Next Article in Journal
Graphene-Based Sensing Platform for On-Chip Ochratoxin A Detection
Next Article in Special Issue
In Vivo Evaluation of the Chronic Oral Toxicity of the Marine Toxin Palytoxin
Previous Article in Journal
Fumonisins at Doses below EU Regulatory Limits Induce Histological Alterations in Piglets
Previous Article in Special Issue
Prodigiosin Promotes Nrf2 Activation to Inhibit Oxidative Stress Induced by Microcystin-LR in HepG2 Cells
Article

Cloning and Expression of Genes for Biodegrading Nodularin by Sphingopyxis sp. USTB-05

1
School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, China
2
School of Architectural and Surveying & Mapping Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, China
*
Author to whom correspondence should be addressed.
Received: 11 August 2019 / Revised: 16 September 2019 / Accepted: 17 September 2019 / Published: 20 September 2019
(This article belongs to the Collection Toxicological Challenges of Aquatic Toxins)
Biodegradation is efficient for removing cyanobacterial toxins, such as microcystins (MCs) and nodularin (NOD). However, not all the microbial strains with the microcystin-biodegrading enzymes MlrA and MlrC could biodegrade NOD. Studies on genes and enzymes for biodegrading NOD can reveal the function and the biodegradation pathway of NOD. Based on successful cloning and expression of the USTB-05-A and USTB-05-C genes from Sphingopyxis sp. USTB-05, which are responsible for the biodegradation of MCs, the pathway for biodegrading NOD by these two enzymes was investigated in this study. The findings showed that the enzyme USTB-05-A converted cyclic NOD (m/z 825.4516) into its linear type as the first product by hydrolyzing the arginine and Adda peptide bond, and that USTB-05-C cut off the Adda and glutamic acid peptide bond of linearized NOD (m/z 843.4616) and produced dimeric Adda (m/z 663.4377) as the second product. Further, based on the homology modeling of enzyme USTB-05-A, site-directed mutants of USTB-05-A were constructed and seven crucial sites for enzyme USTB-05-A activity were found. A complete enzymatic mechanism for NOD biodegradation by USTB-05-A in the first step was proposed: glutamic acid 172 and histidine 205 activate a water molecule facilitating a nucleophilic attack on the arginine and Adda peptide bond of NOD; tryptophan 176 and tryptophan 201 contact the carboxylate side chain of glutamic acid 172 and accelerate the reaction rates; and histidine 260 and asparagine 264 function as an oxyanion hole to stabilize the transition states. View Full-Text
Keywords: nodularin; biodegradation; pathway; mlrA; enzyme; activity site nodularin; biodegradation; pathway; mlrA; enzyme; activity site
Show Figures

Figure 1

MDPI and ACS Style

Xu, Q.; Ma, H.; Fan, J.; Yan, H.; Zhang, H.; Yin, C.; Liu, X.; Liu, Y.; Wang, H. Cloning and Expression of Genes for Biodegrading Nodularin by Sphingopyxis sp. USTB-05. Toxins 2019, 11, 549. https://0-doi-org.brum.beds.ac.uk/10.3390/toxins11100549

AMA Style

Xu Q, Ma H, Fan J, Yan H, Zhang H, Yin C, Liu X, Liu Y, Wang H. Cloning and Expression of Genes for Biodegrading Nodularin by Sphingopyxis sp. USTB-05. Toxins. 2019; 11(10):549. https://0-doi-org.brum.beds.ac.uk/10.3390/toxins11100549

Chicago/Turabian Style

Xu, Qianqian, Hongfei Ma, Jinhui Fan, Hai Yan, Haiyang Zhang, Chunhua Yin, Xiaolu Liu, Yang Liu, and Huasheng Wang. 2019. "Cloning and Expression of Genes for Biodegrading Nodularin by Sphingopyxis sp. USTB-05" Toxins 11, no. 10: 549. https://0-doi-org.brum.beds.ac.uk/10.3390/toxins11100549

Find Other Styles
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Back to TopTop