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Buhrman G, Enríquez P, Dillard L, Baer H, Truong V, Grunden AM, Rose RB. Structure, Function, and Thermal Adaptation of the Biotin Carboxylase Domain Dimer from Hydrogenobacter thermophilus 2-Oxoglutarate Carboxylase. Biochemistry 2021; 60:324-345. [PMID: 33464881 DOI: 10.1021/acs.biochem.0c00815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
2-Oxoglutarate carboxylase (OGC), a unique member of the biotin-dependent carboxylase family from the order Aquificales, captures dissolved CO2 via the reductive tricarboxylic acid (rTCA) cycle. Structure and function studies of OGC may facilitate adaptation of the rTCA cycle to increase the level of carbon fixation for biofuel production. Here we compare the biotin carboxylase (BC) domain of Hydrogenobacter thermophilus OGC with the well-studied mesophilic homologues to identify features that may contribute to thermal stability and activity. We report three OGC BC X-ray structures, each bound to bicarbonate, ADP, or ADP-Mg2+, and propose that substrate binding at high temperatures is facilitated by interactions that stabilize the flexible subdomain B in a partially closed conformation. Kinetic measurements with varying ATP and biotin concentrations distinguish two temperature-dependent steps, consistent with biotin's rate-limiting role in organizing the active site. Transition state thermodynamic values derived from the Eyring equation indicate a larger positive ΔH⧧ and a less negative ΔS⧧ compared to those of a previously reported mesophilic homologue. These thermodynamic values are explained by partially rate limiting product release. Phylogenetic analysis of BC domains suggests that OGC diverged prior to Aquificales evolution. The phylogenetic tree identifies mis-annotations of the Aquificales BC sequences, including the Aquifex aeolicus pyruvate carboxylase structure. Notably, our structural data reveal that the OGC BC dimer comprises a "wet" dimerization interface that is dominated by hydrophilic interactions and structural water molecules common to all BC domains and likely facilitates the conformational changes associated with the catalytic cycle. Mutations in the dimerization domain demonstrate that dimerization contributes to thermal stability.
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Affiliation(s)
- Greg Buhrman
- Department of Molecular & Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695-7622, United States
| | - Paul Enríquez
- Department of Molecular & Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695-7622, United States
| | - Lucas Dillard
- Department of Molecular & Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695-7622, United States
| | - Hayden Baer
- Department of Molecular & Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695-7622, United States
| | - Vivian Truong
- Department of Molecular & Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695-7622, United States
| | - Amy M Grunden
- Department of Plant & Microbial Biology, North Carolina State University, Raleigh, North Carolina 27695-7612, United States
| | - Robert B Rose
- Department of Molecular & Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695-7622, United States
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2
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Tomassetti M, Garavaglia BS, Vranych CV, Gottig N, Ottado J, Gramajo H, Diacovich L. 3-methylcrotonyl Coenzyme A (CoA) carboxylase complex is involved in the Xanthomonas citri subsp. citri lifestyle during citrus infection. PLoS One 2018; 13:e0198414. [PMID: 29879157 PMCID: PMC5991677 DOI: 10.1371/journal.pone.0198414] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 05/19/2018] [Indexed: 01/15/2023] Open
Abstract
Citrus canker is a disease caused by the phytopathogen Xanthomonas citri subsp. citri (Xcc), bacterium which is unable to survive out of the host for extended periods of time. Once established inside the plant, the pathogen must compete for resources and evade the defenses of the host cell. However, a number of aspects of Xcc metabolic and nutritional state, during the epiphytic stage and at different phases of infection, are poorly characterized. The 3-methylcrotonyl-CoA carboxylase complex (MCC) is an essential enzyme for the catabolism of the branched-chain amino acid leucine, which prevents the accumulation of toxic intermediaries, facilitates the generation of branched chain fatty acids and/or provides energy to the cell. The MCC complexes belong to a group of acyl-CoA carboxylases (ACCase) enzymes dependent of biotin. In this work, we have identified two ORFs (XAC0263 and XAC0264) encoding for the α and β subunits of an acyl-CoA carboxylase complex from Xanthomonas and demonstrated that this enzyme has MCC activity both in vitro and in vivo. We also found that this MCC complex is conserved in a group of pathogenic gram negative bacteria. The generation and analysis of an Xcc mutant strain deficient in MCC showed less canker lesions in the interaction with the host plant, suggesting that the expression of these proteins is necessary for Xcc fitness during infection.
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Affiliation(s)
- Mauro Tomassetti
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Betiana S. Garavaglia
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Cecilia V. Vranych
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Natalia Gottig
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Jorgelina Ottado
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Hugo Gramajo
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Lautaro Diacovich
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
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3
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Bennett M, Högbom M. Crystal structure of the essential biotin-dependent carboxylase AccA3 from Mycobacterium tuberculosis. FEBS Open Bio 2017; 7:620-626. [PMID: 28469974 PMCID: PMC5407890 DOI: 10.1002/2211-5463.12212] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 02/20/2017] [Accepted: 02/21/2017] [Indexed: 11/10/2022] Open
Abstract
Biotin‐dependent acetyl‐CoA carboxylases catalyze the committed step in type II fatty acid biosynthesis, the main route for production of membrane phospholipids in bacteria, and are considered a key target for antibacterial drug discovery. Here we describe the first structure of AccA3, an essential component of the acetyl‐CoA carboxylase system in Mycobacterium tuberculosis (MTb). The structure, sequence comparisons, and modeling of ligand‐bound states reveal that the ATP cosubstrate‐binding site shows distinct differences compared to other bacterial and eukaryotic biotin carboxylases, including all human homologs. This suggests the possibility to design MTb AccA3 subtype‐specific inhibitors. Database Coordinates and structure factors have been deposited in the Protein Data Bank with the accession number 5MLK.
