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Chen J, Vishweshwaraiah YL, Mailman RB, Tabdanov ED, Dokholyan NV. A noncommutative combinatorial protein logic circuit controls cell orientation in nanoenvironments. SCIENCE ADVANCES 2023; 9:eadg1062. [PMID: 37235645 PMCID: PMC10219599 DOI: 10.1126/sciadv.adg1062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 04/20/2023] [Indexed: 05/28/2023]
Abstract
Single-protein-based devices that integrate signal sensing with logical operations to generate functional outputs offer exceptional promise for monitoring and modulating biological systems. Engineering such intelligent nanoscale computing agents is challenging, as it requires the integration of sensor domains into a functional protein via intricate allosteric networks. We incorporate a rapamycin-sensitive sensor (uniRapR) and a blue light-responsive LOV2 domain into human Src kinase, creating a protein device that functions as a noncommutative combinatorial logic circuit. In our design, rapamycin activates Src kinase, causing protein localization to focal adhesions, whereas blue light exerts the reverse effect that inactivates Src translocation. Focal adhesion maturation induced by Src activation reduces cell migration dynamics and shifts cell orientation to align along collagen nanolane fibers. Using this protein device, we reversibly control cell orientation by applying the appropriate input signals, a framework that may be useful in tissue engineering and regenerative medicine.
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Affiliation(s)
- Jiaxing Chen
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA 17033-0850, USA
| | | | - Richard B. Mailman
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA 17033-0850, USA
| | - Erdem D. Tabdanov
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA 17033-0850, USA
| | - Nikolay V. Dokholyan
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA 17033-0850, USA
- Department of Biochemistry and Molecular Biology, Penn State College of Medicine, Hershey, PA 17033-0850, USA
- Department of Chemistry, Pennsylvania State University, University Park, PA 16802, USA
- Department of Biomedical Engineering, Pennsylvania State University, University Park, PA 16802, USA
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2
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Zamel J, Chen J, Zaer S, Harris PD, Drori P, Lebendiker M, Kalisman N, Dokholyan NV, Lerner E. Structural and dynamic insights into α-synuclein dimer conformations. Structure 2023; 31:411-423.e6. [PMID: 36809765 PMCID: PMC10081966 DOI: 10.1016/j.str.2023.01.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Revised: 01/12/2023] [Accepted: 01/26/2023] [Indexed: 02/22/2023]
Abstract
Parkinson disease is associated with the aggregation of the protein α-synuclein. While α-synuclein can exist in multiple oligomeric states, the dimer has been a subject of extensive debates. Here, using an array of biophysical approaches, we demonstrate that α-synuclein in vitro exhibits primarily a monomer-dimer equilibrium in nanomolar concentrations and up to a few micromolars. We then use spatial information from hetero-isotopic cross-linking mass spectrometry experiments as restrains in discrete molecular dynamics simulations to obtain the ensemble structure of dimeric species. Out of eight structural sub-populations of dimers, we identify one that is compact, stable, abundant, and exhibits partially exposed β-sheet structures. This compact dimer is the only one where the hydroxyls of tyrosine 39 are in proximity that may promote dityrosine covalent linkage upon hydroxyl radicalization, which is implicated in α-synuclein amyloid fibrils. We propose that this α-synuclein dimer features etiological relevance to Parkinson disease.
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Affiliation(s)
- Joanna Zamel
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Jiaxing Chen
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA 17033, USA
| | - Sofia Zaer
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Paul David Harris
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Paz Drori
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Mario Lebendiker
- Wolfson Centre for Applied Structural Biology, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, The Edmond J. Safra Campus, Givat Ram, Jerusalem, 9190401, Israel
| | - Nir Kalisman
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Nikolay V Dokholyan
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA 17033, USA; Department of Biochemistry & Molecular Biology, Penn State College of Medicine, Hershey, PA 17033, USA; Departments of Chemistry and Biomedical Engineering, Pennsylvania State University, University Park, PA 16802, USA.
| | - Eitan Lerner
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel; The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel.
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3
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Chen J, Zaer S, Drori P, Zamel J, Joron K, Kalisman N, Lerner E, Dokholyan NV. The structural heterogeneity of α-synuclein is governed by several distinct subpopulations with interconversion times slower than milliseconds. Structure 2021; 29:1048-1064.e6. [PMID: 34015255 PMCID: PMC8419013 DOI: 10.1016/j.str.2021.05.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 03/12/2021] [Accepted: 04/30/2021] [Indexed: 11/22/2022]
Abstract
α-Synuclein plays an important role in synaptic functions by interacting with synaptic vesicle membrane, while its oligomers and fibrils are associated with several neurodegenerative diseases. The specific monomer structures that promote its membrane binding and self-association remain elusive due to its transient nature as an intrinsically disordered protein. Here, we use inter-dye distance distributions from bulk time-resolved Förster resonance energy transfer as restraints in discrete molecular dynamics simulations to map the conformational space of the α-synuclein monomer. We further confirm the generated conformational ensemble in orthogonal experiments utilizing far-UV circular dichroism and cross-linking mass spectrometry. Single-molecule protein-induced fluorescence enhancement measurements show that within this conformational ensemble, some of the conformations of α-synuclein are surprisingly stable, exhibiting conformational transitions slower than milliseconds. Our comprehensive analysis of the conformational ensemble reveals essential structural properties and potential conformations that promote its various functions in membrane interaction or oligomer and fibril formation.
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Affiliation(s)
- Jiaxing Chen
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA 17033, USA
| | - Sofia Zaer
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Paz Drori
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Joanna Zamel
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Khalil Joron
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Nir Kalisman
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Eitan Lerner
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel; The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel.
| | - Nikolay V Dokholyan
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA 17033, USA; Department of Biochemistry & Molecular Biology, Penn State College of Medicine, Hershey, PA 17033, USA; Departments of Chemistry and Biomedical Engineering, Pennsylvania State University, University Park, PA 16802, USA.
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Genome-Scale Characterization of Fungal Phytases and a Comparative Study Between Beta-Propeller Phytases and Histidine Acid Phosphatases. Appl Biochem Biotechnol 2020; 192:296-312. [DOI: 10.1007/s12010-020-03309-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 03/12/2020] [Indexed: 01/31/2023]
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Tseng YT, Kawashima S, Kobayashi S, Takeuchi S, Nakamura K. Forecasting the seasonal pollen index by using a hidden Markov model combining meteorological and biological factors. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 698:134246. [PMID: 31505344 DOI: 10.1016/j.scitotenv.2019.134246] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 08/29/2019] [Accepted: 09/01/2019] [Indexed: 06/10/2023]
Abstract
The seasonal pollen index (SPI) is a continuing concern within the fields of aerobiology, ecology, botany, and epidemiology. The SPI of anemophilous trees, which varies substantially from year to year, reflects the flowering intensity. This intensity is regulated by two factors: weather conditions during flower formation and the inner resource for assimilation. A deterministic approach has to date been employed for predicting SPI, in which the forecast is made entirely by parameters. However, given the complexity of the masting mechanism (which has intrinsic stochastic properties), few attempts have been made to apply a stochastic model that considers the inter-annual SPI variation as a stochastic process. We propose a hidden Markov model that can integrate the stochastic process of mast flowering and the meteorological conditions influencing flower formation to predict the annual birch pollen concentration. In experiments conducted, the model was trained and validated by using data in Hokkaido, Japan covering 22 years. In the model, the hidden Markov sequence was assigned to represent the recurrence of mast years via a transition matrix, and the observation sequences were designated as meteorological conditions in the previous summer, which are governed by hidden states with emission distribution. The proposed model achieved accuracies of 83.3% in the training period and 75.0% in the test period. Thus, the proposed model can provide an alternative perspective toward the SPI forecast and probabilistic information of pollen levels as a useful reference for allergy stakeholders.
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Affiliation(s)
- Yi-Ting Tseng
- Graduate School of Agriculture, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-Ku, Kyoto 606-8502, Japan
| | - Shigeto Kawashima
- Graduate School of Agriculture, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-Ku, Kyoto 606-8502, Japan.
| | - Satoshi Kobayashi
- Hokkaido Institute of Public Health, 12 Chome Kita 19 Jonishi, Kita Ward, Sapporo, Hokkaido 060-0819, Japan
| | - Shinji Takeuchi
- Hokkaido Institute of Public Health, 12 Chome Kita 19 Jonishi, Kita Ward, Sapporo, Hokkaido 060-0819, Japan
| | - Kimihito Nakamura
- Graduate School of Agriculture, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-Ku, Kyoto 606-8502, Japan
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6
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El-Din Solliman M, Mohasseb HAA, Al-Khateeb AA, Al-Khateeb SA, Chowdhury K, El-Shemy HA, Aldaej MI. Identification and sequencing of Date-SRY Gene: A novel tool for sex determination of date palm ( Phoenix dactylifera L.). Saudi J Biol Sci 2017; 26:514-523. [PMID: 30899166 PMCID: PMC6410340 DOI: 10.1016/j.sjbs.2017.08.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 08/10/2017] [Accepted: 08/12/2017] [Indexed: 11/29/2022] Open
Abstract
Dioecism has always been an issue in many plant species with its numerous disadvantages, especially in woody trees such as date palms. As one of the most important crops in the Middle Eastern countries, researchers are having problems identifying of sex of the plant in its early stages of development. Hence, proper population stands in the male: female ratio for maintenance is almost impossible in the field for better production. In this study, sex determination of date palm (Phoenix dactilyfera L.) were identified in regions of the Y chromosome (Date-SRY) gene, the pivotal gene that initiates sex determination, using a new technique and thus an economically desirable objective, which will significantly impact profits in seed based cultivations. Partial sequences of the Date-SRY were taken and amplified by nested polymerase chain reaction (PCR). According to the results, the exact sex of date palm was identified in all the tested plants, while amplified regions of the Date-SRY gene closely matched with the human and papaya sequences. In addition, a primer pair was designed to amplify the sequences of the SRY-date gene with confidence that it will identify male date palms. These primer sequences include SRY-date Forward 5'- cggccctctaagtatctgtgcgcaacg-3' (SRY-date F) and the SRY-date Reverse 5'- gtttgcacttcgaagcagag-3' (SRY-date R). The complete sequence of the DNA has been registered and deposited in GenBank (BankIt1598036 DPSRY1 KC577225 thenKJ873056).
