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Nitrophenol monooxygenase RsPNPA from Rhodococcus sp. 21391
Structural highlights
FunctionNPCA_RHOOP Involved in the degradation of para-nitrophenol (4-NP). Catalyzes both the initial hydroxylation of 4-NP to produce 4-nitrocatechol (4-NCA) and the subsequent oxidative release of the nitro group from 4-NCA to produce 2-hydroxy-1,4-benzoquinone. It can also use 4-nitroresorcinol as substrate with a rate of nitrite release similar to that observed with the two physiological substrates, 4-PN and 4-NCA.[1] [2] Publication Abstract from PubMedBACKGROUND: Bioremediation relying on highly efficient degrading bacteria constitutes a promising and sustainable avenue for controlling and reducing nitrophenol contamination in the environment. A thorough understanding of the bacterial degradation mechanism of nitrophenol is of paramount importance for supporting the development of efficient microbial remediation technology. RESULTS: In this study, a new bacterium, Rhodococcus sp. 21391, endowed with superior p-nitrophenol (PNP) degradation ability was obtained. Genomic and comparative proteomic analyses revealed that it utilizes the 1,2,4-benzenetriol (BT) pathway for PNP degradation. The catalytic properties of the two-component p-nitrophenol monooxygenase RsNcpAB from the strain were investigated in vitro. The enzyme exhibited a broad substrate selectivity, catalyzing the oxidation of various nitrophenols and halogenated phenols, with significant potential for further research and development. Additionally, the crystal structure of the oxidative component of p-nitrophenol monooxygenase, RsNcpA, was determined. Structural analysis and site-directed mutagenesis revealed that residues Arg100 and His293 in the active site play a crucial role in enzyme catalysis, and a catalytic mechanism model was subsequently proposed. CONCLUSIONS: This study reports a high-performance nitrophenol-degrading bacterium and enzyme, and reveals their mechanisms at the molecular level. These findings increase the understanding of the bacterial degradation of nitrophenol, thereby providing a crucial foundation for the development of efficient bioremediation technologies. Biodegradation of p-nitrophenol by Rhodococcus sp. 21391 unveils a two-component p-nitrophenol monooxygenase with broad substrate specificity.,Yang J, Lin S, Li W, Wang X, Li R Microb Cell Fact. 2025 Apr 17;24(1):85. doi: 10.1186/s12934-025-02712-1. PMID:40247276[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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