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Tec-Campos D, Posadas C, Tibocha-Bonilla JD, Thiruppathy D, Glonek N, Zuñiga C, Zepeda A, Zengler K. The genome-scale metabolic model for the purple non-sulfur bacterium Rhodopseudomonas palustris Bis A53 accurately predicts phenotypes under chemoheterotrophic, chemoautotrophic, photoheterotrophic, and photoautotrophic growth conditions. PLoS Comput Biol 2023; 19:e1011371. [PMID: 37556472 PMCID: PMC10441798 DOI: 10.1371/journal.pcbi.1011371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 08/21/2023] [Accepted: 07/18/2023] [Indexed: 08/11/2023] Open
Abstract
The purple non-sulfur bacterium Rhodopseudomonas palustris is recognized as a critical microorganism in the nitrogen and carbon cycle and one of the most common members in wastewater treatment communities. This bacterium is metabolically extremely versatile. It is capable of heterotrophic growth under aerobic and anaerobic conditions, but also able to grow photoautotrophically as well as mixotrophically. Therefore R. palustris can adapt to multiple environments and establish commensal relationships with other organisms, expressing various enzymes supporting degradation of amino acids, carbohydrates, nucleotides, and complex polymers. Moreover, R. palustris can degrade a wide range of pollutants under anaerobic conditions, e.g., aromatic compounds such as benzoate and caffeate, enabling it to thrive in chemically contaminated environments. However, many metabolic mechanisms employed by R. palustris to breakdown and assimilate different carbon and nitrogen sources under chemoheterotrophic or photoheterotrophic conditions remain unknown. Systems biology approaches, such as metabolic modeling, have been employed extensively to unravel complex mechanisms of metabolism. Previously, metabolic models have been reconstructed to study selected capabilities of R. palustris under limited experimental conditions. Here, we developed a comprehensive metabolic model (M-model) for R. palustris Bis A53 (iDT1294) consisting of 2,721 reactions, 2,123 metabolites, and comprising 1,294 genes. We validated the model using high-throughput phenotypic, physiological, and kinetic data, testing over 350 growth conditions. iDT1294 achieved a prediction accuracy of 90% for growth with various carbon and nitrogen sources and close to 80% for assimilation of aromatic compounds. Moreover, the M-model accurately predicts dynamic changes of growth and substrate consumption rates over time under nine chemoheterotrophic conditions and demonstrated high precision in predicting metabolic changes between photoheterotrophic and photoautotrophic conditions. This comprehensive M-model will help to elucidate metabolic processes associated with the assimilation of multiple carbon and nitrogen sources, anoxygenic photosynthesis, aromatic compound degradation, as well as production of molecular hydrogen and polyhydroxybutyrate.
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Affiliation(s)
- Diego Tec-Campos
- Facultad de Ingeniería Química, Universidad Autónoma de Yucatán, Mérida, Yucatán, México
- Department of Pediatrics, University of California, San Diego, La Jolla, California, United States of America
| | - Camila Posadas
- Facultad de Ingeniería Química, Universidad Autónoma de Yucatán, Mérida, Yucatán, México
| | - Juan D. Tibocha-Bonilla
- Bioinformatics and Systems Biology Graduate Program, University of California, San Diego, La Jolla, California, United States of America
| | - Deepan Thiruppathy
- Department of Pediatrics, University of California, San Diego, La Jolla, California, United States of America
- Department of Bioengineering, University of California, San Diego, La Jolla California, United States of America
| | - Nathan Glonek
- Department of Pediatrics, University of California, San Diego, La Jolla, California, United States of America
| | - Cristal Zuñiga
- Department of Pediatrics, University of California, San Diego, La Jolla, California, United States of America
| | - Alejandro Zepeda
- Facultad de Ingeniería Química, Universidad Autónoma de Yucatán, Mérida, Yucatán, México
| | - Karsten Zengler
- Department of Pediatrics, University of California, San Diego, La Jolla, California, United States of America
- Department of Bioengineering, University of California, San Diego, La Jolla California, United States of America
- Center for Microbiome Innovation, University of California, San Diego, La Jolla, California, United States of America
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Brown B, Wilkins M, Saha R. Rhodopseudomonas palustris: A biotechnology chassis. Biotechnol Adv 2022; 60:108001. [PMID: 35680002 DOI: 10.1016/j.biotechadv.2022.108001] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 05/18/2022] [Accepted: 06/01/2022] [Indexed: 11/26/2022]
Abstract
Rhodopseudomonas palustris is an attractive option for biotechnical applications and industrial engineering due to its metabolic versatility and its ability to catabolize a wide variety of feedstocks and convert them to several high-value products. Given its adaptable metabolism, R. palustris has been studied and applied in an extensive variety of applications such as examining metabolic tradeoffs for environmental perturbations, biodegradation of aromatic compounds, environmental remediation, biofuel production, agricultural biostimulation, and bioelectricity production. This review provides a holistic summary of the commercial applications for R. palustris as a biotechnology chassis and suggests future perspectives for research and engineering.
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Affiliation(s)
- Brandi Brown
- Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln, NE 68583, USA
| | - Mark Wilkins
- Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln, NE 68583, USA; Industrial Agricultural Products Center, University of Nebraska-Lincoln, Lincoln, NE 68583, USA; Department of Food Science and Technology, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - Rajib Saha
- Department of Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588, USA.
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Thioredoxin Reductase-Type Ferredoxin: NADP+ Oxidoreductase of Rhodopseudomonas palustris: Potentiometric Characteristics and Reactions with Nonphysiological Oxidants. Antioxidants (Basel) 2022; 11:antiox11051000. [PMID: 35624864 PMCID: PMC9137726 DOI: 10.3390/antiox11051000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 05/15/2022] [Accepted: 05/17/2022] [Indexed: 11/17/2022] Open
Abstract
Rhodopseudomonas palustris ferredoxin:NADP+ oxidoreductase (RpFNR) belongs to a novel group of thioredoxin reductase-type FNRs with partly characterized redox properties. Based on the reactions of RpFNR with the 3-acetylpyridine adenine dinucleotide phosphate redox couple, we estimated the two-electron reduction midpoint potential of the FAD cofactor to be −0.285 V. 5-Deaza-FMN-sensitized photoreduction revealed −0.017 V separation of the redox potentials between the first and second electron transfer events. We examined the mechanism of oxidation of RpFNR by several different groups of nonphysiological electron acceptors. The kcat/Km values of quinones and aromatic N-oxides toward RpFNR increase with their single-electron reduction midpoint potential. The lower reactivity, mirroring their lower electron self-exchange rate, is also seen to have a similar trend for nitroaromatic compounds. A mixed single- and two-electron reduction was characteristic of quinones, with single-electron reduction accounting for 54% of the electron flux, whereas nitroaromatics were reduced exclusively via single-electron reduction. It is highly possible that the FADH· to FAD oxidation reaction is the rate-limiting step during the reoxidation of reduced FAD. The calculated electron transfer distances in the reaction with quinones and nitroaromatics were close to those of Anabaena and Plasmodium falciparum FNRs, thus demonstrating their similar “intrinsic” reactivity.
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