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Affiliation(s)
- Mohei El-Din Solliman
- Plant Biotechnology Dept., National Research Centre, Dokki 12622, Cairo, Egypt.,Department of Agricultural Biotechnology, College of Agriculture and Food Sciences, King Faisal University, P.O. Box 420, Al-Hassa 31982, Saudi Arabia
| | | | - Abdullatif A Al-Khateeb
- Department of Agricultural Biotechnology, College of Agriculture and Food Sciences, King Faisal University, P.O. Box 420, Al-Hassa 31982, Saudi Arabia
| | - Suliman A Al-Khateeb
- Environment and Natural Resources Department, College of Agriculture and Food Sciences, King Faisal University, P.O. Box 400, Alhassa 31982, Saudi Arabia
| | - Kamal Chowdhury
- Biology Department, School of Natural Sciences and Mathematics, Claflin University, Orangeburg, SC 29115, USA
| | - Hany A El-Shemy
- Cairo University Research Park (CURP) and Biochemistry Department, Faculty of Agriculture, Cairo University, Giza 12613, Egypt
| | - Mohammed I Aldaej
- Department of Agricultural Biotechnology, College of Agriculture and Food Sciences, King Faisal University, P.O. Box 420, Al-Hassa 31982, Saudi Arabia
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7
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Hidden Markov model and Chapman Kolmogrov for protein structures prediction from images. Comput Biol Chem 2017; 68:231-244. [DOI: 10.1016/j.compbiolchem.2017.04.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 03/11/2017] [Accepted: 04/11/2017] [Indexed: 11/20/2022]
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8
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9
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Slootweg EJ, Spiridon LN, Roosien J, Butterbach P, Pomp R, Westerhof L, Wilbers R, Bakker E, Bakker J, Petrescu AJ, Smant G, Goverse A. Structural determinants at the interface of the ARC2 and leucine-rich repeat domains control the activation of the plant immune receptors Rx1 and Gpa2. PLANT PHYSIOLOGY 2013; 162:1510-28. [PMID: 23660837 PMCID: PMC3707565 DOI: 10.1104/pp.113.218842] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Accepted: 05/07/2013] [Indexed: 05/19/2023]
Abstract
Many plant and animal immune receptors have a modular nucleotide-binding-leucine-rich repeat (NB-LRR) architecture in which a nucleotide-binding switch domain, NB-ARC, is tethered to a LRR sensor domain. The cooperation between the switch and sensor domains, which regulates the activation of these proteins, is poorly understood. Here, we report structural determinants governing the interaction between the NB-ARC and LRR in the highly homologous plant immune receptors Gpa2 and Rx1, which recognize the potato cyst nematode Globodera pallida and Potato virus X, respectively. Systematic shuffling of polymorphic sites between Gpa2 and Rx1 showed that a minimal region in the ARC2 and N-terminal repeats of the LRR domain coordinate the activation state of the protein. We identified two closely spaced amino acid residues in this region of the ARC2 (positions 401 and 403) that distinguish between autoactivation and effector-triggered activation. Furthermore, a highly acidic loop region in the ARC2 domain and basic patches in the N-terminal end of the LRR domain were demonstrated to be required for the physical interaction between the ARC2 and LRR. The NB-ARC and LRR domains dissociate upon effector-dependent activation, and the complementary-charged regions are predicted to mediate a fast reassociation, enabling multiple rounds of activation. Finally, we present a mechanistic model showing how the ARC2, NB, and N-terminal half of the LRR form a clamp, which regulates the dissociation and reassociation of the switch and sensor domains in NB-LRR proteins.
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Affiliation(s)
- Erik J Slootweg
- Laboratory of Nematology, Department of Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands.
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Ullman O, Fisher CK, Stultz CM. Explaining the structural plasticity of α-synuclein. J Am Chem Soc 2011; 133:19536-46. [PMID: 22029383 PMCID: PMC3227348 DOI: 10.1021/ja208657z] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Indexed: 01/10/2023]
Abstract
Given that α-synuclein has been implicated in the pathogenesis of several neurodegenerative disorders, deciphering the structure of this protein is of particular importance. While monomeric α-synuclein is disordered in solution, it can form aggregates rich in cross-β structure, relatively long helical segments when bound to micelles or lipid vesicles, and a relatively ordered helical tetramer within the native cell environment. To understand the physical basis underlying this structural plasticity, we generated an ensemble for monomeric α-synuclein using a Bayesian formalism that combines data from NMR chemical shifts, RDCs, and SAXS with molecular simulations. An analysis of the resulting ensemble suggests that a non-negligible fraction of the ensemble (0.08, 95% confidence interval 0.03-0.12) places the minimal toxic aggregation-prone segment in α-synuclein, NAC(8-18), in a solvent exposed and extended conformation that can form cross-β structure. Our data also suggest that a sizable fraction of structures in the ensemble (0.14, 95% confidence interval 0.04-0.23) contains long-range contacts between the N- and C-termini. Moreover, a significant fraction of structures that contain these long-range contacts also place the NAC(8-18) segment in a solvent exposed orientation, a finding in contrast to the theory that such long-range contacts help to prevent aggregation. Lastly, our data suggest that α-synuclein samples structures with amphipathic helices that can self-associate via hydrophobic contacts to form tetrameric structures. Overall, these observations represent a comprehensive view of the unfolded ensemble of monomeric α-synuclein and explain how different conformations can arise from the monomeric protein.
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Affiliation(s)
- Orly Ullman
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, United States
| | - Charles K. Fisher
- Committee on Higher Degrees in Biophysics, Harvard University Cambridge, Massachusetts 02139-4307, United States
| | - Collin M. Stultz
- Committee on Higher Degrees in Biophysics, Harvard University Cambridge, Massachusetts 02139-4307, United States
- Harvard-MIT Division of Health Sciences and Technology, Department of Electrical Engineering and Computer Science, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, United States
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11
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Smith AA, Plazas MC. In silico Characterization and Homology Modeling of Cyanobacterial Phosphoenolpyruvate Carboxylase Enzymes with Computational Tools and Bioinformatics Servers. ACTA ACUST UNITED AC 2011. [DOI: 10.3923/ajbmb.2011.319.336] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Brueggemann J, Weisshaar B, Sagasser M. A WD40-repeat gene from Malus x domestica is a functional homologue of Arabidopsis thaliana TRANSPARENT TESTA GLABRA1. PLANT CELL REPORTS 2010; 29:285-94. [PMID: 20107808 DOI: 10.1007/s00299-010-0821-0] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2009] [Revised: 01/06/2010] [Accepted: 01/08/2010] [Indexed: 05/19/2023]
Abstract
The WD40 repeat protein TRANSPARENT TESTA GLABRA1 (TTG1) is involved in a multitude of developmental and biochemical reactions in Arabidopsis thaliana such as the production of seed coat colour and mucilage, pigmentation by anthocyanins as well as the formation of trichomes and root hairs. In this study, a putative TTG1 homologue was isolated from apple (Malus x domestica Borkh.) showing 80.2% identity to A. thaliana TTG1 on nucleotide and 90.7% similarity on amino acid level. The MdTTG1 candidate was able to activate the AtBAN promoter in cooperation with the A. thaliana transcription factors TT2 and TT8 in A. thaliana protoplasts. This indicates that the encoded protein can be integrated into the complex that activates BAN in A. thaliana, and that a similar complex might also be present in apple. When transformed into ttg1 mutants of A. thaliana, the apple sequence was able to restore trichome growth, anthocyanin production in young seedlings as well as proanthocyanidin production in seeds. Additionally, roots of complemented mutant plants showed root hair formation resembling wild type. These results show that the studied apple WD40 gene is a functional homologue of AtTTG1 and we refer to this gene as MdTTG1.
