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Abstract
Fatty acid (FA) biosynthesis plays a central role in the metabolism of living cells as building blocks of biological membranes, energy reserves of the cell, and precursors to second messenger molecules. In keeping with its central metabolic role, FA biosynthesis impacts several cellular functions and its misfunction is linked to disease, such as cancer, obesity, and non-alcoholic fatty liver disease. Cellular FA biosynthesis is conducted by fatty acid synthases (FAS). All FAS enzymes catalyze similar biosynthetic reactions, but the functional architectures adopted by these cellular catalysts can differ substantially. This variability in FAS structure amongst various organisms and the essential role played by FA biosynthetic pathways makes this metabolic route a valuable target for the development of antibiotics. Beyond cellular FA biosynthesis, the quest for renewable energy sources has piqued interest in FA biosynthetic pathway engineering to generate biofuels and fatty acid derived chemicals. For these applications, based on FA biosynthetic pathways, to succeed, detailed metabolic, functional and structural insights into FAS are required, along with an intimate knowledge into the regulation of FAS. In this review, we summarize our present knowledge about the functional, structural, and regulatory aspects of FAS.
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Affiliation(s)
- Aybeg N Günenc
- Research Group for Structural Biochemistry and Mechanisms, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Benjamin Graf
- Research Group for Structural Biochemistry and Mechanisms, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Holger Stark
- Department of Structural Dynamics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Ashwin Chari
- Research Group for Structural Biochemistry and Mechanisms, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
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2
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Huang M, Koizumi A, Narita S, Nakanishi H, Sato H, Kashima S, Nara T, Kanda S, Numakura K, Saito M, Satoh S, Nanjo H, Sasaki T, Habuchi T. Altering phosphoinositides in high-fat diet-associated prostate tumor xenograft growth. MedComm (Beijing) 2021; 2:756-764. [PMID: 34977875 PMCID: PMC8706770 DOI: 10.1002/mco2.89] [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: 03/19/2021] [Revised: 08/23/2021] [Accepted: 08/24/2021] [Indexed: 11/08/2022] Open
Abstract
The metabolic reprogramming of phospholipids may affect intracellular signal transduction pathways. A high-fat diet (HFD) is attributed to prostate cancer (PCa) progression, but the expression pattern and role of phospholipids in HFD-mediated PCa progression remains unclear. In this study, HFD enhanced LNCaP xenograft tumor growth by upregulating the phosphatidylinositol (PI) 3-kinase (PI3K)/AKT signaling pathway. A lipidomic analysis using xenograft tumors showed that phosphoinositides, especially PI (3,4,5)-trisphosphate (PIP3), including several species containing C38:4, C38:3, and C40:4 fatty acids, increased in the HFD group compared to control. Fatty acid synthase (FASN) was significantly upregulated in xenograft tumors under HFD in both gene and protein levels. PCa cell growth was significantly inhibited through the decreased AKT signaling pathway by treatment with cerulenin, a chemical FASN inhibitor, which also downregulated PIP, PIP2, and PIP3 but not PI. Thus, dietary fat influences PCa progression and alters phosphoinositides, especially PIP3, a critical player in the PI3K/AKT pathway. These results may offer appropriate targets, such as FASN, for dietary intervention and/or chemoprevention to reduce PCa incidence and progression.
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Affiliation(s)
- Mingguo Huang
- Department of UrologyAkita University Graduate School of MedicineAkitaJapan
| | - Atsushi Koizumi
- Department of UrologyAkita University Graduate School of MedicineAkitaJapan
| | - Shintaro Narita
- Department of UrologyAkita University Graduate School of MedicineAkitaJapan
| | - Hiroki Nakanishi
- Research Center for BiosignalAkita University Graduate School of MedicineAkitaJapan
| | - Hiromi Sato
- Department of UrologyAkita University Graduate School of MedicineAkitaJapan
| | - Soki Kashima
- Department of UrologyAkita University Graduate School of MedicineAkitaJapan
| | - Taketoshi Nara
- Department of UrologyAkita University Graduate School of MedicineAkitaJapan
| | - Sohei Kanda
- Department of UrologyAkita University Graduate School of MedicineAkitaJapan
| | - Kazuyuki Numakura
- Department of UrologyAkita University Graduate School of MedicineAkitaJapan
| | - Mitsuru Saito
- Department of UrologyAkita University Graduate School of MedicineAkitaJapan
| | - Shigeru Satoh
- Department of UrologyAkita University Graduate School of MedicineAkitaJapan
| | - Hiroshi Nanjo
- Department of Clinical PathologyAkita University Graduate School of MedicineAkitaJapan
| | - Takehiko Sasaki
- Department of Biochemical Pathophysiology/Lipid BiologyMedical Research InstituteTokyo Medical and Dental UniversityBunkyo‐kuTokyoJapan
| | - Tomonori Habuchi
- Department of UrologyAkita University Graduate School of MedicineAkitaJapan
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3
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Kalinger RS, Pulsifer IP, Hepworth SR, Rowland O. Fatty Acyl Synthetases and Thioesterases in Plant Lipid Metabolism: Diverse Functions and Biotechnological Applications. Lipids 2020; 55:435-455. [PMID: 32074392 DOI: 10.1002/lipd.12226] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 01/29/2020] [Accepted: 01/30/2020] [Indexed: 11/09/2022]
Abstract
Plants use fatty acids to synthesize acyl lipids for many different cellular, physiological, and defensive roles. These roles include the synthesis of essential membrane, storage, or surface lipids, as well as the production of various fatty acid-derived metabolites used for signaling or defense. Fatty acids are activated for metabolic processing via a thioester linkage to either coenzyme A or acyl carrier protein. Acyl synthetases metabolically activate fatty acids to their thioester forms, and acyl thioesterases deactivate fatty acyl thioesters to free fatty acids by hydrolysis. These two enzyme classes therefore play critical roles in lipid metabolism. This review highlights the surprisingly complex and varying roles of fatty acyl synthetases in plant lipid metabolism, including roles in the intracellular trafficking of fatty acids. This review also surveys the many specialized fatty acyl thioesterases characterized to date in plants, which produce a great diversity of fatty acid products in a tissue-specific manner. While some acyl thioesterases produce fatty acids that clearly play roles in plant-insect or plant-microbial interactions, most plant acyl thioesterases have yet to be fully characterized both in terms of their substrate specificities and their functions. The biotechnological applications of plant acyl thioesterases and synthetases are also discussed, as there is significant interest in these enzymes as catalysts for the sustainable production of fatty acids and their derivatives for industrial uses.
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Affiliation(s)
- Rebecca S Kalinger
- Department of Biology and Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - Ian P Pulsifer
- Department of Biology and Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - Shelley R Hepworth
- Department of Biology and Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - Owen Rowland
- Department of Biology and Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
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4
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Singh M, Devi U, Roy S, Gupta PS, Saraf SA, Kaithwas G. Prolyl hydroxylase mediated inhibition of fatty acid synthase to combat tumor growth in mammary gland carcinoma. Breast Cancer 2016; 23:820-829. [PMID: 26951539 DOI: 10.1007/s12282-016-0683-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 02/24/2016] [Indexed: 12/12/2022]
Abstract
Cancer is a group of cells which grow in an uncontrolled manner and invades to the adjacent organs to form malignant tumors. Tumor hypoxia results due to contrast between the cellular oxygen expenditure and oxygen supply to the cells. Hypoxia inducible factor (HIF) is a heterodimeric transcription factor encompass of oxygen sensitive α subunit and constitutively expressed β subunit both of which are basic helix-loop-helix protein. The stability of HIF is primarily regulated by post translational prolyl hydroxylation, catalyzed by prolyl hydroxylase 2 (Phd-2). Phd-2 is a group of enzymes that acts as an oxygen sensor. Cancer cells have altered metabolism as they fulfil their energy needs through glycolysis and lipid biogenesis. HIF-1α is known to upregulate glycolysis by activating the transcription of enzymes on the glycolytic pathway and through lipogenesis. Cancer cells have over expressed fatty acid synthase owing to altered glycolytic pathway. Considering the above, it is hypothesized that chemical activation of Phd-2 can curtail down HIF-1α and subsequently fatty acid synthase expression.
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Affiliation(s)
- Manjari Singh
- Department of Pharmaceutical Sciences, School of Biosciences and Biotechnology, Babasaheb Bhimrao Ambedkar University (A Central University), Vidya Vihar, Raebareli Road, Lucknow, 226025, India
| | - Uma Devi
- Department of Pharmaceutical Sciences, Faculty of Health Medical Sciences Indigenous and Alternative Medicine, SHIATS-Deemed to be University, Naini, Allahabad, Uttar Pradesh, India
| | - Subhadeep Roy
- Department of Pharmaceutical Sciences, School of Biosciences and Biotechnology, Babasaheb Bhimrao Ambedkar University (A Central University), Vidya Vihar, Raebareli Road, Lucknow, 226025, India
| | - Pushpraj S Gupta
- Department of Pharmaceutical Sciences, Faculty of Health Medical Sciences Indigenous and Alternative Medicine, SHIATS-Deemed to be University, Naini, Allahabad, Uttar Pradesh, India
| | - Shubhini A Saraf
- Department of Pharmaceutical Sciences, School of Biosciences and Biotechnology, Babasaheb Bhimrao Ambedkar University (A Central University), Vidya Vihar, Raebareli Road, Lucknow, 226025, India
| | - Gaurav Kaithwas
- Department of Pharmaceutical Sciences, School of Biosciences and Biotechnology, Babasaheb Bhimrao Ambedkar University (A Central University), Vidya Vihar, Raebareli Road, Lucknow, 226025, India.
