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Dollins DE, Xiong JP, Endo-Streeter S, Anderson DE, Bansal VS, Ponder JW, Ren Y, York JD. A structural basis for lithium and substrate binding of an inositide phosphatase. J Biol Chem 2021; 296:100059. [PMID: 33172890 PMCID: PMC7948987 DOI: 10.1074/jbc.ra120.014057] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 10/29/2020] [Accepted: 11/10/2020] [Indexed: 01/07/2023] Open
Abstract
Inositol polyphosphate 1-phosphatase (INPP1) is a prototype member of metal-dependent/lithium-inhibited phosphomonoesterase protein family defined by a conserved three-dimensional core structure. Enzymes within this family function in distinct pathways including inositide signaling, gluconeogenesis, and sulfur assimilation. Using structural and biochemical studies, we report the effect of substrate and lithium on a network of metal binding sites within the catalytic center of INPP1. We find that lithium preferentially occupies a key site involved in metal-activation only when substrate or product is added. Mutation of a conserved residue that selectively coordinates the putative lithium-binding site results in a dramatic 100-fold reduction in the inhibitory constant as compared with wild-type. Furthermore, we report the INPP1/inositol 1,4-bisphosphate complex which illuminates key features of the enzyme active site. Our results provide insights into a structural basis for uncompetitive lithium inhibition and substrate recognition and define a sequence motif for metal binding within this family of regulatory phosphatases.
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Affiliation(s)
- D Eric Dollins
- Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, USA
| | - Jian-Ping Xiong
- Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, USA
| | - Stuart Endo-Streeter
- Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, USA
| | - David E Anderson
- Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, USA
| | - Vinay S Bansal
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA
| | - Jay W Ponder
- Department of Chemistry, Washington University, St Louis, Missouri, USA
| | - Yi Ren
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA
| | - John D York
- Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, USA; Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA.
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2
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Fenn GD, Waller-Evans H, Atack JR, Bax BD. Crystallization and structure of ebselen bound to Cys141 of human inositol monophosphatase. Acta Crystallogr F Struct Biol Commun 2020; 76:469-476. [PMID: 33006574 PMCID: PMC7531247 DOI: 10.1107/s2053230x20011310] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 08/18/2020] [Indexed: 11/21/2022] Open
Abstract
Inositol monophosphatase (IMPase) is inhibited by lithium, which is the most efficacious treatment for bipolar disorder. Several therapies have been approved, or are going through clinical trials, aimed at the replacement of lithium in the treatment of bipolar disorder. One candidate small molecule is ebselen, a selenium-containing antioxidant, which has been demonstrated to produce lithium-like effects both in a murine model and in clinical trials. Here, the crystallization and the first structure of human IMPase covalently complexed with ebselen, a 1.47 Å resolution crystal structure (PDB entry 6zk0), are presented. In the complex with human IMPase, ebselen in a ring-opened conformation is covalently attached to Cys141, a residue located away from the active site. IMPase is a dimeric enzyme and in the crystal structure two adjacent dimers share four ebselen molecules, creating a tetramer with approximate 222 symmetry. In the crystal structure presented in this publication, the active site in the tetramer is still accessible, suggesting that ebselen may function as an allosteric inhibitor or may block the binding of partner proteins.
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Affiliation(s)
- Gareth D. Fenn
- Medicines Discovery Institute, School of Biosciences, Cardiff University, Cardiff CF10 3AT, United Kingdom
| | - Helen Waller-Evans
- Medicines Discovery Institute, School of Biosciences, Cardiff University, Cardiff CF10 3AT, United Kingdom
| | - John R. Atack
- Medicines Discovery Institute, School of Biosciences, Cardiff University, Cardiff CF10 3AT, United Kingdom
| | - Benjamin D. Bax
- Medicines Discovery Institute, School of Biosciences, Cardiff University, Cardiff CF10 3AT, United Kingdom
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3
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Catazaro J, Caprez A, Swanson D, Powers R. Functional Evolution of Proteins. Proteins 2019; 87:492-501. [PMID: 30714210 DOI: 10.1002/prot.25670] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 11/02/2018] [Accepted: 01/31/2019] [Indexed: 11/12/2022]
Abstract
The functional evolution of proteins advances through gene duplication followed by functional drift, whereas molecular evolution occurs through random mutational events. Over time, protein active-site structures or functional epitopes remain highly conserved, which enables relationships to be inferred between distant orthologs or paralogs. In this study, we present the first functional clustering and evolutionary analysis of the RCSB Protein Data Bank (RCSB PDB) based on similarities between active-site structures. All of the ligand-bound proteins within the RCSB PDB were scored using our Comparison of Protein Active-site Structures (CPASS) software and database (http://cpass.unl.edu/). Principal component analysis was then used to identify 4431 representative structures to construct a phylogenetic tree based on the CPASS comparative scores (http://itol.embl.de/shared/jcatazaro). The resulting phylogenetic tree identified a sequential, step-wise evolution of protein active-sites and provides novel insights into the emergence of protein function or changes in substrate specificity based on subtle changes in geometry and amino acid composition.
