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Yi HB, Lee S, Seo K, Kim H, Kim M, Lee HS. Cellular and Biophysical Applications of Genetic Code Expansion. Chem Rev 2024; 124:7465-7530. [PMID: 38753805 DOI: 10.1021/acs.chemrev.4c00112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/18/2024]
Abstract
Despite their diverse functions, proteins are inherently constructed from a limited set of building blocks. These compositional constraints pose significant challenges to protein research and its practical applications. Strategically manipulating the cellular protein synthesis system to incorporate novel building blocks has emerged as a critical approach for overcoming these constraints in protein research and application. In the past two decades, the field of genetic code expansion (GCE) has achieved significant advancements, enabling the integration of numerous novel functionalities into proteins across a variety of organisms. This technological evolution has paved the way for the extensive application of genetic code expansion across multiple domains, including protein imaging, the introduction of probes for protein research, analysis of protein-protein interactions, spatiotemporal control of protein function, exploration of proteome changes induced by external stimuli, and the synthesis of proteins endowed with novel functions. In this comprehensive Review, we aim to provide an overview of cellular and biophysical applications that have employed GCE technology over the past two decades.
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Affiliation(s)
- Han Bin Yi
- Department of Chemistry, Sogang University, 35 Baekbeom-ro, Mapo-gu, Seoul 04107, Republic of Korea
| | - Seungeun Lee
- Department of Chemistry, Sogang University, 35 Baekbeom-ro, Mapo-gu, Seoul 04107, Republic of Korea
| | - Kyungdeok Seo
- Department of Chemistry, Sogang University, 35 Baekbeom-ro, Mapo-gu, Seoul 04107, Republic of Korea
| | - Hyeongjo Kim
- Department of Chemistry, Sogang University, 35 Baekbeom-ro, Mapo-gu, Seoul 04107, Republic of Korea
| | - Minah Kim
- Department of Chemistry, Sogang University, 35 Baekbeom-ro, Mapo-gu, Seoul 04107, Republic of Korea
| | - Hyun Soo Lee
- Department of Chemistry, Sogang University, 35 Baekbeom-ro, Mapo-gu, Seoul 04107, Republic of Korea
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2
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Moen JM, Mohler K, Rogulina S, Shi X, Shen H, Rinehart J. Enhanced access to the human phosphoproteome with genetically encoded phosphothreonine. Nat Commun 2022; 13:7226. [PMID: 36433969 PMCID: PMC9700786 DOI: 10.1038/s41467-022-34980-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 11/15/2022] [Indexed: 11/27/2022] Open
Abstract
Protein phosphorylation is a ubiquitous post-translational modification used to regulate cellular processes and proteome architecture by modulating protein-protein interactions. The identification of phosphorylation events through proteomic surveillance has dramatically outpaced our capacity for functional assignment using traditional strategies, which often require knowledge of the upstream kinase a priori. The development of phospho-amino-acid-specific orthogonal translation systems, evolutionarily divergent aminoacyl-tRNA synthetase and tRNA pairs that enable co-translational insertion of a phospho-amino acids, has rapidly improved our ability to assess the physiological function of phosphorylation by providing kinase-independent methods of phosphoprotein production. Despite this utility, broad deployment has been hindered by technical limitations and an inability to reconstruct complex phopho-regulatory networks. Here, we address these challenges by optimizing genetically encoded phosphothreonine translation to characterize phospho-dependent kinase activation mechanisms and, subsequently, develop a multi-level protein interaction platform to directly assess the overlap of kinase and phospho-binding protein substrate networks with phosphosite-level resolution.
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Affiliation(s)
- Jack M. Moen
- grid.47100.320000000419368710Department of Cellular & Molecular Physiology, Yale School of Medicine, New Haven, CT 06520 USA ,grid.47100.320000000419368710Systems Biology Institute, Yale University, New Haven, CT 06516 USA
| | - Kyle Mohler
- grid.47100.320000000419368710Department of Cellular & Molecular Physiology, Yale School of Medicine, New Haven, CT 06520 USA ,grid.47100.320000000419368710Systems Biology Institute, Yale University, New Haven, CT 06516 USA
| | - Svetlana Rogulina
- grid.47100.320000000419368710Department of Cellular & Molecular Physiology, Yale School of Medicine, New Haven, CT 06520 USA ,grid.47100.320000000419368710Systems Biology Institute, Yale University, New Haven, CT 06516 USA
| | - Xiaojian Shi
- grid.47100.320000000419368710Department of Cellular & Molecular Physiology, Yale School of Medicine, New Haven, CT 06520 USA ,grid.47100.320000000419368710Systems Biology Institute, Yale University, New Haven, CT 06516 USA ,grid.47100.320000000419368710Wu Tsai Institute, Yale University, New Haven, CT 06520 USA
| | - Hongying Shen
- grid.47100.320000000419368710Department of Cellular & Molecular Physiology, Yale School of Medicine, New Haven, CT 06520 USA ,grid.47100.320000000419368710Systems Biology Institute, Yale University, New Haven, CT 06516 USA ,grid.47100.320000000419368710Wu Tsai Institute, Yale University, New Haven, CT 06520 USA
| | - Jesse Rinehart
- grid.47100.320000000419368710Department of Cellular & Molecular Physiology, Yale School of Medicine, New Haven, CT 06520 USA ,grid.47100.320000000419368710Systems Biology Institute, Yale University, New Haven, CT 06516 USA
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Coordinate regulation of the expression of SdsR toxin and its downstream pphA gene by RyeA antitoxin in Escherichia coli. Sci Rep 2019; 9:9627. [PMID: 31270363 PMCID: PMC6610125 DOI: 10.1038/s41598-019-45998-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 06/10/2019] [Indexed: 12/17/2022] Open
Abstract
In Escherichia coli, SdsR and RyeA, a unique pair of mutually cis-encoded small RNAs (sRNAs), act as toxin and antitoxin, respectively. SdsR and RyeA expression are reciprocally regulated; however, how each regulates the synthesis of the other remains unclear. Here, we characterized the biosynthesis of the two sRNAs during growth and investigated their coordinate regulation using sdsR and ryeA promoter mutant strains. We found that RyeA transcription occurred even upon entry of cells into the stationary phase, but its apparent expression was restricted to exponentially growing cells because of its degradation by SdsR. Likewise, the appearance of SdsR was delayed owing to its RyeA-mediated degradation. We also found that the sdsR promoter was primarily responsible for transcription of the downstream pphA gene encoding a phosphatase and that pphA mRNA was synthesized by transcriptional read-through over the sdsR terminator. Transcription from the σ70-dependent ryeA promoter inhibited transcription from the σS-dependent sdsR promoter through transcriptional interference. This transcriptional inhibition also downregulated pphA expression, but RyeA itself did not downregulate pphA expression.
