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Aguirre-Sampieri S, Casañal A, Emsley P, Garza-Ramos G. Cryo-EM structure of bacterial nitrilase reveals insight into oligomerization, substrate recognition, and catalysis. J Struct Biol 2024; 216:108093. [PMID: 38615726 PMCID: PMC7616060 DOI: 10.1016/j.jsb.2024.108093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 03/26/2024] [Accepted: 04/12/2024] [Indexed: 04/16/2024]
Abstract
Many enzymes can self-assemble into higher-order structures with helical symmetry. A particularly noteworthy example is that of nitrilases, enzymes in which oligomerization of dimers into spiral homo-oligomers is a requirement for their enzymatic function. Nitrilases are widespread in nature where they catalyze the hydrolysis of nitriles into the corresponding carboxylic acid and ammonia. Here, we present the Cryo-EM structure, at 3 Å resolution, of a C-terminal truncate nitrilase from Rhodococcus sp. V51B that assembles in helical filaments. The model comprises a complete turn of the helical arrangement with a substrate-intermediate bound to the catalytic cysteine. The structure was solved having added the substrate to the protein. The length and stability of filaments was made more substantial in the presence of the aromatic substrate, benzonitrile, but not for aliphatic nitriles or dinitriles. The overall structure maintains the topology of the nitrilase family, and the filament is formed by the association of dimers in a chain-like mechanism that stabilizes the spiral. The active site is completely buried inside each monomer, while the substrate binding pocket was observed within the oligomerization interfaces. The present structure is in a closed configuration, judging by the position of the lid, suggesting that the intermediate is one of the covalent adducts. The proximity of the active site to the dimerization and oligomerization interfaces, allows the dimer to sense structural changes once the benzonitrile was bound, and translated to the rest of the filament, stabilizing the helical structure.
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Affiliation(s)
- Sergio Aguirre-Sampieri
- Universidad Nacional Autónoma de México, Facultad de Medicina, Departamento de Bioquímica, Circuito Escolar S/N, Ciudad Universitaria, CDMX, Mexico
| | - Ana Casañal
- Human Technopole, Palazzo Italia, Viale Rita Levi‑Montalcini, 1, 20157 Milan, Italy
| | - Paul Emsley
- MRC Laboratory of Molecular Biology, Structural Studies Division, Francis Crick Avenue, CB2 0QH Cambridge, England
| | - Georgina Garza-Ramos
- Universidad Nacional Autónoma de México, Facultad de Medicina, Departamento de Bioquímica, Circuito Escolar S/N, Ciudad Universitaria, CDMX, Mexico.
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2
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Arya CK, Maurya S, Ramanathan G. Insight into the metabolic pathways of Paracoccus sp. strain DMF: a non-marine halotolerant methylotroph capable of degrading aliphatic amines/amides. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:125947-125964. [PMID: 38010547 DOI: 10.1007/s11356-023-30858-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Accepted: 10/31/2023] [Indexed: 11/29/2023]
Abstract
Paracoccus sp. strain DMF (P. DMF from henceforth) is a gram-negative heterotroph known to tolerate and utilize high concentrations of N,N-dimethylformamide (DMF). The work presented here elaborates on the metabolic pathways involved in the degradation of C1 compounds, many of which are well-known pollutants and toxic to the environment. Investigations on microbial growth and detection of metabolic intermediates corroborate the outcome of the functional genome analysis. Several classes of C1 compounds, such as methanol, methylated amines, aliphatic amides, and naturally occurring quaternary amines like glycine betaine, were tested as growth substrates. The detailed growth and kinetic parameter analyses reveal that P. DMF can efficiently aerobically degrade trimethylamine (TMA) and grow on quaternary amines such as glycine betaine. The results show that the mechanism for halotolerant adaptation in the presence of glycine betaine is dissimilar from those observed for conventional trehalose-mediated halotolerance in heterotrophic bacteria. In addition, a close genomic survey revealed the presence of a Co(I)-based substrate-specific corrinoid methyltransferase operon, referred to as mtgBC. This demethylation system has been associated with glycine betaine catabolism in anaerobic methanogens and is unknown in denitrifying aerobic heterotrophs. This report on an anoxic-specific demethylation system in an aerobic heterotroph is unique. Our finding exposes the metabolic potential for the degradation of a variety of C1 compounds by P. DMF, making it a novel organism of choice for remediating a wide range of possible environmental contaminants.
