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Hemamali EH, Weerasinghe LP, Tanaka H, Kurisu G, Perera IC. LcaR: a regulatory switch from Pseudomonas aeruginosa for bioengineering alkane degrading bacteria. Biodegradation 2022; 33:117-133. [PMID: 34989928 DOI: 10.1007/s10532-021-09970-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 12/22/2021] [Indexed: 11/26/2022]
Abstract
Application of genetically engineered bacterial strains for biodegradation of hydrocarbons is a sustainable solution for treating pollutants as well as in industrial applications. However, the process of bioengineering should be carefully carried out to optimize the output. Investigation of regulatory genes for bioengineering is essential for developing synthetic circuits for effective biocatalysts. Here we focus on LcaR, a putative transcriptional regulator affecting the expression of alkB2 and lcaR operon that has a high potential to become a tool in designing such pathways. Four LcaR dimers bind specifically to the upstream regulatory region where divergent promoters of alkB2 and lcaR genes are located with high affinity at a Kd of 0.94 ± 0.17 nM and a Hill coefficient is 1.7 ± 0.3 demonstrating cooperativity in the association. Ligand binding alters the conformation of LcaR, which releases the regulator from its cognate DNA. Tetradecanal and hexadecanal act as natural ligands of LcaR with an IC50 values of 3.96 ± 0.59 µg/ml and 0.68 ± 0.21 µg/ml, respectively. The structure and function of transcription factors homologous to LcaR have not been characterized to date. This study provides insight into regulatory mechanisms of alkane degradation with a direction towards potential applications in bioengineering for bioremediation and industrial applications.
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Affiliation(s)
- Erandika H Hemamali
- Synthetic Biology Laboratory, Department of Zoology and Environment Sciences, Faculty of Science, University of Colombo, Colombo, Sri Lanka
| | - Laksiri P Weerasinghe
- Department of Chemistry, Faculty of Applied Science, University of Sri Jayewardenapura, Colombo, Sri Lanka
| | - Hideaki Tanaka
- Institute for Protein Research, Osaka University, Osaka, Japan
| | - Genji Kurisu
- Institute for Protein Research, Osaka University, Osaka, Japan
| | - Inoka C Perera
- Synthetic Biology Laboratory, Department of Zoology and Environment Sciences, Faculty of Science, University of Colombo, Colombo, Sri Lanka.
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Lin IC, Hussain B, Hsu BM, Chen JS, Hsu YL, Chiu YC, Huang SW, Wang JL. Prevalence, Genetic Diversity, Antimicrobial Resistance, and Toxigenic Profile of Vibrio vulnificus Isolated from Aquatic Environments in Taiwan. Antibiotics (Basel) 2021; 10:antibiotics10050505. [PMID: 33946739 PMCID: PMC8147101 DOI: 10.3390/antibiotics10050505] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 04/20/2021] [Accepted: 04/24/2021] [Indexed: 12/19/2022] Open
Abstract
Vibrio vulnificus is a gram-negative, opportunistic human pathogen associated with life-threatening wound infections and is commonly found in warm coastal marine water environments, globally. In this study, two fishing harbors and three tributaries of the river basin were analyzed for the prevalence of V. vulnificus in the water bodies and shellfish that are under the pressure of external pollutions. The average detection rate of V. vulnificus in the river basins and fishing harbors was 8.3% and 4.2%, respectively, in all seasons. A total of nine strains of V. vulnificus were isolated in pure cultures from 160 samples belonging to river basins and fishing harbors to analyze the antibiotic susceptibility, virulence gene profiles, and enterobacterial repetitive intergenic consensus PCR (ERIC-PCR) fingerprinting. All isolates were susceptible to 10 tested antibiotics. The genotypic characterization revealed that 11.1% (n = 1/9) strain was nonvirulent, whereas 88.9% (n = 8/9) isolates were virulent strains, which possessed the four most prevalent toxin genes such as vcgC (88.9%), 16S B (88.9%), vvhA (88.9%), and manIIA (88.9%), followed by nanA (77.8%), CPS1 (66.7), and PRXII (44.4%). Additionally, ERIC-PCR fingerprinting grouped these nine isolates into two main clusters, among which the river basin isolates showed genetically diverse profiles, suggesting multiple sources of V. vulnificus. Ultimately, this study highlighted the virulent strains of V. vulnificus in the coastal aquatic environments of Taiwan, harboring a potential risk of infection to human health through water-borne transmission.