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Affiliation(s)
- Jonathan Catazaro
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska
| | - Adam Caprez
- Holland Computing Center, Office of Research, University of Nebraska-Lincoln, Lincoln, Nebraska
| | - David Swanson
- Holland Computing Center, Department of Computer Science and Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska
| | - Robert Powers
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska.,Department of Chemistry, Nebraska Center for Integrated Biomolecular Communication, Lincoln, Nebraska
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4
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Cheng K, Zheng W, Chen H, Zhang YHPJ. Upgrade of wood sugar d-xylose to a value-added nutraceutical by in vitro metabolic engineering. Metab Eng 2018; 52:1-8. [PMID: 30389613 DOI: 10.1016/j.ymben.2018.10.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2018] [Revised: 10/09/2018] [Accepted: 10/27/2018] [Indexed: 11/30/2022]
Abstract
The upgrade of D-xylose, the most abundant pentose, to value-added biochemicals is economically important to next-generation biorefineries. myo-Inositol, as vitamin B8, has a six-carbon carbon-carbon ring. Here we designed an in vitro artificial NAD(P)-free 12-enzyme pathway that can effectively convert the five-carbon xylose to inositol involving xylose phosphorylation, carbon-carbon (C-C) rearrangement, C-C bond circulation, and dephosphorylation. The reaction conditions catalyzed by all thermostable enzymes from hyperthermophilic microorganisms Thermus thermophiles, Thermotoga maritima, and Archaeoglobus fulgidus were optimized in reaction temperature, buffer type and concentration, enzyme composition, Mg2+ concentration, and fed-batch addition of ATP. The 11-enzyme cocktail, whereas a fructose 1,6-bisphosphatase from T. maritima has another function of inositol monophosphatase, converted 20 mM xylose to 16.1 mM inositol with a conversion efficiency of 96.6% at 70 °C. Polyphosphate was found to replace ATP for xylulose phosphorylation due to broad substrate promiscuity of the T. maritima xylulokinase. The Tris-HCl buffer effectively mitigated the Maillard reaction at 70 °C or higher temperature. The co-production of value-added biochemicals, such as inositol, from wood sugar could greatly improve economics of new biorefineries, similar to oil refineries that make value-added plastic precursors to subsidize gasoline/diesel production.
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Affiliation(s)
- Kun Cheng
- Collaborative Innovation Center of Henan Grain Crops, Henan Agricultural University, 95 Wenhua Road, Zhengzhou 450002, China; Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin Airport Economic Area, Tianjin 300308, China
| | - Wenming Zheng
- Collaborative Innovation Center of Henan Grain Crops, Henan Agricultural University, 95 Wenhua Road, Zhengzhou 450002, China; College of Life Sciences, Henan Agricultural University, 95 Wenhua Road, Zhengzhou 450002, China
| | - Hongge Chen
- Collaborative Innovation Center of Henan Grain Crops, Henan Agricultural University, 95 Wenhua Road, Zhengzhou 450002, China; College of Life Sciences, Henan Agricultural University, 95 Wenhua Road, Zhengzhou 450002, China.
| | - Yi-Heng P Job Zhang
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin Airport Economic Area, Tianjin 300308, China.
