DAO 53:107-113 (2003)  -  doi:10.3354/dao053107

Cloning and nucleotide sequence analysis of the chloramphenicol resistance gene on conjugative R plasmids from the fish pathogen Photobacterium damselae subsp. piscicida

Hideaki Morii1,*, Nobutaka Hayashi2, Kiyoko Uramoto2

1Faculty of Fisheries, and
2Graduate School of Science and Technology, Nagasaki University, Bunkyou, Nagasaki 852-8521, Japan

ABSTRACT: Transferable resistance to various drugs was investigated in Photobacterium damselae subsp. piscicida from Japan. Drug resistances were transferred via plasmids of 100, 50, and 40 kb. Resistance to chloramphenicol (Cmr) was transferred on plasmids of all 3 sizes. The Cmr gene (cat) was cloned from the 50 kb plasmids pPDP8511 and pPDP9106 transferred from P. damselae subsp. piscicida strains isolated in different years and places in Japan. Subcloning localized the cat to within 1.5 kb HindIII-HincII (or PstI) fragments. Nucleotide sequences of the coding and flanking region of the cat were determined as 1607 bp (HindIII-HincII fragment) in pPDP8511 and 1568 bp (HindIII-PstI fragment) in pPDP9106, which corresponded with the sequence from nucleotides 40 to 1607 in pPDP8511. The nucleotide sequences identified an open reading frame (ORF) encoding 213 amino acid residues with a calculated molecular mass of about 24.8 kDa, a size consistent with the molecular mass of known cat gene products, and the ORF had maximum homology (99.5%) with a Type II CAT variant from Haemophilus influenzae.

KEY WORDS: Cloning · Nucleotide sequence · Chloramphenicol resistance gene · Transferable R plasmid · Photobacterium damselae subsp.

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