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Affiliation(s)
- Matthew Bennett
- Department of Biochemistry and Biophysics; Arrhenius Laboratories for Natural Sciences; Stockholm University; Sweden
| | - Martin Högbom
- Department of Biochemistry and Biophysics; Arrhenius Laboratories for Natural Sciences; Stockholm University; Sweden
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4
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Broussard TC, Pakhomova S, Neau DB, Bonnot R, Waldrop GL. Structural Analysis of Substrate, Reaction Intermediate, and Product Binding in Haemophilus influenzae Biotin Carboxylase. Biochemistry 2015; 54:3860-70. [PMID: 26020841 DOI: 10.1021/acs.biochem.5b00340] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Acetyl-CoA carboxylase catalyzes the first and regulated step in fatty acid synthesis. In most Gram-negative and Gram-positive bacteria, the enzyme is composed of three proteins: biotin carboxylase, a biotin carboxyl carrier protein (BCCP), and carboxyltransferase. The reaction mechanism involves two half-reactions with biotin carboxylase catalyzing the ATP-dependent carboxylation of biotin-BCCP in the first reaction. In the second reaction, carboxyltransferase catalyzes the transfer of the carboxyl group from biotin-BCCP to acetyl-CoA to form malonyl-CoA. In this report, high-resolution crystal structures of biotin carboxylase from Haemophilus influenzae were determined with bicarbonate, the ATP analogue AMPPCP; the carboxyphosphate intermediate analogues, phosphonoacetamide and phosphonoformate; the products ADP and phosphate; and the carboxybiotin analogue N1'-methoxycarbonyl biotin methyl ester. The structures have a common theme in that bicarbonate, phosphate, and the methyl ester of the carboxyl group of N1'-methoxycarbonyl biotin methyl ester all bound in the same pocket in the active site of biotin carboxylase and as such utilize the same set of amino acids for binding. This finding suggests a catalytic mechanism for biotin carboxylase in which the binding pocket that binds tetrahedral phosphate also accommodates and stabilizes a tetrahedral dianionic transition state resulting from direct transfer of CO₂ from the carboxyphosphate intermediate to biotin.
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Affiliation(s)
- Tyler C Broussard
- †Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Svetlana Pakhomova
- †Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - David B Neau
- ‡Department of Chemistry and Chemical Biology, Cornell University, Northeastern Collaborative Access Team, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Ross Bonnot
- †Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Grover L Waldrop
- †Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, United States
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5
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Lietzan AD, Lin Y, St Maurice M. The role of biotin and oxamate in the carboxyltransferase reaction of pyruvate carboxylase. Arch Biochem Biophys 2014; 562:70-9. [PMID: 25157442 PMCID: PMC4197081 DOI: 10.1016/j.abb.2014.08.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 07/16/2014] [Accepted: 08/12/2014] [Indexed: 01/15/2023]
Abstract
Pyruvate carboxylase (PC) is a biotin-dependent enzyme that catalyzes the MgATP-dependent carboxylation of pyruvate to oxaloacetate, an important anaplerotic reaction in central metabolism. During catalysis, carboxybiotin is translocated to the carboxyltransferase domain where the carboxyl group is transferred to the acceptor substrate, pyruvate. Many studies on the carboxyltransferase domain of PC have demonstrated an enhanced oxaloacetate decarboxylation activity in the presence of oxamate and it has been shown that oxamate accepts a carboxyl group from carboxybiotin during oxaloacetate decarboxylation. The X-ray crystal structure of the carboxyltransferase domain from Rhizobium etli PC reveals that oxamate is positioned in the active site in an identical manner to the substrate, pyruvate, and kinetic data are consistent with the oxamate-stimulated decarboxylation of oxaloacetate proceeding through a simple ping-pong bi bi mechanism in the absence of the biotin carboxylase domain. Additionally, analysis of truncated PC enzymes indicates that the BCCP domain devoid of biotin does not contribute directly to the enzymatic reaction and conclusively demonstrates a biotin-independent oxaloacetate decarboxylation activity in PC. These findings advance the description of catalysis in PC and can be extended to the study of related biotin-dependent enzymes.
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Affiliation(s)
- Adam D Lietzan
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53201, USA
| | - Yi Lin
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53201, USA
| | - Martin St Maurice
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53201, USA.
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6
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Gallego-Villar L, Pérez-Cerdá C, Pérez B, Abia D, Ugarte M, Richard E, Desviat LR. Functional characterization of novel genotypes and cellular oxidative stress studies in propionic acidemia. J Inherit Metab Dis 2013; 36:731-40. [PMID: 23053474 DOI: 10.1007/s10545-012-9545-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Revised: 09/13/2012] [Accepted: 09/17/2012] [Indexed: 12/18/2022]
Abstract
Propionic acidemia (PA), caused by a deficiency of the mitochondrial biotin dependent enzyme propionyl-CoA carboxylase (PCC) is one of the most frequent organic acidurias in humans. PA is caused by mutations in either the PCCA or PCCB genes encoding the α- and β-subunits of the PCC enzyme which are assembled as an α6β6 dodecamer. In this study we have investigated the molecular basis of the defect in ten fibroblast samples from PA patients. Using homology modeling with the recently solved crystal structure of the PCC holoenzyme and a eukaryotic expression system we have analyzed the structural and functional effect of novel point mutations, also revealing a novel splice defect by minigene analysis. In addition, we have investigated the contribution of oxidative stress to cellular damage measuring reactive oxygen species (ROS) levels and apoptosis parameters in patient fibroblasts, as recent studies point to a secondary mitochondrial dysfunction as pathophysiological mechanism in this disorder. The results show an increase in intracellular ROS content compared to controls, correlating with the activation of the JNK and p38 signaling pathways. Highest ROS levels were present in cells harboring functionally null mutations, including one severe missense mutation. This work provides molecular insight into the pathogenicity of PA variants and indicates that oxidative stress may be a major contributing factor to the cellular damage, supporting the proposal of antioxidant strategies as novel supplementary therapy in this rare disease.