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Wang L, Yan F. Exploring the role of active site Mn2+ ions in the binding of protein phosphatase 5 with its substrate using molecular dynamics simulations. Biochem Biophys Res Commun 2019; 511:612-618. [DOI: 10.1016/j.bbrc.2019.02.113] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 02/21/2019] [Indexed: 12/14/2022]
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Discovery of the Elusive UDP-Diacylglucosamine Hydrolase in the Lipid A Biosynthetic Pathway in Chlamydia trachomatis. mBio 2016; 7:e00090. [PMID: 27006461 PMCID: PMC4807358 DOI: 10.1128/mbio.00090-16] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Constitutive biosynthesis of lipid A via the Raetz pathway is essential for the viability and fitness of Gram-negative bacteria, including Chlamydia trachomatis. Although nearly all of the enzymes in the lipid A biosynthetic pathway are highly conserved across Gram-negative bacteria, the cleavage of the pyrophosphate group of UDP-2,3-diacyl-GlcN (UDP-DAGn) to form lipid X is carried out by two unrelated enzymes: LpxH in beta- and gammaproteobacteria and LpxI in alphaproteobacteria. The intracellular pathogen C. trachomatis lacks an ortholog for either of these two enzymes, and yet, it synthesizes lipid A and exhibits conservation of genes encoding other lipid A enzymes. Employing a complementation screen against a C. trachomatis genomic library using a conditional-lethal lpxH mutant Escherichia coli strain, we have identified an open reading frame (Ct461, renamed lpxG) encoding a previously uncharacterized enzyme that complements the UDP-DAGn hydrolase function in E. coli and catalyzes the conversion of UDP-DAGn to lipid X in vitro. LpxG shows little sequence similarity to either LpxH or LpxI, highlighting LpxG as the founding member of a third class of UDP-DAGn hydrolases. Overexpression of LpxG results in toxic accumulation of lipid X and profoundly reduces the infectivity of C. trachomatis, validating LpxG as the long-sought-after UDP-DAGn pyrophosphatase in this prominent human pathogen. The complementation approach presented here overcomes the lack of suitable genetic tools for C. trachomatis and should be broadly applicable for the functional characterization of other essential C. trachomatis genes. Chlamydia trachomatis is a leading cause of infectious blindness and sexually transmitted disease. Due to the lack of robust genetic tools, the functions of many Chlamydia genes remain uncharacterized, including the essential gene encoding the UDP-DAGn pyrophosphatase activity for the biosynthesis of lipid A, the membrane anchor of lipooligosaccharide and the predominant lipid species of the outer leaflet of the bacterial outer membrane. We designed a complementation screen against the C. trachomatis genomic library using a conditional-lethal mutant of E. coli and identified the missing essential gene in the lipid A biosynthetic pathway, which we designated lpxG. We show that LpxG is a member of the calcineurin-like phosphatases and displays robust UDP-DAGn pyrophosphatase activity in vitro. Overexpression of LpxG in C. trachomatis leads to the accumulation of the predicted lipid intermediate and reduces bacterial infectivity, validating the in vivo function of LpxG and highlighting the importance of regulated lipid A biosynthesis in C. trachomatis.
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Abstract
Calcineurin-like metallophosphoesterases (MPEs) form a large superfamily of binuclear metal-ion-centre-containing enzymes that hydrolyse phosphomono-, phosphodi- or phosphotri-esters in a metal-dependent manner. The MPE domain is found in Mre11/SbcD DNA-repair enzymes, mammalian phosphoprotein phosphatases, acid sphingomyelinases, purple acid phosphatases, nucleotidases and bacterial cyclic nucleotide phosphodiesterases. Despite this functional diversity, MPEs show a remarkably similar structural fold and active-site architecture. In the present review, we summarize the available structural, biochemical and functional information on these proteins. We also describe how diversification and specialization of the core MPE fold in various MPEs is achieved by amino acid substitution in their active sites, metal ions and regulatory effects of accessory domains. Finally, we discuss emerging roles of these proteins as non-catalytic protein-interaction scaffolds. Thus we view the MPE superfamily as a set of proteins with a highly conserved structural core that allows embellishment to result in dramatic and niche-specific diversification of function.