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5
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Diet-induced alteration of fatty acid synthase in prostate cancer progression. Oncogenesis 2016; 5:e195. [PMID: 26878389 PMCID: PMC5154344 DOI: 10.1038/oncsis.2015.42] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 11/23/2015] [Accepted: 11/30/2015] [Indexed: 02/01/2023] Open
Abstract
Fatty acid synthase (FASN) is a cytosolic metabolic enzyme that catalyzes de novo fatty acid synthesis. A high-fat diet (HFD) is attributed to prostate cancer (PCa) progression, but the role FASN on HFD-mediated PCa progression remains unclear. We investigated the role of FASN on PCa progression in LNCaP xenograft mice fed with HFD or low-fat diet (LFD), in PCa cells, and in clinical PCa. The HFD promoted tumour growth and FASN expression in the LNCaP xenograft mice. HFD resulted in AKT and extracellular signal-regulated kinase (ERK) activation and 5' adenosine monophosphate-activated protein kinase (AMPK) inactivation. Serum FASN levels were significantly lower in the HFD group (P=0.026) and correlated inversely with tumour volume (P=0.022). Extracellular FASN release was enhanced in the PCa cells with phosphatidylinositol 3-kinase (PI3K)/mitogen-activated protein kinase (MAPK) inhibition and AMPK signalling activation. FASN inhibition resulted in decrease of PCa cell proliferation through PI3K/MAPK downregulation and AMPK activation. Furthermore, AMPK activation was associated with FASN downregulation and PI3K/MAPK inactivation. Clinically, high FASN expression was significantly associated with high Gleason scores and advanced pathological T stage. Moreover, FASN expression was markedly decreased in the PCa response to androgen deprivation therapy and chemotherapy. HFD modulates FASN expression, which may be an important mechanism in HFD-associated PCa progression. Furthermore, a critical stimulatory loop exists between FASN and the PI3K/MAPK system, whereas AMPK signalling was associated with suppression. These may offer appropriate targets for chemoprevention and cancer therapy in HFD-induced PCa.
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6
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Rossato FA, Zecchin KG, La Guardia PG, Ortega RM, Alberici LC, Costa RAP, Catharino RR, Graner E, Castilho RF, Vercesi AE. Fatty acid synthase inhibitors induce apoptosis in non-tumorigenic melan-a cells associated with inhibition of mitochondrial respiration. PLoS One 2014; 9:e101060. [PMID: 24964211 PMCID: PMC4071076 DOI: 10.1371/journal.pone.0101060] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Accepted: 06/03/2014] [Indexed: 12/31/2022] Open
Abstract
The metabolic enzyme fatty acid synthase (FASN) is responsible for the endogenous synthesis of palmitate, a saturated long-chain fatty acid. In contrast to most normal tissues, a variety of human cancers overexpress FASN. One such cancer is cutaneous melanoma, in which the level of FASN expression is associated with tumor invasion and poor prognosis. We previously reported that two FASN inhibitors, cerulenin and orlistat, induce apoptosis in B16-F10 mouse melanoma cells via the intrinsic apoptosis pathway. Here, we investigated the effects of these inhibitors on non-tumorigenic melan-a cells. Cerulenin and orlistat treatments were found to induce apoptosis and decrease cell proliferation, in addition to inducing the release of mitochondrial cytochrome c and activating caspases-9 and -3. Transfection with FASN siRNA did not result in apoptosis. Mass spectrometry analysis demonstrated that treatment with the FASN inhibitors did not alter either the mitochondrial free fatty acid content or composition. This result suggests that cerulenin- and orlistat-induced apoptosis events are independent of FASN inhibition. Analysis of the energy-linked functions of melan-a mitochondria demonstrated the inhibition of respiration, followed by a significant decrease in mitochondrial membrane potential (ΔΨm) and the stimulation of superoxide anion generation. The inhibition of NADH-linked substrate oxidation was approximately 40% and 61% for cerulenin and orlistat treatments, respectively, and the inhibition of succinate oxidation was approximately 46% and 52%, respectively. In contrast, no significant inhibition occurred when respiration was supported by the complex IV substrate N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD). The protection conferred by the free radical scavenger N-acetyl-cysteine indicates that the FASN inhibitors induced apoptosis through an oxidative stress-associated mechanism. In combination, the present results demonstrate that cerulenin and orlistat induce apoptosis in non-tumorigenic cells via mitochondrial dysfunction, independent of FASN inhibition.
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Affiliation(s)
- Franco A. Rossato
- Departamento de Patologia Clínica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brazil
| | - Karina G. Zecchin
- Departamento de Patologia Clínica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brazil
- Departamento de Diagnóstico Oral, Faculdade de Odontologia de Piracicaba, Universidade Estadual de Campinas (UNICAMP), Piracicaba, SP, Brazil
| | - Paolo G. La Guardia
- Departamento de Patologia Clínica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brazil
| | - Rose M. Ortega
- Departamento de Diagnóstico Oral, Faculdade de Odontologia de Piracicaba, Universidade Estadual de Campinas (UNICAMP), Piracicaba, SP, Brazil
| | - Luciane C. Alberici
- Departamento de Química e Física, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo (USP), Ribeirão Preto, SP, Brazil
| | - Rute A. P. Costa
- Departamento de Patologia Clínica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brazil
| | - Rodrigo R. Catharino
- Departamento de Patologia Clínica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brazil
| | - Edgard Graner
- Departamento de Diagnóstico Oral, Faculdade de Odontologia de Piracicaba, Universidade Estadual de Campinas (UNICAMP), Piracicaba, SP, Brazil
| | - Roger F. Castilho
- Departamento de Patologia Clínica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brazil
| | - Aníbal E. Vercesi
- Departamento de Patologia Clínica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brazil
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7
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Abstract
Fungal aromatic polyketides constitute a large family of bioactive natural products and are synthesized by the non-reducing group of iterative polyketide synthases (PKSs). Their diverse structures arise from selective enzymatic modifications of reactive, enzyme-bound poly-β-keto intermediates. How iterative PKSs control starter unit selection, polyketide chain initiation and elongation, intermediate folding and cyclization, selective redox or modification reactions during assembly, and product release are central mechanistic questions underlying iterative catalysis. This Review highlights recent insights into these questions, with a particular focus on the biosynthetic programming of fungal aromatic polyketides, and draws comparisons with the allied biosynthetic processes in bacteria.
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8
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Abstract
In all organisms, fatty acid synthesis is achieved in variations of a common cyclic reaction pathway by stepwise, iterative elongation of precursors with two-carbon extender units. In bacteria, all individual reaction steps are carried out by monofunctional dissociated enzymes, whereas in eukaryotes the fatty acid synthases (FASs) have evolved into large multifunctional enzymes that integrate the whole process of fatty acid synthesis. During the last few years, important advances in understanding the structural and functional organization of eukaryotic FASs have been made through a combination of biochemical, electron microscopic and X-ray crystallographic approaches. They have revealed the strikingly different architectures of the two distinct types of eukaryotic FASs, the fungal and the animal enzyme system. Fungal FAS is a 2·6 MDa α₆β₆ heterododecamer with a barrel shape enclosing two large chambers, each containing three sets of active sites separated by a central wheel-like structure. It represents a highly specialized micro-compartment strictly optimized for the production of saturated fatty acids. In contrast, the animal FAS is a 540 kDa X-shaped homodimer with two lateral reaction clefts characterized by a modular domain architecture and large extent of conformational flexibility that appears to contribute to catalytic efficiency.
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10
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Abstract
This review chronicles the synergistic growth of the fields of fatty acid and polyketide synthesis over the last century. In both animal fatty acid synthases and modular polyketide synthases, similar catalytic elements are covalently linked in the same order in megasynthases. Whereas in fatty acid synthases the basic elements of the design remain immutable, guaranteeing the faithful production of saturated fatty acids, in the modular polyketide synthases, the potential of the basic design has been exploited to the full for the elaboration of a wide range of secondary metabolites of extraordinary structural diversity.
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Affiliation(s)
- Stuart Smith
- Children's Hospital Oakland Research Institute, 5700 Martin Luther King Jr. Way, Oakland, California 94609, USA.
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11
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Hopwood DA, Khosla C. Genes for polyketide secondary metabolic pathways in microorganisms and plants. CIBA FOUNDATION SYMPOSIUM 2007; 171:88-106; discussion 106-12. [PMID: 1302187 DOI: 10.1002/9780470514344.ch6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Recent advances in molecular genetics have led to the isolation, sequencing and functional analysis of genes encoding synthases that catalyse the formation of several classes of polyketides. The structures of the genes and their protein products differ strikingly in the various examples. For Streptomyces aromatic polyketides, exemplified by granaticin and tetracenomycin, the synthases correspond to Type II (bacterial and plant) fatty acid synthases in consisting of distinct proteins for such processes as condensation, acyl carrier function and ketoreduction. In contrast, for actinomycete macrolides such as erythromycin, similar catalytic functions are performed by a set of multifunctional proteins resembling Type I (animal) fatty acid synthases, but with every step in chain-building being catalysed by a different enzymic domain. Penicillium patulum has a simple Type I synthase for 6-methylsalicylic acid. For plant chalcones and stilbenes, a single small polypeptide acts as a condensing enzyme for carbon chain-building and may be unrelated to any of the other polyketide and fatty acid synthases. Thus, although these systems share a common general mechanism of chain assembly, they must differ in the ways that synthase 'programming' has evolved to determine chain length, choice of chain starter and extender units, and handling of successive keto groups during chain assembly, and so control the great diversity of possible chemical products.