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Affiliation(s)
- Lorena Gallego-Villar
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular Severo Ochoa, UAM-CSIC, Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), IdiPAZ, Madrid, Spain
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7
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Waldrop GL, Holden HM, St Maurice M. The enzymes of biotin dependent CO₂ metabolism: what structures reveal about their reaction mechanisms. Protein Sci 2013; 21:1597-619. [PMID: 22969052 DOI: 10.1002/pro.2156] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Biotin is the major cofactor involved in carbon dioxide metabolism. Indeed, biotin-dependent enzymes are ubiquitous in nature and are involved in a myriad of metabolic processes including fatty acid synthesis and gluconeogenesis. The cofactor, itself, is composed of a ureido ring, a tetrahydrothiophene ring, and a valeric acid side chain. It is the ureido ring that functions as the CO₂ carrier. A complete understanding of biotin-dependent enzymes is critically important for translational research in light of the fact that some of these enzymes serve as targets for anti-obesity agents, antibiotics, and herbicides. Prior to 1990, however, there was a dearth of information regarding the molecular architectures of biotin-dependent enzymes. In recent years there has been an explosion in the number of three-dimensional structures reported for these proteins. Here we review our current understanding of the structures and functions of biotin-dependent enzymes. In addition, we provide a critical analysis of what these structures have and have not revealed about biotin-dependent catalysis.
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Affiliation(s)
- Grover L Waldrop
- Division of Biochemistry and Molecular Biology, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
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8
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Zeczycki TN, Menefee AL, Adina-Zada A, Jitrapakdee S, Surinya KH, Wallace JC, Attwood PV, St. Maurice M, Cleland WW. Novel insights into the biotin carboxylase domain reactions of pyruvate carboxylase from Rhizobium etli. Biochemistry 2011; 50:9724-37. [PMID: 21957995 PMCID: PMC3211089 DOI: 10.1021/bi2012788] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The catalytic mechanism of the MgATP-dependent carboxylation of biotin in the biotin carboxylase domain of pyruvate carboxylase from R. etli (RePC) is common to the biotin-dependent carboxylases. The current site-directed mutagenesis study has clarified the catalytic functions of several residues proposed to be pivotal in MgATP-binding and cleavage (Glu218 and Lys245), HCO(3)(-) deprotonation (Glu305 and Arg301), and biotin enolization (Arg353). The E218A mutant was inactive for any reaction involving the BC domain and the E218Q mutant exhibited a 75-fold decrease in k(cat) for both pyruvate carboxylation and the full reverse reaction. The E305A mutant also showed a 75- and 80-fold decrease in k(cat) for both pyruvate carboxylation and the full reverse reaction, respectively. While Glu305 appears to be the active site base which deprotonates HCO(3)(-), Lys245, Glu218, and Arg301 are proposed to contribute to catalysis through substrate binding interactions. The reactions of the biotin carboxylase and carboxyl transferase domains were uncoupled in the R353M-catalyzed reactions, indicating that Arg353 may not only facilitate the formation of the biotin enolate but also assist in coordinating catalysis between the two spatially distinct active sites. The 2.5- and 4-fold increase in k(cat) for the full reverse reaction with the R353K and R353M mutants, respectively, suggests that mutation of Arg353 allows carboxybiotin increased access to the biotin carboxylase domain active site. The proposed chemical mechanism is initiated by the deprotonation of HCO(3)(-) by Glu305 and concurrent nucleophilic attack on the γ-phosphate of MgATP. The trianionic carboxyphosphate intermediate formed reversibly decomposes in the active site to CO(2) and PO(4)(3-). PO(4)(3-) then acts as the base to deprotonate the tethered biotin at the N(1)-position. Stabilized by interactions between the ureido oxygen and Arg353, the biotin-enolate reacts with CO(2) to give carboxybiotin. The formation of a distinct salt bridge between Arg353 and Glu248 is proposed to aid in partially precluding carboxybiotin from reentering the biotin carboxylase active site, thus preventing its premature decarboxylation prior to the binding of a carboxyl acceptor in the carboxyl transferase domain.
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Affiliation(s)
- Tonya N. Zeczycki
- Institute for Enzyme Research and Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53726
| | - Ann L. Menefee
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin 53201
| | - Abdussalam Adina-Zada
- School of Biomedical, Biomolecular and Chemical Sciences, University of Western Australia, Crawley WA, 6009 Australia
| | - Sarawut Jitrapakdee
- Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | - Kathy H. Surinya
- School of Molecular and Biomedical Science, University of Adelaide, Adelaide S.A., 5005, Australia
| | - John C. Wallace
- School of Molecular and Biomedical Science, University of Adelaide, Adelaide S.A., 5005, Australia
| | - Paul V. Attwood
- School of Biomedical, Biomolecular and Chemical Sciences, University of Western Australia, Crawley WA, 6009 Australia
| | - Martin St. Maurice
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin 53201
| | - W. Wallace Cleland
- Institute for Enzyme Research and Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53726
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9
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Gago G, Diacovich L, Arabolaza A, Tsai SC, Gramajo H. Fatty acid biosynthesis in actinomycetes. FEMS Microbiol Rev 2011; 35:475-97. [PMID: 21204864 DOI: 10.1111/j.1574-6976.2010.00259.x] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
All organisms that produce fatty acids do so via a repeated cycle of reactions. In mammals and other animals, these reactions are catalyzed by a type I fatty acid synthase (FAS), a large multifunctional protein to which the growing chain is covalently attached. In contrast, most bacteria (and plants) contain a type II system in which each reaction is catalyzed by a discrete protein. The pathway of fatty acid biosynthesis in Escherichia coli is well established and has provided a foundation for elucidating the type II FAS pathways in other bacteria (White et al., 2005). However, fatty acid biosynthesis is more diverse in the phylum Actinobacteria: Mycobacterium, possess both FAS systems while Streptomyces species have only the multienzyme FAS II system and Corynebacterium species exclusively FAS I. In this review, we present an overview of the genome organization, biochemical properties and physiological relevance of the two FAS systems in the three genera of actinomycetes mentioned above. We also address in detail the biochemical and structural properties of the acyl-CoA carboxylases (ACCases) that catalyzes the first committed step of fatty acid synthesis in actinomycetes, and discuss the molecular bases of their substrate specificity and the structure-based identification of new ACCase inhibitors with antimycobacterial properties.
