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Tsegaye K, Tsehai BA, Getie B. Desirable L-asparaginases for treating cancer and current research trends. Front Microbiol 2024; 15:1269282. [PMID: 38591038 PMCID: PMC11001194 DOI: 10.3389/fmicb.2024.1269282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Accepted: 02/20/2024] [Indexed: 04/10/2024] Open
Abstract
Amino acid depletion therapy is a promising approach for cancer treatment. It exploits the differences in the metabolic processes between healthy and cancerous cells. Certain microbial enzymes induce cancer cell apoptosis by removing essential amino acids. L-asparaginase is an enzyme approved by the FDA for the treatment of acute lymphoblastic leukemia. The enzymes currently employed in clinics come from two different sources: Escherichia coli and Erwinia chrysanthemi. Nevertheless, the search for improved enzymes and other sources continues because of several factors, including immunogenicity, in vivo instability, and protease degradation. Before determining whether L-asparaginase is clinically useful, research should consider the Michaelis constant, turnover number, and maximal velocity. The identification of L-asparaginase from microbial sources has been the subject of various studies. The primary goals of this review are to explore the most current approaches used in the search for therapeutically useful L-asparaginases and to establish whether these investigations identified the crucial characteristics of L-asparaginases before declaring their therapeutic potential.
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Affiliation(s)
- Kindu Tsegaye
- Department of Industrial Biotechnology, Institute of Biotechnology, University of Gondar, Gondar, Ethiopia
| | | | - Birhan Getie
- Department of Industrial Biotechnology, Institute of Biotechnology, University of Gondar, Gondar, Ethiopia
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Darnal S, Raj R, Chhimwal J, Thakur S, Padwad YS, Singh D. Apoptosis and cell cycle arrest of leukemic cells by a robust and stable L-asparaginase from Pseudomonas sp. PCH199. Int J Biol Macromol 2024; 258:128739. [PMID: 38096943 DOI: 10.1016/j.ijbiomac.2023.128739] [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: 02/10/2023] [Revised: 11/07/2023] [Accepted: 12/09/2023] [Indexed: 12/23/2023]
Abstract
Biomolecules obtained from microorganisms living in extreme environments possess properties that have pharmacokinetic advantages. Enzyme assay revealed recombinant L-ASNase, an extremozyme from Pseudomonas sp. PCH199 is to be highly stable with 90 % activity (200 h) at 37 °C. The stability of the enzyme in human serum (50 % activity maintained in 63 h) reveals high therapeutic potential with less dosage. The enzyme exhibited cytotoxicity to K562 blood cancer cell lines with IC50 of 0.37 U/mL without affecting the IEC-6 normal epithelial cell line. Due to the depletion of L-asparagine, K562 cells experience nutritional stress that results in the abruption of metabolic processes and eventually leads to apoptosis. Comparative studies on MCF-7 cells also revealed the same fate. Due to nutritional stress induced by L-ASNase treatment, mitochondrial membrane potential was lost, and reactive oxygen species were increased to 48 % (K562) and 21 % (MCF-7) as indicated by flow cytometric analysis. DAPI staining with prominent nuclear morphological changes visualized under the fluorescent microscope confirmed apoptosis in both cancer cells. Treatment increases pro-apoptotic Bax protein, and eventually, the cell cycle is arrested at the G2/M phase in both cell lines. Therefore, the current study paves the way for PCH199 L-ASNase to be considered a potential chemotherapeutic agent for treating acute lymphoblastic leukemia.
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Affiliation(s)
- Sanyukta Darnal
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh 176 061, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201 002, India
| | - Ravi Raj
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh 176 061, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201 002, India
| | - Jyoti Chhimwal
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201 002, India; Dietetics & Nutrition Technology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh 176 061, India
| | - Shubham Thakur
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh 176 061, India
| | - Yogendra S Padwad
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201 002, India; Dietetics & Nutrition Technology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh 176 061, India.
| | - Dharam Singh
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh 176 061, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201 002, India.