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Adolph KW. Characterization of the cDNA and amino acid sequences ofXenopusMetaxin 3, and relationship toXenopusMetaxins 1 and 2. ACTA ACUST UNITED AC 2009; 16:252-9. [PMID: 16147884 DOI: 10.1080/10425170500129660] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The cDNA and protein structures of Xenopus metaxin 3, along with those of Xenopus metaxins 1 and 2, have been characterized. A protein of 309 amino acid residues is encoded by X. laevis metaxin 3 (XMTX3) cDNA. In comparison, the cDNA of X. laevis metaxin 1 (XMTX1) specifies a protein of 320 residues, while the metaxin 2 cDNAs of X. laevis (XMTX2) and X. tropicalis (SMTX2) both specify proteins of 274 amino acids. Aligning the amino acid sequences of XMTX3 and XMTX1 showed 39% identities; 22% identities were found for XMTX3 and XMTX2. However, 55% amino acid identities were revealed in aligning the XMTX3 and zebrafish metaxin 3 sequences. The construction of a phylogenetic tree gave further evidence for the existence of three distinct groups of metaxin genes and their common ancestry. Two conserved protein domains are present in each of the Xenopus metaxins: a glutathione S-transferase (GST) domain and a thioredoxin-like domain. The protein secondary structure predicted for the Xenopus metaxins is dominated by regions of alpha helix which alternate with regions that are neither alpha helix nor beta strand.
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Affiliation(s)
- Kenneth W Adolph
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, 6-155 Jackson Hall, 321 Church Street SE, Minneapolis, MN, 55455, USA.
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14
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Cormier A, Clément MJ, Knossow M, Lachkar S, Savarin P, Toma F, Sobel A, Gigant B, Curmi PA. The PN2-3 domain of centrosomal P4.1-associated protein implements a novel mechanism for tubulin sequestration. J Biol Chem 2009; 284:6909-17. [PMID: 19131341 DOI: 10.1074/jbc.m808249200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Microtubules are cytoskeletal components involved in multiple cell functions such as mitosis, motility, or intracellular traffic. In vivo, these polymers made of alphabeta-tubulin nucleate mostly from the centrosome to establish the interphasic microtubule network or, during mitosis, the mitotic spindle. Centrosomal P4.1-associated protein (CPAP; also named CENPJ) is a centrosomal protein involved in the assembly of centrioles and important for the centrosome function. This protein contains a microtubule-destabilizing region referred to as PN2-3. Here we decrypt the microtubule destabilization activity of PN2-3 at the molecular level and show that it results from the sequestration of tubulin by PN2-3 in a non-polymerizable 1:1 complex. We also map the tubulin/PN2-3 interaction both on the PN2-3 sequence and on the tubulin surface. NMR and CD data on free PN2-3 in solution show that this is an intrinsically unstructured protein that comprises a 23-amino acid residue alpha-helix. This helix is embedded in a 76-residue region that interacts strongly with tubulin. The interference of PN2-3 with well characterized tubulin properties, namely GTPase activity, nucleotide exchange, vinblastine-induced self-assembly, and stathmin family protein binding, highlights the beta subunit surface located at the intermolecular longitudinal interface when tubulin is embedded in a microtubule as a tubulin/PN2-3 interaction area. These findings characterize the PN2-3 fragment of CPAP as a protein with an unprecedented tubulin sequestering mechanism distinct from that of stathmin family proteins.
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Affiliation(s)
- Anthony Cormier
- Laboratoire d'Enzymologie et Biochimie Structurales, CNRS, Bâtiment 34, 1 avenue de la Terrasse, 91198 Gif-sur-Yvette, France
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15
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Lara J, Wohlhueter RM, Dimitrova Z, Khudyakov YE. Artificial neural network for prediction of antigenic activity for a major conformational epitope in the hepatitis C virus NS3 protein. Bioinformatics 2008; 24:1858-64. [DOI: 10.1093/bioinformatics/btn339] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
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16
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Dehlin E, Liu J, Yun SH, Fox E, Snyder S, Gineste C, Willingham L, Geysen M, Gaylinn BD, Sando JJ. Regulation of ghrelin structure and membrane binding by phosphorylation. Peptides 2008; 29:904-11. [PMID: 18343535 PMCID: PMC2413428 DOI: 10.1016/j.peptides.2008.02.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2007] [Revised: 01/31/2008] [Accepted: 02/04/2008] [Indexed: 12/15/2022]
Abstract
The peptide hormone ghrelin requires Ser-3 acylation for receptor binding, orexigenic and anti-inflammatory effects. Functions of desacylghrelin are less well understood. In vitro kinase assays reveal that the evolutionarily conserved Ser-18 in the basic C-terminus is an excellent substrate for protein kinase C. Circular dichroism reveals that desacylghrelin is approximately 12% helical in aqueous solution and approximately 50% helical in trifluoroethanol. Ser-18-phosphorylation, Ser-18-Ala substitution, or Ser-3-acylation reduces the helical character in trifluoroethanol to approximately 24%. Both ghrelin and desacylghrelin bind to phosphatidylcholine:phosphatidylserine sucrose-loaded vesicles in a phosphatidylserine-dependent manner. Phosphoghrelin and phosphodesacylghrelin show greatly diminished phosphatidylserine-dependent binding. These results are consistent with binding of ghrelin and desacylghrelin to acidic lipids via the basic face of an amphipathic helix with Ser-18 phosphorylation disrupting both helical character and membrane binding.
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Affiliation(s)
- Eva Dehlin
- Department of Anesthesiology, University of Virginia, Charlottesville, VA 22908
| | - Jianhua Liu
- Department of Medicine Division of Endocrinology, University of Virginia, Charlottesville, VA 22908
| | - Samuel H. Yun
- Department of Anesthesiology, University of Virginia, Charlottesville, VA 22908
| | - Elizabeth Fox
- Department of Anesthesiology, University of Virginia, Charlottesville, VA 22908
| | - Sandra Snyder
- Department of Anesthesiology, University of Virginia, Charlottesville, VA 22908
| | - Cyrille Gineste
- Department of Chemistry, University of Virginia, Charlottesville, VA 22908
| | - Leslie Willingham
- Department of Chemistry, University of Virginia, Charlottesville, VA 22908
| | - Mario Geysen
- Department of Chemistry, University of Virginia, Charlottesville, VA 22908
| | - Bruce D. Gaylinn
- Department of Medicine Division of Endocrinology, University of Virginia, Charlottesville, VA 22908
| | - Julianne J. Sando
- Department of Anesthesiology, University of Virginia, Charlottesville, VA 22908
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17
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Yao XQ, Zhu H, She ZS. A dynamic Bayesian network approach to protein secondary structure prediction. BMC Bioinformatics 2008; 9:49. [PMID: 18218144 PMCID: PMC2266706 DOI: 10.1186/1471-2105-9-49] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2007] [Accepted: 01/25/2008] [Indexed: 11/19/2022] Open
Abstract
Background Protein secondary structure prediction method based on probabilistic models such as hidden Markov model (HMM) appeals to many because it provides meaningful information relevant to sequence-structure relationship. However, at present, the prediction accuracy of pure HMM-type methods is much lower than that of machine learning-based methods such as neural networks (NN) or support vector machines (SVM). Results In this paper, we report a new method of probabilistic nature for protein secondary structure prediction, based on dynamic Bayesian networks (DBN). The new method models the PSI-BLAST profile of a protein sequence using a multivariate Gaussian distribution, and simultaneously takes into account the dependency between the profile and secondary structure and the dependency between profiles of neighboring residues. In addition, a segment length distribution is introduced for each secondary structure state. Tests show that the DBN method has made a significant improvement in the accuracy compared to other pure HMM-type methods. Further improvement is achieved by combining the DBN with an NN, a method called DBNN, which shows better Q3 accuracy than many popular methods and is competitive to the current state-of-the-arts. The most interesting feature of DBN/DBNN is that a significant improvement in the prediction accuracy is achieved when combined with other methods by a simple consensus. Conclusion The DBN method using a Gaussian distribution for the PSI-BLAST profile and a high-ordered dependency between profiles of neighboring residues produces significantly better prediction accuracy than other HMM-type probabilistic methods. Owing to their different nature, the DBN and NN combine to form a more accurate method DBNN. Future improvement may be achieved by combining DBNN with a method of SVM type.
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Affiliation(s)
- Xin-Qiu Yao
- State Key Laboratory for Turbulence and Complex Systems and Department of Biomedical Engineering, Peking University, Beijing 100871, China.
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18
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Hidden Markov Models for prediction of protein features. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2008; 413:173-98. [PMID: 18075166 DOI: 10.1007/978-1-59745-574-9_7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Hidden Markov Models (HMMs) are an extremely versatile statistical representation that can be used to model any set of one-dimensional discrete symbol data. HMMs can model protein sequences in many ways, depending on what features of the protein are represented by the Markov states. For protein structure prediction, states have been chosen to represent either homologous sequence positions, local or secondary structure types, or transmembrane locality. The resulting models can be used to predict common ancestry, secondary or local structure, or membrane topology by applying one of the two standard algorithms for comparing a sequence to a model. In this chapter, we review those algorithms and discuss how HMMs have been constructed and refined for the purpose of protein structure prediction.
