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Wu X, Xu M, Geng M, Chen S, Little PJ, Xu S, Weng J. Targeting protein modifications in metabolic diseases: molecular mechanisms and targeted therapies. Signal Transduct Target Ther 2023; 8:220. [PMID: 37244925 DOI: 10.1038/s41392-023-01439-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 03/01/2023] [Accepted: 04/06/2023] [Indexed: 05/29/2023] Open
Abstract
The ever-increasing prevalence of noncommunicable diseases (NCDs) represents a major public health burden worldwide. The most common form of NCD is metabolic diseases, which affect people of all ages and usually manifest their pathobiology through life-threatening cardiovascular complications. A comprehensive understanding of the pathobiology of metabolic diseases will generate novel targets for improved therapies across the common metabolic spectrum. Protein posttranslational modification (PTM) is an important term that refers to biochemical modification of specific amino acid residues in target proteins, which immensely increases the functional diversity of the proteome. The range of PTMs includes phosphorylation, acetylation, methylation, ubiquitination, SUMOylation, neddylation, glycosylation, palmitoylation, myristoylation, prenylation, cholesterylation, glutathionylation, S-nitrosylation, sulfhydration, citrullination, ADP ribosylation, and several novel PTMs. Here, we offer a comprehensive review of PTMs and their roles in common metabolic diseases and pathological consequences, including diabetes, obesity, fatty liver diseases, hyperlipidemia, and atherosclerosis. Building upon this framework, we afford a through description of proteins and pathways involved in metabolic diseases by focusing on PTM-based protein modifications, showcase the pharmaceutical intervention of PTMs in preclinical studies and clinical trials, and offer future perspectives. Fundamental research defining the mechanisms whereby PTMs of proteins regulate metabolic diseases will open new avenues for therapeutic intervention.
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Affiliation(s)
- Xiumei Wu
- Department of Endocrinology, Institute of Endocrine and Metabolic Diseases, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Clinical Research Hospital of Chinese Academy of Sciences (Hefei), University of Science and Technology of China, Hefei, Anhui, 230001, China
- Department of Endocrinology and Metabolism, Guangdong Provincial Key Laboratory of Diabetology, The Third Affiliated Hospital of Sun Yat-sen University, 510000, Guangzhou, China
| | - Mengyun Xu
- Department of Endocrinology, Institute of Endocrine and Metabolic Diseases, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Clinical Research Hospital of Chinese Academy of Sciences (Hefei), University of Science and Technology of China, Hefei, Anhui, 230001, China
| | - Mengya Geng
- Department of Endocrinology, Institute of Endocrine and Metabolic Diseases, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Clinical Research Hospital of Chinese Academy of Sciences (Hefei), University of Science and Technology of China, Hefei, Anhui, 230001, China
| | - Shuo Chen
- Department of Endocrinology, Institute of Endocrine and Metabolic Diseases, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Clinical Research Hospital of Chinese Academy of Sciences (Hefei), University of Science and Technology of China, Hefei, Anhui, 230001, China
| | - Peter J Little
- School of Pharmacy, University of Queensland, Pharmacy Australia Centre of Excellence, Woolloongabba, QLD, 4102, Australia
- Sunshine Coast Health Institute and School of Health and Behavioural Sciences, University of the Sunshine Coast, Birtinya, QLD, 4575, Australia
| | - Suowen Xu
- Department of Endocrinology, Institute of Endocrine and Metabolic Diseases, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Clinical Research Hospital of Chinese Academy of Sciences (Hefei), University of Science and Technology of China, Hefei, Anhui, 230001, China
| | - Jianping Weng
- Department of Endocrinology, Institute of Endocrine and Metabolic Diseases, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Clinical Research Hospital of Chinese Academy of Sciences (Hefei), University of Science and Technology of China, Hefei, Anhui, 230001, China.
- Department of Endocrinology and Metabolism, Guangdong Provincial Key Laboratory of Diabetology, The Third Affiliated Hospital of Sun Yat-sen University, 510000, Guangzhou, China.
- Bengbu Medical College, Bengbu, 233000, China.