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Patial V, Kumar S, Joshi R, Singh D. Biochemical characterization of glutaminase-free L-asparaginases from Himalayan Pseudomonas and Rahnella spp. for acrylamide mitigation. Int J Biol Macromol 2024; 257:128576. [PMID: 38048933 DOI: 10.1016/j.ijbiomac.2023.128576] [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: 07/07/2023] [Revised: 11/20/2023] [Accepted: 12/01/2023] [Indexed: 12/06/2023]
Abstract
L-asparaginase having low glutaminase activity is important in clinical and food applications. Herein, glutaminase-free L-asparaginase (type I) coding genes from Pseudomonas sp. PCH182 (Ps-ASNase I) and Rahnella sp. PCH162 (Rs-ASNase I) was amplified using gene-specific primers, cloned into a pET-47b(+) vector, and plasmids were transformed into Escherichia coli (E. coli). Further, affinity chromatography purified recombinant proteins to homogeneity with monomer sizes of ~37.0 kDa. Purified Ps-ASNase I and Rs-ASNase I were active at wide pHs and temperatures with optimum activity at 50 °C (492 ± 5 U/mg) and 37 °C (308 ± 4 U/mg), respectively. Kinetic constant Km and Vmax for L-asparagine (Asn) were 2.7 ± 0.06 mM and 526.31 ± 4.0 U/mg for Ps-ASNase I, and 4.43 ± 1.06 mM and 434.78 ± 4.0 U/mg for Rs-ASNase I. Circular dichroism study revealed 29.3 % and 24.12 % α-helix structures in Ps-ASNase I and Rs-ASNase I, respectively. Upon their evaluation to mitigate acrylamide formation, 43 % and 34 % acrylamide (AA) reduction were achieved after pre-treatment of raw potato slices, consistent with 65 % and 59 % Asn reduction for Ps-ASNase I and Rs-ASNase I, respectively. Current findings suggested the potential of less explored intracellular L-asparaginase in AA mitigation for food safety.
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Affiliation(s)
- Vijeta Patial
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur 176 061, Himachal Pradesh, India; Academy of Scientific & Innovative Research (AcSIR), Ghaziabad 201 002, India
| | - Subhash Kumar
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur 176 061, Himachal Pradesh, India; Academy of Scientific & Innovative Research (AcSIR), Ghaziabad 201 002, India
| | - Robin Joshi
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur 176 061, Himachal Pradesh, India
| | - Dharam Singh
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur 176 061, Himachal Pradesh, India; Academy of Scientific & Innovative Research (AcSIR), Ghaziabad 201 002, India.
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Kumar V, Patial V, Thakur V, Singh R, Singh D. Genomics assisted characterization of plant growth-promoting and metabolite producing psychrotolerant Himalayan Chryseobacterium cucumeris PCH239. Arch Microbiol 2023; 205:108. [PMID: 36884102 DOI: 10.1007/s00203-023-03456-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 02/13/2023] [Accepted: 02/26/2023] [Indexed: 03/09/2023]
Abstract
Here, we report the first complete genome of a psychrotolerant and yellow-pigmented rhizobacteria Chryseobacterium cucumeris PCH239. It was obtained from the rhizospheric soil of the Himalayan plant Bergenia ciliata. The genome consists of a single contig (5.098 Mb), 36.3% G + C content, and 4899 genes. The cold adaptation, stress response, and DNA repair genes promote survivability in a high-altitude environment. PCH239 grows in temperature (10-37 °C), pH (6.0-8.0), and NaCl (2.0%). The genome derived plant growth-promoting activities of siderophore production (siderophore units 53 ± 0.6), phosphate metabolism (PSI 5.0 ± 0.8), protease, indole acetic acid production (17.3 ± 0.5 µg/ml), and ammonia (2.89 ± 0.4 µmoles) were experimentally validated. Interestingly, PCH239 treatment of Arabidopsis seeds significantly enhances germination, primary, and hairy root growth. In contrast, Vigna radiata and Cicer arietinum seeds had healthy radicle and plumule elongation, suggesting varied plant growth-promotion effects. Our findings suggested the potential of PCH239 as a bio-fertilizer and biocontrol agent in the challenging conditions of cold and hilly regions.