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Affiliation(s)
- Chetan Kumar Arya
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Shiwangi Maurya
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Gurunath Ramanathan
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India.
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3
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The structures of the C146A variant of the amidase from Pyrococcus horikoshii bound to glutaramide and acetamide suggest the basis of amide recognition. J Struct Biol 2022; 214:107859. [DOI: 10.1016/j.jsb.2022.107859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 04/07/2022] [Accepted: 04/12/2022] [Indexed: 11/23/2022]
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4
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Wu Z, Liu C, Zhang Z, Zheng R, Zheng Y. Amidase as a versatile tool in amide-bond cleavage: From molecular features to biotechnological applications. Biotechnol Adv 2020; 43:107574. [PMID: 32512219 DOI: 10.1016/j.biotechadv.2020.107574] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 05/31/2020] [Accepted: 06/01/2020] [Indexed: 12/27/2022]
Abstract
Amidases (EC 3. 5. 1. X) are versatile biocatalysts for synthesis of chiral carboxylic acids, α-amino acids and amides due to their hydrolytic and acyl transfer activity towards the C-N linkages. They have been extensively exploited and studied during the past years for their high specific activity and excellent enantioselectivity involved in various biotechnological applications in pharmaceutical and agrochemical industries. Additionally, they have attracted considerable attentions in biodegradation and bioremediation owing to environmental pressures. Motivated by industrial demands, crystallographic investigations and catalytic mechanisms of amidases based on structural biology have witnessed a dramatic promotion in the last two decades. The protein structures showed that different types of amidases have their typical stuctural elements, such as the conserved AS domains in signature amidases and the typical architecture of metal-associated active sites in acetamidase/formamidase family amidases. This review provides an overview of recent research advances in various amidases, with a focus on their structural basis of phylogenetics, substrate specificities and catalytic mechanisms as well as their biotechnological applications. As more crystal structures of amidases are determined, the structure/function relationships of these enzymes will also be further elucidated, which will facilitate molecular engineering and design of amidases to meet industrial requirements.
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Affiliation(s)
- Zheming Wu
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China; Engineering Research Center of Bioconversion and Biopurification of Ministry of Education, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China; The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China
| | - Changfeng Liu
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China; Engineering Research Center of Bioconversion and Biopurification of Ministry of Education, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China; The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China
| | - Zhaoyu Zhang
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China; Engineering Research Center of Bioconversion and Biopurification of Ministry of Education, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China; The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China
| | - Renchao Zheng
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China; Engineering Research Center of Bioconversion and Biopurification of Ministry of Education, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China; The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China.
