Branching of the p-nitrophenol (PNP) degradation pathway in burkholderia sp. Strain SJ98: Evidences from genetic characterization of PNP gene cluster.

Vikram, Surendra and Pandey, Janmejay and Bhalla, Nidhi and Pandey, Gunjan and Ghosh, Anuradha and Khan, Fazlurrahman and Jain, R K and Raghava, G.P.S. (2012) Branching of the p-nitrophenol (PNP) degradation pathway in burkholderia sp. Strain SJ98: Evidences from genetic characterization of PNP gene cluster. AMB Express, 2 (1). p. 30. ISSN 2191-0855

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Abstract

Aerobic microbial degradation of p-nitrophenol (PNP) has been classically shown to proceed via 'Hydroquinone (HQ) pathway' in Gram-negative bacteria, whereas in Gram-positive PNP degraders it proceed via 'Benzenetriol (BT) pathway'. These pathways are characterized by the ring cleavage of HQ and BT as terminal aromatic intermediates respectively. Earlier reports on PNP degradation have indicated these pathways to be mutually exclusive. We report involvement of both 'HQ' and 'BT' ring cleavage pathways in PNP degradation by Burkholderia sp. strain SJ98. Genetic characterization of an ~41 Kb DNA fragment harboring PNP degradation gene cluster cloned and sequenced from strain SJ98 showed presence of multiple orfs including pnpC and pnpD which corresponded to previously characterized 'benzenetriol-dioxygenase (BtD)' and 'maleylacetate reductase (MaR)' respectively. This gene cluster also showed presence of pnpE1 and pnpE2, which shared strong sequence identity to cognate sub-units of 'hydroquinone dioxygenase' (HqD). Heterologous expression and biochemical characterization ascertained the identity of PnpE1 and PnpE2. In in vitro assay reconstituted heterotetrameric complex of PnpE1 and PnpE2 catalyzed transformation of hydroquinone (HQ) into corresponding hydroxymuconic semialdehyde (HMS) in a substrate specific manner. Together, these results clearly establish branching of PNP degradation in strain SJ98. We propose that strain SJ98 presents a useful model system for future studies on evolution of microbial degradation of PNP.

Item Type: Article
Additional Information: his is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Subjects: Q Science > QR Microbiology
Depositing User: Dr. K.P.S.Sengar
Date Deposited: 29 Jan 2013 06:03
Last Modified: 08 Jan 2015 09:22
URI: http://crdd.osdd.net/open/id/eprint/1242

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