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Affiliation(s)
- Virender Kumar
- Molecular and Microbial Genetics Lab, Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Post Box No. 6, Palampur, Himachal Pradesh, 176061, India
| | - Vijeta Patial
- Molecular and Microbial Genetics Lab, Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Post Box No. 6, Palampur, Himachal Pradesh, 176061, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Vikas Thakur
- Molecular and Microbial Genetics Lab, Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Post Box No. 6, Palampur, Himachal Pradesh, 176061, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Ravinder Singh
- Molecular and Microbial Genetics Lab, Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Post Box No. 6, Palampur, Himachal Pradesh, 176061, India
| | - Dharam Singh
- Molecular and Microbial Genetics Lab, Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Post Box No. 6, Palampur, Himachal Pradesh, 176061, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India.
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Darnal S, Patial V, Kumar V, Kumar S, Kumar V, Padwad YS, Singh D. Biochemical characterization of extremozyme L-asparaginase from Pseudomonas sp. PCH199 for therapeutics. AMB Express 2023; 13:22. [PMID: 36828987 PMCID: PMC9958223 DOI: 10.1186/s13568-023-01521-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 01/25/2023] [Indexed: 02/26/2023] Open
Abstract
L-asparaginase (L-ASNase) from microbial sources is a commercially vital enzyme to treat acute lymphoblastic leukemia. However, the side effects associated with the commercial formulations of L-ASNases intrigued to explore for efficient and desired pharmacological enzymatic features. Here, we report the biochemical and cytotoxic evaluation of periplasmic L-ASNase of Pseudomonas sp. PCH199 isolated from the soil of Betula utilis, the Himalayan birch. L-ASNase production from wild-type PCH199 was enhanced by 2.2-fold using the Response Surface Methodology (RSM). Increased production of periplasmic L-ASNase was obtained using an optimized osmotic shock method followed by its purification. The purified L-ASNase was a monomer of 37.0 kDa with optimum activity at pH 8.5 and 60 ℃. It also showed thermostability retaining 100.0% (200 min) and 90.0% (70 min) of the activity at 37 and 50 ℃, respectively. The Km and Vmax values of the purified enzyme were 0.164 ± 0.009 mM and 54.78 ± 0.4 U/mg, respectively. L-ASNase was cytotoxic to the K562 blood cancer cell line (IC50 value 0.309 U/mL) within 24 h resulting in apoptotic nuclear morphological changes as examined by DAPI staining. Therefore, the dynamic functionality in a wide range of pH and temperature and stability of PCH199 L-ASNase at 37 ℃ with cytotoxic potential proves to be pharmaceutically important for therapeutic application.
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Affiliation(s)
- Sanyukta Darnal
- grid.417640.00000 0004 0500 553XMolecular and Microbial Genetics Lab, Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh 176 061 India ,grid.469887.c0000 0004 7744 2771Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201 002 India
| | - Vijeta Patial
- grid.417640.00000 0004 0500 553XMolecular and Microbial Genetics Lab, Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh 176 061 India ,grid.469887.c0000 0004 7744 2771Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201 002 India
| | - Virender Kumar
- grid.417640.00000 0004 0500 553XMolecular and Microbial Genetics Lab, Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh 176 061 India
| | - Subhash Kumar
- grid.417640.00000 0004 0500 553XMolecular and Microbial Genetics Lab, Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh 176 061 India ,grid.469887.c0000 0004 7744 2771Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201 002 India
| | - Vijay Kumar
- grid.417640.00000 0004 0500 553XMolecular and Microbial Genetics Lab, Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh 176 061 India
| | - Yogendra S. Padwad
- grid.469887.c0000 0004 7744 2771Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201 002 India ,grid.417640.00000 0004 0500 553XDietetics & Nutrition Technology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh 176 061 India
| | - Dharam Singh
- Molecular and Microbial Genetics Lab, Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh, 176 061, India. .,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201 002, India.
