IDENTIFICATION AND CHARACTERIZATION OF GENES ENCODING CARBAZOLE 1,9A-DIOXYGENASE IN PSEUDOMONAS SP STRAIN CA10

Citation
Si. Sato et al., IDENTIFICATION AND CHARACTERIZATION OF GENES ENCODING CARBAZOLE 1,9A-DIOXYGENASE IN PSEUDOMONAS SP STRAIN CA10, Journal of bacteriology, 179(15), 1997, pp. 4850-4858
Citations number
43
Categorie Soggetti
Microbiology
Journal title
ISSN journal
00219193
Volume
179
Issue
15
Year of publication
1997
Pages
4850 - 4858
Database
ISI
SICI code
0021-9193(1997)179:15<4850:IACOGE>2.0.ZU;2-6
Abstract
Nucleotide sequence analysis of the flanking regions of the carBC gene s of Pseudomonas sp, strain CA10 revealed that there were two open rea ding frames (ORFs) ORF4 and ORF5, in the upstream region of carBC, Sim ilarly, three ORFs, ORF6 to ORF8, were found in the downstream region of carBC, The deduced amino acid sequences of ORF6 and ORF8 showed hom ologies with ferredoxin and ferredoxin reductase components of bacteri al multicomponent dioxygenase systems, respectively, ORF4 and ORF5 had the same sequence and were tandemly linked, Their deduced amino acid sequences showed about 30% homology with large (alpha) subunits of oth er terminal oxygenase components. Functional analysis using resting ce lls harboring the deleted plasmids revealed that the products of ORF4 and -5, ORF6, and ORF8 were terminal dioxygenase, ferredoxin, and ferr edoxin reductase, respectively, of carbazole 1,9a-dioxygenase (CARDO), which attacks the angular position adjacent to the nitrogen atom of c arbazole, and that the product of ORF7 is not indispensable for CARDO activity, Based on the results, ORF4, ORF5, ORF6, and ORF8 were design ated car Aa, carAa, carAc, and carAd, respectively, The products of ca rAa, carAd, and ORF7 were shown by sodium dodecyl sulfate-polyacrylami de gel electrophoresis to be polypeptides with molecular masses of 43, 36, and 11 kDa, respectively, However, the product of carAc was not d etected in Escherichia coli, CARDO has the ability to oxidize a wide v ariety of polyaromatic compounds, including dibenzo-p-dioxin, dibenzof uran, biphenyl, and polycyclic aromatic hydrocarbons such as naphthale ne and phenanthrene, Since 2,2',3-trihydroxydiphenyl ether and 2,2',3- trihydroxybiphenyl were identified as metabolites of dibenzo-p-dioxin and dibenzofuran, respectively, it was considered that CARDO attacked at the angular position adjacent to the oxygen atom of dibenzo-p-dioxi n and dibenzofuran as in the case with carbazole.