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19
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Yang IS, Ryu C, Cho KJ, Kim JK, Ong SH, Mitchell WP, Kim BS, Oh HB, Kim KH. IDBD: infectious disease biomarker database. Nucleic Acids Res 2007; 36:D455-60. [PMID: 17982173 PMCID: PMC2238845 DOI: 10.1093/nar/gkm925] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Biomarkers enable early diagnosis, guide molecularly targeted therapy and monitor the activity and therapeutic responses across a variety of diseases. Despite intensified interest and research, however, the overall rate of development of novel biomarkers has been falling. Moreover, no solution is yet available that efficiently retrieves and processes biomarker information pertaining to infectious diseases. Infectious Disease Biomarker Database (IDBD) is one of the first efforts to build an easily accessible and comprehensive literature-derived database covering known infectious disease biomarkers. IDBD is a community annotation database, utilizing collaborative Web 2.0 features, providing a convenient user interface to input and revise data online. It allows users to link infectious diseases or pathogens to protein, gene or carbohydrate biomarkers through the use of search tools. It supports various types of data searches and application tools to analyze sequence and structure features of potential and validated biomarkers. Currently, IDBD integrates 611 biomarkers for 66 infectious diseases and 70 pathogens. It is publicly accessible at http://biomarker.cdc.go.kr and http://biomarker.korea.ac.kr.
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Affiliation(s)
- In Seok Yang
- Department of Life Sciences & Biotechnology, School of Life Sciences & Biotechnology, Korea University, Seoul, Korea
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20
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Rogers EA, Marconi RT. Delineation of species-specific binding properties of the CspZ protein (BBH06) of Lyme disease spirochetes: evidence for new contributions to the pathogenesis of Borrelia spp. Infect Immun 2007; 75:5272-81. [PMID: 17846117 PMCID: PMC2168308 DOI: 10.1128/iai.00850-07] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Borrelia burgdorferi CspZ (TIGR open reading frame designation, BBH06) is part of a functionally related group of proteins that bind one or more members of the factor H (FH) protein family. In this report we assess the conservation, distribution, properties, and ligand binding abilities of CspZ from the three main Borrelia species associated with Lyme disease infections in humans. CspZ (also referred to as BbCRASP-2 in the literature) was found to be highly conserved at the intraspecies level but divergent at the interspecies level. All CspZ orthologs that originated from B. burgdorferi isolates bound FH from a diverse group of mammals. In contrast, CspZ derived from B. garinii and B. afzelii did not. Regardless of the Borrelia species of origin, all CspZ proteins tested bound to unknown approximately 60-kDa serum proteins produced by different mammals. To further define the molecular basis for the differential binding of CspZ orthologs to host proteins, DNA sequence, truncation, and site-directed mutagenesis analyses were performed. DNA sequence analyses revealed that B. garinii and B. afzelii CspZ orthologs possess a 64-amino-acid N-terminal domain that is absent from B. burgdorferi CspZ. However, binding analyses of recombinant proteins revealed that this domain does not in and of itself influence ligand binding properties. Truncation and mutagenesis analyses further revealed that the key determinants required for ligand binding are discontinuous and that the presentation of the ligand binding pocket is dependent on alpha helices with high coiled-coil formation probability. The data presented here provide insight into the molecular basis of CspZ-ligand interactions and suggest that CspZ orthologs from diverse Borrelia species can contribute to the host-pathogen interaction through their interaction with serum proteins.
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Affiliation(s)
- Elizabeth A Rogers
- Department of Microbiology and Immunology, Medical College of Virginia at Virginia Commonwealth University, Richmond, VA 23298-0678, USA
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21
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Smedley JG, Uzal FA, McClane BA. Identification of a prepore large-complex stage in the mechanism of action of Clostridium perfringens enterotoxin. Infect Immun 2007; 75:2381-90. [PMID: 17307943 PMCID: PMC1865780 DOI: 10.1128/iai.01737-06] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2006] [Revised: 12/26/2006] [Accepted: 02/07/2007] [Indexed: 11/20/2022] Open
Abstract
Clostridium perfringens enterotoxin (CPE) is the etiological agent of the third most common food-borne illness in the United States. The enteropathogenic effects of CPE result from formation of large CPE-containing complexes in eukaryotic cell membranes. Formation of these approximately 155- and approximately 200-kDa complexes coincides with plasma membrane permeability changes in eukaryotic cells, causing a Ca2+ influx that drives cell death pathways. CPE contains a stretch of amino acids (residues 81 to 106) that alternates markedly in side chain polarity (a pattern shared by the transmembrane domains of the beta-barrel pore-forming toxin family). The goal of this study, therefore, was to investigate whether this CPE region is involved in pore formation. Complete deletion of the CPE region from 81 to 106 produced a CPE variant that was noncytotoxic for Caco-2 cells and was unable to form CPE pores. However, this variant maintained the ability to form the approximately 155-kDa large complex. This large complex appears to be a prepore present on the plasma membrane surface since it showed greater susceptibility to proteases, increased complex instability, and a higher degree of dissociation from membranes compared to the large complex formed by recombinant CPE. When a D48A mutation was engineered into this prepore-forming CPE variant, the resultant variant was unable to form any prepore approximately 155-kDa large complex. Collectively these findings reveal a new step in CPE action, whereby receptor binding is followed by formation of a prepore large complex, which then inserts into membranes to form a pore.
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Affiliation(s)
- James G Smedley
- Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
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22
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Liu H, Wei C, Zhong Y, Li Y. Rice black-streaked dwarf virus outer capsid protein P10 has self-interactions and forms oligomeric complexes in solution. Virus Res 2007; 127:34-42. [PMID: 17442443 DOI: 10.1016/j.virusres.2007.03.017] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2007] [Accepted: 03/17/2007] [Indexed: 11/28/2022]
Abstract
The P10 protein encoded by S10 ORF of Rice black-streaked dwarf virus (RBSDV) was thought to be the component of outer shell of viral particle. In the present study, P10 has an ability for self-interaction as shown by a GAL4 transcription activator-based yeast two-hybrid assay system and further confirmed by in vitro far-Western blot analysis. The domain responsible for P10-P10 self-interaction was mapped to the first 230 amino acids at the N-terminal region of the protein. The oligomerization property of P10 was further investigated using chemical cross-linking with purified recombinant P10 proteins expressed in a baculovirus expression system and glutaraldehyde. Intact P10 recombinants existed predominantly as trimers in solution in the absence of other viral proteins and displayed the oligomeric nature common to all known second-layer protein units of the Reoviridae. A truncated P10 mutant encoding the first 230 N-terminal amino acids lost its ability to form trimers even though dimeric forms were detected during the cross-linking assay. Polyacrylamide gel electrophoresis under reducing or non-reducing conditions suggested that P10 subunits were oligomerized not through intermolecular disulfide bonds, but perhaps through some other type of association, such as hydrophobic or charge interactions.
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Affiliation(s)
- Huijun Liu
- Peking-Yale Joint Center for Plant Molecular Genetics and Agrobiotechnology, The National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, China
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23
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Martin J, Gibrat JF, Rodolphe F. Analysis of an optimal hidden Markov model for secondary structure prediction. BMC STRUCTURAL BIOLOGY 2006; 6:25. [PMID: 17166267 PMCID: PMC1769381 DOI: 10.1186/1472-6807-6-25] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2006] [Accepted: 12/13/2006] [Indexed: 11/10/2022]
Abstract
BACKGROUND Secondary structure prediction is a useful first step toward 3D structure prediction. A number of successful secondary structure prediction methods use neural networks, but unfortunately, neural networks are not intuitively interpretable. On the contrary, hidden Markov models are graphical interpretable models. Moreover, they have been successfully used in many bioinformatic applications. Because they offer a strong statistical background and allow model interpretation, we propose a method based on hidden Markov models. RESULTS Our HMM is designed without prior knowledge. It is chosen within a collection of models of increasing size, using statistical and accuracy criteria. The resulting model has 36 hidden states: 15 that model alpha-helices, 12 that model coil and 9 that model beta-strands. Connections between hidden states and state emission probabilities reflect the organization of protein structures into secondary structure segments. We start by analyzing the model features and see how it offers a new vision of local structures. We then use it for secondary structure prediction. Our model appears to be very efficient on single sequences, with a Q3 score of 68.8%, more than one point above PSIPRED prediction on single sequences. A straightforward extension of the method allows the use of multiple sequence alignments, rising the Q3 score to 75.5%. CONCLUSION The hidden Markov model presented here achieves valuable prediction results using only a limited number of parameters. It provides an interpretable framework for protein secondary structure architecture. Furthermore, it can be used as a tool for generating protein sequences with a given secondary structure content.
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Affiliation(s)
- Juliette Martin
- INSERM U726, Equipe de Bioinformatique Génomique et Moléculaire Université Denis Diderot Paris 7, 2 place jussieu, 75251 Paris Cedex 05, France
- INRA, Unité Mathématiques Informatique et Génome, Domaine de Vilvert, 78352 Jouy en Josas Cedex, France
| | - Jean-François Gibrat
- INRA, Unité Mathématiques Informatique et Génome, Domaine de Vilvert, 78352 Jouy en Josas Cedex, France
| | - François Rodolphe
- INRA, Unité Mathématiques Informatique et Génome, Domaine de Vilvert, 78352 Jouy en Josas Cedex, France
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24
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Mildiner-Earley S, Miller VL. Characterization of a novel porin involved in systemic Yersinia enterocolitica infection. Infect Immun 2006; 74:4361-5. [PMID: 16790812 PMCID: PMC1489722 DOI: 10.1128/iai.00154-06] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Yersinia enterocolitica is an enteric pathogen capable of causing systemic disease in a murine model. We have identified a novel protein, systemic factor protein A (SfpA), conserved in other pathogenic bacteria that is involved in systemic disease. Analysis of bacterial colonization revealed that a DeltasfpA strain is defective in mesenteric lymph node colonization. Bioinformatics and functional studies suggest that SfpA is a porin.