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Molecular Characterization of a Stable and Robust L-Asparaginase from Pseudomonas sp. PCH199: Evaluation of Cytotoxicity and Acrylamide Mitigation Potential. FERMENTATION-BASEL 2022. [DOI: 10.3390/fermentation8100568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
L-asparaginase is an important industrial enzyme widely used to treat acute lymphoblastic leukemia (ALL) and to reduce acrylamide formation in food products. In the current study, a stable and robust L-asparaginase from Pseudomonas sp. PCH199, with a high affinity for L-asparagine, was cloned and expressed in Escherichia coli BL21(DE3). Recombinant L-asparaginase (Pg-ASNase II) was purified with a monomer size of 37.0 kDa and a native size of 148.0 kDa. During characterization, Pg-ASNase II exhibited 75.8 ± 3.84 U/mg specific activities in 50.0 mM Tris-HCl buffer (pH 8.5) at 50 °C. However, it retained 80 and 70% enzyme activity at 37 °C and 50 °C after 60 min, respectively. The half-life and kd values were 625.15 min and 1.10 × 10−3 min−1 at 37 °C. The kinetic constant Km, Vmax, kcat, and kcat/Km values were 0.57 mM, 71.42 U/mg, 43.34 s−1, and 77.90 ± 9.81 s−1 mM−1 for L-asparagine, respectively. In addition, the enzyme has shown stability in the presence of most metal ions and protein-modifying agents. Pg-ASNase II was cytotoxic towards the MCF-7 cell line (breast cancer) with an estimated IC50 value of 0.169 U/mL in 24 h. Further, Pg-ASNase II treatment led to a 70% acrylamide reduction in baked foods. These findings suggest the potential of Pg-ASNase II in therapeutics and the food industry.
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Kumar S, Kumar V, Nag D, Kumar V, Darnal S, Thakur V, Patial V, Singh D. Microbial pigments: Learning from Himalayan perspective to industrial applications. J Ind Microbiol Biotechnol 2022; 49:kuac017. [PMID: 35933162 PMCID: PMC9559291 DOI: 10.1093/jimb/kuac017] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 05/21/2022] [Indexed: 11/19/2022]
Abstract
Pigments are an essential part of life on earth, ranging from microbes to plants and humans. The physiological and environmental cues induce microbes to produce a broad spectrum of pigments, giving them adaptation and survival advantages. Microbial pigments are of great interest due to their natural origin, diverse biological activities, and wide applications in the food, pharmaceutical, cosmetics, and textile industries. Despite noticeable research on pigment-producing microbes, commercial successes are scarce, primarily from higher, remote, and inaccessible Himalayan niches. Therefore, substantial bioprospection integrated with advanced biotechnological strategies is required to commercialize microbial pigments successfully. The current review elaborates on pigment-producing microbes from a Himalayan perspective, offering tremendous opportunities for industrial applications. Additionally, it illustrates the ecological significance of microbial pigments and emphasizes the current status and prospects of microbial pigments production above the test tube scale.
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Affiliation(s)
- Subhash Kumar
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh 176 061, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Vijay Kumar
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh 176 061, India
| | - Deepika Nag
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh 176 061, India
| | - Virender Kumar
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh 176 061, India
| | - Sanyukta Darnal
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh 176 061, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Vikas Thakur
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh 176 061, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Vijeta Patial
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh 176 061, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Dharam Singh
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh 176 061, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
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Kumar V, Kashyap P, Kumar S, Thakur V, Kumar S, Singh D. Multiple Adaptive Strategies of Himalayan Iodobacter sp. PCH194 to High-Altitude Stresses. Front Microbiol 2022; 13:881873. [PMID: 35875582 PMCID: PMC9298515 DOI: 10.3389/fmicb.2022.881873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 06/01/2022] [Indexed: 11/24/2022] Open
Abstract
Bacterial adaption to the multiple stressed environments of high-altitude niches in the Himalayas is intriguing and is of considerable interest to biotechnologists. Previously, we studied the culturable and unculturable metagenome microbial diversity from glacial and kettle lakes in the Western Himalayas. In this study, we explored the adaptive strategies of a unique Himalayan eurypsychrophile Iodobacter sp. PCH194, which can synthesize polyhydroxybutyrate (PHB) and violacein pigment. Whole-genome sequencing and analysis of Iodobacter sp. PCH194 (4.58 Mb chromosome and three plasmids) revealed genetic traits associated with adaptive strategies for cold/freeze, nutritional fluctuation, defense against UV, acidic pH, and the kettle lake's competitive environment. Differential proteome analysis suggested the adaptive role of chaperones, ribonucleases, secretion systems, and antifreeze proteins under cold stress. Antifreeze activity inhibiting the ice recrystallization at −9°C demonstrated the bacterium's survival at subzero temperature. The bacterium stores carbon in the form of PHB under stress conditions responding to nutritional fluctuations. However, violacein pigment protects the cells from UV radiation. Concisely, genomic, proteomic, and physiological studies revealed the multiple adaptive strategies of Himalayan Iodobacter to survive the high-altitude stresses.