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Paull TT, Deshpande RA. The Mre11/Rad50/Nbs1 complex: recent insights into catalytic activities and ATP-driven conformational changes. Exp Cell Res 2014; 329:139-47. [PMID: 25016281 PMCID: PMC4252570 DOI: 10.1016/j.yexcr.2014.07.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Accepted: 07/01/2014] [Indexed: 10/25/2022]
Abstract
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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Affiliation(s)
- Tanya T Paull
- The Howard Hughes Medical Institute, The Department of Molecular Biosciences, The Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA.
| | - Rajashree A Deshpande
- The Howard Hughes Medical Institute, The Department of Molecular Biosciences, The Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA
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8
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Catalytic and noncatalytic roles of the CtIP endonuclease in double-strand break end resection. Mol Cell 2014; 54:1022-1033. [PMID: 24837676 DOI: 10.1016/j.molcel.2014.04.011] [Citation(s) in RCA: 144] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 11/11/2013] [Accepted: 04/04/2014] [Indexed: 12/22/2022]
Abstract
The carboxy-terminal binding protein (CtBP)-interacting protein (CtIP) is known to function in 5' strand resection during homologous recombination, similar to the budding yeast Sae2 protein, but its role in this process is unclear. Here, we characterize recombinant human CtIP and find that it exhibits 5' flap endonuclease activity on branched DNA structures, independent of the MRN complex. Phosphorylation of CtIP at known damage-dependent sites and other sites is essential for its catalytic activity, although the S327 and T847 phosphorylation sites are dispensable. A catalytic mutant of CtIP that is deficient in endonuclease activity exhibits wild-type levels of homologous recombination at restriction enzyme-generated breaks but is deficient in processing topoisomerase adducts and radiation-induced breaks in human cells, suggesting that the nuclease activity of CtIP is specifically required for the removal of DNA adducts at sites of DNA breaks.
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9
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Li N, Yang XY, Guo Z, Zhang J, Cao K, Han J, Zhang G, Liu L, Sun X, He QY. Varied metal-binding properties of lipoprotein PsaA in Streptococcus pneumoniae. J Biol Inorg Chem 2014; 19:829-38. [PMID: 24553956 DOI: 10.1007/s00775-014-1114-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Accepted: 01/28/2014] [Indexed: 11/29/2022]
Abstract
Streptococcus pneumoniae is a Gram-positive pathogen responsible for pneumonia, otitis media, and meningitis. Manganese and zinc ions are essential for this bacterium, playing regulatory, structural, or catalytic roles as the critical cofactors in the bacterial proteins and metabolic enzymes. Lipoprotein PsaA has been found to mediate Mn(2+) and Zn(2+) transportation in Streptococcus pneumoniae. In the present work, we conducted a systemic study on the contributions from key amino acids in the metal-binding site of PsaA using various spectroscopic and biochemical methods. Our experimental data indicate that four metal-binding residues contribute unequally to the Mn(2+) and Zn(2+) binding, and His139 is most important for both the structural stability and metal binding of the protein. PsaA-Mn(2+) has a lower thermal stability than PsaA-Zn(2+), possibly due to the different coordination preferences of the metals. Kinetics analysis revealed that PsaA-Mn(2+) binding is a fast first-order reaction, whereas PsaA-Zn(2+) binding is a slow second-order reaction, implying that PsaA kinetically prefers binding Mn(2+) to Zn(2+). The present results provide complementary information for understanding the mechanisms of metal transport and bacterial virulence via lipoproteins in Streptococcus pneumoniae.
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Affiliation(s)
- Nan Li
- Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou, 510632, China
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Young HE, Donohue MP, Smirnova TI, Smirnov AI, Zhou P. The UDP-diacylglucosamine pyrophosphohydrolase LpxH in lipid A biosynthesis utilizes Mn2+ cluster for catalysis. J Biol Chem 2013; 288:26987-27001. [PMID: 23897835 DOI: 10.1074/jbc.m113.497636] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In Escherichia coli and the majority of β- and γ-proteobacteria, the fourth step of lipid A biosynthesis, i.e. cleavage of the pyrophosphate group of UDP-2,3-diacyl-GlcN, is carried out by LpxH. LpxH has been previously suggested to contain signature motifs found in the calcineurin-like phosphoesterase (CLP) family of metalloenzymes; however, it cleaves a pyrophosphate bond instead of a phosphoester bond, and its substrate contains nucleoside diphosphate moieties more common to the Nudix family rather than to the CLP family. Furthermore, the extent of biochemical data fails to demonstrate a significant level of metal activation in enzymatic assays, which is inconsistent with the behavior of a metalloenzyme. Here, we report cloning, purification, and detailed enzymatic characterization of Haemophilus influenzae LpxH (HiLpxH). HiLpxH shows over 600-fold stimulation of hydrolase activity in the presence of Mn(2+). EPR studies reveal the presence of a Mn(2+) cluster in LpxH. Finally, point mutants of residues in the conserved metal-binding motifs of the CLP family greatly inhibit HiLpxH activity, highlighting their importance in enzyme function. Contrary to previous analyses of LpxH, we find HiLpxH does not obey surface dilution kinetics. Overall, our work unambiguously establishes LpxH as a calcineurin-like phosphoesterase containing a Mn(2+) cluster coordinated by conserved residues. These results set the scene for further structural investigation of the enzyme and for design of novel antibiotics targeting lipid A biosynthesis.