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Udenwobele DI, Su RC, Good SV, Ball TB, Varma Shrivastav S, Shrivastav A. Myristoylation: An Important Protein Modification in the Immune Response. Front Immunol 2017; 8:751. [PMID: 28713376 PMCID: PMC5492501 DOI: 10.3389/fimmu.2017.00751] [Citation(s) in RCA: 112] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 06/13/2017] [Indexed: 01/24/2023] Open
Abstract
Protein N-myristoylation is a cotranslational lipidic modification specific to the alpha-amino group of an N-terminal glycine residue of many eukaryotic and viral proteins. The ubiquitous eukaryotic enzyme, N-myristoyltransferase, catalyzes the myristoylation process. Precisely, attachment of a myristoyl group increases specific protein–protein interactions leading to subcellular localization of myristoylated proteins with its signaling partners. The birth of the field of myristoylation, a little over three decades ago, has led to the understanding of the significance of protein myristoylation in regulating cellular signaling pathways in several biological processes especially in carcinogenesis and more recently immune function. This review discusses myristoylation as a prerequisite step in initiating many immune cell signaling cascades. In particular, we discuss the hitherto unappreciated implication of myristoylation during myelopoiesis, innate immune response, lymphopoiesis for T cells, and the formation of the immunological synapse. Furthermore, we discuss the role of myristoylation in inducing the virological synapse during human immunodeficiency virus infection as well as its clinical implication. This review aims to summarize existing knowledge in the field and to highlight gaps in our understanding of the role of myristoylation in immune function so as to further investigate into the dynamics of myristoylation-dependent immune regulation.
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Affiliation(s)
- Daniel Ikenna Udenwobele
- Department of Biology, University of Winnipeg, Winnipeg, MB, Canada.,Department of Biochemistry, University of Nigeria, Nsukka, Enugu, Nigeria
| | - Ruey-Chyi Su
- JC Wilt Infectious Diseases Research Institute, National HIV and Retrovirology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
| | - Sara V Good
- Department of Biology, University of Winnipeg, Winnipeg, MB, Canada
| | - Terry Blake Ball
- JC Wilt Infectious Diseases Research Institute, National HIV and Retrovirology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada.,Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, MB, Canada
| | - Shailly Varma Shrivastav
- Department of Biology, University of Winnipeg, Winnipeg, MB, Canada.,VastCon Inc., Winnipeg, MB, Canada
| | - Anuraag Shrivastav
- Department of Biology, University of Winnipeg, Winnipeg, MB, Canada.,Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, MB, Canada
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Rampoldi F, Sandhoff R, Owen RW, Gröne HJ, Porubsky S. A new, robust, and nonradioactive approach for exploring N-myristoylation. J Lipid Res 2012; 53:2459-68. [PMID: 22829651 DOI: 10.1194/jlr.d026997] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Myristoyl-CoA (CoA):protein N-myristoyltransferase (NMT) catalyzes protein modification through covalent attachment of a C14 fatty acid (myristic acid) to the N-terminal glycine of proteins, thus promoting protein-protein and protein-membrane interactions. NMT is essential for the viability of numerous human pathogens and is also up-regulated in several tumors. Here we describe a new, nonradioactive, ELISA-based method for measuring NMT activity. After the NMT-catalyzed reaction between a FLAG-tagged peptide and azido-dodecanoyl-CoA (analog of myristoyl-CoA), the resulting azido-dodecanoyl-peptide-FLAG was coupled to phosphine-biotin by Staudinger ligation, captured by plate-bound anti-FLAG antibodies and detected by streptavidin-peroxidase. The assay was validated with negative controls (including inhibitors), corroborated by HPLC analysis, and demonstrated to function with fresh or frozen tissues. Recombinant murine NMT1 and NMT2 were characterized using this new method. This versatile assay is applicable for exploring recombinant NMTs with regard to their activity, substrate specificity, and possible inhibitors as well as for measuring NMT-activity in tissues.
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Affiliation(s)
- Francesca Rampoldi
- Department of Cellular and Molecular Pathology, German Cancer Research Center, Heidelberg, Germany
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Wright MH, Heal WP, Mann DJ, Tate EW. Protein myristoylation in health and disease. J Chem Biol 2010; 3:19-35. [PMID: 19898886 PMCID: PMC2816741 DOI: 10.1007/s12154-009-0032-8] [Citation(s) in RCA: 182] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2009] [Revised: 10/05/2009] [Accepted: 10/19/2009] [Indexed: 02/07/2023] Open
Abstract
N-myristoylation is the attachment of a 14-carbon fatty acid, myristate, onto the N-terminal glycine residue of target proteins, catalysed by N-myristoyltransferase (NMT), a ubiquitous and essential enzyme in eukaryotes. Many of the target proteins of NMT are crucial components of signalling pathways, and myristoylation typically promotes membrane binding that is essential for proper protein localisation or biological function. NMT is a validated therapeutic target in opportunistic infections of humans by fungi or parasitic protozoa. Additionally, NMT is implicated in carcinogenesis, particularly colon cancer, where there is evidence for its upregulation in the early stages of tumour formation. However, the study of myristoylation in all organisms has until recently been hindered by a lack of techniques for detection and identification of myristoylated proteins. Here we introduce the chemistry and biology of N-myristoylation and NMT, and discuss new developments in chemical proteomic technologies that are meeting the challenge of studying this important co-translational modification in living systems.
