Chloroplast-type Ferredoxin Involved in Reactivation of Catechol 2,3-Dioxygenase from Pseudomonas sp.S-47

Abstract

Pseudomonas sp. S-47 is capable of degrading catechol and 4-chlorocatechol via the meta-cleavage pathway. XylTE products catalyze the dioxygenation of the aromatics. The xylT of the strain S-47 is located just upstream of the xylE gene. XylT is a typical chloroplast-type ferredoxin, which is characterized by 4 cystein residues that are located at positions 41, 46, 49, and 81. The chloroplast-type ferredoxin of Pseudomonas sp. S-47 exhibited a 98% identity with that of P. putida mt-2 (TOL plasmid) in the amino acid sequence, but only about a 40 to 60% identity with the corresponding enzymes from other organisms. We constructed two recombinant plasmids (pRES1 containing xylTE and pRES101 containing xylE without xylT) in order to examine the function of XylT for the reactivation of the catechol 2,3-dioxygenase (XylE) that is oxidized with hydrogen peroxide. The pRES1 that was treated with hydrogen peroxide was recovered in the catechol 2,3-dioxygenase (C23O) activity about 4 minutes after incubation, but the pRES101 showed no recovery. That means that the typical chloroplast-type ferredoxin (XylT) of Pseudomonas sp. S-47 is involved in the reactivation of the oxidized C23O in the dioxygenolytic cleavage of aromatic compounds.