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Affiliation(s)
- D A Hopwood
- John Innes Institute, John Innes Centre, Norwich, UK
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12
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Toyomasu T, Tsukahara M, Kaneko A, Niida R, Mitsuhashi W, Dairi T, Kato N, Sassa T. Fusicoccins are biosynthesized by an unusual chimera diterpene synthase in fungi. Proc Natl Acad Sci U S A 2007; 104:3084-8. [PMID: 17360612 PMCID: PMC1805559 DOI: 10.1073/pnas.0608426104] [Citation(s) in RCA: 141] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2006] [Indexed: 11/18/2022] Open
Abstract
Fusicoccins are a class of diterpene glucosides produced by the plant-pathogenic fungus Phomopsis amygdali. As modulators of 14-3-3 proteins, fusicoccins function as potent activators of plasma membrane H(+)-ATPase in plants and also exhibit unique biological activity in animal cells. Despite their well studied biological activities, no genes encoding fusicoccin biosynthetic enzymes have been identified. Cyclic diterpenes are commonly synthesized via cyclization of a C(20) precursor, geranylgeranyl diphosphate (GGDP), which is produced through condensation of the universal C(5) isoprene units dimethylallyl diphosphate and isopentenyl diphosphate by prenyltransferases. We found that (+)-fusicocca-2,10 (14)-diene, a tricyclic hydrocarbon precursor for fusicoccins, is biosynthesized from the C(5) isoprene units by an unusual multifunctional enzyme, P. amygdali fusicoccadiene synthase (PaFS), which shows both prenyltransferase and terpene cyclase activities. The functional analysis of truncated mutants and site-directed mutagenesis demonstrated that PaFS consists of two domains: a terpene cyclase domain at the N terminus and a prenyltransferase domain at the C terminus. These findings suggest that fusicoccadiene can be produced efficiently in the fungus by using the C(5) precursors, irrespective of GGDP availability. In fact, heterologous expression of PaFS alone resulted in the accumulation of fusicocca-2,10 (14)-diene in Escherichia coli cells, whereas no product was detected in E. coli cells expressing Gibberella fujikuroi ent-kaurene synthase, another fungal diterpene cyclase that also uses GGDP as a substrate but does not contain a prenyltransferase domain. Genome walking suggested that fusicoccin biosynthetic enzymes are encoded as a gene cluster near the PaFS gene.
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Affiliation(s)
- Tomonobu Toyomasu
- Department of Bioresource Engineering, Yamagata University, Tsuruoka, Yamagata 997-8555, Japan.
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Browne CD, Hindmarsh EJ, Smith JW. Inhibition of endothelial cell proliferation and angiogenesis by orlistat, a fatty acid synthase inhibitor. FASEB J 2006; 20:2027-35. [PMID: 17012255 DOI: 10.1096/fj.05-5404com] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Orlistat, an antiobesity drug, is cytostatic and cytotoxic to tumor cells. The antitumor activity of orlistat can be attributed to its ability to inhibit the thioesterase domain of fatty acid synthase (FAS). The objective of the present study was to test the effect of orlistat on endothelial cell proliferation and angiogenesis. Orlistat inhibits endothelial cell FAS, blocks the synthesis of fatty acids, and prevents endothelial cell proliferation. More significantly, orlistat inhibits human neovascularization in an ex vivo assay, which suggests that it may be useful as an antiangiogenic drug. The mechanism of these effects can be traced to the fact that orlistat prevents the display of the vascular endothelial growth factor (VEGF) receptor (VEGFR2/KDR/Flk1) on the endothelial cell surface. Thus, orlistat is an antiangiogenic agent with a novel mechanism of action.
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Affiliation(s)
- Cecille D Browne
- Cancer Research Center, Burnham Institute for Medical Research, 10901 North Torrey Pines Rd., La Jolla, CA 92037, USA
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14
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Menendez JA, Vellon L, Lupu R. Antitumoral actions of the anti-obesity drug orlistat (XenicalTM) in breast cancer cells: blockade of cell cycle progression, promotion of apoptotic cell death and PEA3-mediated transcriptional repression of Her2/neu (erbB-2) oncogene. Ann Oncol 2005; 16:1253-67. [PMID: 15870086 DOI: 10.1093/annonc/mdi239] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Orlistat (Xenicaltrade mark), a US Food and Drug Administration (FDA)-approved drug for bodyweight loss, has recently been demonstrated to exhibit antitumor properties towards prostate cancer cells by virtue of its ability to block the lipogenic activity of fatty acid synthase (FAS). FAS (oncogenic antigen-519) is up-regulated in about 50% of breast cancers, is an indicator of poor prognosis, and has recently been functionally associated with the Her2/neu (erbB-2) oncogene. MATERIALS AND METHODS We assessed the antitumoral effects of orlistat against the human breast cancer cell line SK-Br3, an in vitro paradigm of FAS and Her2/neu overexpression in breast cancer. RESULTS Cell cycle analyses revealed that micromolar concentrations of orlistat induced, in a time- and dose-dependent manner, significant changes in the distribution of cell populations including a complete loss of G2-M phase, S-phase accumulation and a concomitant increase in the emerging sub-G1 (apoptotic) cells. Poly (ADP-ribose) polymerase (PARP) cleavage, an early event required for cells committed to apoptosis, was more predominant in orlistat-treated G1 phase cells. When we characterized signaling molecules participating in the cellular events following orlistat-induced inhibition of FAS activity and preceded inhibition of breast cancer cell proliferation, a dramatic down-regulation of Her2/neu-coded p185(Her2/neu) oncoprotein was found in orlistat-treated SK-Br3 cells (>90% reduction). Interestingly, a significant accumulation of the DNA-binding protein PEA3, a member of the Ets transcription factor family that specifically targets a PEA3-binding motif present on the Her2/neu gene promoter and down-regulates its activity, was observed in orlistat-treated SK-Br3 cells. When a Luciferase reporter gene driven by the Her2/neu promoter was transiently transfected in SK-Br3 cells, orlistat exposure was found to dramatically repress the promoter activity of Her2/neu gene, whereas a Her2/neu promoter bearing a mutated binding DNA sequence was not subject to negative regulation by orlistat, thus demonstrating that the intact PEA3 binding site on the Her2/neu promoter is required for the orlistat-induced transcriptional repression of Her2/neu overexpression. RNA interference (RNAi)-mediated silencing of FAS gene expression similarly repressed Her2/neu gene expression in a PEA3-dependent manner, thus ruling out a role for non-FAS orlistat-mediated effects. When the combination of orlistat and the anti-Her2/neu antibody trastuzumab (Herceptintrade mark) in either concurrent (orlistat + trastuzumab) or sequential (orlistat --> trastuzumab; trastuzumab --> orlistat) schedules was tested for synergism, addition or antagonism using the combination index (CI) method of Chou-Talalay, co-exposure of orlistat and trastuzumab demonstrated strong synergistic effects (CI10-90 = 0.110-0.847), whereas sequential exposure to orlistat followed by trastuzumab (CI10-90 = 0.380-1.210) and trastuzumab followed by orlistat (CI10-90 = 0.605-1.278) mainly showed additive or antagonistic interactions. Indeed, orlistat-induced FAS inhibition synergistically promoted apoptotic cell death when concurrently combined with trastuzumab as determined by an ELISA for histone-associated DNA fragments. Importantly, the degree of FAS expression in a panel of human breast cancer cell lines was predictive of sensitivity to orlistat-induced anti-proliferative effects as determined by a MTT-based characterization of metabolically viable breast cancer cells. Moreover, hypersensitivity to orlistat-induced cytotoxicity was observed in MCF-7 breast cancer cells engineered to overexpress Her2/neu (MCF-7/Her2-18 cells), which exhibit a significant up-regulation of FAS expression and activity. CONCLUSIONS These findings reveal that the development of more potent and/or bioavailable orlistat's variants targeting the lipogenic activity of FAS may open a novel therapeutic avenue for treating Her2/neu-overexpressing breast carcinomas.
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MESH Headings
- Anti-Obesity Agents/pharmacology
- Antibodies, Monoclonal/pharmacology
- Antibodies, Monoclonal, Humanized
- Antineoplastic Agents/pharmacology
- Apoptosis/drug effects
- Breast Neoplasms/drug therapy
- Breast Neoplasms/metabolism
- Cell Cycle/drug effects
- Down-Regulation
- Drug Synergism
- Drug Therapy, Combination
- Female
- Flow Cytometry
- Gene Expression Regulation, Neoplastic/drug effects
- Humans
- Immunoblotting
- Lactones/pharmacology
- Lipase/antagonists & inhibitors
- Luciferases/metabolism
- Orlistat
- Poly(ADP-ribose) Polymerases/metabolism
- Promoter Regions, Genetic/genetics
- RNA, Small Interfering/pharmacology
- Receptor, ErbB-2/genetics
- Receptor, ErbB-2/metabolism
- Receptors, Tumor Necrosis Factor/antagonists & inhibitors
- Receptors, Tumor Necrosis Factor/genetics
- Receptors, Tumor Necrosis Factor/metabolism
- Transcription Factors/metabolism
- Transcription, Genetic
- Trastuzumab
- Tumor Cells, Cultured
- fas Receptor
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Affiliation(s)
- J A Menendez
- Department of Medicine, Breast Cancer Translational Research Program, Evanston Northwestern Healthcare Research Institute, Evanston, IL, USA.