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Affiliation(s)
- Gabriela Gago
- Microbiology Division, IBR (Instituto de Biología Molecular y Celular de Rosario), Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
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10
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Arabolaza A, Shillito ME, Lin TW, Diacovich L, Melgar M, Pham H, Amick D, Gramajo H, Tsai SC. Crystal structures and mutational analyses of acyl-CoA carboxylase beta subunit of Streptomyces coelicolor. Biochemistry 2010; 49:7367-76. [PMID: 20690600 DOI: 10.1021/bi1005305] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The first committed step of fatty acid and polyketides biosynthesis, the biotin-dependent carboxylation of an acyl-CoA, is catalyzed by acyl-CoA carboxylases (ACCases) such as acetyl-CoA carboxylase (ACC) and propionyl-CoA carboxylase (PCC). ACC and PCC in Streptomyces coelicolor are homologue multisubunit complexes that can carboxylate different short chain acyl-CoAs. While ACC is able to carboxylate acetyl-, propionyl-, or butyryl-CoA with approximately the same specificity, PCC only recognizes propionyl- and butyryl-CoA as substrates. How ACC and PCC have such different specificities toward these substrates is only partially understood. To further understand the molecular basis of how the active site residues can modulate the substrate recognition, we mutated D422, N80, R456, and R457 of PccB, the catalytic beta subunit of PCC. The crystal structures of six PccB mutants and the wild type crystal structure were compared systematically to establish the sequence-structure-function relationship that correlates the observed substrate specificity toward acetyl-, propionyl-, and butyryl-CoA with active site geometry. The experimental data confirmed that D422 is a key determinant of substrate specificity, influencing not only the active site properties but further altering protein stability and causing long-range conformational changes. Mutations of N80, R456, and R457 lead to variations in the quaternary structure of the beta subunit and to a concomitant loss of enzyme activity, indicating the importance of these residues in maintaining the active protein conformation as well as a critical role in substrate binding.
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Affiliation(s)
- Ana Arabolaza
- Instituto de Biología Molecular y Celular de Rosario (IBR-Consejo Nacional de Investigaciones Científicas y Técnicas) and Departamento de Microbiología, Facultad de Ciencias Bioquímicasy Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000 Rosario, Argentina
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11
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Chou CY, Yu LPC, Tong L. Crystal structure of biotin carboxylase in complex with substrates and implications for its catalytic mechanism. J Biol Chem 2009; 284:11690-7. [PMID: 19213731 DOI: 10.1074/jbc.m805783200] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Biotin-dependent carboxylases are widely distributed in nature and have important functions in many cellular processes. These enzymes share a conserved biotin carboxylase (BC) component, which catalyzes the ATP-dependent carboxylation of biotin using bicarbonate as the donor. Despite the availability of a large amount of biochemical and structural information on BC, the molecular basis for its catalysis is currently still poorly understood. We report here the crystal structure at 2.0 A resolution of wild-type Escherichia coli BC in complex with its substrates biotin, bicarbonate, and Mg-ADP. The structure suggests that Glu(296) is the general base that extracts the proton from bicarbonate, and Arg(338) is the residue that stabilizes the enolate biotin intermediate in the carboxylation reaction. The B domain of BC is positioned closer to the active site, leading to a 2-A shift in the bound position of the adenine nucleotide and bringing it near the bicarbonate for catalysis. One of the oxygen atoms of bicarbonate is located in the correct position to initiate the nucleophilic attack on ATP to form the carboxyphosphate intermediate. This oxygen is also located close to the N1' atom of biotin, providing strong evidence that the phosphate group, derived from decomposition of carboxyphosphate, is the general base that extracts the proton on this N1' atom. The structural observations are supported by mutagenesis and kinetic studies. Overall, this first structure of BC in complex with substrates offers unprecedented insights into the molecular mechanism for the catalysis by this family of enzymes.
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Affiliation(s)
- Chi-Yuan Chou
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
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12
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Mochalkin I, Miller JR, Evdokimov A, Lightle S, Yan C, Stover CK, Waldrop GL. Structural evidence for substrate-induced synergism and half-sites reactivity in biotin carboxylase. Protein Sci 2008; 17:1706-18. [PMID: 18725455 PMCID: PMC2548373 DOI: 10.1110/ps.035584.108] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Bacterial acetyl-CoA carboxylase is a multifunctional biotin-dependent enzyme that consists of three separate proteins: biotin carboxylase (BC), biotin carboxyl carrier protein (BCCP), and carboxyltransferase (CT). Acetyl-CoA carboxylase is a potentially attractive target for novel antibiotics because it catalyzes the first committed step in fatty acid biosynthesis. In the first half-reaction, BC catalyzes the ATP-dependent carboxylation of BCCP. In the second half-reaction, the carboxyl group is transferred from carboxybiotinylated BCCP to acetyl-CoA to produce malonyl-CoA. A series of structures of BC from several bacteria crystallized in the presence of various ATP analogs is described that addresses three major questions concerning the catalytic mechanism. The structure of BC bound to AMPPNP and the two catalytically essential magnesium ions resolves inconsistencies between the kinetics of active-site BC mutants and previously reported BC structures. Another structure of AMPPNP bound to BC shows the polyphosphate chain folded back on itself, and not in the correct (i.e., extended) conformation for catalysis. This provides the first structural evidence for the hypothesis of substrate-induced synergism, which posits that ATP binds nonproductively to BC in the absence of biotin. The BC homodimer has been proposed to exhibit half-sites reactivity where the active sites alternate or "flip-flop" their catalytic cycles. A crystal structure of BC showed the ATP analog AMPPCF(2)P bound to one subunit while the other subunit was unliganded. The liganded subunit was in the closed or catalytic conformation while the unliganded subunit was in the open conformation. This provides the first structural evidence for half-sites reactivity in BC.