| | - Yuguo Zheng
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China; Engineering Research Center of Bioconversion and Biopurification of Ministry of Education, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China; The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China
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5
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Kumari P, Poddar R. Computational modeling for mutational analysis of nitrilase enzyme towards enhancement of binding empathy. J Biomol Struct Dyn 2020; 39:2289-2301. [PMID: 32216606 DOI: 10.1080/07391102.2020.1747546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Nitrilase enzyme (a green catalyst) is an industrially important enzyme which hydrolyses various nitrile compounds (containing -CN functional group) into amides and corresponding carboxylic acids. The current study explored the binding affinity and a method to enhance the catalysis activity of the enzyme using computational approaches. Four mutants were generated using sequential site-directed mutagenesis aiming that an increase in hydrogen bonds that will further increase binding efficiency towards the ligand. Molecular dynamics simulation was rigorously performed to check the stability of those mutants followed by docking to verify its interaction with the ligand. Various statistical dynamics analyses were performed to validate the structure. All the studies predict that built mutants are stable. Mutants 2 and 3 showed a better affinity towards acrylamide by forming the highest number of hydrogen bonds implying better catalysis. The binding affinity values of the Mutant 2 and Mutant 3 with acrylamide are -7.44 kcal/mol and -7.17 kcal/mol, respectively. This study may prove useful for the industry to develop efficient nitrilase enzymes with improved catalytic activity.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Priya Kumari
- Department of Bioengineering, Birla Institute of Technology-Mesra, Ranchi, JH, India
| | - Raju Poddar
- Department of Bioengineering, Birla Institute of Technology-Mesra, Ranchi, JH, India
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6
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Genetic and Functional Diversity of Nitrilases in Agaricomycotina. Int J Mol Sci 2019; 20:ijms20235990. [PMID: 31795104 PMCID: PMC6928751 DOI: 10.3390/ijms20235990] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 11/20/2019] [Accepted: 11/22/2019] [Indexed: 12/27/2022] Open
Abstract
Nitrilases participate in the nitrile metabolism in microbes and plants. They are widely used to produce carboxylic acids from nitriles. Nitrilases were described in bacteria, Ascomycota and plants. However, they remain unexplored in Basidiomycota. Yet more than 200 putative nitrilases are found in this division via GenBank. The majority of them occur in the subdivision Agaricomycotina. In this work, we analyzed their sequences and classified them into phylogenetic clades. Members of clade 1 (61 proteins) and 2 (25 proteins) are similar to plant nitrilases and nitrilases from Ascomycota, respectively, with sequence identities of around 50%. The searches also identified five putative cyanide hydratases (CynHs). Representatives of clade 1 and 2 (NitTv1 from Trametes versicolor and NitAg from Armillaria gallica, respectively) and a putative CynH (NitSh from Stereum hirsutum) were overproduced in Escherichia coli. The substrates of NitTv1 were fumaronitrile, 3-phenylpropionitrile, β-cyano-l-alanine and 4-cyanopyridine, and those of NitSh were hydrogen cyanide (HCN), 2-cyanopyridine, fumaronitrile and benzonitrile. NitAg only exhibited activities for HCN and fumaronitrile. The substrate specificities of these nitrilases were largely in accordance with substrate docking in their homology models. The phylogenetic distribution of each type of nitrilase was determined for the first time.
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Xu Z, Cai T, Xiong N, Zou SP, Xue YP, Zheng YG. Engineering the residues on “A” surface and C-terminal region to improve thermostability of nitrilase. Enzyme Microb Technol 2018; 113:52-58. [DOI: 10.1016/j.enzmictec.2018.03.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 02/28/2018] [Accepted: 03/04/2018] [Indexed: 12/29/2022]
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Cheng W, Doyle DA, El Arnaout T. The N-acyltransferase Lnt: Structure-function insights from recent simultaneous studies. Int J Biol Macromol 2018; 117:870-877. [PMID: 29859843 DOI: 10.1016/j.ijbiomac.2018.05.229] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 05/29/2018] [Accepted: 05/30/2018] [Indexed: 02/05/2023]
Abstract
Bacterial lipoproteins have been researched for decades due to their roles in a large number of biological functions. There were no structures of their main three membrane processing enzymes, until 2016 for Lgt and LspA, and then 2017 for Lnt with not one but three simultaneous, independent publications. We have analyzed the recent findings for this apolipoprotein N-acyltransferase Lnt, with comparisons between the novel structures, and with soluble nitrilases, to determine the significance of unique features in terms of substrate's recognition and binding mechanism influenced by exclusive residues, two transmembrane helices, and a flexible loop.