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Affiliation(s)
- Hayley E Young
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710
| | - Matthew P Donohue
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695
| | - Tatyana I Smirnova
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695
| | - Alex I Smirnov
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695
| | - Pei Zhou
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710.
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Rodrigues JR, Fernández A, Canales J, Cabezas A, Ribeiro JM, Costas MJ, Cameselle JC. Characterization of Danio rerio Mn2+-dependent ADP-ribose/CDP-alcohol diphosphatase, the structural prototype of the ADPRibase-Mn-like protein family. PLoS One 2012; 7:e42249. [PMID: 22848751 PMCID: PMC3407115 DOI: 10.1371/journal.pone.0042249] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Accepted: 07/04/2012] [Indexed: 11/30/2022] Open
Abstract
The ADPRibase-Mn-like protein family, that belongs to the metallo-dependent phosphatase superfamily, has different functional and structural prototypes. The functional one is the Mn2+-dependent ADP-ribose/CDP-alcohol diphosphatase from Rattus norvegicus, which is essentially inactive with Mg2+ and active with low micromolar Mn2+ in the hydrolysis of the phosphoanhydride linkages of ADP-ribose, CDP-alcohols and cyclic ADP-ribose (cADPR) in order of decreasing efficiency. The structural prototype of the family is a Danio rerio protein with a known crystallographic structure but functionally uncharacterized. To estimate the structure-function correlation with the same protein, the activities of zebrafish ADPRibase-Mn were studied. Differences between zebrafish and rat enzymes are highlighted. The former showed a complex activity dependence on Mn2+, significant (≈25%) Mg2+-dependent activity, but was almost inactive on cADPR (150-fold less efficient than the rat counterpart). The low cADPR hydrolase activity agreed with the zebrafish genome lacking genes coding for proteins with significant homology with cADPR-forming enzymes. Substrate-docking to zebrafish wild-type protein, and characterization of the ADPRibase-Mn H97A mutant pointed to a role of His-97 in catalysis by orientation, and to a bidentate water bridging the dinuclear metal center as the potential nucleophile. Finally, three structural elements that delimit the active site entrance in the zebrafish protein were identified as unique to the ADPRibase-Mn-like family within the metallo-dependent phosphatase superfamily.
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Affiliation(s)
- Joaquim Rui Rodrigues
- Grupo de Enzimología, Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Medicina, Universidad de Extremadura, Badajoz, Spain
- Escola Superior de Tecnologia e Gestão, Instituto Politécnico de Leiria, Leiria, Portugal
| | - Ascensión Fernández
- Grupo de Enzimología, Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Medicina, Universidad de Extremadura, Badajoz, Spain
| | - José Canales
- Grupo de Enzimología, Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Medicina, Universidad de Extremadura, Badajoz, Spain
| | - Alicia Cabezas
- Grupo de Enzimología, Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Medicina, Universidad de Extremadura, Badajoz, Spain
| | - João Meireles Ribeiro
- Grupo de Enzimología, Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Medicina, Universidad de Extremadura, Badajoz, Spain
| | - María Jesús Costas
- Grupo de Enzimología, Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Medicina, Universidad de Extremadura, Badajoz, Spain
| | - José Carlos Cameselle
- Grupo de Enzimología, Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Medicina, Universidad de Extremadura, Badajoz, Spain
- * E-mail:
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Tiwari MK, Singh RK, Singh R, Jeya M, Zhao H, Lee JK. Role of conserved glycine in zinc-dependent medium chain dehydrogenase/reductase superfamily. J Biol Chem 2012; 287:19429-39. [PMID: 22500022 DOI: 10.1074/jbc.m111.335752] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The medium-chain dehydrogenase/reductase (MDR) superfamily consists of a large group of enzymes with a broad range of activities. Members of this superfamily are currently the subject of intensive investigation, but many aspects, including the zinc dependence of MDR superfamily proteins, have not yet have been adequately investigated. Using a density functional theory-based screening strategy, we have identified a strictly conserved glycine residue (Gly) in the zinc-dependent MDR superfamily. To elucidate the role of this conserved Gly in MDR, we carried out a comprehensive structural, functional, and computational analysis of four MDR enzymes through a series of studies including site-directed mutagenesis, isothermal titration calorimetry, electron paramagnetic resonance (EPR), quantum mechanics, and molecular mechanics analysis. Gly substitution by other amino acids posed a significant threat to the metal binding affinity and activity of MDR superfamily enzymes. Mutagenesis at the conserved Gly resulted in alterations in the coordination of the catalytic zinc ion, with concomitant changes in metal-ligand bond length, bond angle, and the affinity (K(d)) toward the zinc ion. The Gly mutants also showed different spectroscopic properties in EPR compared with those of the wild type, indicating that the binding geometries of the zinc to the zinc binding ligands were changed by the mutation. The present results demonstrate that the conserved Gly in the GHE motif plays a role in maintaining the metal binding affinity and the electronic state of the catalytic zinc ion during catalysis of the MDR superfamily enzymes.