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Affiliation(s)
- Igor Mochalkin
- Pfizer Global Research and Development, Ann Arbor, Michigan 48105, USA
| | - J. Richard Miller
- Pfizer Global Research and Development, Ann Arbor, Michigan 48105, USA
| | - Artem Evdokimov
- Pfizer Global Research and Development, Ann Arbor, Michigan 48105, USA
| | - Sandra Lightle
- Pfizer Global Research and Development, Ann Arbor, Michigan 48105, USA
| | - Chunhong Yan
- Pfizer Global Research and Development, Ann Arbor, Michigan 48105, USA
| | | | - Grover L. Waldrop
- Division of Biochemistry and Molecular Biology, Louisiana State University, Baton Rouge, Louisiana 70803, USA
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13
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Jitrapakdee S, Maurice MS, Rayment I, Cleland WW, Wallace JC, Attwood PV. Structure, mechanism and regulation of pyruvate carboxylase. Biochem J 2008; 413:369-87. [PMID: 18613815 PMCID: PMC2859305 DOI: 10.1042/bj20080709] [Citation(s) in RCA: 289] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
PC (pyruvate carboxylase) is a biotin-containing enzyme that catalyses the HCO(3)(-)- and MgATP-dependent carboxylation of pyruvate to form oxaloacetate. This is a very important anaplerotic reaction, replenishing oxaloacetate withdrawn from the tricarboxylic acid cycle for various pivotal biochemical pathways. PC is therefore considered as an enzyme that is crucial for intermediary metabolism, controlling fuel partitioning toward gluconeogenesis or lipogenesis and in insulin secretion. The enzyme was discovered in 1959 and over the last decade there has been much progress in understanding its structure and function. PC from most organisms is a tetrameric protein that is allosterically regulated by acetyl-CoA and aspartate. High-resolution crystal structures of the holoenzyme with various ligands bound have recently been determined, and have revealed details of the binding sites and the relative positions of the biotin carboxylase, carboxyltransferase and biotin carboxyl carrier domains, and also a unique allosteric effector domain. In the presence of the allosteric effector, acetyl-CoA, the biotin moiety transfers the carboxy group between the biotin carboxylase domain active site on one polypeptide chain and the carboxyltransferase active site on the adjacent antiparallel polypeptide chain. In addition, the bona fide role of PC in the non-gluconeogenic tissues has been studied using a combination of classical biochemistry and genetic approaches. The first cloning of the promoter of the PC gene in mammals and subsequent transcriptional studies reveal some key cognate transcription factors regulating tissue-specific expression. The present review summarizes these advances and also offers some prospects in terms of future directions for the study of this important enzyme.
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Affiliation(s)
- Sarawut Jitrapakdee
- Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | - Martin St. Maurice
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
| | - Ivan Rayment
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
| | - W. Wallace Cleland
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
| | - John C. Wallace
- School of Molecular & Biomedical Science, University of Adelaide, SA 5005, Australia
| | - Paul V. Attwood
- School of Biomedical, Biomolecular and Chemical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6100, Australia
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14
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Nilsson Lill SO, Gao J, Waldrop GL. Molecular dynamics simulations of biotin carboxylase. J Phys Chem B 2008; 112:3149-56. [PMID: 18271571 DOI: 10.1021/jp076326c] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Biotin carboxylase catalyzes the ATP-dependent carboxylation of biotin and is one component of the multienzyme complex acetyl-CoA carboxylase that catalyzes the first committed step in fatty acid synthesis in all organisms. Biotin carboxylase from Escherichia coli, whose crystal structures with and without ATP bound have been determined, has served as a model system for this component of the acetyl-CoA carboxylase complex. The two crystal structures revealed a large conformational change of one domain relative to the other domains when ATP is bound. Unfortunately, the crystal structure with ATP bound was obtained with an inactive site-directed mutant of the enzyme. As a consequence the structure with ATP bound lacked key structural information such as for the Mg2+ ions and contained altered conformations of key active-site residues. Therefore, nanosecond molecular dynamics studies of the wild-type biotin carboxylase were undertaken to supplant and amend the results of the crystal structures. Specifically, the protein-metal interactions of the two catalytically critical Mg2+ ions bound in the active site are presented along with a reevaluation of the conformations of active-site residues bound to ATP. In addition, the regions of the polypeptide chain that serve as hinges for the large conformational change were identified. The results of the hinge analysis complemented a covariance analysis that identified the individual structural elements of biotin carboxylase that change their conformation in response to ATP binding.
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Affiliation(s)
- Sten O Nilsson Lill
- Department of Chemistry and Supercomputing Institute, University of Minnesota, Minneapolis, MN 55415, USA.
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15
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Ito Y, Kondo H, Shiota Y, Yoshizawa K. Theoretical Analysis of the Reaction Mechanism of Biotin Carboxylase. J Chem Theory Comput 2008; 4:366-74. [DOI: 10.1021/ct700260f] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yuko Ito
- Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, 680-4 Kawazu, Iizuka 820-8502, Japan, and Institute for Materials Chemistry and Engineering, Kyushu University, Nishi-ku, Fukuoka 819-0395, Japan
| | - Hiroki Kondo
- Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, 680-4 Kawazu, Iizuka 820-8502, Japan, and Institute for Materials Chemistry and Engineering, Kyushu University, Nishi-ku, Fukuoka 819-0395, Japan
| | - Yoshihito Shiota
- Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, 680-4 Kawazu, Iizuka 820-8502, Japan, and Institute for Materials Chemistry and Engineering, Kyushu University, Nishi-ku, Fukuoka 819-0395, Japan
| | - Kazunari Yoshizawa
- Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, 680-4 Kawazu, Iizuka 820-8502, Japan, and Institute for Materials Chemistry and Engineering, Kyushu University, Nishi-ku, Fukuoka 819-0395, Japan
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16
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Kristie J, Toth JG, Silverstrim C, Pickett W, Landro JA. A High-throughput two-phase partition assay to measure the activity of lipid-metabolizing enzymes. Anal Biochem 2006; 358:266-72. [PMID: 16962554 DOI: 10.1016/j.ab.2006.07.036] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2006] [Revised: 07/26/2006] [Accepted: 07/27/2006] [Indexed: 11/26/2022]
Abstract
A new method to measure the activity of lipid-metabolizing enzymes is described. Subsequent to an enzymatic reaction, a two-phase system (organic/aqueous) is established by the addition of a phase partition scintillation fluid (PPSF). The PPSF serves as a scintillation fluid, a phase partition agent, and a carrier/separator of an organic-soluble radiolabeled reaction substrate or product. Applying an empirically derived set of conditions typically enhances the separation of substrate from product whereby one species is effectively solubilized in the PPSF. In situ partitioning of the radionuclide-containing organic/lipid phase from the aqueous phase occurs within individual wells of 96-well or 384-well density PPSF-resistant microtiter plates without the requirement for multiple organic solvent extractions and aspirations, making this method applicable to high-throughput screening. The utility of this method for both kinetic characterization and high-throughput screening is demonstrated with acetyl-CoA carboxylase and fatty acid synthase.