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Affiliation(s)
- Wei Cheng
- Division of Respiratory and Critical Care Medicine, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University and Collaborative Innovation Center of Biotherapy, Chengdu, Sichuan 610041, China
| | - Declan A Doyle
- Biological Sciences, University of Southampton, Southampton SO17 1BJ, UK
| | - Toufic El Arnaout
- School of Food Science and Environmental Health, Dublin Institute of Technology, Marlborough St, Dublin 1, Ireland.
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9
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Sharma N, Verma R, Bhalla TC. Classifying nitrilases as aliphatic and aromatic using machine learning technique. 3 Biotech 2018; 8:68. [PMID: 29354379 DOI: 10.1007/s13205-018-1102-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 01/06/2018] [Indexed: 11/30/2022] Open
Abstract
ProCos (Protein Composition Server, script version), one of the machine learning techniques, was used to classify nitrilases as aliphatic and aromatic nitrilases. Some important feature vectors were used to train the algorithm, which included pseudo-amino acid composition (PAAC) and five-factor solution score (5FSS). This clearly differentiated into two groups of nitrilases, i.e., aliphatic and aromatic, achieving maximum sensitivity of 100.00%, specificity of 90.00%, accuracy of 95.00% and Mathew Correlation Coefficient (MCC) of about 0.90 for the pseudo-amino acid composition. On the other hand, five-factor solution score achieved a sensitivity of 96.00%, specificity of 84.00%, accuracy of 90.00% and Mathew Correlation Coefficient (MCC) of about 0.81. The total count of aliphatic amino acids, Ala (A), Gly (G), Leu (L), Ile (I), Val (V), Met (M) and Pro (P), was found to be higher, i.e., 42.7 in case of aliphatic nitrilases, whereas it was 40.1 in aromatic nitrilases. On the other hand, aromatic amino acids, Tyr (Y), Trp (W), His (H) and Phe (F) number, were found to be higher, i.e., 12.7 in aromatic nitrilases as compared to aliphatic nitrilases which was 10.7. This approach will help in predicting a nitrilase as aromatic or aliphatic nitrilase based on its amino acid sequence. Access to the scripts can be done logging onto GitHub using keyword 'Nitrilase' or 'https://github.com/rover2380/Nitrilase.git'.
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Affiliation(s)
- Nikhil Sharma
- 1Bioinformatics Centre, Himachal Pradesh University, Summer Hill, Shimla, 171005 India
| | - Ruchi Verma
- 1Bioinformatics Centre, Himachal Pradesh University, Summer Hill, Shimla, 171005 India
- 2Department of Biotechnology, Himachal Pradesh University, Summer Hill, Shimla, Himachal Pradesh 171005 India
| | - Tek Chand Bhalla
- 2Department of Biotechnology, Himachal Pradesh University, Summer Hill, Shimla, Himachal Pradesh 171005 India
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10
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Lu G, Xu Y, Zhang K, Xiong Y, Li H, Cui L, Wang X, Lou J, Zhai Y, Sun F, Zhang XC. Crystal structure of E. coli apolipoprotein N-acyl transferase. Nat Commun 2017; 8:15948. [PMID: 28885614 PMCID: PMC5500890 DOI: 10.1038/ncomms15948] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 05/13/2017] [Indexed: 11/09/2022] Open
Abstract
In Gram-negative bacteria, lipid modification of proteins is catalysed in a three-step pathway. Apolipoprotein N-acyl transferase (Lnt) catalyses the third step in this pathway, whereby it transfers an acyl chain from a phospholipid to the amine group of the N-terminal cysteine residue of the apolipoprotein. Here, we report the 2.6-Å crystal structure of Escherichia coli Lnt. This enzyme contains an exo-membrane nitrilase domain fused to a transmembrane (TM) domain. The TM domain of Lnt contains eight TM helices which form a membrane-embedded cavity with a lateral opening and a periplasmic exit. The nitrilase domain is located on the periplasmic side of the membrane, with its catalytic cavity connected to the periplasmic exit of the TM domain. An amphipathic lid loop from the nitrilase domain interacts with the periplasmic lipid leaflet, forming an interfacial entrance from the lipid bilayer to the catalytic centre for both the lipid donor and acceptor substrates.