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Affiliation(s)
- I-Ching Lin
- Department of Kinesiology, Health and Leisure, Chienkuo Technology University, Changhua City 500, Taiwan;
- Department of Family Medicine, Asia University Hospital, Taichung City 413, Taiwan
| | - Bashir Hussain
- Department of Earth and Environmental Sciences, National Chung Cheng University, Chiayi 621, Taiwan;
- Department of Biomedical Sciences, National Chung Cheng University, Chiayi 621, Taiwan
| | - Bing-Mu Hsu
- Department of Earth and Environmental Sciences, National Chung Cheng University, Chiayi 621, Taiwan;
- Center for Innovative on Aging Society (CIRAS), National Chung Cheng University, Chiayi 621, Taiwan
- Correspondence: ; Tel.: +886-5272-0411 (ext. 66218)
| | - Jung-Sheng Chen
- Department of Medical Research, E-Da Hospital, Kaohsiung City 824, Taiwan;
| | - Yu-Ling Hsu
- Department of Nuclear Medicine, Ditmanson Medical Foundation Chia-Yi Christian Hospital, Chiayi 600, Taiwan;
| | - Yi-Chou Chiu
- General Surgery, Surgical Department, Cheng Hsin General Hospital, Taipei 112, Taiwan;
| | - Shih-Wei Huang
- Center for Environmental Toxin and Emerging Contaminant Research, Cheng Shiu University, Kaohsiung City 833, Taiwan;
- Super Micro Research and Technology Center, Cheng Shiu University, Kaohsiung City 833, Taiwan
| | - Jiun-Ling Wang
- Department of Internal Medicine, National Cheng Kung University Hospital, Tainan 704, Taiwan;
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Deochand DK, Pande A, Meariman JK, Grove A. Redox Sensing by PecS from the Plant Pathogen Pectobacterium atrosepticum and Its Effect on Gene Expression and the Conformation of PecS-Bound Promoter DNA. Biochemistry 2019; 58:2564-2575. [PMID: 31046241 DOI: 10.1021/acs.biochem.9b00288] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The plant pathogen Pectobacterium atrosepticum encounters a stressful environment when it colonizes the plant apoplast. Chief among the stressors are the reactive oxygen species (ROS) that are produced by the host as a first line of defense. Bacterial transcription factors in turn use these signals as cues to upregulate expression of virulence-associated genes. We have previously shown that the transcription factor PecS from P. atrosepticum binds the promoters that drive expression of pecS and pecM, which encodes an efflux pump, to repress gene expression. We show here that addition of oxidant relieves repression in vivo and in vitro. While reduced PecS distorts promoter DNA on binding, oxidized PecS does not, as evidenced by DNaseI footprinting. PecS oxidation is reversible, as shown by an oxidant-dependent quenching of the intrinsic tryptophan fluorescence that is completely reversed upon addition of a reducing agent. Cysteine 45 positioned at the PecS dimer interface is the redox sensor. Reduced PecS-C45A causes less DNA distortion on binding compared to wild-type PecS; addition of an oxidant has no effect on binding, and PecS-C45A cannot repress gene expression. Our data suggest that reduced PecS distorts its cognate DNA on binding, perhaps inducing a conformation in which promoter elements are suboptimally aligned for RNA polymerase binding, resulting in transcriptional repression. In contrast, oxidized PecS binds promoter DNA such that RNA polymerase may successfully compete with PecS for binding, allowing gene expression. This mode of regulation would facilitate induction of the PecS regulon when the bacteria encounter host-derived ROS in the plant apoplast.
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Affiliation(s)
- Dinesh K Deochand
- Department of Biological Sciences , Louisiana State University , Baton Rouge , Louisiana 70803 , United States
| | - Anuja Pande
- Department of Biological Sciences , Louisiana State University , Baton Rouge , Louisiana 70803 , United States
| | - Jacob K Meariman
- Department of Biological Sciences , Louisiana State University , Baton Rouge , Louisiana 70803 , United States
| | - Anne Grove
- Department of Biological Sciences , Louisiana State University , Baton Rouge , Louisiana 70803 , United States
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