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Affiliation(s)
- James Kristie
- Bayer Healthcare, Pharmaceuticals Corp., 400 Morgan Lane, West Haven, CT 06516, USA
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17
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Vergauwen B, De Vos D, Van Beeumen JJ. Characterization of the Bifunctional γ-Glutamate-cysteine Ligase/Glutathione Synthetase (GshF) of Pasteurella multocida. J Biol Chem 2006; 281:4380-94. [PMID: 16339152 DOI: 10.1074/jbc.m509517200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glutamate-cysteine ligase (gamma-ECL) and glutathione synthetase (GS) are the two unrelated ligases that constitute the glutathione biosynthesis pathway in most eukaryotes, purple bacteria, and cyanobacteria. gamma-ECL is a member of the glutamine synthetase family, whereas GS enzymes group together with highly diverse carboxyl-to-amine/thiol ligases, all characterized by the so-called two-domain ATP-grasp fold. This generalized scheme toward the formation of glutathione, however, is incomplete, as functional steady-state levels of intracellular glutathione may also accumulate solely by import, as has been reported for the Pasteurellaceae member Haemophilus influenzae, as well as for certain Gram-positive enterococci and streptococci, or by the action of a bifunctional fusion protein (termed GshF), as has been reported recently for the Gram-positive firmicutes Streptococcus agalactiae and Listeria monocytogenes. Here, we show that yet another member of the Pasteurellaceae family, Pasteurella multocida, acquires glutathione both by import and GshF-driven biosynthesis. Domain architecture analysis shows that this P. multocida GshF bifunctional ligase contains an N-terminal gamma-proteobacterial gamma-ECL-like domain followed by a typical ATP-grasp domain, which most closely resembles that of cyanophycin synthetases, although it has no significant homology with known GS ligases. Recombinant P. multocida GshF overexpresses as an approximately 85-kDa protein, which, on the basis of gel-sizing chromatography, forms dimers in solution. The gamma-ECL activity of GshF is regulated by an allosteric type of glutathione feedback inhibition (K(i) = 13.6 mM). Furthermore, steady-state kinetics, on the basis of which we present a novel variant of half-of-the-sites reactivity, indicate intimate domain-domain interactions, which may explain the bifunctionality of GshF proteins.
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Affiliation(s)
- Bjorn Vergauwen
- Laboratory of Protein Biochemistry and Protein Engineering, Ghent University, Belgium
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18
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Abstract
Biotin (1), a water-soluble B series vitamin, distributes widely in microorganisms, plants, and animals. Biosynthesis of 1 involves five steps sequence starting from pimelic acid. The last step, a transformation from dethiobiotin (DTB) to 1, includes an iron clusters-mediated radical process. The compound 1 is a cofactor of carboxylation enzymes and plays crucial roles in the metabolism of fatty acids, sugars, and alpha-amino acids. In addition to the increasing application to feed additives, recent reports have revealed that 1 enhances insulin secretion in animals, suggesting it for a promising therapeutic candidate for an anti-diabetes drug. The remarkably strong affinity of 1 with avidin and streptavidin has been extensively applied for such technologies as photoaffinity labeling. Among the number of approaches to 1 so far developed in 50 years, a synthesis using L-cysteine and thiolactone as a starting material and a key intermediate, respectively, represents one of the best routes leading to 1, because of short steps, high yield, use of inexpensive reagents, and ease of operation.
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Affiliation(s)
- Masahiko Seki
- Tanabe Seiyaku Co., Ltd., 3-2-10, Dosho-Machi, Osaka 541-8505, Japan.
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19
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Sueda S, Islam MN, Kondo H. Protein engineering of pyruvate carboxylase: investigation on the function of acetyl-CoA and the quaternary structure. ACTA ACUST UNITED AC 2004; 271:1391-400. [PMID: 15030490 DOI: 10.1111/j.1432-1033.2004.04051.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Pyruvate carboxylase (PC) from Bacillus thermodenitrificans was engineered in such a way that the polypeptide chain was divided into two, between the biotin carboxylase (BC) and carboxyl transferase (CT) domains. The two proteins thus formed, PC-(BC) and PC-(CT+BCCP), retained their catalytic activity as assayed by biotin-dependent ATPase and oxamate-dependent oxalacetate decarboxylation, for the former and the latter, respectively. Neither activity was dependent on acetyl-CoA, in sharp contrast to the complete reaction of intact PC. When assessed by gel filtration chromatography, PC-(BC) was found to exist either in dimers or monomers, depending on the protein concentration, while PC-(CT + BCCP) occurred in dimers for the most part. The two proteins do not associate spontaneously or in the presence of acetyl-CoA. Based on these observations, this paper discusses how the tetrameric structure of PC is built up and how acetyl-CoA modulates the protein structure.
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Affiliation(s)
- Shinji Sueda
- Department of Biochemical Engineering and Science, Kyushu Institute of Technology, Japan.