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Affiliation(s)
- Megan H. Wright
- Chemical Biology Centre, Imperial College London, Exhibition Rd., London, SW72AZ UK
- Department of Chemistry, Imperial College London, Exhibition Rd., London, SW72AZ UK
- Department of Life Sciences, Imperial College London, Exhibition Rd., London, SW72AZ UK
| | - William P. Heal
- Department of Chemistry, Imperial College London, Exhibition Rd., London, SW72AZ UK
- Department of Life Sciences, Imperial College London, Exhibition Rd., London, SW72AZ UK
| | - David J. Mann
- Chemical Biology Centre, Imperial College London, Exhibition Rd., London, SW72AZ UK
- Department of Life Sciences, Imperial College London, Exhibition Rd., London, SW72AZ UK
| | - Edward W. Tate
- Chemical Biology Centre, Imperial College London, Exhibition Rd., London, SW72AZ UK
- Department of Chemistry, Imperial College London, Exhibition Rd., London, SW72AZ UK
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Islam NN, Igarashi K, Tachibana T, Ooshima H, Azuma M. Synthesis and degradation of acyl peptide using enzyme from Pseudomonas aeruginosa. J Biosci Bioeng 2008; 105:282-7. [PMID: 18397780 DOI: 10.1263/jbb.105.282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2007] [Accepted: 12/22/2007] [Indexed: 11/17/2022]
Abstract
The detailed properties of the enzyme from Pseudomonas aeruginosa, which catalyzes the N-acyl linkage between myristic acid and the N-terminal glycine residue of the octapeptide GNAAAARR-NH(2) (PKA) in aqueous solution without ATP and CoA, were studied. The substrate specificity for the acyl peptide in the synthetic reaction was examined, and it was found that at least eight amino acid residues are required for the reaction and that the N-terminal glycine residue is not absolutely essential for the reaction because the activity was detected using the octapeptide that has an N-terminal alanine. The activity was also strongly affected by the amino acid sequence because the activity was very weak in the reaction using GARASVLS-NH(2) (HIV-1p17(gag)). The substrate specificity for fatty acids was also examined. In the reactions using lauric acid and decanoic acid, only slight activities were detected; however, those activities were very small compared with the activity in the reaction using myristic acid. In addition, the degradation of myristoyl PKA by the enzyme was detected, although there are only a few reports on demyristoylation. The optimum pH and temperature of the degradation reaction were consistent with those of the synthetic reaction. The degradation reaction was inhibited by divalent cations.
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Affiliation(s)
- Nazneen Naher Islam
- Department of Applied Chemistry and Bioengineering, Graduate School of Engineering, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan
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Burdock GA, Carabin IG. Safety assessment of myristic acid as a food ingredient. Food Chem Toxicol 2007; 45:517-29. [PMID: 17141389 DOI: 10.1016/j.fct.2006.10.009] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2006] [Revised: 10/09/2006] [Accepted: 10/17/2006] [Indexed: 11/15/2022]
Abstract
Myristic acid is used in the food industry as a flavor ingredient. It is found widely distributed in fats throughout the plant and animal kingdom, including common human foodstuffs, such as nutmeg. Myristic acid (a 14-carbon, straight-chain saturated fatty acid) has been shown to have a low order of acute oral toxicity in rodents. It may be irritating in pure form to skin and eyes under exaggerated exposure conditions, but is not known or predicted to induce sensitization responses. Myristic acid did not induce a mutagenic response in either bacterial or mammalian systems in vitro. Relevant subchronic toxicity data are available on closely related fatty acid analogs. In particular, a NOEL of >6000mg/kg was reported for lauric acid (a 12-carbon, straight-chain saturated fatty acid) following dietary exposure to male rats for 18 weeks and a NOEL of >5000mg/kg was reported for palmitic acid (a 16-carbon, straight-chain saturated fatty acid) following dietary exposure to rats for 150 days. The data and information that are available indicate that at the current level of intake, food flavoring use of myristic acid does not pose a health risk to humans.