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5
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Razali R, Bougouffa S, Morton MJL, Lightfoot DJ, Alam I, Essack M, Arold ST, Kamau AA, Schmöckel SM, Pailles Y, Shahid M, Michell CT, Al-Babili S, Ho YS, Tester M, Bajic VB, Negrão S. The Genome Sequence of the Wild Tomato Solanum pimpinellifolium Provides Insights Into Salinity Tolerance. FRONTIERS IN PLANT SCIENCE 2018; 9:1402. [PMID: 30349549 PMCID: PMC6186997 DOI: 10.3389/fpls.2018.01402] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2018] [Accepted: 09/04/2018] [Indexed: 05/19/2023]
Abstract
Solanum pimpinellifolium, a wild relative of cultivated tomato, offers a wealth of breeding potential for desirable traits such as tolerance to abiotic and biotic stresses. Here, we report the genome assembly and annotation of S. pimpinellifolium 'LA0480.' Moreover, we present phenotypic data from one field experiment that demonstrate a greater salinity tolerance for fruit- and yield-related traits in S. pimpinellifolium compared with cultivated tomato. The 'LA0480' genome assembly size (811 Mb) and the number of annotated genes (25,970) are within the range observed for other sequenced tomato species. We developed and utilized the Dragon Eukaryotic Analyses Platform (DEAP) to functionally annotate the 'LA0480' protein-coding genes. Additionally, we used DEAP to compare protein function between S. pimpinellifolium and cultivated tomato. Our data suggest enrichment in genes involved in biotic and abiotic stress responses. To understand the genomic basis for these differences in S. pimpinellifolium and S. lycopersicum, we analyzed 15 genes that have previously been shown to mediate salinity tolerance in plants. We show that S. pimpinellifolium has a higher copy number of the inositol-3-phosphate synthase and phosphatase genes, which are both key enzymes in the production of inositol and its derivatives. Moreover, our analysis indicates that changes occurring in the inositol phosphate pathway may contribute to the observed higher salinity tolerance in 'LA0480.' Altogether, our work provides essential resources to understand and unlock the genetic and breeding potential of S. pimpinellifolium, and to discover the genomic basis underlying its environmental robustness.
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Affiliation(s)
- Rozaimi Razali
- Computational Bioscience Research Center, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Salim Bougouffa
- Computational Bioscience Research Center, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Mitchell J. L. Morton
- Division of Biological and Environmental Sciences and Engineering, The Bioactives Lab, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Damien J. Lightfoot
- Division of Biological and Environmental Sciences and Engineering, The Bioactives Lab, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Intikhab Alam
- Computational Bioscience Research Center, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
- Division of Computer, Electrical and Mathematical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Magbubah Essack
- Computational Bioscience Research Center, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Stefan T. Arold
- Computational Bioscience Research Center, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
- Division of Biological and Environmental Sciences and Engineering, The Bioactives Lab, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Allan A. Kamau
- Computational Bioscience Research Center, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
- Division of Computer, Electrical and Mathematical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Sandra M. Schmöckel
- Division of Biological and Environmental Sciences and Engineering, The Bioactives Lab, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Yveline Pailles
- Division of Biological and Environmental Sciences and Engineering, The Bioactives Lab, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Mohammed Shahid
- International Center for Biosaline Agriculture, Dubai, United Arab Emirates
| | - Craig T. Michell
- Red Sea Research Center, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Salim Al-Babili
- Division of Biological and Environmental Sciences and Engineering, The Bioactives Lab, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Yung Shwen Ho
- Division of Biological and Environmental Sciences and Engineering, The Bioactives Lab, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Mark Tester
- Division of Biological and Environmental Sciences and Engineering, The Bioactives Lab, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Vladimir B. Bajic
- Computational Bioscience Research Center, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
- Division of Computer, Electrical and Mathematical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Sónia Negrão
- Division of Biological and Environmental Sciences and Engineering, The Bioactives Lab, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
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6