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20
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Sloane V, Waldrop GL. Kinetic characterization of mutations found in propionic acidemia and methylcrotonylglycinuria: evidence for cooperativity in biotin carboxylase. J Biol Chem 2004; 279:15772-8. [PMID: 14960587 DOI: 10.1074/jbc.m311982200] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Acetyl-CoA carboxylase catalyzes the committed step in fatty acid synthesis in all plants, animals, and bacteria. The Escherichia coli form is a multifunctional enzyme consisting of three separate proteins: biotin carboxylase, carboxyltransferase, and the biotin carboxyl carrier protein. The biotin carboxylase component, which catalyzes the ATP-dependent carboxylation of biotin using bicarbonate as the carboxylate source, has a homologous functionally identical subunit in the mammalian biotin-dependent enzymes propionyl-CoA carboxylase and 3-methylcrotonyl-CoA carboxylase. In humans, mutations in either of these enzymes result in the metabolic deficiency propionic acidemia or methylcrotonylglycinuria. The lack of a system for structure-function studies of these two biotin-dependent carboxylases has prevented a detailed analysis of the disease-causing mutations. However, structural data are available for E. coli biotin carboxylase as is a system for its overexpression and purification. Thus, we have constructed three site-directed mutants of biotin carboxylase that are homologous to three missense mutations found in propionic acidemia or methylcrotonylglycinuria patients. The mutants M169K, R338Q, and R338S of E. coli biotin carboxylase were selected for study to mimic the disease-causing mutations M204K and R374Q of propionyl-CoA carboxylase and R385S of 3-methylcrotonyl-CoA carboxylase. These three mutants were subjected to a rigorous kinetic analysis to determine the function of the residues in the catalytic mechanism of biotin carboxylase as well as to establish a molecular basis for the two diseases. The results of the kinetic studies have revealed the first evidence for negative cooperativity with respect to bicarbonate and suggest that Arg-338 serves to orient the carboxyphosphate intermediate for optimal carboxylation of biotin.
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Affiliation(s)
- Valerie Sloane
- Division of Biochemistry and Molecular Biology, Louisiana State University, Baton Rouge, Louisiana 70803, USA
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21
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Chuakrut S, Arai H, Ishii M, Igarashi Y. Characterization of a bifunctional archaeal acyl coenzyme A carboxylase. J Bacteriol 2003; 185:938-47. [PMID: 12533469 PMCID: PMC142822 DOI: 10.1128/jb.185.3.938-947.2003] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Acyl coenzyme A carboxylase (acyl-CoA carboxylase) was purified from Acidianus brierleyi. The purified enzyme showed a unique subunit structure (three subunits with apparent molecular masses of 62, 59, and 20 kDa) and a molecular mass of approximately 540 kDa, indicating an alpha(4)beta(4)gamma(4) subunit structure. The optimum temperature for the enzyme was 60 to 70 degrees C, and the optimum pH was around 6.4 to 6.9. Interestingly, the purified enzyme also had propionyl-CoA carboxylase activity. The apparent K(m) for acetyl-CoA was 0.17 +/- 0.03 mM, with a V(max) of 43.3 +/- 2.8 U mg(-1), and the K(m) for propionyl-CoA was 0.10 +/- 0.008 mM, with a V(max) of 40.8 +/- 1.0 U mg(-1). This result showed that A. brierleyi acyl-CoA carboxylase is a bifunctional enzyme in the modified 3-hydroxypropionate cycle. Both enzymatic activities were inhibited by malonyl-CoA, methymalonyl-CoA, succinyl-CoA, or CoA but not by palmitoyl-CoA. The gene encoding acyl-CoA carboxylase was cloned and characterized. Homology searches of the deduced amino acid sequences of the 62-, 59-, and 20-kDa subunits indicated the presence of functional domains for carboxyltransferase, biotin carboxylase, and biotin carboxyl carrier protein, respectively. Amino acid sequence alignment of acetyl-CoA carboxylases revealed that archaeal acyl-CoA carboxylases are closer to those of Bacteria than to those of Eucarya. The substrate-binding motifs of the enzymes are highly conserved among the three domains. The ATP-binding residues were found in the biotin carboxylase subunit, whereas the conserved biotin-binding site was located on the biotin carboxyl carrier protein. The acyl-CoA-binding site and the carboxybiotin-binding site were found in the carboxyltransferase subunit.
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Affiliation(s)
- Songkran Chuakrut
- Laboratory of Applied Microbiology, Department of Biotechnology, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8567, Japan
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22
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Jank MM, Sadowsky JD, Peikert C, Berger S. NMR studies on the solution structure of a deletion mutant of the transcarboxylase biotin carrier subunit. Int J Biol Macromol 2002; 30:233-42. [PMID: 12297230 DOI: 10.1016/s0141-8130(02)00033-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A deletion mutant of the transcarboxylase biotin carrier protein was completely labeled with 13C and 15N. A multitude of 2D and 3D NMR spectra were recorded and assigned. An NMR solution structure was derived from the data and compared in detail with the recently published structure of the wild-type. It is shown that deletion of 30% of the amino acids does not alter the structure of the rigid protein core.
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Affiliation(s)
- Matthias M Jank
- Institut für Analytische Chemie, Universität Leipzig, Linnestrasse 3, D-04103, Leipzig, Germany
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23
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Abstract
Acetyl-CoA carboxylase (ACC) catalyses the first committed step of fatty acid synthesis, the carboxylation of acetyl-CoA to malonyl-CoA. Two physically distinct types of enzymes are found in nature. Bacterial and most plant chloroplasts contain a multi-subunit ACC (MS-ACC) enzyme that is readily dissociated into its component proteins. Mammals, fungi, and plant cytosols contain the second type of ACC, a single large multifunctional polypeptide. This review will focus on the structures, regulation, and enzymatic mechanisms of the bacterial and plant MS-ACCs.
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Affiliation(s)
- John E Cronan
- Department of Microbiology, B103 Chemical and Life Sciences Laboratory, University of Illinois, 601 S. Goodwin Avenue, Urbana, IL 61801, USA.
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24
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Jitrapakdee S, Nezic MG, Cassady AI, Khew-Goodall Y, Wallace JC. Molecular cloning and domain structure of chicken pyruvate carboxylase. Biochem Biophys Res Commun 2002; 295:387-93. [PMID: 12150961 DOI: 10.1016/s0006-291x(02)00651-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Pyruvate carboxylase (PC) [EC 6.4.1.1] is a biotin-dependent carboxylase that catalyses the conversion of pyruvate to oxaloacetate. Here we have determined the complete nucleotide sequence encoding chicken PC (cPC) by screening a liver cDNA library, by RT-PCR of poly(A)(+) RNA, and by PCR of genomic DNA. The full-length transcript contains an open reading frame of 3537 nucleotides, including the stop codon, encoding a polypeptide of 1178 amino acids with M(r) of 127,262. The amino acid sequence of cPC shows approximately 77% identity to mammalian PC. Limited proteolysis of pure cPC with chymotrypsin yields a major stable 75 kDa C-terminal peptide, including the biotinyl domain and a minor, unstable 39 kDa N-terminal peptide. Northern analysis of poly(A)(+) RNA isolated from chicken liver has shown that cPC's mRNA is approximately 5 kb in length, including a very long 3'-untranslated region.