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Affiliation(s)
- Shirly Mildiner-Earley
- Department of Molecular Microbiology, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110, USA
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25
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Hovis KM, Jones JP, Sadlon T, Raval G, Gordon DL, Marconi RT. Molecular analyses of the interaction of Borrelia hermsii FhbA with the complement regulatory proteins factor H and factor H-like protein 1. Infect Immun 2006; 74:2007-14. [PMID: 16552029 PMCID: PMC1418896 DOI: 10.1128/iai.74.4.2007-2014.2006] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Borrelia hermsii, the primary etiological agent of tick-borne relapsing fever in North America, binds the complement regulatory protein factor H (FH) as a means of evading opsonophagocytosis and the alternative complement pathway. The ability of FH-binding protein A (FhbA) to bind FH-like protein 1 (FHL-1) has not been assessed previously. In this study, using a whole-cell absorption assay, we demonstrated that B. hermsii absorbs both FH and FHL-1 from human serum. Consistent with this, affinity ligand binding immunoblot analyses revealed that FH constructs spanning short consensus repeats 1 to 7 and 16 to 20 bind to FhbA. To investigate the molecular basis of the interaction of FhbA with FH/FHL-1, recombinant FhbA truncated proteins were generated and tested for FH/FHL-1 binding. Binding required determinants located in both the N- and C-terminal domains of FhbA, suggesting that long-range intramolecular interactions are involved in the formation and presentation of the FH/FHL-1-binding pocket. To identify specific FhbA residues involved in binding, random mutagenesis was performed. These analyses identified a loop region of FhbA that may serve as a contact point for FH/FHL-1. The data presented here expand our understanding of the pathogenic mechanisms of the relapsing fever spirochetes and of the molecular nature of the interaction between FH/FHL-1 and FhbA.
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Affiliation(s)
- Kelley M Hovis
- Department of Microbiology and Immunology, Medical College of Virginia at Virginia Commonwealth University, Richmond, VA 23298-0678, USA
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26
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Amin DN, Taylor BL, Johnson MS. Topology and boundaries of the aerotaxis receptor Aer in the membrane of Escherichia coli. J Bacteriol 2006; 188:894-901. [PMID: 16428392 PMCID: PMC1347347 DOI: 10.1128/jb.188.3.894-901.2006] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2005] [Accepted: 11/10/2005] [Indexed: 01/29/2023] Open
Abstract
Escherichia coli chemoreceptors are type I membrane receptors that have a periplasmic sensing domain, a cytosolic signaling domain, and two transmembrane segments. The aerotaxis receptor, Aer, is different in that both its sensing and signaling regions are proposed to be cytosolic. This receptor has a 38-residue hydrophobic segment that is thought to form a membrane anchor. Most transmembrane prediction programs predict a single transmembrane-spanning segment, but such a topology is inconsistent with recent studies indicating that there is direct communication between the membrane flanking PAS and HAMP domains. We studied the overall topology and membrane boundaries of the Aer membrane anchor by a cysteine-scanning approach. The proximity of 48 cognate cysteine replacements in Aer dimers was determined in vivo by measuring the rate and extent of disulfide cross-linking after adding the oxidant copper phenanthroline, both at room temperature and to decrease lateral diffusion in the membrane, at 4 degrees C. Membrane boundaries were identified in membrane vesicles using 5-iodoacetamidofluorescein and methoxy polyethylene glycol 5000 (mPEG). To map periplasmic residues, accessible cysteines were blocked in whole cells by pretreatment with 4-acetamido-4'-maleimidylstilbene-2, 2' disulfonic acid before the cells were lysed in the presence of mPEG. The data were consistent with two membrane-spanning segments, separated by a short periplasmic loop. Although the membrane anchor contains a central proline residue that reaches the periplasm, its position was permissive to several amino acid and peptide replacements.
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Affiliation(s)
- Divya N Amin
- Division of Microbiology and Molecular Genetics, Loma Linda University, Loma Linda, CA 92350, USA
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27
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Brylinski M, Konieczny L, Czerwonko P, Jurkowski W, Roterman I. Early-stage folding in proteins (in silico) sequence-to-structure relation. J Biomed Biotechnol 2006; 2005:65-79. [PMID: 16046811 PMCID: PMC1184056 DOI: 10.1155/jbb.2005.65] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A sequence-to-structure library has been created based on the
complete PDB database. The tetrapeptide was selected as a unit
representing a well-defined structural motif. Seven structural
forms were introduced for structure classification. The
early-stage folding conformations were used as the objects for
structure analysis and classification. The degree of
determinability was estimated for the sequence-to-structure and
structure-to-sequence relations. Probability calculus and
informational entropy were applied for quantitative estimation of
the mutual relation between them. The structural motifs
representing different forms of loops and bends were found to
favor particular sequences in structure-to-sequence analysis.
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Affiliation(s)
- Michał Brylinski
- Department of Bioinformatics and
Telemedicine, Medical College, Jagiellonian University,
Kopernika 17, 31-501, Poland
| | - Leszek Konieczny
- Institute of Biochemistry,
Medical Faculty, Jagiellonian University, Kopernika 7, 31-501
Cracow, Poland
| | - Patryk Czerwonko
- Department of Bioinformatics and
Telemedicine, Medical College, Jagiellonian University,
Kopernika 17, 31-501, Poland
| | - Wiktor Jurkowski
- Department of Bioinformatics and
Telemedicine, Medical College, Jagiellonian University,
Kopernika 17, 31-501, Poland
| | - Irena Roterman
- Department of Bioinformatics and
Telemedicine, Medical College, Jagiellonian University,
Kopernika 17, 31-501, Poland
- *Irena Roterman:
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28
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Boydston JA, Chen P, Steichen CT, Turnbough CL. Orientation within the exosporium and structural stability of the collagen-like glycoprotein BclA of Bacillus anthracis. J Bacteriol 2005; 187:5310-7. [PMID: 16030225 PMCID: PMC1196033 DOI: 10.1128/jb.187.15.5310-5317.2005] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacillus anthracis spores, which cause anthrax, are enclosed by an exosporium consisting of a basal layer and an external hair-like nap. The filaments of the nap are composed of BclA, a glycoprotein containing distinct N-terminal (NTD) and C-terminal (CTD) domains separated by an extended collagen-like central region. In this study, we used immunogold electron microscopy to show that the CTD of BclA forms the distal end of each filament of the hair-like nap, indicating that the NTD is attached to the basal layer. Ten randomly chosen anti-BclA monoclonal antibodies, raised against spores or exosporium, reacted with the CTD, consistent with its exterior location. We showed that recombinant BclA (rBclA), encoded by the B. anthracis Sterne strain and synthesized in Escherichia coli, forms a collagen-like triple helix as judged by collagenase sensitivity and circular dichroism spectroscopy. In contrast, native BclA in spores was resistant to collagenase digestion. Thermal denaturation studies showed that the collagen-like region of rBclA exhibited a melting temperature (T(m)) of 37 degrees C, like mammalian collagen. However, rBclA trimers exhibited T(m) values of 84 degrees C and 95 degrees C in buffer with and without sodium dodecyl sulfate, respectively. CTD trimers exhibited the same T(m) values, indicating that the high temperature and detergent resistances of rBclA were due to strong CTD interactions. We observed that CTD trimers are resistant to many proteases and readily form large crystalline sheets. Structural data indicate that the CTD is composed of multiple beta strands. Taken together, our results suggest that BclA and particularly its CTD form a rugged shield around the spore.
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Affiliation(s)
- Jeremy A Boydston
- UAB Department of Microbiology, BBRB 409, 1530 3rd Ave. S, Birmingham, AL 35294-2170, USA
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29
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Choo KH, Tong JC, Zhang L. Recent applications of Hidden Markov Models in computational biology. GENOMICS PROTEOMICS & BIOINFORMATICS 2005; 2:84-96. [PMID: 15629048 PMCID: PMC5172443 DOI: 10.1016/s1672-0229(04)02014-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
This paper examines recent developments and applications of Hidden Markov Models (HMMs) to various problems in computational biology, including multiple sequence alignment, homology detection, protein sequences classification, and genomic annotation.
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Affiliation(s)
- Khar Heng Choo
- Department of Biochemistry, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260
| | - Joo Chuan Tong
- Department of Biochemistry, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260
| | - Louxin Zhang
- Department of Mathematics, National University of Singapore, 2 Science Drive 2, Singapore 117543
- Corresponding author.
