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Shah BA, Kasarlawar ST, Phale PS. Glucose-6-Phosphate Dehydrogenase, ZwfA, a Dual Cofactor-Specific Isozyme Is Predominantly Involved in the Glucose Metabolism of Pseudomonas bharatica CSV86 T. Microbiol Spectr 2022; 10:e0381822. [PMID: 36354357 PMCID: PMC9769727 DOI: 10.1128/spectrum.03818-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 10/12/2022] [Indexed: 11/12/2022] Open
Abstract
Glucose-6-phosphate dehydrogenase (Zwf) is an important enzyme in glucose metabolism via the Entner-Doudoroff pathway and the first enzyme in the oxidative pentose-phosphate pathway. It generates NAD(P)H during the conversion of glucose-6-phosphate (G6P) to 6-phosphogluconolactone, thus aiding in anabolic processes, energy yield, and oxidative stress responses. Pseudomonas bharatica CSV86T preferentially utilized aromatic compounds over glucose and exhibited a significantly lower growth rate on glucose (0.24 h-1) with a prolonged lag phase (~10 h). In strain CSV86T, glucose was metabolized via the intracellular phosphorylative route only because it lacked an oxidative (gluconate and 2-ketogluconate) route. The genome harbored three genes zwfA, zwfB, and zwfC encoding three Zwf isozymes. The present study aimed to understand gene arrangement, gene expression profiling, and molecular and kinetic properties of the purified enzymes to unveil their physiological significance in the strain CSV86T. The zwfA was found to be a part of the zwfA-pgl-eda operon, which was proximal to other glucose transport and metabolic clusters. The zwfB was found to be arranged as a gnd-zwfB operon, while zwfC was present independently. Among the three, zwfA was transcribed maximally, and the purified ZwfA displayed the highest catalytic efficiency, cooperativity with respect to G6P, and dual cofactor specificity. Isozymes ZwfB and ZwfC were NADP+-preferring and NADP+-specific, respectively. Among other functionally characterized Zwfs, ZwfA from strain CSV86T displayed poor catalytic efficiency and the further absence of oxidative routes of glucose metabolism reflected its lower growth rate on glucose compared to P. putida KT2440 and could be probable reasons for the unique carbon source utilization hierarchy. IMPORTANCE Pseudomonas bharatica CSV86T metabolizes glucose exclusively via the intracellular phosphorylative Entner-Doudoroff pathway leading the entire glucose flux through Zwf as the strain lacks oxidative routes. This may lead to limiting the concentration of downstream metabolic intermediates. The strain CSV86T possesses three isoforms of glucose-6-phosphate dehydrogenase, ZwfA, ZwfB, and ZwfC. The expression profile and kinetic properties of purified enzymes will help to understand glucose metabolism. Isozyme ZwfA dominated in terms of expression and displayed cooperativity with dual cofactor specificity. ZwfB preferred NADP+, and ZwfC was NADP+ specific, which may aid in redox cofactor balance. Such beneficial metabolic flexibility facilitated the regulation of metabolic pathways giving survival/fitness advantages in dynamic environments. Additionally, multiple genes allowed the distribution of function among these isoforms where the primary function was allocated to one of the isoforms.