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Affiliation(s)
- Sarawut Jitrapakdee
- Department of Molecular Biosciences, Adelaide University, Adelaide, SA 5005, Australia
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25
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Affiliation(s)
- Charles O Rock
- The Protein Science Division, Department of Infectious Diseases, St. Jude Children's Research Hospital, 332 N. Lauderdale Street, Memphis, TN 38105, USA.
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26
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Attwood PV, Wallace JC. Chemical and catalytic mechanisms of carboxyl transfer reactions in biotin-dependent enzymes. Acc Chem Res 2002; 35:113-20. [PMID: 11851389 DOI: 10.1021/ar000049+] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Biotin-dependent carboxylases catalyze a variety of carboxyl transfer reactions in a number of metabolic pathways and are found in all free-living organisms. They are large molecules which can comprise a single polypeptide chain with three domains or up to three subunits, each of which performs a particular part of the overall reaction. Biotin plays a central role in the action of these enzymes. In this Account we examine the current state of knowledge of the chemistry of catalysis and consider how the recent explosion of available protein sequence and structural information has assisted our understanding of the mechanisms of biotin-dependent enzymes.
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Affiliation(s)
- Paul V Attwood
- Department of Biochemistry, The University of Western Australia, Nedlands, WA 6907, Australia.
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27
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Janiyani K, Bordelon T, Waldrop GL, Cronan JE. Function of Escherichia coli biotin carboxylase requires catalytic activity of both subunits of the homodimer. J Biol Chem 2001; 276:29864-70. [PMID: 11390406 DOI: 10.1074/jbc.m104102200] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Biotin carboxylase catalyzes the ATP-dependent carboxylation of biotin and is one component of the multienzyme complex acetyl-CoA carboxylase that catalyzes the first committed step in fatty acid synthesis. The Escherichia coli biotin carboxylase is readily isolated from the other components of the acetyl-CoA carboxylase complex such that enzymatic activity is retained. The three-dimensional structure of biotin carboxylase, determined by x-ray crystallography, demonstrated that the enzyme is a homodimer consisting of two active sites in which each subunit contains a complete active site. To understand how each subunit contributes to the overall function of biotin carboxylase, we made hybrid molecules in which one subunit had a wild-type active site, and the other subunit contained an active site mutation known to significantly affect the activity of the enzyme. One of the two genes encoded a poly-histidine tag at its N terminus, whereas the other gene had an N-terminal FLAG epitope tag. The two genes were assembled into a mini-operon that was induced to give high level expression of both enzymes. "Hybrid" dimers composed of one subunit with a wild-type active site and a second subunit having a mutant active site were obtained by sequential chromatographic steps on columns of immobilized nickel chelate and anti-FLAG affinity matrices. In vitro kinetic studies of biotin carboxylase dimers in which both subunits were wild type revealed that the presence of the N-terminal tags did not alter the activity of the enzyme. However, kinetic assays of hybrid dimer biotin carboxylase molecules in which one subunit had an active site mutation (R292A, N290A, K238Q, or E288K) and the other subunit had a wild-type active site resulted in 39-, 28-, 94-, and 285-fold decreases in the activity of these enzymes, respectively. The dominant negative effects of these mutant subunits were also detected in vivo by monitoring the rate of fatty acid biosynthesis by [(14)C]acetate labeling of cellular lipids. Expression of the mutant biotin carboxylase genes from an inducible arabinose promoter resulted in a significantly reduced rate of fatty acid synthesis relative to the same strain that expressed the wild type gene. Thus, both the in vitro and in vivo data indicate that both subunits of biotin carboxylase are required for activity and that the two subunits must be in communication during enzyme function.
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Affiliation(s)
- K Janiyani
- Departments of Microbiology and Biochemistry, University of Illinois, Urbana, Illinois 61801, USA
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28
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Sloane V, Blanchard CZ, Guillot F, Waldrop GL. Site-directed mutagenesis of ATP binding residues of biotin carboxylase. Insight into the mechanism of catalysis. J Biol Chem 2001; 276:24991-6. [PMID: 11346647 DOI: 10.1074/jbc.m101472200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Acetyl-CoA carboxylase catalyzes the first committed step in fatty acid synthesis in all plants, animals, and bacteria. The Escherichia coli form is a multimeric protein complex consisting of three distinct and separate components: biotin carboxylase, carboxyltransferase, and the biotin carboxyl carrier protein. The biotin carboxylase component catalyzes the ATP-dependent carboxylation of biotin using bicarbonate as the carboxylate source and has a distinct architecture that is characteristic of the ATP-grasp superfamily of enzymes. Included in this superfamily are d-Ala d-Ala ligase, glutathione synthetase, carbamyl phosphate synthetase, N(5)-carboxyaminoimidazole ribonucleotide synthetase, and glycinamide ribonucleotide transformylase, all of which have known three-dimensional structures and contain a number of highly conserved residues between them. Four of these residues of biotin carboxylase, Lys-116, Lys-159, His-209, and Glu-276, were selected for site-directed mutagenesis studies based on their structural homology with conserved residues of other ATP-grasp enzymes. These mutants were subjected to kinetic analysis to characterize their roles in substrate binding and catalysis. In all four mutants, the K(m) value for ATP was significantly increased, implicating these residues in the binding of ATP. This result is consistent with the crystal structures of several other ATP-grasp enzymes, which have shown specific interactions between the corresponding homologous residues and cocrystallized ADP or nucleotide analogs. In addition, the maximal velocity of the reaction was significantly reduced (between 30- and 260-fold) in the 4 mutants relative to wild type. The data suggest that the mutations have misaligned the reactants for optimal catalysis.
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Affiliation(s)
- V Sloane
- Division of Biochemistry and Molecular Biology, Louisiana State University, Baton Rouge, LA 70803, USA
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