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15
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Menendez JA, Colomer R, Lupu R. Why does tumor-associated fatty acid synthase (oncogenic antigen-519) ignore dietary fatty acids? Med Hypotheses 2005; 64:342-9. [PMID: 15607569 DOI: 10.1016/j.mehy.2004.07.022] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2004] [Accepted: 07/09/2004] [Indexed: 12/13/2022]
Abstract
The hyperactivation of fatty acid synthase (FAS)-catalyzed de novo biosynthesis of fatty acids is a molecular marker linked to tumor virulence in population studies of human malignancies. This activation appears to be linked to neoplastic transformation, since high levels of FAS have also been identified in pre-malignant lesions. This dependence of cancer upon accelerated lipogenesis differs from normal human tissues, in which FAS is suppressed by the presence of small amounts of fatty acids in the diet. The molecular mechanisms by which cancer cells constitutively exhibit FAS overexpression and hyperactivity have begun to emerge. The active involvement of the mitogen-activated protein kinase (MAPK) extracellular signal-regulated kinase (MAPK ERK1/2) and phosphatidylinositol-3'-kinase (PI-3'K)/protein kinase B (AKT) transduction cascades in the overexpression of FAS has been recently demonstrated in several cancer cell models. Strikingly, insulin-regulated stimulation of FAS expression in adipose cells is also mediated by the PI-3'K pathway with AKT being involved as a downstream effector. Moreover, FAS overexpression in tumor cells has been demonstrated to occur through a modification of the transcription factor sterol regulatory element-binding protein-1c (SREBP-1c), the major regulatory factor of FAS in liver and adipose tissues, which, in turn, is known to be regulated by MAPK ERK1/2 and PI-3'K/AKT pathways. Therefore, the signal transduction pathways regulating FAS expression in normal and cancer cells seem to share several downstream elements. However, the upstream mechanisms controlling FAS expression in cancer cells must be different from those in normal tissues, since tumor-associated FAS expression seems to be insensitive to nutritional signals. In pre-neoplastic lesions, we hypothesize that the early activation of FAS in pre-malignant cells represents a survival strategy which occurs to compensate for an insufficiency of both oxygen and dietary fatty acids due to, e.g., lack of angiogenesis. Thus, FAS activation reflects an epigenetic dysregulation of the lipogenic pathway in response to the microenvironment of tumors containing regions of poor oxygenation. Upon this unusual metabolic situation, FAS up-regulation also represent a metabolic strategy to maintain high proliferation rates of surviving cells in the absence of exogenous dietary fatty acids. Concomitantly, a variety of oncogenic changes (H-ras, erb B-2, etc.) may result in the constitutive activation of MAPK and PI-3'K/AKT signaling cascades, which, in turn, can activate SREBP-1c and, subsequently, tumor-associated FAS-catalyzed endogenous lipogenesis. Thereafter, high levels of FAS are maintained in coordination with increased demand for fatty acid metabolism and/or membrane synthesis in response to cancer-related overexpression of growth factors (e.g., EGF, heregulin) and/or growth factor receptors (e.g., EGFR, Her-2/neu). The aberrant MAPK and PI-3'K/AKT cascades driven by these oncogenic changes subvert the downregulatory effects of physiological concentrations of dietary fatty acids, resulting in a cancer-associated FAS insensitivity to nutritional signals. This model does not exclude that fundamental differences in the ability of FAS gene to respond to normal fatty acid's downregulatory actions may also synergistically interact with oncogenic signals to constitutively maintain an elevated FAS-dependent de novo endogenous fatty acid biogenesis in cancer cells in spite of high levels of circulating dietary fatty acids.
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Affiliation(s)
- Javier A Menendez
- Department of Medicine, Evanston Northwestern Healthcare Research Institute, 1001 University Place, Evanston, IL 60201, USA.
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16
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Knowles LM, Axelrod F, Browne CD, Smith JW. A fatty acid synthase blockade induces tumor cell-cycle arrest by down-regulating Skp2. J Biol Chem 2004; 279:30540-5. [PMID: 15138278 DOI: 10.1074/jbc.m405061200] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In eukaryotes, fatty acid synthase (FAS) is the enzyme responsible for synthesis of palmitate, the precursor of long-chain nonessential fatty acids. FAS is up-regulated in a wide range of cancers and has been suggested as a relevant drug target. Here, two independent approaches are taken toward knocking down FAS and then probing its connection to tumor cell proliferation. In one approach, Orlistat, a drug approved for treating obesity, is used as a potent inhibitor of the thioesterase function of FAS. In a separate strategy, the expression of FAS is suppressed by targeted knock-down with small interfering RNA. In both circumstances, the ablation of FAS activity causes a dramatic down-regulation of Skp2, a component of the E3 ubiquitin ligase that controls the turnover of p27Kip1. These effects ultimately tie into the retinoblastoma protein pathway and lead to a cell-cycle arrest at the G1/S boundary. Altogether, the findings of the study reveal unappreciated links between fatty acid synthase and ubiquitin-dependent proteolysis of cell-cycle regulatory proteins.
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Affiliation(s)
- Lynn M Knowles
- Cancer Research Center, The Burnham Institute, La Jolla, California 92037, USA
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17
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Brink J, Ludtke SJ, Kong Y, Wakil SJ, Ma J, Chiu W. Experimental Verification of Conformational Variation of Human Fatty Acid Synthase as Predicted by Normal Mode Analysis. Structure 2004; 12:185-91. [PMID: 14962379 DOI: 10.1016/j.str.2004.01.015] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2003] [Revised: 10/23/2003] [Accepted: 10/29/2003] [Indexed: 11/15/2022]
Abstract
Fatty acid synthase (FAS) is a 550 kDa homodimeric enzyme with multiple functional and structural domains. Normal mode analysis of a previously determined 19 A structure of FAS suggested that this enzyme might assume different conformational states with several distinct hinge movements. We have used a simultaneous multiple-model refinement method to search for the presence of the structural conformers from the electron images of FAS. We have demonstrated that the resulting models observed in the electron images are consistent with the predicted conformational changes. This technique demonstrates the potential of the combination of normal mode analysis with multiple model refinement to elucidate the multiple conformations of flexible proteins. Since each of these structures is based on a more homogeneous particle set, this technique has the potential, provided that sufficient references are used, to improve the resolution of the final reconstructions of single particles from electron cryomicroscopy.
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Affiliation(s)
- Jacob Brink
- National Center for Macromolecular Imaging, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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18
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Smith S, Witkowski A, Joshi AK. Structural and functional organization of the animal fatty acid synthase. Prog Lipid Res 2003; 42:289-317. [PMID: 12689621 DOI: 10.1016/s0163-7827(02)00067-x] [Citation(s) in RCA: 406] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The entire pathway of palmitate synthesis from malonyl-CoA in mammals is catalyzed by a single, homodimeric, multifunctional protein, the fatty acid synthase. Each subunit contains three N-terminal domains, the beta-ketoacyl synthase, malonyl/acetyl transferase and dehydrase separated by a structural core from four C-terminal domains, the enoyl reductase, beta-ketoacyl reductase, acyl carrier protein and thiosterase. The kinetics and specificities of the substrate loading reaction catalyzed by the malonyl/acetyl transferase, the condensation reaction catalyzed by beta-ketoacyl synthase and chain-terminating reaction catalyzed by the thioesterase ensure that intermediates do not leak off the enzyme, saturated chains exclusively are elongated and palmitate is released as the major product. Only in the fatty acid synthase dimer do the subunits adopt conformations that facilitate productive coupling of the individual reactions for fatty acid synthesis at the two acyl carrier protein centers. Introduction of a double tagging and dual affinity chromatographic procedure has permitted the engineering and isolation of heterodimeric fatty acid synthases carrying different mutations on each subunit. Characterization of these heterodimers, by activity assays and chemical cross-linking, has been exploited to map the functional topology of the protein. The results reveal that the two acyl carrier protein domains engage in substrate loading and condensation reactions catalyzed by the malonyl/acetyl transferase and beta-ketoacyl synthase domains of either subunit. In contrast, the reactions involved in processing of the beta-carbon atom, following each chain elongation step, together with the release of palmitate, are catalyzed by the cooperation of the acyl carrier protein with catalytic domains of the same subunit. These findings suggest a revised model for the fatty acid synthase in which the two polypeptides are oriented such that head-to-tail contacts are formed both between and within subunits.
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Affiliation(s)
- Stuart Smith
- Children's Hospital Oakland Research Institute, 5700 Martin Luther King Jr. Way, Oakland, CA 94609, USA.
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19
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Slayden RA, Barry CE. The role of KasA and KasB in the biosynthesis of meromycolic acids and isoniazid resistance in Mycobacterium tuberculosis. Tuberculosis (Edinb) 2003; 82:149-60. [PMID: 12464486 DOI: 10.1054/tube.2002.0333] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Mycobacterium tuberculosis has two discrete beta-ketoacyl synthases encoded by kasA and kasB that are located in tandem within a five-gene operon that has been implicated in isoniazid-sensitivity and mycolic acid synthesis. We have developed an in vitro meromycolic acid synthase assay to elucidate the anabolic role of these enzymes. Overproduction of KasA and KasB individually and together in M. smegmatis enabled cell-free incorporation of [(14)C]malonyl-CoA into lipids whose chain length was dependent upon the M. tuberculosis elongating enzyme used. KasA specifically elongated palmitoyl-CoA to monounsaturated fatty acids that averaged 40 carbons in length. KasB hyperproduction in the presence of KasA produced longer chain multiunsaturated hydrocarbons averaging 54 carbons in length. These products comigrated with a synthetic standard of meromycolic acid and their production was sensitive to isoniazid, thiolactomycin, and triclosan. KasA mutations associated with isoniazid resistance produced an enzyme that had a diminished overall catalytic activity but conferred enhanced resistance to isoniazid. In vivo analysis confirmed that overexpression of each of the four mutant KasAs enhanced isoniazid resistance when compared to overexpression of wild-type KasA. These results suggest discrete anabolic roles for both KasA and KasB in mycolic acid synthesis and substantiate the involvement of KasA mutations in isoniazid resistance.