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30
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Yamada T, Komoto J, Watanabe K, Ohmiya Y, Takusagawa F. Crystal Structure and Possible Catalytic Mechanism of Microsomal Prostaglandin E Synthase Type 2 (mPGES-2). J Mol Biol 2005; 348:1163-76. [PMID: 15854652 DOI: 10.1016/j.jmb.2005.03.035] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2004] [Revised: 03/09/2005] [Accepted: 03/14/2005] [Indexed: 02/02/2023]
Abstract
Prostaglandin (PG) H(2) (PGH(2)), formed from arachidonic acid, is an unstable intermediate and is converted efficiently into more stable arachidonate metabolites (PGD(2), PGE(2), and PGF(2)) by the action of three groups of enzymes. Prostaglandin E synthase catalyzes an isomerization reaction, PGH(2) to PGE(2). Microsomal prostaglandin E synthase type-2 (mPGES-2) has been crystallized with an anti-inflammatory drug indomethacin (IMN), and the complex structure has been determined at 2.6A resolution. mPGES-2 forms a dimer and is attached to lipid membrane by anchoring the N-terminal section. Two hydrophobic pockets connected to form a V shape are located in the bottom of a large cavity. IMN binds deeply in the cavity by placing the OMe-indole and chlorophenyl moieties into the V-shaped pockets, respectively, and the carboxyl group interacts with S(gamma) of C110 by forming a H-bond. A characteristic H-bond chain formation (N-H...S(gamma)-H...S(gamma)...H-N) is seen through Y107-C113-C110-F112, which apparently decreases the pK(a) of S(gamma) of C110. The geometry suggests that the S(gamma) of C110 is most likely the catalytic site of mPGES-2. A search of the RCSB Protein Data Bank suggests that IMN can fit into the PGH(2) binding site in various proteins. On the basis of the crystal structure and mutation data, a PGH(2)-bound model structure was built. PGH(2) fits well into the IMN binding site by placing the alpha and omega-chains in the V-shaped pockets, and the endoperoxide moiety interacts with S(gamma) of C110. A possible catalytic mechanism is proposed on the basis of the crystal and model structures, and an alternative catalytic mechanism is described. The fold of mPGES-2 is quite similar to those of GSH-dependent hematopoietic prostaglandin D synthase, except for the two large loop sections.
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Affiliation(s)
- Taro Yamada
- Department of Molecular Biosciences, University of Kansas, 1200 Sunnyside Ave, Lawrence, KS 66045-7534, USA
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31
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Fransen M, Vastiau I, Brees C, Brys V, Mannaerts GP, Van Veldhoven PP. Analysis of Human Pex19p's Domain Structure by Pentapeptide Scanning Mutagenesis. J Mol Biol 2005; 346:1275-86. [PMID: 15713480 DOI: 10.1016/j.jmb.2005.01.013] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2004] [Revised: 01/04/2005] [Accepted: 01/05/2005] [Indexed: 10/25/2022]
Abstract
Pex19p, a primarily cytosolic protein, is essential for the biogenesis of numerous peroxisomal membrane proteins (PMPs); however, its precise function is unclear. Pex19p might function as a PMP-specific chaperone, a cycling PMP-receptor protein, a PMP membrane insertion factor, or an association/dissociation factor of membrane-associated protein complexes. Alternatively, Pex19p might act as a multifunctional peroxin and participate in a number of these activities. Here, we have employed transposon mutagenesis to generate a library of human pex19 alleles coding for Pex19p variants containing random in-frame pentapeptide insertions. A total of 87 different variants were characterized to identify functionally important regions. These studies revealed that Pex19p has a tripartite domain structure consisting of: (i) an amino-terminal domain that binds to Pex3p and is essential for docking at the peroxisome membrane; (ii) a central domain that competes with Pex5p and Pex13p for binding to Pex14p and may play a role in the assembly of PTS-receptor docking complexes; and (iii) a carboxy-terminal domain that interacts with multiple PMPs including Pex3p, Pex11pbeta, Pex12p, Pex13p, Pex16p, and Pex26p. Whether the latter interactions constitute the chaperone or transport functions (or both), remains to be determined. Finally, our observation that Pex19p contains two distinct binding sites for Pex3p suggests that the peroxin may bind PMPs in multiple places and for multiple purposes.
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Affiliation(s)
- Marc Fransen
- Departement Moleculaire Celbiologie, Afdeling Farmacologie, Katholieke Universiteit Leuven, Faculteit Geneeskunde, Campus Gasthuisberg (O/N 6, box 601), Herestraat 49, 3000 Leuven, Belgium.
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Hong SG, Cramer RA, Lawrence CB, Pryor BM. Alt a 1 allergen homologs from Alternaria and related taxa: analysis of phylogenetic content and secondary structure. Fungal Genet Biol 2005; 42:119-29. [PMID: 15670710 DOI: 10.1016/j.fgb.2004.10.009] [Citation(s) in RCA: 159] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2004] [Revised: 09/24/2004] [Accepted: 10/09/2004] [Indexed: 11/23/2022]
Abstract
A gene for the Alternaria major allergen, Alt a 1, was amplified from 52 species of Alternaria and related genera, and sequence information was used for phylogenetic study. Alt a 1 gene sequences evolved 3.8 times faster and contained 3.5 times more parsimony-informative sites than glyceraldehyde-3-phosphate dehydrogenase (gpd) sequences. Analyses of Alt a 1 gene and gpd exon sequences strongly supported grouping of Alternaria spp. and related taxa into several species-groups described in previous studies, especially the infectoria, alternata, porri, brassicicola, and radicina species-groups and the Embellisia group. The sonchi species-group was newly suggested in this study. Monophyly of the Nimbya group was moderately supported, and monophyly of the Ulocladium group was weakly supported. Relationships among species-groups and among closely related species of the same species-group were not fully resolved. However, higher resolution could be obtained using Alt a 1 sequences or a combined dataset than using gpd sequences alone. Despite high levels of variation in amino acid sequences, results of in silico prediction of protein secondary structure for Alt a 1 demonstrated a high degree of structural similarity for most of the species suggesting a conservation of function.
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Affiliation(s)
- Soon Gyu Hong
- Division of Plant Pathology and Microbiology, Department of Plant Sciences, College of Agriculture, University of Arizona, Tucson, AZ 85721, USA
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Dahinden P, Pos KM, Dimroth P. Identification of a domain in the α-subunit of the oxaloacetate decarboxylase Na+ pump that accomplishes complex formation with the γ-subunit. FEBS J 2005; 272:846-55. [PMID: 15670164 DOI: 10.1111/j.1742-4658.2004.04524.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The oxaloacetate decarboxylase Na+ pumps OAD-1 and OAD-2 of Vibrio cholerae are composed of a peripheral alpha-subunit associated with two integral membrane-bound subunits (beta and gamma). The alpha-subunit contains the carboxyltransferase domain in its N-terminal portion and the biotin-binding domain in its C-terminal portion. The gamma-subunit plays a profound role in the assembly of the complex. It interacts with the beta-subunit through its N-terminal membrane-spanning region and with the alpha-subunit through its hydrophilic C-terminal domain. The biochemical and structural requirements for the latter interaction were analysed with OAD-2 expression clones for subunit alpha-2 and the C-terminal domain of gamma-2, termed gamma'-2. If the two proteins were synthesized together in Escherichia coli they formed a complex that was stable at neutral pH and dissociated at pH<5.0. An internal stretch of 40 amino acids of alpha-2 was identified by deletion mutagenesis to be essential for the binding with gamma'-2. This portion of the alpha-subunit is connected via flexible linker peptides to the carboxyltransferase domain at its N terminus and to the biotin-binding domain at its C terminus. Results of site-directed mutagenesis indicated that a conserved tyrosine (491) and threonine 494 of this peptide contributed significantly to the stability of the complex with gamma'-2. This peptide therefore represents a newly identified, separate domain of the alpha-subunit and has been called the 'association domain'.
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Affiliation(s)
- Pius Dahinden
- Institute of Microbiology ETH Zürich, ETH Hönggerberg, Zürich, Switzerland
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Ma Q, Johnson MS, Taylor BL. Genetic analysis of the HAMP domain of the Aer aerotaxis sensor localizes flavin adenine dinucleotide-binding determinants to the AS-2 helix. J Bacteriol 2005; 187:193-201. [PMID: 15601703 PMCID: PMC538817 DOI: 10.1128/jb.187.1.193-201.2005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2004] [Accepted: 09/17/2004] [Indexed: 11/20/2022] Open
Abstract
HAMP domains are signal transduction domains typically located between the membrane anchor and cytoplasmic signaling domain of the proteins in which they occur. The prototypical structure consists of two helical amphipathic sequences (AS-1 and AS-2) connected by a region of undetermined structure. The Escherichia coli aerotaxis receptor, Aer, has a HAMP domain and a PAS domain with a flavin adenine dinucleotide (FAD) cofactor that senses the intracellular energy level. Previous studies reported mutations in the HAMP domain that abolished FAD binding to the PAS domain. In this study, using random and site-directed mutagenesis, we identified the distal helix, AS-2, as the component of the HAMP domain that stabilizes FAD binding. AS-2 in Aer is not amphipathic and is predicted to be buried. Mutations in the sequence coding for the contiguous proximal signaling domain altered signaling by Aer but did not affect FAD binding. The V264M residue replacement in this region resulted in an inverted response in which E. coli cells expressing the mutant Aer protein were repelled by oxygen. Bioinformatics analysis of aligned HAMP domains indicated that the proximal signaling domain is conserved in other HAMP domains that are not involved in chemotaxis or aerotaxis. Only one null mutation was found in the coding sequence for the HAMP AS-1 and connector regions, suggesting that these are not active signal transduction sites. We consider a model in which the signal from FAD is transmitted across a PAS-HAMP interface to AS-2 or the proximal signaling domain.