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Affiliation(s)
- Bhavik A. Shah
- Department of Biosciences and Bioengineering, Indian Institute of Technology-Mumbai, Mumbai, India
| | - Sravanti T. Kasarlawar
- Department of Biosciences and Bioengineering, Indian Institute of Technology-Mumbai, Mumbai, India
| | - Prashant S. Phale
- Department of Biosciences and Bioengineering, Indian Institute of Technology-Mumbai, Mumbai, India
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Dhamale T, Saha BK, Papade SE, Singh S, Phale PS. A unique global metabolic trait of Pseudomonas bharatica CSV86 T: metabolism of aromatics over simple carbon sources and co-metabolism with organic acids. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 35925665 DOI: 10.1099/mic.0.001206] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Hierarchical utilization of substrate by microbes (utilization of simple carbon sources prior to complex ones) poses a major limitation to the efficient remediation of aromatic pollutants. Aromatic compounds, being complex and reduced in nature, appear to be a deferred choice as the carbon source in the presence of a plethora of simple organic compounds in the environment. The soil bacterium Pseudomonas bharatica CSV86T displays a unique carbon source utilization hierarchy. It preferentially utilizes aromatics over glucose and co-metabolizes them with succinate or pyruvate (Basu et al., 2006, Applied and Environmental Microbiology, 72 : 22226-2230). In the present study, the substrate utilization hierarchy for strain CSV86T was tested for additional simple carbon sources such as glycerol, acetate, and tri-carboxylic acid (TCA) cycle intermediates like α-ketoglutarate and fumarate. When grown on a mixture of aromatics (benzoate or naphthalene) plus glycerol, the strain displayed a diauxic growth profile with significantly high activity of aromatic utilization enzymes (catechol 1,2- or 2,3-dioxygenase, respectively) in the first-log phase. This suggests utilization of aromatics in the first-log phase followed by glycerol in the second-log phase. On a mixture of an aromatic plus organic acid (acetate, α-ketoglutarate or fumarate), the strain displayed a monoauxic growth profile, indicating co-metabolism. Interestingly, the presence of glycerol, acetate, α-ketoglutarate or fumarate does not repress metabolism/utilization of the aromatic. Thus, the substrate utilization hierarchy of strain CSV86T is aromatics=organic acids>glucose/glycerol, which is unique as compared to other Pseudomonas species, where degradation of aromatics is repressed by glycerol, glucose, acetate or organic acids, including TCA cycle intermediates. This novel substrate utilization hierarchy appears to be a global metabolic phenomenon in strain CSV86T, thus implying it to be an ideal host for metabolic engineering as well as for its potential application in bioremediation.
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Affiliation(s)
- Tushar Dhamale
- Department of Biosciences and Bioengineering, Indian Institute of Technology-Bombay, Powai, Mumbai 400 076, India
| | - Braja Kishor Saha
- Department of Biosciences and Bioengineering, Indian Institute of Technology-Bombay, Powai, Mumbai 400 076, India
| | - Sandesh E Papade
- Department of Biosciences and Bioengineering, Indian Institute of Technology-Bombay, Powai, Mumbai 400 076, India
| | - Srushti Singh
- Department of Biosciences and Bioengineering, Indian Institute of Technology-Bombay, Powai, Mumbai 400 076, India.,Present address: Presently affiliated to TCR Therapeutics, Inc., 100 Binney Street, Cambridge, MA 02142, USA
| | - Prashant S Phale
- Department of Biosciences and Bioengineering, Indian Institute of Technology-Bombay, Powai, Mumbai 400 076, India
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Mohapatra B, Nain S, Sharma R, Phale PS. Functional genome mining and taxono-genomics reveal eco-physiological traits and species distinctiveness of aromatic-degrading Pseudomonas bharatica sp. nov. ENVIRONMENTAL MICROBIOLOGY REPORTS 2022; 14:464-474. [PMID: 35388632 DOI: 10.1111/1758-2229.13066] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 03/24/2022] [Accepted: 03/25/2022] [Indexed: 06/14/2023]
Abstract
Assistive eco-physiological traits are necessary for microbes to adapt and colonize at polluted niches, enabling efficient clean-up. To demarcate species distinctiveness and eco-physiological traits of aromatic compounds metabolizing Pseudomonas sp. CSV86T (earlier identified as Pseudomonas putida), an Indian isolate from a petrol station soil, comparative genome mining, taxono-genomic, and physiological analyses were performed. A 6.79 Mbp genome (62.72 G + C mol%) of CSV86T encodes 6798 CDS and 238 unique genes. Naphthalene metabolism and Co-Zn-Cd resistance gene clusters were part of distinct genomic islands. Abundance of transporters (aromatics, organic acids, amino acids, and metals) and mobile elements (integrases, transposases, conjugative proteins) differentiated CSV86T from its closest relatives. Enhanced siderophore production for Fe-uptake during aromatic metabolism, indole acetic acid production, and fusaric acid resistance wasvalidated by genomic attributes. Full-length 16S-rRNA phylogeny revealed Pseudomonas japonica WLT as a closest relative of CSV86T . However, lower genomic indices (<97% gyrB-rpoB-rpoD homology, <90% ANI, <50% DNA-DNA relatedness) and taxonomic differences (assimilation of organic acids, amino acids, fatty acids composition) substantially differentiated CSV86T from its closest relatives, indicating it to be a novel species as Pseudomonas bharatica. Preferential metabolism of aromatics with advantageous eco-physiological traits renders CSV86T an ideal candidate for bioremediation and host for metabolic engineering.