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Lu Y, Wang L, Teng F, Zhang J, Hu M, Tao Y. Production of myo-inositol from glucose by a novel trienzymatic cascade of polyphosphate glucokinase, inositol 1-phosphate synthase and inositol monophosphatase. Enzyme Microb Technol 2018; 112:1-5. [DOI: 10.1016/j.enzmictec.2018.01.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 12/20/2017] [Accepted: 01/15/2018] [Indexed: 02/06/2023]
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7
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Erickson AI, Sarsam RD, Fisher AJ. Crystal Structures of Mycobacterium tuberculosis CysQ, with Substrate and Products Bound. Biochemistry 2015; 54:6830-41. [PMID: 26512869 DOI: 10.1021/acs.biochem.5b01000] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
In many organisms, 3'-phosphoadenosine 5'-phosphate (PAP) is a product of two reactions in the sulfur activation pathway. The sulfurylation of biomolecules, catalyzed by sulfotransferases, uses 3'-phosphoadenosine 5'-phosphosulfate (PAPS) as a sulfate donor, producing the sulfated biomolecule and PAP product. Additionally, the first step in sulfate reduction for many bacteria and fungi reduces the sulfate moiety of PAPS, producing PAP and sulfite, which is subsequently reduced to sulfide. PAP is removed by the phosphatase activity of CysQ, a 3',5'-bisphosphate nucleotidase, yielding AMP and phosphate. Because excess PAP alters the equilibrium of the sulfur pathway and inhibits sulfotransferases, PAP concentrations can affect the levels of sulfur-containing metabolites. Therefore, CysQ, a divalent cation metal-dependent phosphatase, is a major regulator of this pathway. CysQ (Rv2131c) from Mycobacterium tuberculosis (Mtb) was successfully expressed, purified, and crystallized in a variety of ligand-bound states. Here we report six crystal structures of Mtb CysQ, including a ligand-free structure, a lithium-inhibited state with substrate PAP bound, and a product-bound complex with AMP, phosphate, and three Mg(2+) ions bound. Comparison of these structures together with homologues of the superfamily has provided insight into substrate specificity, metal coordination, and catalytic mechanism.
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Affiliation(s)
- Anna I Erickson
- Department of Chemistry, ‡Department of Molecular and Cellular Biology, and §Graduate Program in Biochemistry and Molecular, Cellular and Developmental Biology, University of California , One Shields Avenue, Davis, California 95616, United States
| | - Reta D Sarsam
- Department of Chemistry, ‡Department of Molecular and Cellular Biology, and §Graduate Program in Biochemistry and Molecular, Cellular and Developmental Biology, University of California , One Shields Avenue, Davis, California 95616, United States
| | - Andrew J Fisher
- Department of Chemistry, ‡Department of Molecular and Cellular Biology, and §Graduate Program in Biochemistry and Molecular, Cellular and Developmental Biology, University of California , One Shields Avenue, Davis, California 95616, United States
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8
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Hwang HJ, Park SY, Kim JS. Crystal structure of cbbF from Zymomonas mobilis and its functional implication. Biochem Biophys Res Commun 2014; 445:78-83. [PMID: 24491569 DOI: 10.1016/j.bbrc.2014.01.152] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Accepted: 01/24/2014] [Indexed: 12/24/2022]
Abstract
A phosphate group at the C1-atom of inositol-monophosphate (IMP) and fructose-1,6-bisphosphate (FBP) is hydrolyzed by a phosphatase IMPase and FBPase in a metal-dependent way, respectively. The two enzymes are almost indiscernible from each other because of their highly similar sequences and structures. Metal ions are bound to residues on the β1- and β2-strands and one mobile loop. However, FBP has another phosphate and FBPases exist as a higher oligomeric state, which may discriminate FBPases from IMPases. There are three genes annotated as FBPases in Zymomonas mobilis, termed also cbbF (ZmcbbF). The revealed crystal structure of one ZmcbbF shows a globular structure formed by five stacked layers. Twenty-five residues in the middle of the sequence form an α-helix and a β-strand, which occupy one side of the catalytic site. A non-polar Leu residue among them is protruded to the active site, pointing out unfavorable access of a bulky charged group to this side. In vitro assays have shown its dimeric form in solution. Interestingly, two β-strands of β1 and β2 are disordered in the ZmcbbF structure. These data indicate that ZmcbbF might structurally belong to IMPase, and imply that its active site would be reorganized in a yet unreported way.
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Affiliation(s)
- Hyo-Jeong Hwang
- Department of Chemistry, Chonnam National University, Gwangju 500-757, Republic of Korea
| | - Suk-Youl Park
- Department of Chemistry, Chonnam National University, Gwangju 500-757, Republic of Korea
| | - Jeong-Sun Kim
- Department of Chemistry, Chonnam National University, Gwangju 500-757, Republic of Korea.