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Affiliation(s)
- R A Slayden
- Tuberculosis Research Section, Laboratory of Host Defenses, NIAID, NIH, 12441 Parklawn Dr, Rockville, MD 20852, USA
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20
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Udwary DW, Merski M, Townsend CA. A method for prediction of the locations of linker regions within large multifunctional proteins, and application to a type I polyketide synthase. J Mol Biol 2002; 323:585-98. [PMID: 12381311 PMCID: PMC3400148 DOI: 10.1016/s0022-2836(02)00972-5] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Multifunctional proteins often appear to result from fusion of smaller proteins and in such cases typically can be separated into their ancestral components simply by cleaving the linker regions that separate the domains. Though possibly guided by sequence alignment, structural evidence, or light proteolysis, determination of the locations of linker regions remains empirical. We have developed an algorithm, named UMA, to predict the locations of linker regions in multifunctional proteins by quantification of the conservation of several properties within protein families, and the results agree well with structurally characterized proteins. This technique has been applied to a family of fungal type I iterative polyketide synthases (PKS), allowing prediction of the locations of all of the standard PKS domains, as well as two previously unidentified domains. Using these predictions, we report the cloning of the first fragment from the PKS norsolorinic acid synthase, responsible for biosynthesis of the first isolatable intermediate in aflatoxin production. The expression, light proteolysis and catalytic abilities of this acyl carrier protein-thioesterase didomain are discussed.
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21
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Ming D, Kong Y, Wakil SJ, Brink J, Ma J. Domain movements in human fatty acid synthase by quantized elastic deformational model. Proc Natl Acad Sci U S A 2002; 99:7895-9. [PMID: 12060737 PMCID: PMC122991 DOI: 10.1073/pnas.112222299] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2002] [Accepted: 04/12/2002] [Indexed: 11/18/2022] Open
Abstract
This paper reports the results of applying a computational method called the quantized elastic deformational model, to the determination of conformational flexibility of the supermolecular complex of human fatty acid synthase. The essence of this method is the ability to model large-scale conformational changes such as domain movements by treating the protein as an elastic object without the knowledge of protein primary sequence and atomic coordinates. The calculation was based on the electron density maps of the synthase at 19 A. The results suggest that the synthase is a very flexible molecule. Two types of flexible hinges in the structure were identified. One is an intersubunit hinge formed by the intersubunit connection and the other is an intrasubunit hinge located between domains I and II. Despite the fact that the dimeric synthase has a chemically symmetric structure, large domain movements around the hinge region occur in various directions and allow the molecule to adopt a wide range of conformations. These domain movements are likely to be important in facilitating and regulating the entire palmitate synthesis by coordinating the communication between components of the molecule, for instance, adjusting the distance between various active sites inside the catalytic reaction center. Finally, the ability to describe protein motions of a supermolecular complex, without the information of protein sequence and atomic coordinates, is a major advance in computational modeling of protein dynamics. The method provides an unprecedented ability to model protein motions at such a low resolution of structure.
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Affiliation(s)
- Dengming Ming
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, BCM-125, Houston, TX 77030, USA
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22
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Brink J, Ludtke SJ, Yang CY, Gu ZW, Wakil SJ, Chiu W. Quaternary structure of human fatty acid synthase by electron cryomicroscopy. Proc Natl Acad Sci U S A 2002; 99:138-43. [PMID: 11756679 PMCID: PMC117528 DOI: 10.1073/pnas.012589499] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We present the first three-dimensional reconstruction of human fatty acid synthase obtained by electron cryomicroscopy and single-particle image processing. The structure shows that the synthase is composed of two monomers, arranged in an antiparallel orientation, which is consistent with biochemical data. The monomers are connected to each other at their middle by a bridge of density, a site proposed to be the combination of the interdomain regions of the two monomers. Each monomer subunit appears to be subdivided into three structural domains. With this reconstruction of the synthase, we propose a location for the enzyme's two fatty acid synthesis sites.
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Affiliation(s)
- Jacob Brink
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology and National Center for Macromolecular Imaging, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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23
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Rangan VS, Joshi AK, Smith S. Mapping the functional topology of the animal fatty acid synthase by mutant complementation in vitro. Biochemistry 2001; 40:10792-9. [PMID: 11535054 DOI: 10.1021/bi015535z] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An in vitro mutant complementation approach has been used to map the functional topology of the animal fatty acid synthase. A series of knockout mutants was engineered, each mutant compromised in one of the seven functional domains, and heterodimers generated by hybridizing all possible combinations of the mutated subunits were isolated and characterized. Heterodimers comprised of a subunit containing either a beta-ketoacyl synthase or malonyl/acetyltransferase mutant, paired with a subunit containing mutations in any one of the other five domains, are active in fatty acid synthesis. Heterodimers in which both subunits carry a knockout mutation in either the dehydrase, enoyl reductase, keto reductase, or acyl carrier protein are inactive. Heterodimers comprised of a subunit containing a thioesterase mutation paired with a subunit containing a mutation in either the dehydrase, enoyl reductase, beta-ketoacyl reductase, or acyl carrier protein domains exhibit very low fatty acid synthetic ability. The results are consistent with a model for the fatty acid synthase in which the substrate loading and condensation reactions are catalyzed by cooperation of an acyl carrier protein domain of one subunit with the malonyl/acetyltransferase or beta-ketoacyl synthase domains, respectively, of either subunit. The beta-carbon-processing reactions, responsible for the complete reduction of the beta-ketoacyl moiety following each condensation step, are catalyzed by cooperation of an acyl carrier protein domain with the beta-ketoacyl reductase, dehydrase, and enoyl reductase domains associated exclusively with the same subunit. The chain-terminating reaction is carried out most efficiently by cooperation of an acyl carrier protein domain with the thioesterase domain of the same subunit. These results are discussed in the context of a revised model for the fatty acid synthase.
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Affiliation(s)
- V S Rangan
- Children's Hospital Oakland Research Institute, 5700 Martin Luther King Jr. Way, Oakland, California 94609, USA
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24
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Chirala SS, Jayakumar A, Gu ZW, Wakil SJ. Human fatty acid synthase: role of interdomain in the formation of catalytically active synthase dimer. Proc Natl Acad Sci U S A 2001; 98:3104-8. [PMID: 11248039 PMCID: PMC30614 DOI: 10.1073/pnas.051635998] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The human and animal fatty acid synthases are dimers of two identical multifunctional proteins (M(r) 272,000) arranged in an antiparallel configuration. This arrangement generates two active centers for fatty acid synthesis separated by interdomain (ID) regions and predicts that two appropriate halves of the monomer should be able to reconstitute an active fatty acid synthesizing center. This prediction was confirmed by the reconstitution of the synthase active center by using two heterologously expressed halves of the monomer protein. Each of these recombinant halves of synthase monomer contains half of the ID regions. We show here that the fatty acid synthase activity could not be reconstituted when the ID sequences present in the two recombinant halves are deleted, suggesting that these ID sequences are essential for fatty acid synthase dimer formation. Further, we confirm that the ID sequences are the only regions of fatty acid synthase monomers that showed significant dimer formation, by using the yeast two-hybrid system. These results are consistent with the proposal that the ID region, which has no known catalytic activity, associates readily and holds together the two dynamic active centers of the fatty acid synthase dimer, therefore playing an important role in the architecture of catalytically active fatty acid synthase.
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Affiliation(s)
- S S Chirala
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
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25
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Mukherjee S, Katiyar SS. Inhibition of pigeon liver fatty acid synthetase by specific modification of lysine residues with 2,4,6-trinitrobenzenesulphonic acid. JOURNAL OF ENZYME INHIBITION 2001; 15:421-7. [PMID: 10995072 DOI: 10.1080/14756360009040698] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Pigeon liver fatty acid synthetase was inactivated irreversibly by 2,4,6-trinitrobenzenesulphonic acid (TNBS). Biphasic inactivation of the enzyme was observed with the inhibitor. NADPH provided protection to the enzyme against inactivation by TNBS and the extent of protection increased with NADPH concentration indicating that the essential lysine residues are present at the NADPH binding site. The stoichiometric results with TNBS showed that 4 mol of lysine residues are modified per mole of fatty acid synthetase upon complete inactivation. The rapid reaction of two amino groups per enzyme molecule led to the loss of 60% of the enzyme activity. These approaches suggested that two lysine residues present at the active site are essential for the enzymatic activity of fatty acid synthetase.
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Affiliation(s)
- S Mukherjee
- Department of Chemistry, Indian Institute of Technology, Kanpur
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26
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Abstract
Fatty acid desaturases are enzymes that introduce double bonds into fatty acyl chains. They are present in all groups of organisms, i.e., bacteria, fungi, plants and animals, and play a key role in the maintenance of the proper structure and functioning of biological membranes. The desaturases are characterized by the presence of three conserved histidine tracks which are presumed to compose the Fe-binding active centers of the enzymes. Recent findings on the structure and expression of different types of fatty acid desaturase in cyanobacteria, plants and animals are reviewed in this article. Roles of individual desaturases in temperature acclimation and principles of regulation of the desaturase genes are discussed.
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Affiliation(s)
- D A Los
- Institute of Plant Physiology, Moscow, Russia
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27
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Mukherjee S, Katiyar SS. Inactivation of enoyl-CoA reductase in pigeon liver fatty acid synthetase by pyridoxal 5'-phosphate: evidence for the presence of one lysine residue at the active site. JOURNAL OF ENZYME INHIBITION 1998; 13:217-28. [PMID: 9629539 DOI: 10.3109/14756369809028342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Pigeon liver fatty acid synthetase (FAS) was rapidly inactivated by pyridoxal 5'-phosphate (PLP). Assays of the partial activities of the PLP-treated synthetase showed that only the enoyl-CoA reductase was decreased significantly. The inactivation of both the overall activity and enoyl-CoA reductase activity of FAS by PLP could be reversed by dialysis or dilution but not by reduction with sodium borohydride. Malonyl-CoA and acetyl-CoA did not protect the enzyme, whereas NADPH provided 68% protection against PLP-inactivation indicating that PLP modified lysine residues present at or near the co-enzyme binding site. PLP-treated enzyme after reduction with sodium borohydride exhibited fluorescence with a maximum at 397 nm (irradiation at 325 nm). Stoichiometric analysis showed that modification of four lysine residues per enzyme molecule resulted in complete inactivation of the overall and enoyl-CoA reductase activities of FAS. NADPH prevented the inactivation by protecting two of these lysine residues from modification, suggesting the presence of two essential lysine residues per enzyme molecule. These results are consistent with the hypothesis that each subunit of the enzyme contains an enoyl-CoA reductase domain in which a lysine residue, at or near the active site, interacts with NADPH.
