Evidence for natural horizontal transfer of the pcpB gene in the evolution of polychlorophenol-degrading sphingomonads.
The chlorophenol degradation pathway in Sphingobium chlorophenolicum is initiated by the pcpB gene product, pentachlorophenol-4-monooxygenase. The distribution of the gene was studied in a phylogenetically diverse group of polychlorophenol-degrading bacteria isolated from contaminated groundwater in Kärkölä, Finland. All the sphingomonads isolated were shown to share pcpB gene homologs with 98.9 to 100% sequence identity. The gene product was expressed when the strains were induced by 2,3,4,6-tetrachlorophenol. A comparative analysis of the 16S rDNA and pcpB gene trees suggested that a recent horizontal transfer of the pcpB gene was involved in the evolution of the catabolic pathway in the Kärkölä sphingomonads. The full-length Kärkölä pcpB gene allele had approximately 70% identity with the three pcpB genes previously sequenced from sphingomonads. It was very closely related to the environmental clones obtained from chlorophenol-enriched soil samples (M. Beaulieu, V. Becaert, L. Deschenes, and R. Villemur, Microbiol. Ecol. 40:345-355, 2000). The gene was not present in polychlorophenol-degrading nonsphingomonads isolated from the Kärkölä source.
Department of Biological and Environmental Science, FIN-400014 University of Jyväskylä, Finland. mtiirola@jyu.fi
Marja A
MA
Tiirola
Hong
H
Wang
Lars
L
Paulin
Markku S
MS
Kulomaa
D000595:Amino Acid Sequence; D005075:Biological Evolution; D002733:Chlorophenols / Q000378:metabolism*; D006899:Mixed Function Oxygenases / Q000235:genetics*; D008969:Molecular Sequence Data; D012336:RNA, Ribosomal, 16S / Q000032:analysis / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D020578:Sphingomonas / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D014161:Transduction, Genetic
D002733:Chlorophenols; D012336:RNA, Ribosomal, 16S; D006899:Mixed Function Oxygenases; C069781:pentachlorophenol monooxygenase