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Affiliation(s)
- Guangyuan Lu
- National Laboratory of Macromolecules, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China.,School of Life Sciences, University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049, China
| | - Yingzhi Xu
- National Laboratory of Macromolecules, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
| | - Kai Zhang
- National Laboratory of Macromolecules, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
| | - Yong Xiong
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06411, USA
| | - He Li
- National Laboratory of Macromolecules, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
| | - Lei Cui
- National Laboratory of Macromolecules, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
| | - Xianping Wang
- National Laboratory of Macromolecules, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China.,School of Life Sciences, University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049, China
| | - Jizhong Lou
- National Laboratory of Macromolecules, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China.,School of Life Sciences, University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049, China
| | - Yujia Zhai
- National Laboratory of Macromolecules, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
| | - Fei Sun
- National Laboratory of Macromolecules, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China.,School of Life Sciences, University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049, China
| | - Xuejun C Zhang
- National Laboratory of Macromolecules, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China.,School of Life Sciences, University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049, China
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11
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Krasnikov BF, Deryabina YI, Isakova EP, Biriukova IK, Shevelev AB, Antipov AN. New recombinant producer of human ω-amidase based on Escherichia coli. APPL BIOCHEM MICRO+ 2017. [DOI: 10.1134/s0003683817030115] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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12
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Nit1 is a metabolite repair enzyme that hydrolyzes deaminated glutathione. Proc Natl Acad Sci U S A 2017; 114:E3233-E3242. [PMID: 28373563 DOI: 10.1073/pnas.1613736114] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The mammalian gene Nit1 (nitrilase-like protein 1) encodes a protein that is highly conserved in eukaryotes and is thought to act as a tumor suppressor. Despite being ∼35% sequence identical to ω-amidase (Nit2), the Nit1 protein does not hydrolyze efficiently α-ketoglutaramate (a known physiological substrate of Nit2), and its actual enzymatic function has so far remained a puzzle. In the present study, we demonstrate that both the mammalian Nit1 and its yeast ortholog are amidases highly active toward deaminated glutathione (dGSH; i.e., a form of glutathione in which the free amino group has been replaced by a carbonyl group). We further show that Nit1-KO mutants of both human and yeast cells accumulate dGSH and the same compound is excreted in large amounts in the urine of Nit1-KO mice. Finally, we show that several mammalian aminotransferases (transaminases), both cytosolic and mitochondrial, can form dGSH via a common (if slow) side-reaction and provide indirect evidence that transaminases are mainly responsible for dGSH formation in cultured mammalian cells. Altogether, these findings delineate a typical instance of metabolite repair, whereby the promiscuous activity of some abundant enzymes of primary metabolism leads to the formation of a useless and potentially harmful compound, which needs a suitable "repair enzyme" to be destroyed or reconverted into a useful metabolite. The need for a dGSH repair reaction does not appear to be limited to eukaryotes: We demonstrate that Nit1 homologs acting as excellent dGSH amidases also occur in Escherichia coli and other glutathione-producing bacteria.
