The molecular cloning of genes specifying some enzymes of the 3,5-xylenol degradative pathway

Jain, R K (1996) The molecular cloning of genes specifying some enzymes of the 3,5-xylenol degradative pathway. Applied Microbiology and Biotechnology, 45. pp. 502-508.

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Enzymes for the degradation of 3,5-xylenol of Pseudomonas putida NCIB9869 are encoded on a transmissible plasmid, pRA500. Genes specifying the inducible synthesis of some enzymes encoded on pRA500, namely, citraconase (G), citramalate coenzyme-Atransferase (H), citramalyl-coenzyme-A lyase (I), maleylpyruvate isomerase (J) and fumarylpyruvate hydrolase (K) have been cloned on a 7.9-kb HindIII fragment into the vector pKT231 to give pRA507. Biochemical and restriction analysis of pRA507 and some of its deleted derivatives has enabled preliminary locations to be assigned to the genes encoding these enzymes. The structural genes for enzymes H and I, together with a regulatory gene controlling their expression, are located on a 1.6-kb HindIII/XhoI fragment of pRA507 and the genes for enzymes G, J and K are located within a 4.5-kb XhoI/C1aI fragment of pRA507, which lies immediately adjacent to the former fragment. Biochemical analysis of the strain carrying pRA507, of its plasmid-free derivative and of other plasmid-free derivatives of the wild-type P. putida has provided indirect evidence for the presence of two isofunctional enzymes at three di¤erent steps of the degradative pathway. One set of 3-hydroxybenzoate 6-hydroxylase, gentisate 1,2- dioxygenase and maleylpyruvate hydrolase is encoded on pRA500 and these enzymes are inducible only. A second set is encoded on the chromosome and these enzymes are constitutive and not further inducible. The chromosomally located genes appeared to be silent until 3,5-xylenol-negative strains were incubated for prolonged periods with compounds such as m-hydroxybenzoate or p-cresol.

Item Type: Article
Additional Information: Copyright of this article belongs to Springer-Verlag.
Subjects: Q Science > QR Microbiology
Depositing User: Dr. K.P.S.Sengar
Date Deposited: 27 Jan 2012 15:30
Last Modified: 03 Apr 2012 06:59

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