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14
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Hadler KS, Mitić N, Ely F, Hanson GR, Gahan LR, Larrabee JA, Ollis DL, Schenk G. Structural Flexibility Enhances the Reactivity of the Bioremediator Glycerophosphodiesterase by Fine-Tuning Its Mechanism of Hydrolysis. J Am Chem Soc 2009; 131:11900-8. [DOI: 10.1021/ja903534f] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kieran S. Hadler
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, 4072, Australia, Centre for Magnetic Resonance, The University of Queensland, St. Lucia, Queensland, 4072, Australia, Department of Chemistry and Biochemistry, Middlebury College, Middlebury, Vermont 05753, and Research School of Chemistry, Australian National University, Canberra, ACT, 0200, Australia
| | - Nataša Mitić
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, 4072, Australia, Centre for Magnetic Resonance, The University of Queensland, St. Lucia, Queensland, 4072, Australia, Department of Chemistry and Biochemistry, Middlebury College, Middlebury, Vermont 05753, and Research School of Chemistry, Australian National University, Canberra, ACT, 0200, Australia
| | - Fernanda Ely
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, 4072, Australia, Centre for Magnetic Resonance, The University of Queensland, St. Lucia, Queensland, 4072, Australia, Department of Chemistry and Biochemistry, Middlebury College, Middlebury, Vermont 05753, and Research School of Chemistry, Australian National University, Canberra, ACT, 0200, Australia
| | - Graeme R. Hanson
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, 4072, Australia, Centre for Magnetic Resonance, The University of Queensland, St. Lucia, Queensland, 4072, Australia, Department of Chemistry and Biochemistry, Middlebury College, Middlebury, Vermont 05753, and Research School of Chemistry, Australian National University, Canberra, ACT, 0200, Australia
| | - Lawrence R Gahan
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, 4072, Australia, Centre for Magnetic Resonance, The University of Queensland, St. Lucia, Queensland, 4072, Australia, Department of Chemistry and Biochemistry, Middlebury College, Middlebury, Vermont 05753, and Research School of Chemistry, Australian National University, Canberra, ACT, 0200, Australia
| | - James A. Larrabee
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, 4072, Australia, Centre for Magnetic Resonance, The University of Queensland, St. Lucia, Queensland, 4072, Australia, Department of Chemistry and Biochemistry, Middlebury College, Middlebury, Vermont 05753, and Research School of Chemistry, Australian National University, Canberra, ACT, 0200, Australia
| | - David L. Ollis
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, 4072, Australia, Centre for Magnetic Resonance, The University of Queensland, St. Lucia, Queensland, 4072, Australia, Department of Chemistry and Biochemistry, Middlebury College, Middlebury, Vermont 05753, and Research School of Chemistry, Australian National University, Canberra, ACT, 0200, Australia
| | - Gerhard Schenk
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, 4072, Australia, Centre for Magnetic Resonance, The University of Queensland, St. Lucia, Queensland, 4072, Australia, Department of Chemistry and Biochemistry, Middlebury College, Middlebury, Vermont 05753, and Research School of Chemistry, Australian National University, Canberra, ACT, 0200, Australia
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15
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Hadler KS, Tanifum EA, Yip SHC, Mitić N, Guddat LW, Jackson CJ, Gahan LR, Nguyen K, Carr PD, Ollis DL, Hengge AC, Larrabee JA, Schenk G. Substrate-promoted formation of a catalytically competent binuclear center and regulation of reactivity in a glycerophosphodiesterase from Enterobacter aerogenes. J Am Chem Soc 2008; 130:14129-38. [PMID: 18831553 PMCID: PMC4887195 DOI: 10.1021/ja803346w] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The glycerophosphodiesterase (GpdQ) from Enterobacter aerogenes is a promiscuous binuclear metallohydrolase that catalyzes the hydrolysis of mono-, di-, and triester substrates, including some organophosphate pesticides and products of the degradation of nerve agents. GpdQ has attracted recent attention as a promising enzymatic bioremediator. Here, we have investigated the catalytic mechanism of this versatile enzyme using a range of techniques. An improved crystal structure (1.9 A resolution) illustrates the presence of (i) an extended hydrogen bond network in the active site, and (ii) two possible nucleophiles, i.e., water/hydroxide ligands, coordinated to one or both metal ions. While it is at present not possible to unambiguously distinguish between these two possibilities, a reaction mechanism is proposed whereby the terminally bound H2O/OH(-) acts as the nucleophile, activated via hydrogen bonding by the bridging water molecule. Furthermore, the presence of substrate promotes the formation of a catalytically competent binuclear center by significantly enhancing the binding affinity of one of the metal ions in the active site. Asn80 appears to display coordination flexibility that may modulate enzyme activity. Kinetic data suggest that the rate-limiting step occurs after hydrolysis, i.e., the release of the phosphate moiety and the concomitant dissociation of one of the metal ions and/or associated conformational changes. Thus, it is proposed that GpdQ employs an intricate regulatory mechanism for catalysis, where coordination flexibility in one of the two metal binding sites is essential for optimal activity.