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Affiliation(s)
- S Mukherjee
- Department of Chemistry, Indian Institute of Technology Kanpur, India
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28
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Tropf S, Revill WP, Bibb MJ, Hopwood DA, Schweizer M. Heterologously expressed acyl carrier protein domain of rat fatty acid synthase functions in Escherichia coli fatty acid synthase and Streptomyces coelicolor polyketide synthase systems. CHEMISTRY & BIOLOGY 1998; 5:135-46. [PMID: 9545424 DOI: 10.1016/s1074-5521(98)90058-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
INTRODUCTION Fatty acid synthases (FASs) catalyze the de novo biosynthesis of long-chain saturated fatty acids by a process common to eubacteria and eukaryotes, using either a set of monofunctional proteins (Type II FAS) or a polypeptide containing several catalytic functions (Type I FAS). To compare the features of a Type I domain with its Type II counterpart we expressed and characterized an acyl carrier protein (ACP) domain of the Type I rat FAS. RESULTS An ACP domain of rat FAS was defined that allows expression of a small percentage of active holo-ACP both in Escherichia coli, increasing fivefold upon co-expression with an E. coli holo-ACP synthase, and in Streptomyces coelicolor. The rat ACP domain functions with some components of the E. coli FAS, and can replace the actinorhodin polyketide synthase (PKS) ACP in S. coelicolorA3(2). Purification of the rat ACP domain from E. coli resulted in loss of its functionality. Purified apo-ACP could be converted to its holo-form upon incubation with purified E. coli holo-ACP synthase in vitro, however, suggesting that the loss of functionality was not due to a conformational change. CONCLUSIONS Functionality of the recombinant rat ACP was shown in distantly related and diverse enzyme systems, suggesting that Type I and Type II ACPs have a similar conformation. A procedure was described that might permit the production of rat FAS holo-ACP for structural and further biochemical characterization.
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Affiliation(s)
- S Tropf
- Genetics and Microbiology Department, Institute of Food Research, Colney, UK
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29
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Joshi AK, Rangan VS, Smith S. Differential affinity labeling of the two subunits of the homodimeric animal fatty acid synthase allows isolation of heterodimers consisting of subunits that have been independently modified. J Biol Chem 1998; 273:4937-43. [PMID: 9478938 DOI: 10.1074/jbc.273.9.4937] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
To explore the domain interactions that are required for catalytic activity of the multifunctional, homodimeric fatty acid synthase (FAS), we have formulated a strategy that allows isolation of modified dimers containing independently mutated subunits. Either a hexahistidine or a FLAG octapeptide tag was incorporated into the FAS at either the amino terminus, within an internal noncatalytic domain, or at the carboxyl terminus. The presence of the tags had no effect on the activity of the wild-type FAS. His-tagged dimers were mixed with FLAG-tagged dimers, and the subunits were randomized to produce a mixture of His-tagged homodimers, FLAG-tagged homodimers, and doubly tagged heterodimers. The doubly tagged heterodimers could be purified to homogeneity by chromatography on an anti-FLAG immunoaffinity column followed by a metal ion chelating column. This procedure for isolation of FAS heterodimers was utilized to determine whether the two centers for fatty acid synthesis in the FAS dimer can function independently of each other. Doubly tagged heterodimers, consisting of one wild-type subunit and one subunit in which the thioesterase activity had been eliminated, either by mutation or by treatment with phenylmethanesulfonyl fluoride, have 50% of the wild-type thioesterase activity and, in the presence of substrates, accumulate a long chain fatty acyl moiety on the modified subunit, thus blocking further substrate turnover at this center. Nevertheless, the ability of the heterodimer to synthesize fatty acids is also 50% of the wild-type FAS, demonstrating that an individual center for fatty acid synthesis has the same activity when paired with either a functional or nonfunctional catalytic center.
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Affiliation(s)
- A K Joshi
- Children's Hospital Oakland Research Institute, Oakland, California 94609, USA
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30
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Jayakumar A, Chirala SS, Wakil SJ. Human fatty acid synthase: assembling recombinant halves of the fatty acid synthase subunit protein reconstitutes enzyme activity. Proc Natl Acad Sci U S A 1997; 94:12326-30. [PMID: 9356448 PMCID: PMC24928 DOI: 10.1073/pnas.94.23.12326] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Our model of the native fatty acid synthase (FAS) depicts it as a dimer of two identical multifunctional proteins (Mr approximately 272,000) arranged in an antiparallel configuration so that the active Cys-SH of the beta-ketoacyl synthase of one subunit (where the acyl group is attached) is juxtaposed within 2 A of the pantetheinyl-SH of the second subunit (where the malonyl group is bound). This arrangement generates two active centers for fatty acid synthesis and predicts that if we have two appropriate halves of the monomer, we should be able to reconstitute an active fatty acid-synthesizing site. We cloned, expressed, and purified catalytically active thioredoxin (TRX) fusion proteins of the NH2-terminal half of the human FAS subunit protein (TRX-hFAS-dI; residues 1-1,297; Mr approximately 166) and of the C-terminal half (TRX-hFAS-dII-III; residues 1,296-2,504; Mr approximately 155). Adding equivalent amounts of TRX-hFAS-dI and TRX-hFAS-dII-III to a reaction mixture containing acetyl-CoA, malonyl-CoA, and NADPH resulted in the synthesis of long-chain fatty acids. The rate of synthesis was dependent upon the presence of both recombinant proteins and reached a constant level when they were present in equivalent amounts, indicating that the reconstitution of an active fatty acid-synthesizing site required the presence of every partial activity associated with the subunit protein. Analyses of the product acids revealed myristate to be the most abundant with small amounts of palmitate and stearate, possibly because of the way the fused recombinant proteins interacted with each other so that the thioesterase hydrolyzed the acyl group in its myristoyl state. The successful reconstitution of the human FAS activity from its domain I and domains II and III fully supports our model for the structure-function relationship of FAS in animal tissues.
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Affiliation(s)
- A Jayakumar
- Verna and Marrs McLean Department of Biochemistry, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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31
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Gu P, Welch WH, Guo L, Schegg KM, Blomquist GJ. Characterization of a novel microsomal fatty acid synthetase (FAS) compared to a cytosolic FAS in the housefly, Musca domestica. Comp Biochem Physiol B Biochem Mol Biol 1997; 118:447-56. [PMID: 9440236 DOI: 10.1016/s0305-0491(97)00112-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A novel membrane-bound fatty acid synthetase (FAS) associated with the microsomal fraction from the housefly, Musca domestica, was solubilized and purified to homogeneity. The microsomal FAS was solubilized by 0.75 M KCl in phosphate buffer and was purified to homogeneity by the sequential use of ammonium sulfate precipitation followed by Sepharose CL-6B, DEAE Sephacel and Red Agarose (dye ligand affinity) chromatography. The specific activity of the microsomal FAS was increased 1,440-fold to 6,522 U/mg during purification. The cytosolic FAS from the housefly was also purified by similar methods and the specific activity increased 183-fold to 7,533 U/mg. The relative molecular mass of the microsomal and cytosolic FAS are 419 +/- 22 kDa and 405 +/- 18 kDa, respectively, for the dimers as determined by gel permeation chromatography. The microsomal and the cytosolic FAS yield different tryptic digestion maps and have slightly different amino acid compositions, which demonstrate structural differences between the two FASs. In addition, there are differences between the two FASs in their kinetic characteristics and their ability to incorporate methylmalonylCoA into the growing fatty acyl chain.
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Affiliation(s)
- P Gu
- Department of Biochemistry/MS 330, University of Nevada, Reno 89557-0014, USA
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32
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Chirala SS, Huang WY, Jayakumar A, Sakai K, Wakil SJ. Animal fatty acid synthase: functional mapping and cloning and expression of the domain I constituent activities. Proc Natl Acad Sci U S A 1997; 94:5588-93. [PMID: 9159116 PMCID: PMC20822 DOI: 10.1073/pnas.94.11.5588] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/31/1997] [Indexed: 02/04/2023] Open
Abstract
Animal fatty acid synthase (FAS; EC 2.3.1.85) is a homodimer of a multifunctional subunit protein and catalyzes the synthesis of palmitate from acetyl-CoA, malonyl-CoA, and NADPH. The subunit (Mr approximately 270,000) carries seven distinct component activities and a site for the prosthetic group 4'-phosphopantetheine (acyl carrier protein). Based on proteolytic mapping, the organization of the activity domains along the subunit polypeptide from the N terminus is as follows: beta-ketoacyl synthase, acetyl and malonyl transacylases, beta-hydroxyacyl dehydratase, enoyl reductase, beta-ketoacyl reductase, acyl carrier protein, and thioesterase. By comparing the amino acid sequences of the chicken, rat, and human synthases, we found that kallikrein cleavage sites occur in the least conserved regions of the FAS polypeptide subunit. Determining the amino acid sequences of the N-terminal end of the major kallikrein cleavage peptides helped delineate the most likely boundaries of the component activities in the cDNA-derived amino acid sequence. To confirm this organization, we cloned the chicken FAS cDNA coding for domain I and expressed it in Escherichia coli as a maltose-binding fusion protein. The isolated recombinant protein contained the activities of the acetyl and malonyl transacylases and the beta-hydroxyacyl dehydratase. Based on the boundaries of the acetyl and malonyl transacylases and the beta-hydroxyacyl dehydratase, we also cloned the appropriate cDNA fragments encoding the domains that contain the transacylases and the dehydratase in pET vectors and expressed them in E. coli as thioredoxin-6xHis fusion proteins. The purified recombinant proteins contained, respectively, the activities of the acetyl and malonyl transacylases and the dehydratase. These results not only confirmed the order of the component activities in domain I, but also paved the way for successful expression and characterization of the remaining activities.
