for catechol 2,3-oxygenase from two different TOL plasmids. The organization of the catabolic genes on pWW60-1 suggests a separation into two operons as also described for the naphthalene catabolic plasmid NAH7 (alternatively called pIG7), but the relative directions of their transcription differs from that in NAH7.