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Selvakumar P, Lakshmikuttyamma A, Shrivastav A, Das SB, Dimmock JR, Sharma RK. Potential role of N-myristoyltransferase in cancer. Prog Lipid Res 2007; 46:1-36. [PMID: 16846646 DOI: 10.1016/j.plipres.2006.05.002] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Colorectal cancer is the second leading cause of malignant death, and better preventive strategies are needed. The treatment of colonic cancer remains difficult because of the lack of effective chemotherapeutic agents; therefore it is important to continue to search for cellular functions that can be disrupted by chemotherapeutic drugs resulting in the inhibition of the development and progression of cancer. The current knowledge of the modification of proteins by myristoylation involving myristoyl-CoA: protein N-myristoyltransferase (NMT) is in its infancy. This process is involved in the pathogenesis of cancer. We have reported for the first time that NMT activity and protein expression were higher in human colorectal cancer, gallbladder carcinoma and brain tumors. In addition, an increase in NMT activity appeared at an early stage in colonic carcinogenesis. It is conceivable therefore that NMT can be used as a potential marker for the early detection of cancer. These observations lead to the possibility of developing NMT specific inhibitors, which may be therapeutically useful. We proposed that HSC70 and/or enolase could be used as an anticancer therapeutic target. This review summarized the status of NMT in cancer which has been carried in our laboratory.
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Affiliation(s)
- Ponniah Selvakumar
- Department of Pathology and Laboratory Medicine, College of Medicine, and Health Research Division, Saskatchewan Cancer Agency, University of Saskatchewan, 20 Campus Drive, Saskatoon, Sask., Canada S7N 4H4
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Jyomoto T, Azuma M, Islam NN, Fujinami R, Takao T, Ogawa T, Tabuchi M, Igarashi K, Kato J, Ooshima H. Purification and characterization of enzyme responsible for N-myristoylation of octapeptide in aqueous solution without ATP and coenzyme a from Pseudomonas aeruginosa. J Biosci Bioeng 2006; 102:193-7. [PMID: 17046532 DOI: 10.1263/jbb.102.193] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2006] [Accepted: 05/30/2006] [Indexed: 11/17/2022]
Abstract
The enzyme that catalyzes N-acyl linkage between myristic acid and the NH(2)-terminal glycine residue of the octapeptide Gly-Asn-Ala-Ala-Ala-Ala-Arg-Arg-NH(2) in aqueous solution without ATP and coenzyme A was found in Pseudomonas aeruginosa. The enzyme was purified from cell-free crude extract using DEAE-Cellulose, Sephadex G-200, CM-Sephadex C-50, and hydroxyapatite column chromatographies, and then purified approximately 1900-fold with about 1.5% recovery of enzyme activity from the crude extract. Finally, the purified enzyme showed a main band on SDS polyacrylamide gel electrophoresis after staining with Coomassie Brilliant Blue. The band corresponded to a molecular mass of approximately 60 kDa. The K(m)s of the purified enzyme for the substrate myristic acid and the octapeptide were 0.36 and 2.6 mM, respectively. When myristoyl-CoA instead of myristic acid was used as the substrate for the enzyme reaction, myristoyl octapeptide could be synthesized as observed in the case of myristic acid. The K(m) of myristoyl-CoA was 0.17 mM.
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Affiliation(s)
- Takahiro Jyomoto
- Department of Applied Chemistry and Bioengineering, Graduate School of Engineering, Osaka City University, Sugimoto, Osaka, Japan
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Lu JY, Hofmann SL. Thematic review series: Lipid Posttranslational Modifications. Lysosomal metabolism of lipid-modified proteins. J Lipid Res 2006; 47:1352-7. [PMID: 16627894 DOI: 10.1194/jlr.r600010-jlr200] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Much is now understood concerning the synthesis of prenylated and palmitoylated proteins, but what is known of their metabolic fate? This review details metabolic pathways for the lysosomal degradation of S-fatty acylated and prenylated proteins. Central to these pathways are two lysosomal enzymes, palmitoyl-protein thioesterase (PPT1) and prenylcysteine lyase (PCL). PPT1 is a soluble lipase that cleaves fatty acids from cysteine residues in proteins during lysosomal protein degradation. Notably, deficiency in the enzyme causes a neurodegenerative lysosomal storage disorder, infantile neuronal ceroid lipofuscinosis. PCL is a membrane-associated flavin-containing lysosomal monooxygenase that metabolizes prenylcysteine to prenyl aldehyde through a completely novel mechanism. The eventual metabolic fates of other lipidated proteins (such as glycosylphosphatidylinositol-anchored and N-myristoylated proteins) are poorly understood, suggesting directions for future research.