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Affiliation(s)
- S S Chirala
- Verna and Marrs McLean Department of Biochemistry, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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33
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Jayakumar A, Huang WY, Raetz B, Chirala SS, Wakil SJ. Cloning and expression of the multifunctional human fatty acid synthase and its subdomains in Escherichia coli. Proc Natl Acad Sci U S A 1996; 93:14509-14. [PMID: 8962082 PMCID: PMC26163 DOI: 10.1073/pnas.93.25.14509] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/17/1996] [Indexed: 02/03/2023] Open
Abstract
We engineered a full-length (8.3-kbp) cDNA coding for fatty acid synthase (FAS; EC 2.3.1.85) from the human brain FAS cDNA clones we characterized previously. In the process of accomplishing this task, we developed a novel PCR procedure, recombinant PCR, which is very useful in joining two overlapping DNA fragments that do not have a common or unique restriction site. The full-length cDNA was cloned in pMAL-c2 for heterologous expression in Escherichia coli as a maltose-binding protein fusion. The recombinant protein was purified by using amylose-resin affinity and hydroxylapatite chromatography. As expected from the coding capacity of the cDNA expressed, the chimeric recombinant protein has a molecular weight of 310,000 and reacts with antibodies against both human FAS and maltose-binding protein. The maltose-binding protein-human FAS (MBP-hFAS) catalyzed palmitate synthesis from acetyl-CoA, malonyl-CoA, and NADPH and exhibited all of the partial activities of FAS at levels comparable with those of the native human enzyme purified from HepG2 cells. Like the native HepG2 FAS, the products of MBP-hFAS are mainly palmitic acid (> 90%) and minimal amounts of stearic and arachidic acids. Similarly, a human FAS cDNA encoding domain I (beta-ketoacyl synthase, acetyl-CoA and malonyl-CoA transacylases, and beta-hydroxyacyl dehydratase) was cloned and expressed in E. coli using pMAL-c2. The expressed fusion protein, MBP-hFAS domain I, was purified to apparent homogeneity (M(r) 190,000) and exhibited the activities of the acetyl/malonyl transacylases and the beta-hydroxyacyl dehydratase. In addition, a human FAS cDNA encoding domains II and III (enoyl and beta-ketoacyl reductases, acyl carrier protein, and thioesterase) was cloned in pET-32b(+) and expressed in E. coli as a fusion protein with thioredoxin and six in-frame histidine residues. The recombinant fusion protein, thioredoxin-human FAS domains II and III, that was purified from E. coli had a molecular weight of 159,000 and exhibited the activities of the enoyl and beta-ketoacyl reductases and the thioesterase. Both the MBP and the thioredoxin-His-tags do not appear to interfere with the catalytic activity of human FAS or its partial activities.
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Affiliation(s)
- A Jayakumar
- Verna and Marrs McLean Department of Biochemistry, Baylor College of Medicine, Houston, TX 77030, USA
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34
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Rangan VS, Smith S. Expression in Escherichia coli and refolding of the malonyl-/acetyltransferase domain of the multifunctional animal fatty acid synthase. J Biol Chem 1996; 271:31749-55. [PMID: 8940200 DOI: 10.1074/jbc.271.49.31749] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
A cDNA encoding residues 429-815 of the multifunctional rat fatty acid synthase has been expressed in Escherichia coli and the recombinant protein refolded in vitro as a catalytically active malonyl-/acetyltransferase. Kinetic properties of the refolded recombinant enzyme were indistinguishable from those of a transferase preparation derived from the natural fatty acid synthase by limited proteolysis, indicating that the transferase domain is capable of folding correctly as an independent protein. Replacement of the active site Ser-581 (full-length fatty acid synthase numbering) with alanine completely eliminated catalytic activity, whereas replacement with cysteine resulted in retention of about 1% activity. The wild type transferase was extremely susceptible to inhibition by diethyl pyrocarbonate, and protection against inhibition was afforded by both malonyl- and acetyl-CoA. Replacement of the highly conserved residue His-683 with Ala reduced activity by 99.95%, and the residual activity was relatively unaffected by diethyl pyrocarbonate. The rate of acylation of the active site serine residue was also reduced by several orders of magnitude in the His-683 --> Ala mutant. These results indicate that His-683 plays an essential role in catalysis, likely by accepting a proton from the active site serine, thus increasing its nucleophilicity.
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Affiliation(s)
- V S Rangan
- Children's Hospital Oakland Research Institute, Oakland, California 94609, USA.
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35
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Lambalot RH, Gehring AM, Flugel RS, Zuber P, LaCelle M, Marahiel MA, Reid R, Khosla C, Walsh CT. A new enzyme superfamily - the phosphopantetheinyl transferases. CHEMISTRY & BIOLOGY 1996; 3:923-36. [PMID: 8939709 DOI: 10.1016/s1074-5521(96)90181-7] [Citation(s) in RCA: 625] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND All polyketide synthases, fatty acid synthases, and non-ribosomal peptide synthetases require posttranslational modification of their constituent acyl carrier protein domain(s) to become catalytically active. The inactive apoproteins are converted to their active holo-forms by posttranslational transfer of the 4'-phosphopantetheinyl (P-pant) moiety of coenzyme A to the sidechain hydroxyl of a conserved serine residue in each acyl carrier protein domain. The first P-pant transferase to be cloned and characterized was the recently reported Escherichia coli enzyme ACPS, responsible for apo to holo conversion of fatty acid synthase. Surprisingly, initial searches of sequence databases did not reveal any proteins with significant peptide sequence similarity with ACPS. RESULTS Through refinement of sequence alignments that indicated low level similarity with the ACPS peptide sequence, we identified two consensus motifs shared among several potential ACPS homologs. This has led to the identification of a large family of proteins having 12-22 % similarity with ACPS, which are putative P-pant transferases. Three of these proteins, E. coli EntD and o195, and B. subtilis Sfp, have been overproduced, purified and found to have P-pant transferase activity, confirming that the observed low level of sequence homology correctly predicted catalytic function. Three P-pant transferases are now known to be present in E. coli (ACPS, EntD and o195); ACPS and EntD are specific for the activation of fatty acid synthase and enterobactin synthetase, respectively. The apo-protein substrate for o195 has not yet been identified. Sfp is responsible for the activation of the surfactin synthetase. CONCLUSIONS The specificity of ACPS and EntD for distinct P-pant-requiring enzymes suggests that each P-pant-requiring synthase has its own partner enzyme responsible for apo to holo activation of its acyl carrier domains. This is the first direct evidence that in organisms containing multiple P-pant-requiring pathways, each pathway has its own posttranslational modifying activity.
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Affiliation(s)
- R H Lambalot
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA.
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36
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Schneider F, Cassagne C. Specific inhibition of plant fatty acid elongation by a long-chain cerulenin analogue. EUROPEAN JOURNAL OF BIOCHEMISTRY 1995; 228:704-9. [PMID: 7737167 DOI: 10.1111/j.1432-1033.1995.tb20313.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Cerulenin analogues with 16 or 18 carbon atoms inhibit both ATP-dependent and acyl-CoA-dependent fatty acid elongations. Prior incubation of microsomes with inhibitors is necessary to obtain maximal inhibition. The analogues act on the first reaction of the elongation process catalysed by the 3-ketoacyl-CoA synthase. The 18-carbon analogue has no, or little, effect on the fatty acid synthesis, while cerulenin and its 16-carbon analogue totally inhibit this synthesis. The 18-carbon analogue appears to be a specific inhibitor of the synthesis of very long-chain fatty acids, with no effect on de novo fatty acid synthesis.
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Affiliation(s)
- F Schneider
- Laboratoire de Biogenèse Membranaire, Centre National de la Recherche Scientifique, URA 1811, Université de Bordeaux 2, France
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37
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Joshi A, Smith S. Construction, expression, and characterization of a mutated animal fatty acid synthase deficient in the dehydrase function. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)41558-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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38
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Morisaki N, Funabashi H, Shimazawa R, Furukawa J, Kawaguchi A, Okuda S, Iwasaki S. Effect of side-chain structure on inhibition of yeast fatty-acid synthase by cerulenin analogues. EUROPEAN JOURNAL OF BIOCHEMISTRY 1993; 211:111-5. [PMID: 8425521 DOI: 10.1111/j.1432-1033.1993.tb19876.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Yeast fatty-acid synthase (FAS) inhibition by cerulenin analogs with varying side-chain lengths was compared with that of cerulenin, tetrahydrocerulenin and iodoacetamide. Although inhibition by cerulenin was the highest, the analogs having (E,E)-delta 7,10 double bonds showed high inhibition. This strongly suggests that the (E,E)-delta 7,10 double bonds play an important role in the interaction of the inhibitors with the enzyme. It was suggested that the size of the hydrophobic cavity in the condensing enzyme terminates fatty-acid chain elongation by decreasing inhibition by the C18 analog. Like cerulenin itself, the shortest analog (C6) did not induce malonyl-CoA decarboxylase activity.