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Kurnasov OV, Luk HJD, Roberts MF, Stec B. Structure of the inositol-1-phosphate cytidylyltransferase from Thermotoga maritima. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2013; 69:1808-17. [DOI: 10.1107/s0907444913015278] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Accepted: 06/02/2013] [Indexed: 11/10/2022]
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10
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Abstract
We report an unexpected finding of common structural principles in two unrelated signaling systems: the FAS death domain transformation that initializes the extrinsic apoptotic pathway and signaling by calmodulin bending. The location and design of the hinge is postulated to be a general principle for creating potential signaling event. We suggest that already existing tool can predict the existence of such a hinge and formulate the hypothesis that the internal instabilities designed into the hinge sequences are necessary devices in effective signaling events.
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Affiliation(s)
- Boguslaw Stec
- Sanford-Burnham Medical Research Institute, 10901 N. Torrey Pines Rd., La Jolla, CA 92037, United States.
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11
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Bhattacharyya S, Dutta D, Saha B, Ghosh AK, Das AK. Crystal structure of Staphylococcal dual specific inositol monophosphatase/NADP(H) phosphatase (SAS2203) delineates the molecular basis of substrate specificity. Biochimie 2012; 94:879-90. [DOI: 10.1016/j.biochi.2011.12.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2011] [Accepted: 12/07/2011] [Indexed: 10/14/2022]
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12
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Li Z, Stieglitz KA, Shrout AL, Wei Y, Weis RM, Stec B, Roberts MF. Mobile loop mutations in an archaeal inositol monophosphatase: modulating three-metal ion assisted catalysis and lithium inhibition. Protein Sci 2010; 19:309-18. [PMID: 20027624 PMCID: PMC2865715 DOI: 10.1002/pro.315] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2009] [Revised: 11/20/2009] [Accepted: 12/10/2009] [Indexed: 01/20/2023]
Abstract
The inositol monophosphatase (IMPase) enzyme from the hyperthermophilic archaeon Methanocaldococcus jannaschii requires Mg(2+) for activity and binds three to four ions tightly in the absence of ligands: K(D) = 0.8 muM for one ion with a K(D) of 38 muM for the other Mg(2+) ions. However, the enzyme requires 5-10 mM Mg(2+) for optimum catalysis, suggesting substrate alters the metal ion affinity. In crystal structures of this archaeal IMPase with products, one of the three metal ions is coordinated by only one protein contact, Asp38. The importance of this and three other acidic residues in a mobile loop that approaches the active site was probed with mutational studies. Only D38A exhibited an increased kinetic K(D) for Mg(2+); D26A, E39A, and E41A showed no significant change in the Mg(2+) requirement for optimal activity. D38A also showed an increased K(m), but little effect on k(cat). This behavior is consistent with this side chain coordinating the third metal ion in the substrate complex, but with sufficient flexibility in the loop such that other acidic residues could position the Mg(2+) in the active site in the absence of Asp38. While lithium ion inhibition of the archaeal IMPase is very poor (IC(50) approximately 250 mM), the D38A enzyme has a dramatically enhanced sensitivity to Li(+) with an IC(50) of 12 mM. These results constitute additional evidence for three metal ion assisted catalysis with substrate and product binding reducing affinity of the third necessary metal ion. They also suggest a specific mode of action for lithium inhibition in the IMPase superfamily.