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Affiliation(s)
- Kieran S. Hadler
- School of Molecular and Microbial Sciences, The University of Queensland, St Lucia, Queensland, 4072, Australia
| | - Eric A. Tanifum
- Department of Chemistry and Biochemistry, Utah State University, Logan, UT, 84322, USA
| | - Sylvia Hsu-Chen Yip
- Research School of Chemistry, Australian National University, Canberra, ACT, 0200, Australia
| | - Nataša Mitić
- School of Molecular and Microbial Sciences, The University of Queensland, St Lucia, Queensland, 4072, Australia
| | - Luke W. Guddat
- School of Molecular and Microbial Sciences, The University of Queensland, St Lucia, Queensland, 4072, Australia
| | - Colin J. Jackson
- Research School of Chemistry, Australian National University, Canberra, ACT, 0200, Australia
| | - Lawrence R. Gahan
- School of Molecular and Microbial Sciences, The University of Queensland, St Lucia, Queensland, 4072, Australia
| | - Kelly Nguyen
- Research School of Chemistry, Australian National University, Canberra, ACT, 0200, Australia
| | - Paul D. Carr
- Research School of Chemistry, Australian National University, Canberra, ACT, 0200, Australia
| | - David L. Ollis
- Research School of Chemistry, Australian National University, Canberra, ACT, 0200, Australia
| | - Alvan C. Hengge
- Department of Chemistry and Biochemistry, Utah State University, Logan, UT, 84322, USA
| | - James A. Larrabee
- Department of Chemistry and Biochemistry, Middlebury College, Middlebury, VT, 05753, USA
| | - Gerhard Schenk
- School of Molecular and Microbial Sciences, The University of Queensland, St Lucia, Queensland, 4072, Australia
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16
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Keppetipola N, Shuman S. A phosphate-binding histidine of binuclear metallophosphodiesterase enzymes is a determinant of 2',3'-cyclic nucleotide phosphodiesterase activity. J Biol Chem 2008; 283:30942-9. [PMID: 18757371 DOI: 10.1074/jbc.m805064200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Binuclear metallophosphoesterases are an enzyme superfamily defined by a shared fold and a conserved active site. Although many family members have been characterized biochemically or structurally, the physiological substrates are rarely known, and the features that determine monoesterase versus diesterase activity are obscure. In the case of the dual phosphomonoesterase/diesterase enzyme CthPnkp, a phosphate-binding histidine was implicated as a determinant of 2',3'-cyclic nucleotide phosphodiesterase activity. Here we tested this model by comparing the catalytic repertoires of Mycobacterium tuberculosis Rv0805, which has this histidine in its active site (His(98)), and Escherichia coli YfcE, which has a cysteine at the equivalent position (Cys(74)). We find that Rv0805 has a previously unappreciated 2',3'-cyclic nucleotide phosphodiesterase function. Indeed, Rv0805 was 150-fold more active in hydrolyzing 2',3'-cAMP than 3',5'-cAMP. Changing His(98) to alanine or asparagine suppressed the 2',3'-cAMP phosphodiesterase activity of Rv0805 without adversely affecting hydrolysis of bis-p-nitrophenyl phosphate. Further evidence for a defining role of the histidine derives from our ability to convert the inactive YfcE protein to a vigorous and specific 2',3'-cNMP phosphodiesterase by introducing histidine in lieu of Cys(74). YfcE-C74H cleaved the P-O2' bond of 2',3'-cAMP to yield 3'-AMP as the sole product. Rv0805, on the other hand, hydrolyzed either P-O2' or P-O3' to yield a mixture of 3'-AMP and 2'-AMP products, with a bias toward 3'-AMP. These reaction outcomes contrast with that of CthPnkp, which cleaves the P-O3' bond of 2',3'-cAMP to generate 2'-AMP exclusively. It appears that enzymic features other than the phosphate-binding histidine can influence the orientation of the cyclic nucleotide and thereby dictate the choice of the leaving group.
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17
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Wehenkel A, Bellinzoni M, Schaeffer F, Villarino A, Alzari PM. Structural and Binding Studies of the Three-metal Center in Two Mycobacterial PPM Ser/Thr Protein Phosphatases. J Mol Biol 2007; 374:890-8. [DOI: 10.1016/j.jmb.2007.09.076] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2007] [Revised: 09/25/2007] [Accepted: 09/26/2007] [Indexed: 10/22/2022]
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18
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Mitić N, Smith SJ, Neves A, Guddat LW, Gahan LR, Schenk G. The catalytic mechanisms of binuclear metallohydrolases. Chem Rev 2007; 106:3338-63. [PMID: 16895331 DOI: 10.1021/cr050318f] [Citation(s) in RCA: 352] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Natasa Mitić
- School of Molecular and Microbial Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
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19
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Kisseleva N, Kraut S, Jäschke A, Schiemann O. Characterizing multiple metal ion binding sites within a ribozyme by cadmium-induced EPR silencing. HFSP JOURNAL 2007; 1:127-36. [PMID: 19404418 PMCID: PMC2639839 DOI: 10.2976/1.2756332] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2007] [Accepted: 06/18/2007] [Indexed: 11/19/2022]
Abstract
In ribozyme catalysis, metal ions are generally known to make structural andor mechanistic contributions. The catalytic activity of a previously described Diels-Alderase ribozyme was found to depend on the concentration of divalent metal ions, and crystallographic data revealed multiple binding sites. Here, we elucidate the interactions of this ribozyme with divalent metal ions in solution using electron paramagnetic resonance (EPR) spectroscopy. Manganese ion titrations revealed five high-affinity Mn(2+) binding sites with an upper K(d) of 0.6+/-0.2 muM. In order to characterize each binding site individually, EPR-silent Cd(2+) ions were used to saturate the other binding sites. This cadmium-induced EPR silencing showed that the Mn(2+) binding sites possess different affinities. In addition, these binding sites could be assigned to three different types, including innersphere, outersphere, and a Mn(2+) dimer. Based on simulations, the Mn(2+)-Mn(2+) distance within the dimer was found to be approximately 6 A, which is in good agreement with crystallographic data. The EPR-spectroscopic characterization reveals no structural changes upon addition of a Diels-Alder product, supporting the concept of a preorganized catalytic pocket in the Diels-Alder ribozyme and the structural role of these ions.