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Affiliation(s)
- N Morisaki
- Institute of Applied Microbiology, University of Tokyo, Japan
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39
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Beck KF, Schreglmann R, Stathopulos I, Klein H, Hoch J, Schweizer M. The fatty acid synthase (FAS) gene and its promoter in Rattus norvegicus. DNA SEQUENCE : THE JOURNAL OF DNA SEQUENCING AND MAPPING 1992; 2:359-86. [PMID: 1339331 DOI: 10.3109/10425179209020817] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Screening of rat liver genomic libraries yielded 5 overlapping clones for rat fatty acid synthase (FAS). From these clones we determined the 18,170 bp sequence of the rat FAS together with 5,028 bp of the 5'-flanking region and 515 bp of the 3'-adjacent genomic sequence. The two FAS transcripts which differ only in the positions of their polyadenylation/termination sites consist of one untranslated and 42 translated exons. Surprisingly, the substrate binding site for enoyl reductase, one of the FAS component functions, is interrupted by an intron. The sizes and the boundaries of the individual domains could be mapped in relation to the exon/intron structure of the gene. These eight partial functions coincide with discrete units of exons. The acyl carrier protein with its prosthetic 4'-phosphopantetheine group is located within a single exon supporting the idea that rat FAS has evolved by gene fusion. Using primer extension the main transcription start site of the FAS mRNA in both hepatic and mammary gland tissues was located at 5,028 bp in the sequence determined. As expected of a gene which is pretranslationally regulated the 5'-flanking region contains, in addition to TATA and CAAT boxes, consensus sequences for several DNA binding proteins.
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Affiliation(s)
- K F Beck
- Institut für Mikrobiologie und Biochemie, Universität Erlangen-Nürnberg, Germany
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40
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Site-directed mutagenesis studies on the recombinant thioesterase domain of chicken fatty acid synthase expressed in Escherichia coli. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)54802-x] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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41
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Robinson JA. Chemical and biochemical aspects of polyether-ionophore antibiotic biosynthesis. FORTSCHRITTE DER CHEMIE ORGANISCHER NATURSTOFFE = PROGRESS IN THE CHEMISTRY OF ORGANIC NATURAL PRODUCTS. PROGRES DANS LA CHIMIE DES SUBSTANCES ORGANIQUES NATURELLES 1991; 58:1-81. [PMID: 1778521 DOI: 10.1007/978-3-7091-9141-5_1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- J A Robinson
- Organisch-Chemisches Institut, Universität Zürich, Switzerland
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42
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Characterization of recombinant thioesterase and acyl carrier protein domains of chicken fatty acid synthase expressed in Escherichia coli. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(19)84696-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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43
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Affiliation(s)
- S J Wakil
- Verna and Marrs McLean Department of Biochemistry, Baylor College of Medicine, Houston, Texas 77030
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44
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Huang WY, Stoops JK, Wakil SJ. Complete amino acid sequence of chicken liver acyl carrier protein derived from the fatty acid synthase. Arch Biochem Biophys 1989; 270:92-8. [PMID: 2648999 DOI: 10.1016/0003-9861(89)90011-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The acyl carrier protein domain of the chicken liver fatty acid synthase has been isolated after tryptic treatment of the synthase. The isolated domain functions as an acceptor of acetyl and malonyl moieties in the synthase-catalyzed transfer of these groups from their coenzyme A esters and therefore indicates that the acyl carrier protein domain exists in the complex as a discrete entity. The amino acid sequence of the acyl carrier protein was derived from analyses of peptide fragments produced by cyanogen bromide cleavage and trypsin and Staphylococcus aureus V8 protease digestions of the molecule. The isolated acyl carrier protein domain consists of 89 amino acid residues and has a calculated molecular weight of 10,127. The protein contains the phosphopantetheine group attached to the serine residue at position 38. The isolated acyl carrier protein peptide shows some sequence homology with the acyl carrier protein of Escherichia coli, particularly in the vicinity of the site of phosphopantetheine attachment, and shows extensive sequence homology with the acyl carrier protein from the uropygial gland of goose.
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Affiliation(s)
- W Y Huang
- Verna and Marrs McLean Department of Biochemistry, Baylor College of Medicine, Houston, Texas 77030
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45
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46
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Paulauskis JD, Sul HS. Structure of mouse fatty acid synthase mRNA. Identification of the two NADPH binding sites. Biochem Biophys Res Commun 1989; 158:690-5. [PMID: 2920037 DOI: 10.1016/0006-291x(89)92776-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Overlapping cDNA clones corresponding to 3.3 kb covering the carboxy-half and 3' non-coding regions of the single 8.2 kb mouse fatty acid synthase mRNA were isolated and sequenced. The sequence coded for 838 amino acid residues, followed by termination codon TAG, 771 nucleotides of 3' untranslated sequence and a poly A tail. For the first time, the two putative components of the NADPH binding sites of fatty acid synthase were identified, thereby making it possible to assign the enoyl reductase and beta-ketoacyl reductase domains of the multifunctional fatty acid synthase. Overall, the deduced amino acid sequence provides the domains for enoyl reductase, beta-ketoacyl reductase, acyl carrier protein and thioesterase of the mouse fatty acid synthase.
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Affiliation(s)
- J D Paulauskis
- Department of Nutrition, Harvard School of Public Health, Boston, MA 02115
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47
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Isolation and mapping of the beta-hydroxyacyl dehydratase activity of chicken liver fatty acid synthase. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)37582-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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48
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Kitamoto T, Nishigai M, Sasaki T, Ikai A. Structure of fatty acid synthetase from the Harderian gland of guinea pig. Proteolytic dissection and electron microscopic studies. J Mol Biol 1988; 203:183-95. [PMID: 3184185 DOI: 10.1016/0022-2836(88)90101-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Limited proteolysis and electron microscopic observation of fatty acid synthetase from the Harderian gland of guinea pig was performed to elucidate the higher-order structures of this multifunctional protein. Staphylococcus aureus V8 protease dissected the 250,000 Mr subunit of fatty acid synthetase into 120,000, 70,000, 35,000 and 30,000 Mr fragments, which were aligned in this order from the NH2 terminus. Some of the protease-resistant fragments produced with elastase, trypsin and lysyl endopeptidase were purified and fragment-specific antibodies (A40L, A33E and A25T) were prepared. A25T and A33F specifically bound the 35,000 and 30,000 Mr fragments, and A40L recognized the region between the 120,000 and 70,000 Mr fragments. Electron microscopic studies employing rotary shadowing, unidirectional shadowing and negative staining revealed that the overall dimension of the enzyme was 22 nm x 15 nm x 7 nm, and that two elongated subunits mainly composed of three subregions were in contact with each other at a few, three at most, points with two holes between them. The outer two attachment sites were often not in contact, indicating a certain flexibility of subunits at their ends. Immunocomplexes composed of fatty acid synthetase and fragment-specific antibodies were isolated and observed under the electron microscope. The attachment sites of A40L and A33E were located at the end of the minor and the major axes of the ellipsoidal contour of the molecule, respectively. Based on these results, the three-dimensional structure of animal fatty acid synthetase is discussed.
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Affiliation(s)
- T Kitamoto
- Department of Biophysics and Biochemistry, Faculty of Science, University of Tokyo, Japan
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49
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Chang SI, Hammes GG. Amino acid sequences of substrate-binding sites in chicken liver fatty acid synthase. Biochemistry 1988; 27:4753-60. [PMID: 3167014 DOI: 10.1021/bi00413a026] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The amino acid sequences of three essential regions of chicken liver fatty acid synthase have been determined: that around 4'-phosphopantetheine ("carrier" site), the substrate "loading" site containing serine, and a "waiting" site for the growing fatty acid containing cysteine. The amino acid sequence of the 4'-phosphopantetheine region was determined for the acetyl-, malonyl-, hydroxybutyryl-, and butyryl-enzyme with peptides obtained by hydrolysis of the enzyme with trypsin and Staphylococcus aureus (V8) protease. The sequence region around the essential serine was obtained for the acetyl- and malonyl-enzyme. The N-terminus of the tryptic peptide was blocked. However, the same sequence is obtained for the acetyl- and malonyl-peptide after S. aureus protease digestion, suggesting that the enzyme contains a single acyl transferase rather than two separate transacylases. The sequence around the cysteine was obtained by use of a radioactive iodoacetamide label. An unusual sequence of three serines adjacent to the cysteine was found. The strong similarities between peptides from different species for all three of the regions suggest that the multifunctional polypeptides from yeast and animals have evolved from the monofunctional enzymes of lower species.
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Affiliation(s)
- S I Chang
- Department of Chemistry, Cornell University, Ithaca, New York 14853-1301
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50
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Safford R, Windust JH, Lucas C, De Silva J, James CM, Hellyer A, Smith CG, Slabas AR, Hughes SG. Plastid-localised seed acyl-carrier protein of Brassica napus is encoded by a distinct, nuclear multigene family. EUROPEAN JOURNAL OF BIOCHEMISTRY 1988; 174:287-95. [PMID: 3383847 DOI: 10.1111/j.1432-1033.1988.tb14096.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Acyl-carrier protein (ACP) is a key component involved in the regulation of fatty acid biosynthesis in plants. cDNA clones encoding ACP from Brassica napus (oil seed rape) embryos have been isolated using oligonucleotide probes derived from heterologous ACPs. Analysis of the DNA sequence data, in conjunction with N-terminal amino acid sequence data, revealed ACP to be synthesized from nuclear DNA as a precursor containing a 51-amino-acid N-terminal extension. Immunocytochemical studies showed ACP to be localised solely within the plastids of B. napus seed tissue and it would therefore appear that the N-terminal extension functions as a transit peptide to direct ACP into these organelles. Analysis of several cDNA clones revealed sequence heterogeneity and thus evidence for an ACP multigene family. From ten cDNA clones, six unique genes, encoding five different mature ACP polypeptides, were identified. Northern blot hybridisation studies provide evidence that the seed and leaf forms of rape ACP are encoded by structurally distinct gene sets.
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Affiliation(s)
- R Safford
- Biosciences Division, Unilever Research Laboratory, Sharnbrook, Bedfordshire, England
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