This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Takeo, M.
Right arrow Articles by Negoro, S.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Takeo, M.
Right arrow Articles by Negoro, S.

 Previous Article  |  Next Article 

Journal of Bacteriology, November 2008, p. 7367-7374, Vol. 190, No. 22
0021-9193/08/$08.00+0     doi:10.1128/JB.00742-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Mechanism of 4-Nitrophenol Oxidation in Rhodococcus sp. Strain PN1: Characterization of the Two-Component 4-Nitrophenol Hydroxylase and Regulation of Its Expression{triangledown}

Masahiro Takeo,* Masumi Murakami, Sanae Niihara, Kenta Yamamoto, Munehiro Nishimura, Dai-ichiro Kato, and Seiji Negoro

Department of Materials Science and Chemistry, Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2201, Japan

Received 25 May 2008/ Accepted 9 September 2008

4-Nitrophenol (4-NP) is a toxic product of the hydrolysis of organophosphorus pesticides such as parathion in soil. Rhodococcus sp. strain PN1 degrades 4-NP via 4-nitrocatechol (4-NC) for use as the sole carbon, nitrogen, and energy source. A 5-kb EcoRI DNA fragment previously cloned from PN1 contained a gene cluster (nphRA1A2) involved in 4-NP oxidation. From sequence analysis, this gene cluster is expected to encode an AraC/XylS family regulatory protein (NphR) and a two-component 4-NP hydroxylase (NphA1 and NphA2). A transcriptional assay in a Rhodococcus strain revealed that the transcription of nphA1 is induced by only 4-NP (of several phenolic compounds tested) in the presence of nphR, which is constitutively expressed. Disruption of nphR abolished transcriptional activity, suggesting that nphR encodes a positive regulatory protein. The two proteins of the 4-NP hydroxylase, NphA1 and NphA2, were independently expressed in Escherichia coli and purified by ion-exchange chromatography or affinity chromatography. The purified NphA2 reduced flavin adenine dinucleotide (FAD) with the concomitant oxidation of NADH, while the purified NphA1 oxidized 4-NP into 4-NC almost quantitatively in the presence of FAD, NADH, and NphA2. This functional analysis, in addition to the sequence analysis, revealed that this enzyme system belongs to the two-component flavin-diffusible monooxygenase family. The 4-NP hydroxylase showed comparable oxidation activities for phenol and 4-chlorophenol to that for 4-NP and weaker activities for 3-NP and 4-NC.

* Corresponding author. Mailing address: Department of Materials Science and Chemistry, Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2201, Japan. Phone and fax: 81 792 67 4893. E-mail: takeo{at}eng.u-hyogo.ac.jp

{triangledown} Published ahead of print on 19 September 2008.

Journal of Bacteriology, November 2008, p. 7367-7374, Vol. 190, No. 22
0021-9193/08/$08.00+0     doi:10.1128/JB.00742-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Zhang, J.-J., Liu, H., Xiao, Y., Zhang, X.-E., Zhou, N.-Y. (2009). Identification and Characterization of Catabolic para-Nitrophenol 4-Monooxygenase and para-Benzoquinone Reductase from Pseudomonas sp. Strain WBC-3. J. Bacteriol. 191: 2703-2710 [Abstract] [Full Text]  


Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»