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Affiliation(s)
- Vijay Kumar
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, India
| | - Prakriti Kashyap
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, India
| | - Subhash Kumar
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, India.,Academy of Scientific and Innovative Research (AcSIR), CSIR-Human Resource Development Centre (CSIR-HRDC), Ghaziabad, India
| | - Vikas Thakur
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, India.,Academy of Scientific and Innovative Research (AcSIR), CSIR-Human Resource Development Centre (CSIR-HRDC), Ghaziabad, India
| | - Sanjay Kumar
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, India
| | - Dharam Singh
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, India.,Academy of Scientific and Innovative Research (AcSIR), CSIR-Human Resource Development Centre (CSIR-HRDC), Ghaziabad, India
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Molecular cloning, characterization, and in-silico analysis of l-asparaginase from Himalayan Pseudomonas sp. PCH44. 3 Biotech 2022; 12:162. [PMID: 35822154 PMCID: PMC9271149 DOI: 10.1007/s13205-022-03224-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 06/17/2022] [Indexed: 11/01/2022] Open
Abstract
l-Asparaginase (l-ASNase) is a key enzyme used to treat acute lymphoblastic leukemia, a childhood blood cancer. Here, we report on the characterization of a recombinant l-ASNase (Ps44-asn II) from Pseudomonas sp. PCH44. The gene was identified from its genome, cloned, and overexpressed in the host Escherichia coli (E. coli). The recombinant l-ASNase (Ps44-ASNase II) was purified with a monomer size of 37.0 kDa and a homotetrameric size of 148.0 kDa. The purified Ps44-ASNase II exhibited optimum activity of 40.84 U/mg in Tris-HCl buffer (50 mM, pH 8.5) at 45 °C for 15 min. It retained 76.53% of enzyme activity at 45 °C after 120 min of incubation. The half-life and K d values were 600 min and 1.10 × 10-3 min-1, respectively, at 45 °C. The kinetic constants values K m and V max were 0.56, 0.728 mM, and 29.41, 50.12 U/mg for l-asparagine and l-glutamine, respectively. However, k cat for l-glutamine is more (30.91 s-1) than l-asparagine (18.06 s-1), suggesting that enzymes act more efficiently on l-glutamine than l-asparagine. The docking analysis of l-asparagine and l-glutamine with active site residues of the enzyme revealed a molecular basis for high l-glutaminase (L-GLNase) activity and provided insights into the role of key amino acid residues in the preferential enzymatic activities. Supplementary Information The online version contains supplementary material available at 10.1007/s13205-022-03224-0.
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Metagenomic insights into Himalayan glacial and kettle lake sediments revealed microbial community structure, function, and stress adaptation strategies. Extremophiles 2021; 26:3. [PMID: 34878610 DOI: 10.1007/s00792-021-01252-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Accepted: 11/13/2021] [Indexed: 12/31/2022]
Abstract
Glacial and kettle lakes in the high-altitude Himalayas are unique habitats with significant scope for microbial ecology. The present study provides insights into bacterial community structure and function of the sediments of two high-altitude lakes using 16S amplicon and whole-genome shotgun (WGS) metagenomics. Microbial communities in the sediments of Parvati kund (glacial lake) and Bhoot ground (kettle lake) majorly consist of bacteria and a small fraction of archaea and eukaryota. The bacterial population has an abundance of phyla Proteobacteria, Bacteroidetes, Acidobacteria, Actinobacteria, Firmicutes, and Verrucomicrobia. Despite the common phyla, the sediments from each lake have a distinct distribution of bacterial and archaeal taxa. The analysis of the WGS metagenomes at the functional level provides a broad picture of microbial community metabolism of key elements and suggested chemotrophs as the major primary producers. In addition, the findings also revealed that polyhydroxyalkanoates (PHA) are a crucial stress adaptation molecule. The abundance of PHA metabolism in Alpha- and Betaproteobacteria and less representation in other bacterial and archaeal classes in both metagenomes was disclosed. The metagenomic insights provided an incisive view of the microbiome from Himalayan lake's sediments. It has also opened the scope for further bioprospection from virgin Himalayan niches.
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