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Affiliation(s)
- Jui-Yun Lu
- Hamon Center for Therapeutic Oncology Research and Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, 75390, USA
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DeMar JC, Rundle DR, Wensel TG, Anderson RE. Heterogeneous N-terminal acylation of retinal proteins. Prog Lipid Res 1999; 38:49-90. [PMID: 10396602 DOI: 10.1016/s0163-7827(98)00020-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- J C DeMar
- Department of Biochemistry, Baylor College of Medicine, Houston, Texas 77030, USA
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Raju RV, Datla RS, Kakkar R, Sharma RK. Recombinant bovine spleen myristoyl CoA: protein N-myristoyltransferase. Mol Cell Biochem 1998; 189:91-7. [PMID: 9879658 DOI: 10.1023/a:1006861417562] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Myristoyl-CoA:protein N-myristoyltransferase (NMT) is an essential eukaryotic enzyme that catalyzes the co-translational transfer of myristate to the NH2-terminal glycine residue of a number of important proteins of diverse function. Recently, we have isolated full length cDNA encoding bovine spleen NMT [27] the full length cDNA was cloned and expressed in E. coli, resulting in the expression of functionally active 50 kDa NMT. Using the combination of SP-Sepharose fast flow and Mono S fast protein liquid chromatography, the enzyme was purified 20-fold with a high yield. The spleen NMT (sNMT) fusion protein exhibited an apparent molecular weight of 53 kDa on SDS-PAGE. Upon cleavage by the Enterokinase the sNMT exhibited an apparent molecular weight of 50 kDa without loss of catalytic activity. The two synthetic peptide substrates based on the N-terminal sequence of pp60src (GSSKSKMR) and cAMP dependent protein kinase (GNAAAKKRR) have different kinetic parameters of Km values of 40 and 200 microM. Recombinant sNMT was also potently inhibited by Ni2+ (histidine binder) in a concentration dependent manner with a half maximal inhibition of 280 microM. The E. coli expressed sNMT was homogenous and showed enzyme activity.
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Affiliation(s)
- R V Raju
- Department of Pathology and Saskatoon Cancer Centre, College of Medicine, University of Saskatchewan, Canada
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Raju RV, Anderson JW, Datla RS, Sharma RK. Molecular cloning and biochemical characterization of bovine spleen myristoyl CoA:protein N-myristoyltransferase. Arch Biochem Biophys 1997; 348:134-42. [PMID: 9390183 DOI: 10.1006/abbi.1997.0333] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Myristoyl-CoA:protein N-myristoyltransferase (NMT) is an essential eukaryotic enzyme that catalyzes the cotranslational transfer of myristate to the NH2-terminal glycine residue of a number of important proteins of diverse function. We have isolated full-length cDNA encoding bovine spleen NMT (sNMT). The single long open reading frame of 1248 bp of sNMT specifies a protein of 416 amino acids with a predicted mass of 46,686 Da. The protein coding sequence was expressed in Escherichia coli resulting in the production of functionally active 50-kDa NMT. Deletion mutagenesis showed that the C-terminus is essential for activity whereas up to 52 amino acids can be deleted from the N-terminus without affecting the function. One of the N-terminal deletions resulted in threefold higher NMT activity. Genomic Southern analysis indicated the presence of two strong hybridizing bands with three different restriction enzyme digests suggesting the possibility of two copies of the NMT gene in the bovine genome. RNA blot hybridization analysis of total cellular RNA prepared from bovine brain, heart, spleen, lung, liver, kidney, and skeletal muscle probed with bovine sNMT cDNA revealed a single 1.7-kb mRNA. Western blot analysis of various bovine tissues with human NMT peptide antibody indicated a common prominent immunoreactive band with an apparent molecular mass of 48.5-50 kDa in all tissues. Additional immunoreactive bands were observed in brain (84 and 50 kDa), lung (58 kDa), and skeletal muscle (58 kDa). Activity measurements demonstrated that brain contained the highest NMT activity followed by spleen, lung, kidney, heart, skeletal muscle, pancreas, and liver. It appears therefore that mRNA and protein expression do not correlate with NMT activity, suggesting the presence of regulators of the enzyme activity.
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Affiliation(s)
- R V Raju
- Department of Pathology, College of Medicine, Royal University Hospital, University of Saskatchewan, Saskatoon, Canada
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