Expanded insecticide catabolic activity gained by a single nucleotide substitution in a bacterial carbamate hydrolase gene.
Carbofuran-mineralizing strain Novosphingobium sp. KN65.2 produces the CfdJ enzyme that converts the N-methylcarbamate insecticide to carbofuran phenol. Purified CfdJ shows a remarkably low KMtowards carbofuran. Together with the carbaryl hydrolase CehA of Rhizobium sp. strain AC100, CfdJ represents a new protein family with several uncharacterized bacterial members outside the proteobacteria. Although both enzymes differ by only four amino acids, CehA does not recognize carbofuran as a substrate whereas CfdJ also hydrolyzes carbaryl. None of the CfdJ amino acids that differ from CehA were shown to be silent regarding carbofuran hydrolytic activity but one particular amino acid substitution, i.e., L152 to F152, proved crucial. CfdJ is more efficient in degrading methylcarbamate pesticides with an aromatic side chain whereas CehA is more efficient in degrading the oxime carbamate nematicide oxamyl. The presence of common flanking sequences suggest that the cfdJ gene is located on a remnant of the mobile genetic element Tnceh carrying cehA. Our results suggest that these enzymes can be acquired through horizontal gene transfer and can evolve to degrade new carbamate substrates by limited amino acid substitutions. We demonstrate that a carbaryl hydrolase can gain the additional capacity to degrade carbofuran by a single nucleotide transversion.
Division of Soil and Water Management, KU Leuven, Leuven, Belgium.
Başak
B
Öztürk
Centre of Microbial and Plant Genetics, KU Leuven, Leuven, Belgium.
Maarten
M
Ghequire
Division of Soil and Water Management, KU Leuven, Leuven, Belgium.|Department of Biology, College of Natural Sciences, Cantho University, Vietnam.
Thi Phi Oanh
TP
Nguyen
Centre of Microbial and Plant Genetics, KU Leuven, Leuven, Belgium.
René
R
De Mot
Department of Proteomics and Microbiology, University of Mons, Mons, Belgium.
Ruddy
R
Wattiez
Division of Soil and Water Management, KU Leuven, Leuven, Belgium.
Dirk
D
Springael
D019943:Amino Acid Substitution / Q000235:genetics; D002219:Carbamates / Q000378:metabolism; D012721:Carbaryl / Q000378:metabolism; D002235:Carbofuran / Q000378:metabolism*; D002265:Carboxylic Ester Hydrolases / Q000235:genetics / Q000378:metabolism*; D007306:Insecticides / Q000378:metabolism*; D020071:Interspersed Repetitive Sequences / Q000235:genetics; D009711:Nucleotides; D012231:Rhizobium / Q000201:enzymology / Q000378:metabolism*; D042301:Sphingomonadaceae / Q000201:enzymology / Q000378:metabolism*
D002219:Carbamates; D007306:Insecticides; D009711:Nucleotides; C020401:N-methylcarbamate; C036868:methyl carbamate; D002265:Carboxylic Ester Hydrolases; C077242:carbamate hydrolase; D012721:Carbaryl; D002235:Carbofuran; C011960:oxamyl