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Affiliation(s)
- Natalia Kisseleva
- Institute of Physical and Theoretical Chemistry, Center of
Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University,
Max-von-Laue Strasse 7, 60438 Frankfurt am Main, Germany
| | - Stefanie Kraut
- Institute of Pharmacy and Molecular Biotechnology, University
of Heidelberg, Im Neuenheimer Feld 364, 69120 Heidelberg, Germany
| | - Andres Jäschke
- Institute of Pharmacy and Molecular Biotechnology, University
of Heidelberg, Im Neuenheimer Feld 364, 69120 Heidelberg, Germany
| | - Olav Schiemann
- Institute of Physical and Theoretical Chemistry, Center of
Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University,
Max-von-Laue Strasse 7, 60438 Frankfurt am Main, Germany
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20
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Jackson CJ, Carr PD, Liu JW, Watt SJ, Beck JL, Ollis DL. The structure and function of a novel glycerophosphodiesterase from Enterobacter aerogenes. J Mol Biol 2007; 367:1047-62. [PMID: 17306828 DOI: 10.1016/j.jmb.2007.01.032] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2006] [Revised: 01/10/2007] [Accepted: 01/11/2007] [Indexed: 11/20/2022]
Abstract
The structure of the glycerophosphodiesterase (GDPD) from Enterobacter aerogenes, GpdQ, has been solved by SAD phasing from the active site metal ions. Structural analysis indicates that GpdQ belongs to the alpha/beta sandwich metallo-phosphoesterase family, rather than the (alpha/beta)(8) barrel GDPD family, suggesting that GpdQ is a structurally novel GDPD. Hexameric GpdQ is generated by interactions between three dimers. The dimers are formed through domain swapping, stabilised by an inter-chain disulfide bond, and beta-sheet extension. The active site contains a binuclear metal centre, with a fully occupied alpha-metal ion site, and partially occupied beta-metal ion site, as revealed by anomalous scattering analysis. Using a combination of TLS refinement and normal mode analysis, the dynamic movement of GpdQ was investigated. This analysis suggests that the hexameric quaternary structure stabilises the base of the dimer, which promotes "breathing" of the active site cleft. Comparison with other metallo-phosphodiesterases shows that although the central, catalytic, domain is highly conserved, many of these enzymes possess structurally unrelated secondary domains located at the entrance of the active site. We suggest that this could be a common structural feature of metallo-phosphodiesterases that constrains substrate specificity, preventing non-specific phosphodiester hydrolysis.
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Affiliation(s)
- Colin J Jackson
- Research School of Chemistry, Australian National University, ACT, 0200, Australia
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21
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Keppetipola N, Shuman S. Mechanism of the phosphatase component of Clostridium thermocellum polynucleotide kinase-phosphatase. RNA (NEW YORK, N.Y.) 2006; 12:73-82. [PMID: 16301605 PMCID: PMC1370887 DOI: 10.1261/rna.2196406] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2005] [Accepted: 09/30/2005] [Indexed: 05/02/2023]
Abstract
Polynucleotide kinase-phosphatase (Pnkp) from Clostridium thermocellum catalyzes ATP-dependent phosphorylation of 5'-OH termini of DNA or RNA polynucleotides and Ni(2+)/Mn(2+)-dependent dephosphorylation of 2',3' cyclic phosphate, 2'-phosphate, and 3'-phosphate ribonucleotides. CthPnkp is an 870-amino-acid polypeptide composed of three domains: an N-terminal module similar to bacteriophage T4 polynucleotide kinase, a central module that resembles the dinuclear metallo-phosphoesterase superfamily, and a C-terminal ligase-like adenylyltransferase domain. Here we conducted a mutational analysis of CthPnkp that identified 11 residues required for Ni(2+)-dependent phosphatase activity with 2'-AMP and 3'-AMP. Eight of the 11 CthPnkp side chains were also required for Ni(2+)-dependent hydrolysis of p-nitrophenyl phosphate. The ensemble of essential side chains includes the conserved counterparts (Asp187, His189, Asp233, Arg237, Asn263, His264, His323, His376, and Asp392 in CthPnkp) of all of the amino acids that form the dinuclear metal-binding site and the phosphate-binding site of bacteriophage lambda phosphatase. Three residues (Asp236, His264, and Arg237) required for activity with 2'-AMP or 3'-AMP were dispensable for Ni(2+)-dependent hydrolysis of p-nitrophenyl phosphate. Our findings, together with available structural information, provide fresh insights to the metallophosphoesterase mechanism, including the roles of His264 and Asp236 in proton donation to the leaving group. Deletion analysis defined an autonomous phosphatase domain, CthPnkp-(171-424).
