Abstract

Pseudomonas fluorescens SM11 is a naphthalene-degrading strain whose dissimilatory genes are chromosomally encoded. We have cloned the 2.9 kb Sal I fragment harboring genes for the naphthalene-degradation upper pathway. The nucleotide sequences were determined to be nahQ, tnpA, and partial regions of nahE genes. The nahQ encodes a protein of 188 amino acid residues with a deduced molecular weight of 20.8 kDa. The high homology with other proteins suggests that NahQ may be an active and useful protein which gives a selective advantage to naphthalene degradation. Transposase(TnpA) encodes a polypeptide chain with a molecular mass of 41.8 kDa consisting of 376 amino acid residues. The deduced anino acid sequence of tnpA revealed 96% idenitity with putative transposase of P. stutzeri OX1. It was assumed that transposase plays an important role in the evolution of the catabolic-pathway in the regulation of nah expression.

• Keywords: Pseudomonas fluorescens; nahQ; tnpA; transposase