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Affiliation(s)
- Balaram Mohapatra
- Department of Biosciences and Bioengineering, Indian Institute of Technology-Bombay, Powai, Mumbai, Maharashtra, India
| | - Sonam Nain
- Microbial Biotechnology and Genomics, Institute of Genomics and Integrative Biology, Council of Scientific and Industrial Research (CSIR), Delhi, India
| | - Rakesh Sharma
- Microbial Biotechnology and Genomics, Institute of Genomics and Integrative Biology, Council of Scientific and Industrial Research (CSIR), Delhi, India
| | - Prashant S Phale
- Department of Biosciences and Bioengineering, Indian Institute of Technology-Bombay, Powai, Mumbai, Maharashtra, India
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Phale PS, Mohapatra B, Malhotra H, Shah BA. Eco-physiological portrait of a novel Pseudomonas sp. CSV86: an ideal host/candidate for metabolic engineering and bioremediation. Environ Microbiol 2021; 24:2797-2816. [PMID: 34347343 DOI: 10.1111/1462-2920.15694] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Revised: 07/27/2021] [Accepted: 07/28/2021] [Indexed: 11/30/2022]
Abstract
Pseudomonas sp. CSV86, an Indian soil isolate, degrades wide range of aromatic compounds like naphthalene, benzoate and phenylpropanoids, amongst others. Isolate displays the unique and novel property of preferential utilization of aromatics over glucose and co-metabolizes them with organic acids. Interestingly, as compared to other Pseudomonads, strain CSV86 harbours only high-affinity glucokinase pathway (and absence of low-affinity oxidative route) for glucose metabolism. Such lack of gluconate loop might be responsible for the novel phenotype of preferential utilization of aromatics. The genome analysis and comparative functional mining indicated a large genome (6.79 Mb) with significant enrichment of regulators, transporters as well as presence of various secondary metabolite production clusters, suggesting its eco-physiological and metabolic versatility. Strain harbours various integrative conjugative elements (ICEs) and genomic islands, probably acquired through horizontal gene transfer events, leading to genome mosaicity and plasticity. Naphthalene degradation genes are arranged as regulonic clusters and found to be part of ICECSV86nah . Various eco-physiological properties and absence of major pathogenicity and virulence factors (risk group-1) in CSV86 suggest it to be an ideal candidate for bioremediation. Further, strain can serve as an ideal chassis for metabolic engineering to degrade various xenobiotics preferentially over simple carbon sources for efficient remediation.
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Affiliation(s)
- Prashant S Phale
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Mumbai, Maharashtra, 400076, India
| | - Balaram Mohapatra
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Mumbai, Maharashtra, 400076, India
| | - Harshit Malhotra
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Mumbai, Maharashtra, 400076, India
| | - Bhavik A Shah
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Mumbai, Maharashtra, 400076, India
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Phale PS, Malhotra H, Shah BA. Degradation strategies and associated regulatory mechanisms/features for aromatic compound metabolism in bacteria. ADVANCES IN APPLIED MICROBIOLOGY 2020; 112:1-65. [PMID: 32762865 DOI: 10.1016/bs.aambs.2020.02.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
As a result of anthropogenic activity, large number of recalcitrant aromatic compounds have been released into the environment. Consequently, microbial communities have adapted and evolved to utilize these compounds as sole carbon source, under both aerobic and anaerobic conditions. The constitutive expression of enzymes necessary for metabolism imposes a heavy energy load on the microbe which is overcome by arrangement of degradative genes as operons which are induced by specific inducers. The segmentation of pathways into upper, middle and/or lower operons has allowed microbes to funnel multiple compounds into common key aromatic intermediates which are further metabolized through central carbon pathway. Various proteins belonging to diverse families have evolved to regulate the transcription of individual operons participating in aromatic catabolism. These proteins, complemented with global regulatory mechanisms, carry out the regulation of aromatic compound metabolic pathways in a concerted manner. Additionally, characteristics like chemotaxis, preferential utilization, pathway compartmentalization and biosurfactant production confer an advantage to the microbe, thus making bioremediation of the aromatic pollutants more efficient and effective.
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Affiliation(s)
- Prashant S Phale
- Department of Biosciences and Bioengineering, Indian Institute of Technology-Bombay, Mumbai, India.
| | - Harshit Malhotra
- Department of Biosciences and Bioengineering, Indian Institute of Technology-Bombay, Mumbai, India
| | - Bhavik A Shah
- Department of Biosciences and Bioengineering, Indian Institute of Technology-Bombay, Mumbai, India
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