Cloning of genes participating in aerobic biodegradation of p-cumate from Rhodopseudomonas palustris.
Rhodopseudomonas palustris utilizes p-cumate as a carbon source both under anaerobic light and aerobic dark conditions. A gene cluster was isolated whose sequence showed high homology to genes which have been implicated the degradation of p-cumate in Pseudomonas pitida. Seven structural genes coding for dioxygenase-reductase, dihydroxy-dihydro dehydrogenase, and ring cleavage oxygenases were identified. A putative regulator and its possible recognition site was suggested on the basis of homology data. Mutant cells in which a kanamycin cassette was inserted into the dihydroxy-dihydro dehydrogenase gene could not grow aerobically on p-cumate. The mutation had no effect on growth using the para substituted benzoate derivatives 4-hydroxycinnamate, ferulate, protocatechuate, and 2,3,4-trihydroxybenzoate as sole carbon source. Moreover, mutant cells showed a growth pattern similar to wild type cells grown on these compounds under photoheterotrophic anaerobic conditions. These data suggest that genes of this operon are involved specifically in aerobic dissimilation of p-cumate. Intermediate products of p-cumate degradation could be detected from extracts of Escherichia coli heterologously expressing the first 5 genes responsible for the first two steps of p-cumate degradation in R. palustris. Primer extension analysis revealed the transcription regulation of the gene cluster which could be induced with para methyl-, ethyl- and isopropyl (cumate) benzoates. This is the first report on genes involved in aerobic degradation of these compounds in photosynthetic bacteria.
Puskás
L G
LG
Research Institute of Innovative Technology for the Earth, Soraku, Kyoto, Japan.
Inui
M
M
Kele
Z
Z
Yukawa
H
H
D000332:Aerobiosis; D000595:Amino Acid Sequence; D001483:Base Sequence; D001565:Benzoates / Q000378:metabolism*; D001673:Biodegradation, Environmental; D003001:Cloning, Molecular; D004269:DNA, Bacterial; D015870:Gene Expression; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D005810:Multigene Family; D016254:Mutagenesis, Insertional; D009876:Operon; D010105:Oxygenases / Q000235:genetics; D012241:Rhodopseudomonas / Q000201:enzymology* / Q000235:genetics; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic
D001565:Benzoates; D004269:DNA, Bacterial; C055607:cumic acid; D010105:Oxygenases