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Affiliation(s)
- Zheng Li
- Department of Chemistry, Boston CollegeChestnut Hill, Massachusetts 02467
| | - Kimberly A Stieglitz
- Science, Technology, Engineering, and Mathematics, Roxbury Community CollegeBoston, Massachusetts 02120
| | - Anthony L Shrout
- Department of Chemistry, University of MassachusettsAmherst, Massachusetts 01003
| | - Yang Wei
- Department of Chemistry, Boston CollegeChestnut Hill, Massachusetts 02467
| | - Robert M Weis
- Department of Chemistry, University of MassachusettsAmherst, Massachusetts 01003
| | - Boguslaw Stec
- The Burnham Institute for Medical ResearchLa Jolla, California 92037
| | - Mary F Roberts
- Department of Chemistry, Boston CollegeChestnut Hill, Massachusetts 02467
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13
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Global distribution of conformational states derived from redundant models in the PDB points to non-uniqueness of the protein structure. Proc Natl Acad Sci U S A 2009; 106:10505-10. [PMID: 19553204 DOI: 10.1073/pnas.0812152106] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
It is commonly accepted that proteins have evolutionarily conserved 3-dimensional structures, uniquely defined by their amino acid sequence. Here, we question the direct association of structure to sequence by comparing multiple models of identical proteins. Rapidly growing structural databases contain models of proteins determined independently multiple times. We have collected these models in the database of the redundant sets of protein structures and then derived their conformational states by clustering the models with low root-mean-square deviations (RMSDs). The distribution of conformational states represented in these sets is wider than commonly believed, in fact exceeding the possible range of structure determination errors, by at least an order of magnitude. We argue that differences among the models represent the natural distribution of conformational states. Our results suggest that we should change the common notion of a protein structure by augmenting a single 3-dimensional model by the width of the ensemble distribution. This width must become an indispensible attribute of the protein description. We show that every protein contains regions of high rigidity (solid-like) and regions of high mobility (liquid-like) in different and characteristic contribution. We also show that the extent of local flexibility is correlated with the functional class of the protein. This study suggests that the protein-folding problem has no unique solution and should be limited to defining the folding class of the solid-like fragments even though they may constitute only a small part of the protein. These results limit the capability of modeling protein structures with multiple conformational states.
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15
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Brown AK, Meng G, Ghadbane H, Scott DJ, Dover LG, Nigou J, Besra GS, Fütterer K. Dimerization of inositol monophosphatase Mycobacterium tuberculosis SuhB is not constitutive, but induced by binding of the activator Mg2+. BMC STRUCTURAL BIOLOGY 2007; 7:55. [PMID: 17725819 PMCID: PMC2080633 DOI: 10.1186/1472-6807-7-55] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2007] [Accepted: 08/28/2007] [Indexed: 12/21/2022]
Abstract
BACKGROUND The cell wall of Mycobacterium tuberculosis contains a wide range of phosphatidyl inositol-based glycolipids that play critical structural roles and, in part, govern pathogen-host interactions. Synthesis of phosphatidyl inositol is dependent on free myo-inositol, generated through dephosphorylation of myo-inositol-1-phosphate by inositol monophosphatase (IMPase). Human IMPase, the putative target of lithium therapy, has been studied extensively, but the function of four IMPase-like genes in M. tuberculosis is unclear. RESULTS We determined the crystal structure, to 2.6 A resolution, of the IMPase M. tuberculosis SuhB in the apo form, and analysed self-assembly by analytical ultracentrifugation. Contrary to the paradigm of constitutive dimerization of IMPases, SuhB is predominantly monomeric in the absence of the physiological activator Mg2+, in spite of a conserved fold and apparent dimerization in the crystal. However, Mg2+ concentrations that result in enzymatic activation of SuhB decisively promote dimerization, with the inhibitor Li+ amplifying the effect of Mg2+, but failing to induce dimerization on its own. CONCLUSION The correlation of Mg2+-driven enzymatic activity with dimerization suggests that catalytic activity is linked to the dimer form. Current models of lithium inhibition of IMPases posit that Li+ competes for one of three catalytic Mg2+ sites in the active site, stabilized by a mobile loop at the dimer interface. Our data suggest that Mg2+/Li+-induced ordering of this loop may promote dimerization by expanding the dimer interface of SuhB. The dynamic nature of the monomer-dimer equilibrium may also explain the extended concentration range over which Mg2+ maintains SuhB activity.
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Affiliation(s)
- Alistair K Brown
- School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Guoyu Meng
- School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
- Present address : School of Crystallography, Birkbeck College, Malet Street, London WC1E 7HX, UK
| | - Hemza Ghadbane
- School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - David J Scott
- National Centre for Macromolecular Hydrodynamics, School of Biosciences, University of Nottingham, Sutton Bonington, LE12 5RD, UK
| | - Lynn G Dover
- School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Jérôme Nigou
- Department of Molecular Mechanisms of Mycobacterial Infections, Institut de Pharmacologie et de Biologie Structurale, Centre National de la Recherche Scientifique Unité Mixte de Recherche 5089, Toulouse, France
| | - Gurdyal S Besra
- School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Klaus Fütterer
- School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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