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Affiliation(s)
- Qinhong Ma
- Division of Microbiology and Molecular Genetics, Loma Linda University, Loma Linda, CA 92350, USA
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Mu XQ, Jiang ZG, Bullitt E. Localization of a critical interface for helical rod formation of bacterial adhesion P-pili. J Mol Biol 2004; 346:13-20. [PMID: 15663923 DOI: 10.1016/j.jmb.2004.11.037] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2004] [Revised: 11/10/2004] [Accepted: 11/16/2004] [Indexed: 11/30/2022]
Abstract
Pyelonephritic Escherichia coli cause urinary tract infections that involve the kidneys. Initiation of infection is dependent on P-pili expressed on the bacterial surface. In this work, an essential interface for assembly of the helical rod structure of P-pili has been located on the major pilin subunit, PapA. Based on primary sequence alignment, secondary structure analysis, and quaternary structure modeling of the PapA subunit, we predicted the location of a site that is critical for in vivo assembly of the native macromolecular structure of P-pili. A rigid helical rod of PapA subunits comprising most of the pilus length is stabilized by n to n+3 subunit-subunit interactions, and is important for normal function of these pili. Using site-directed mutagenesis, ultrastructural analysis by electron cryomicroscopy, immunocytochemistry, and molecular modeling we show that residues 106-109 (Asn, Gly, Ala, Gly) are essential for assembly of native P-pilus filaments. Mutation of these residues disrupts assembly of the native P-pilus helix. Extended fibrillar structures do still assemble, verifying that n to n+1 subunit-subunit interactions are maintained in the mutant fiber morphology. Observation of this fibrillar morphology in the mutant fiber was predicted by our modeling studies. These mutant P-pili data validate the predictive value of our model for understanding subunit-subunit interactions between PapA monomers. Alteration of the pilus structure from a 7-8 nm helical rod to a 2 nm fibrillar structure may compromise the ability of these bacteria to adhere and remain bound to the host cell, thus providing a possible therapeutic target for antimicrobial drugs.
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Affiliation(s)
- Xiang-Qi Mu
- Department of Physiology and Biophysics, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118-2526, USA
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Santelli RV, Siviero F, Machado-Santelli GM, Lara FJS, Stocker AJ. Molecular characterization of the B-2 DNA puff gene of Rhynchosciara americana. Chromosoma 2004; 113:167-76. [PMID: 15375665 DOI: 10.1007/s00412-004-0304-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2003] [Revised: 05/14/2004] [Accepted: 06/23/2004] [Indexed: 10/26/2022]
Abstract
We have sequenced a 2.5-kb DNA fragment of the B-2 DNA puff from the sciarid Rhynchosciara americana and have defined its transcription unit. This puff is active during the formation of the communal cocoon, which is important for successful metamorphosis of this species and coincides with the final cycle of polytenization in its salivary glands. The B-2 polypeptide, together with the products of two other previously characterized DNA puffs, seems to be engaged in an interaction that results in a gradual modification and hardening of the cocoon structure. The B-2 messenger is temporally regulated in apparent coordination with the other puff products. The predicted polypeptide has characteristics similar to polypeptides from previously sequenced DNA puff genes, in particular those from the R. americana C-8 gene and the Bradysia hygida C-4 gene. The cloned sequence of the B-2 puff is differentially amplified in the three gland regions examined, achieving its highest amplification level of approximately fourfold (two extra cycles) in the anterior segment of the gland. The C-3 DNA puff sequence was also found to be differentially amplified in the different gland regions. Implications of the widespread presence of DNA amplification as a form of gene regulation in the Sciaridae are discussed.
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Affiliation(s)
- Roberto Vicente Santelli
- Depto. Bioquímica, Instituto de Química, Universidade de São Paulo, Cidade Universitária, Av Prof Lineu Prestes, 748, CEP 05508-900, São Paulo, Brazil
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Anderson SL, Ekstein J, Donnelly MC, Keefe EM, Toto NR, LeVoci LA, Rubin BY. Nemaline myopathy in the Ashkenazi Jewish population is caused by a deletion in the nebulin gene. Hum Genet 2004; 115:185-90. [PMID: 15221447 DOI: 10.1007/s00439-004-1140-8] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2004] [Accepted: 04/25/2004] [Indexed: 11/28/2022]
Abstract
Nemaline myopathy (NM) is a neuromuscular disorder that is clinically diverse and can be attributed to mutations in any of several genes. The Ashkenazi Jewish population, which represents a relatively genetically homogeneous group, has an increased frequency of several genetic disorders and has been the beneficiary of genetic screening programs that have reduced the incidence of these diseases. The identification of individuals with NM in this population has prompted a study of its cause. Our study has revealed that five NM patients from five families bear an identical 2,502-bp deletion that lies in the nebulin gene and that includes exon 55 and parts of introns 54 and 55. The absence of this exon results in the generation of a transcript that encodes 35 fewer amino acids. An analysis of the gene frequency of this mutation in a random sample of 4,090 Ashkenazi Jewish individuals has revealed a carrier frequency of one in 108.
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Affiliation(s)
- Sylvia L Anderson
- Department of Biological Sciences, Fordham University, Larkin Hall 160, Bronx, NY 10458, USA
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Adolph KW. The zebrafish metaxin 3 gene (mtx3): cDNA and protein structure, and comparison to zebrafish metaxins 1 and 2. Gene 2004; 330:67-73. [PMID: 15087125 DOI: 10.1016/j.gene.2004.01.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2003] [Revised: 12/11/2003] [Accepted: 01/08/2004] [Indexed: 10/26/2022]
Abstract
The metaxin genes of zebrafish have been investigated by determining the sequences of metaxin cDNAs and analyzing the translated amino acid sequences. A zebrafish cDNA corresponding to a third metaxin gene was identified. Zebrafish cDNAs representing metaxins 1 and 2, previously described in human and mouse, were also identified. The zebrafish metaxin genes are designated mtx1, mtx2 and mtx3, following zebrafish nomenclature guidelines. The zebrafish metaxin 3 (ZMTX3) cDNA codes for a protein of 313 amino acids (MW 35,208), while the ZMTX1 and ZMTX2 cDNAs specify proteins of 317 residues (MW 35,906) and 274 residues (MW 30,852), respectively. Alignment of the ZMTX3 and ZMTX1 amino acid sequences revealed 40% identities, while 26% identities were found for the ZMTX3/ZMTX2 alignment. A phylogenetic tree showed that the metaxins share a common ancestry, with the grouping of the zebrafish sequences with the homologous human and mouse sequences. Analysis of the domain structure of the zebrafish metaxins uncovered a glutathione S-transferase (GST) domain for each protein and, in addition, a thioredoxin-like domain for ZMTX2. A region of transmembrane helices was found near the C-terminus for the ZMTX1 protein. In addition, regions of alpha helix were seen to be the predominant feature of zebrafish metaxin secondary structure, particularly for ZMTX2 and ZMTX3. The ZMTX3 cDNA sequence has the greatest homology to a human sequence at cytogenetic location 5q14.1, close to the thrombospondin 4 gene (THBS4). Also, the mouse metaxin 3 homologue is adjacent to Thbs4 at 13C3.
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Affiliation(s)
- Kenneth W Adolph
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, 6-155 Jackson Hall, 321 Church St. S.E., Minneapolis, MN 55455, USA.
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Adams J, Chen ZP, Van Denderen BJW, Morton CJ, Parker MW, Witters LA, Stapleton D, Kemp BE. Intrasteric control of AMPK via the gamma1 subunit AMP allosteric regulatory site. Protein Sci 2004; 13:155-65. [PMID: 14691231 PMCID: PMC2286513 DOI: 10.1110/ps.03340004] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2003] [Revised: 09/12/2003] [Accepted: 09/12/2003] [Indexed: 10/26/2022]
Abstract
AMP-activated protein kinase (AMPK) is a alphabetagamma heterotrimer that is activated in response to both hormones and intracellular metabolic stress signals. AMPK is regulated by phosphorylation on the alpha subunit and by AMP allosteric control previously thought to be mediated by both alpha and gamma subunits. Here we present evidence that adjacent gamma subunit pairs of CBS repeat sequences (after Cystathionine Beta Synthase) form an AMP binding site related to, but distinct from the classical AMP binding site in phosphorylase, that can also bind ATP. The AMP binding site of the gamma(1) CBS1/CBS2 pair, modeled on the structures of the CBS sequences present in the inosine monophosphate dehydrogenase crystal structure, contains three arginine residues 70, 152, and 171 and His151. The yeast gamma homolog, snf4 contains a His151Gly substitution, and when this is introduced into gamma(1), AMP allosteric control is substantially lost and explains why the yeast snf1p/snf4p complex is insensitive to AMP. Arg70 in gamma(1) corresponds to the site of mutation in human gamma(2) and pig gamma(3) genes previously identified to cause an unusual cardiac phenotype and glycogen storage disease, respectively. Mutation of any of AMP binding site Arg residues to Gln substantially abolishes AMP allosteric control in expressed AMPK holoenzyme. The Arg/Gln mutations also suppress the previously described inhibitory properties of ATP and render the enzyme constitutively active. We propose that ATP acts as an intrasteric inhibitor by bridging the alpha and gamma subunits and that AMP functions to derepress AMPK activity.