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Sekula B, Ruszkowski M, Malinska M, Dauter Z. Structural Investigations of N-carbamoylputrescine Amidohydrolase from Medicago truncatula: Insights into the Ultimate Step of Putrescine Biosynthesis in Plants. FRONTIERS IN PLANT SCIENCE 2016; 7:350. [PMID: 27066023 PMCID: PMC4812014 DOI: 10.3389/fpls.2016.00350] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 03/07/2016] [Indexed: 05/17/2023]
Abstract
Putrescine, 1,4-diaminobutane, is an intermediate in the biosynthesis of more complexed polyamines, spermidine and spermine. Unlike other eukaryotes, plants have evolved a multistep pathway for putrescine biosynthesis that utilizes arginine. In the final reaction, N-carbamoylputrescine is hydrolyzed to putrescine by N-carbamoylputrescine amidohydrolase (CPA, EC 3.5.1.53). During the hydrolysis, consecutive nucleophilic attacks on the substrate by Cys158 and water lead to formation of putrescine and two by-products, ammonia and carbon dioxide. CPA from the model legume plant, Medicago truncatula (MtCPA), was investigated in this work. Four crystal structures were determined: the wild-type MtCPA in complex with the reaction intermediate, N-(dihydroxymethyl)putrescine as well as with cadaverine, which is a longer analog of putrescine; and also structures of MtCPA-C158S mutant unliganded and with putrescine. MtCPA assembles into octamers, which resemble an incomplete left-handed helical twist. The active site of MtCPA is funnel-like shaped, and its entrance is walled with a contribution of the neighboring protein subunits. Deep inside the catalytic cavity, Glu48, Lys121, and Cys158 form the catalytic triad. In this studies, we have highlighted the key residues, highly conserved among the plant kingdom, responsible for the activity and selectivity of MtCPA toward N-carbamoylputrescine. Moreover, since, according to previous reports, a close MtCPA relative from Arabidopsis thaliana, along with several other nitrilase-like proteins, are subjected to allosteric regulation by substrates, we have used the structural information to indicate a putative secondary binding site. Based on the docking experiment, we postulate that this site is adjacent to the entrance to the catalytic pocket.
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Affiliation(s)
- Bartosz Sekula
- Institute of Technical Biochemistry, Faculty of Biotechnology and Food Sciences, Lodz University of TechnologyLodz, Poland
| | - Milosz Ruszkowski
- Synchrotron Radiation Research Section, Macromolecular Crystallography Laboratory, National Cancer Institute, ArgonneIL, USA
- *Correspondence: Milosz Ruszkowski,
| | - Maura Malinska
- Synchrotron Radiation Research Section, Macromolecular Crystallography Laboratory, National Cancer Institute, ArgonneIL, USA
- Faculty of Chemistry, University of WarsawWarsaw, Poland
| | - Zbigniew Dauter
- Synchrotron Radiation Research Section, Macromolecular Crystallography Laboratory, National Cancer Institute, ArgonneIL, USA
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14
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Zhang L, Yin B, Wang C, Jiang S, Wang H, Yuan YA, Wei D. Structural insights into enzymatic activity and substrate specificity determination by a single amino acid in nitrilase from Syechocystis sp. PCC6803. J Struct Biol 2014; 188:93-101. [PMID: 25450592 DOI: 10.1016/j.jsb.2014.10.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 10/05/2014] [Accepted: 10/07/2014] [Indexed: 11/19/2022]
Abstract
Nitrilases are enzymes widely expressed in prokaryotes and eukaryotes that utilize a Cys–Glu–Lys catalytic triad to hydrolyze non-peptide carbon–nitrogen bonds. Nitrilase from Syechocystis sp. Strain PCC6803 (Nit6803) shows hydrolysis activity towards a broad substrate spectrum, ranging from mononitriles to dinitriles and from aromatic nitriles to aliphatic nitriles. Yet, the structural principle of the substrate specificity of this nitrilase is still unknown. We report the crystal structure of Nit6803 at 3.1 Å resolution and propose a structural mechanism of substrate selection. Our mutagenesis data exhibited that the aromaticity of the amino acid at position 146 of Nit6803 is absolutely required for its nitrilase activity towards any substrates tested. Moreover, molecular docking and dynamic simulation analysis indicated that the distance between the sulfhydryl group of the catalytic cysteine residue and the cyano carbon of the substrate plays a crucial role in determining the nitrilase catalytic activity of Nit6803 and its mutants towards different nitrile substrates.
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