Isolation and characterization of the gene encoding the chloroplast-type ferredoxin component of carbazole 1,9a-dioxygenase from a putative Kordiimonas sp.
Carbazole (CAR)-degrading genes (carRAaCBaBb) were isolated from marine CAR-degrading isolate strain OC9 (probably Kordiimonas gwangyangensis) using shotgun cloning experiments and showed 35-65% similarity with previously reported CAR-degrading genes. In addition, a ferredoxin-like gene (carAc) was found downstream of carR, although it was not homologous with any reported ferredoxin components of the CAR 1,9a-dioxygenase (CARDO) system. The carAc-deduced amino acid sequence possessed consensus sequences for chloroplast-type iron-sulfur proteins for binding the [2Fe-2S] cluster. These car genes were arranged in the order of carAcRAaCBaBb, but carRAc and carAaCBaBb genes were the opposite orientation. Escherichia coli JM109 cells harboring pBOC91 (carAa) converted CAR to 2'-aminobiphenyl-2,3-diol at a ratio of 12%, and the transformation ratio of CAR increased from 12 to 100% when carAc was added, indicating that CarAc is the ferredoxin component of the CARDO system in strain OC9. This is the first finding of a chloroplast-type ferredoxin component in a CARDO system. Biotransformation tests with aromatic compounds revealed that the strain OC9 CarAaAc showed activity with polycyclic aromatic hydrocarbons and dioxin compounds and exhibited significant activity for fluorene, unlike previously reported CARDOs.
Maeda
Rintaro
R
Shibaura Institute of Technology, 3-7-5 Toyosu, Koto-ku, Tokyo 135-8548, Japan.
Ishii
Takanori
T
Ito
Yoshihiko
Y
Zulkharnain
Azham Bin
AB
Iwata
Kenichi
K
Omori
Toshio
T
D020561:Alphaproteobacteria / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000378:metabolism*; D002227:Carbazoles / Q000378:metabolism; D002736:Chloroplasts / Q000201:enzymology; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D049308:Dioxygenases / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D005288:Ferredoxins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D023061:Gene Order; D008969:Molecular Sequence Data; D005810:Multigene Family; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D001426:Bacterial Proteins; D002227:Carbazoles; D004269:DNA, Bacterial; D005288:Ferredoxins; D011994:Recombinant Proteins; C041514:carbazole; D049308:Dioxygenases; C108434:carbazole 1,9a-dioxygenase