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Affiliation(s)
- Niroshika Keppetipola
- Molecular Biology Program, Sloan-Kettering Institute, 1275 York Avenue, New York, NY 10021, USA
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22
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Funhoff EG, Wang Y, Andersson G, Averill BA. Substrate positioning by His92 is important in catalysis by purple acid phosphatase. FEBS J 2005; 272:2968-77. [PMID: 15955057 DOI: 10.1111/j.1742-4658.2005.04686.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Proteolysis of single polypeptide mammalian purple acid phosphatases (PAPs) results in the loss of an interaction between the loop residue Asp146 and the active site residues Asn91 and/or His92. While Asn91 is a ligand to the divalent metal of the mixed-valent di-iron center, the role of His92 in the catalytic mechanism is unknown. Site-directed mutagenesis of His92 was performed to examine the role of this residue in single polypeptide PAP. Conversion of His92 into Ala, which eliminates polar interactions of this residue with the active site, resulted in a 10-fold decrease in catalytic activity at the optimal pH. Conversely, conversion of this residue into Asn, which cannot function as either a proton donor or acceptor, but can provide hydrogen-bonding interactions, resulted in a three-fold increase in activity at the optimal pH. Both mutant enzymes had more acidic pH optima, with pK(es,1) values consistent with the involvement of an iron(III) hydroxide unit or a hydroxide in the second coordination sphere in catalysis. These results, together with EPR data, support a role of His92 in positioning either the nucleophile or the substrate, rather than directly in acid or base catalysis. The existence of an extensive hydrogen-bonding network that could fine-tune the position of His92 is consistent with this proposal.
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Affiliation(s)
- Enrico G Funhoff
- Swammerdam Institute for Life Sciences, University of Amsterdam, Netherlands
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23
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Boyd JM, Ellsworth H, Ensign SA. Bacterial acetone carboxylase is a manganese-dependent metalloenzyme. J Biol Chem 2004; 279:46644-51. [PMID: 15337755 DOI: 10.1074/jbc.m407177200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Bacterial acetone carboxylase catalyzes the ATP-dependent carboxylation of acetone to acetoacetate with the concomitant production of AMP and two inorganic phosphates. The importance of manganese in Rhodobacter capsulatus acetone carboxylase has been established through a combination of physiological, biochemical, and spectroscopic studies. Depletion of manganese from the R. capsulatus growth medium resulted in inhibition of acetone-dependent but not malate-dependent cell growth. Under normal growth conditions (0.5 microm Mn2+ in medium), growth with acetone as the carbon source resulted in a 4-fold increase in intracellular protein-bound manganese over malate-grown cells and the appearance of a Mn2+ EPR signal centered at g = 2 that was absent in malate-grown cells. Acetone carboxylase purified from cells grown with 50 microm Mn2+ had a 1.6-fold higher specific activity and 1.9-fold higher manganese content than cells grown with 0.5 microm Mn2+, consistently yielding a stoichiometry of 1.9 manganese/alpha2beta2gamma2 multimer, or 0.95 manganese/alphabetagamma protomer. Manganese in acetone carboxylase was tightly bound and not removed upon dialysis against various metal ion chelators. The addition of acetone to malate-grown cells grown in medium depleted of manganese resulted in the high level synthesis of acetone carboxylase (15-20% soluble protein), which, upon purification, exhibited 7% of the activity and 6% of the manganese content of the enzyme purified from acetone-grown cells. EPR analysis of purified acetone carboxylase indicates the presence of a mononuclear Mn2+ center, with possible spin coupling of two mononuclear sites. The addition of Mg.ATP or Mg.AMP resulted in EPR spectral changes, whereas the addition of acetone, CO2, inorganic phosphate, and acetoacetate did not perturb the EPR. These studies demonstrate that manganese is essential for acetone carboxylation and suggest a role for manganese in nucleotide binding and activation.
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Affiliation(s)
- Jeffrey M Boyd
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322-0300, USA
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24
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Reiter TA, Rusnak F. Electrochemical Studies of the Mono-Fe, Fe−Zn, and Fe−Fe Metalloisoforms of Bacteriophage λ Protein Phosphatase. Biochemistry 2003; 43:782-90. [PMID: 14730983 DOI: 10.1021/bi0356956] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Bacteriophage lambda protein phosphatase (lambdaPP) is a member of a large superfamily of metallophosphoesterases, including serine/threonine protein phosphatases, purple acid phosphatases, 5'-nucleotidase, and DNA repair enzymes such as Mre11. Members of this family share several common characteristics, including a common phosphoesterase motif, secondary structural fold (betaalphabetaalphabeta), and metal ligand environment, and often accommodate a dinuclear metal center. The identity of the active site metals often differs between family members. Despite the extensive spectroscopic studies of several family members, only the standard redox potential of porcine purple acid phosphate (PAP) has been measured. In this report, we investigate the redox properties of another member of this protein family. The standard redox potentials of the mono-Fe, Fe-Zn, and Fe-Fe metalloisoforms of lambdaPP were determined from anaerobic redox titration experiments. Two different S = 5/2, mono-Fe3+ lambdaPP species were identified: the first with an E/D approximately 0.17, g = 8.9 and 4.8, and an Eo' approximately +130 mV; the second with E/D approximately 0.05, g = 6.7, 5.9, and 4.4, and an Eo' approximately +120 mV. The first and second mono-Fe3+ species are thought to represent Fe present in the M2 and M1 sites, respectively. The addition of Zn2+ to mono-Fe3+ lambdaPP results in a decrease in both mono-Fe3+ species and the appearance of a new S = 5/2, Fe(3+)-Zn2+ species (E/D approximately 0.02, g = 5.9, and an Eo' > +175 mV). The Fe-Fe lambdaPP titration revealed an S = 1/2, Fe(3+)-Fe2+ (g < 2) species with an Eo' > +128 mV. These results suggest that the active site of lambdaPP supports a high oxidation potential for both metal sites and may indicate an equally oxidizing active site for other member metallophosphoesterases.
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Affiliation(s)
- Tiffany A Reiter
- Section of Hematology Research and the Department of Biochemistry and Molecular Biology, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA.
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