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Affiliation(s)
- Julian Adams
- St. Vincent's Institute of Medical Research, Fitzroy, Victoria 3065, Australia
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40
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Hitt AL, Iijima-Shimizu M, DuBay MJ, Antonette LL, Urushihara H, Wilkerson CG. Identification of a second member of the ponticulin gene family and its differential expression pattern. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1628:79-87. [PMID: 12890554 DOI: 10.1016/s0167-4781(03)00115-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
We have identified a homologue (ponB) of the ponticulin gene (ponA), an F-actin binding protein, in the expressed sequence tag library generated to mRNA isolated from fusion-competent cells of Dictyostelium discoideum. PonB is predicted to have many of the same characteristics as ponticulin. Both proteins are predicted to possess a cleaved signal peptide, a glycosyl anchor, an amphipathic beta-strand structure and six conserved cysteines. Because of the sequence similarity and predicted conserved structures, this gene constitutes the second member of a ponticulin gene family. Unlike ponticulin, ponB is not expressed in axenically grown cells or during the asexual reproductive phase of D. discoideum. PonB is expressed by cells grown on bacterial lawns and by cells induced to be fusion-competent, i.e., gametes. The expression of ponB correlates with the appearance of a new F-actin binding activity in cell lysates of bacterially grown ponA(-) cells. By immunofluorescence microscopy, ponB appears to be localized to vesicles and to the plasma membrane of bacterially grown cells. Because ponticulin is the major high-affinity link between the plasma membrane and the cytoskeleton, the ponticulin gene family is likely to be part of the redundant system of proteins involved in connecting the cytoskeleton to the plasma membrane.
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Affiliation(s)
- Anne L Hitt
- Department of Biological Sciences, Oakland University, Rochester, MI 48309, USA.
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De Mendonça RL, Bouton D, Bertin B, Escriva H, Noël C, Vanacker JM, Cornette J, Laudet V, Pierce RJ. A functionally conserved member of the FTZ-F1 nuclear receptor family from Schistosoma mansoni. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:5700-11. [PMID: 12423370 DOI: 10.1046/j.1432-1033.2002.03287.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The fushi tarazu factor 1 (FTZ-F1) nuclear receptor subfamily comprises orphan receptors with crucial roles in development and sexual differentiation in vertebrates and invertebrates. We describe the structure and functional properties of an FTZ-F1 from the platyhelminth parasite of humans, Schistosoma mansoni, the first receptor from this family to be characterized in a Lophotrochozoan. It contains a well conserved DNA-binding domain (55-63% identity to other family members) and a poorly conserved ligand-binding domain (20% identity to that of zebrafish FF1a). However, both the ligand domain signature sequence and the activation function 2-activation domain (AF2-AD) are perfectly conserved. Phylogenetic analysis confirmed that SmFTZ-F1 is a member of nuclear receptor subfamily 5, but that it clustered with the Drosophila receptor DHR39 and has consequently been named NR5B1. The gene showed a complex structure with 10 exons and an overall size of 18.4 kb. Two major transcripts were detected, involving alternative promoter usage and splicing of the two 5' exons, but which encoded identical proteins. SmFTZ-F1 mRNA is expressed at all life-cycle stages with the highest amounts in the larval forms (miracidia, sporocysts and cercariae). However, expression of the protein showed a different pattern; low in miracidia and higher in adult male worms. The protein bound the same monomeric response element as mammalian SF-1 (SF-1 response element, SFRE) and competition experiments with mutant SFREs showed that its specificity was identical. Moreover, SmFTZ-F1 transactivated reporter gene transcription from SFRE similarly to SF-1. This functional conservation argues for a conserved biological role of the FTZ-F1 nuclear receptor family throughout the metazoa.
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Affiliation(s)
- Ricardo L De Mendonça
- INSERM U 547, Institut Pasteur, Lille, France; CNRS UMR 49, Ecole Normale Supérieure de Lyon, Lyon, France
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42
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Abstract
We have constructed, in a completely automated fashion, a new structure template library for threading that represents 358 distinct SCOP folds where each model is mathematically represented as a Hidden Markov model (HMM). Because the large number of models in the library can potentially dilute the prediction measure, a new triage method for fold prediction is employed. In the first step of the triage method, the most probable structural class is predicted using a set of manually constructed, high-level, generalized structural HMMs that represent seven general protein structural classes: all-alpha, all-beta, alpha/beta, alpha+beta, irregular small metal-binding, transmembrane beta-barrel, and transmembrane alpha-helical. In the second step, only those fold models belonging to the determined structural class are selected for the final fold prediction. This triage method gave more predictions as well as more correct predictions compared with a simple prediction method that lacks the initial classification step. Two different schemes of assigning Bayesian model priors are presented and discussed.
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Affiliation(s)
- Hongxian He
- BioMolecular Engineering Research Center, Biomedical Engineering Department, Boston University, Boston, Massachusetts 02215, USA
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Komoto J, Huang Y, Takata Y, Yamada T, Konishi K, Ogawa H, Gomi T, Fujioka M, Takusagawa F. Crystal structure of guanidinoacetate methyltransferase from rat liver: a model structure of protein arginine methyltransferase. J Mol Biol 2002; 320:223-35. [PMID: 12079381 DOI: 10.1016/s0022-2836(02)00448-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Guanidinoacetate methyltransferase (GAMT) is the enzyme that catalyzes the last step of creatine biosynthesis. The enzyme is found in abundance in the livers of all vertebrates. Recombinant rat liver GAMT has been crystallized with S-adenosylhomocysteine (SAH), and the crystal structure has been determined at 2.5 A resolution. The 36 amino acid residues at the N terminus were cleaved during the purification and the truncated enzyme was crystallized. The truncated enzyme forms a dimer, and each subunit contains one SAH molecule in the active site. Arg220 of the partner subunit forms a pair of hydrogen bonds with Asp134 at the guanidinoacetate-binding site. On the basis of the crystal structure, site-directed mutagenesis on Asp134, and chemical modification and limited proteolysis studies, we propose a catalytic mechanism of this enzyme. The truncated GAMT dimer structure can be seen as a ternary complex of protein arginine methyltransferase (one subunit) complexed with a protein substrate (the partner subunit) and the product SAH. Therefore, this structure provides insight into the structure and catalysis of protein arginine methyltransferases.
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Affiliation(s)
- Junichi Komoto
- Department of Molecular Biosciences, The University of Kansas, 1200 Sunnyside Avenue, 2034 Howorth Hall, Lawrence, KS 66045-7534, USA
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Holmes KD, Mattar P, Marsh DR, Jordan V, Weaver LC, Dekaban GA. The C-terminal C1 cassette of the N -methyl-D-aspartate receptor 1 subunit contains a bi-partite nuclear localization sequence. J Neurochem 2002; 81:1152-65. [PMID: 12068064 DOI: 10.1046/j.1471-4159.2002.00865.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The N -methyl-D-aspartate receptor (NMDAR) is a multimeric transmembrane protein composed of at least two subunits. One subunit, NR1, is derived from a single gene and can be subdivided into three regions: the N-terminal extracellular domain, the transmembrane regions, and the C-terminal intracellular domain. The N-terminal domain is responsible for Mg2+ metal ion binding and channel activity, while the transmembrane domains are important for ion channel formation. The intracellular C-terminal domain is involved in regulating receptor activity and subcellular localization. Our recent experiments indicated that the intracellular C-terminal domain, when expressed independently, localizes almost exclusively in the nucleus. An examination of the amino acid sequence reveals the presence of a putative nuclear localization sequence (NLS) in the C1 cassette of the NR1 intracellular C-terminus. Using an expression vector designed to test whether a putative NLS sequence is a valid, functional NLS, we have demonstrated that a bi-partite NLS does in fact exist within the NR1-1 C-terminus. Computer algorithms identified a putative helix-loop-helix motif that spanned the C0C1 cassettes of the C-terminus. These data suggest that the NR1 subunit may represent another member of a family of transmembrane proteins that undergo intramembrane proteolysis, releasing a cytosolic peptide that is actively translocated to the nucleus leading to alterations in gene regulation.
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Affiliation(s)
- K D Holmes
- The Gene Therapy and Molecular Virology Group and the Neurodegeneration Group, The John P. Robarts Research Institute, London, Ontario, Canada
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Graber JH, McAllister GD, Smith TF. Probabilistic prediction of Saccharomyces cerevisiae mRNA 3'-processing sites. Nucleic Acids Res 2002; 30:1851-8. [PMID: 11937640 PMCID: PMC113205 DOI: 10.1093/nar/30.8.1851] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present a tool for the prediction of mRNA 3'-processing (cleavage and polyadenylation) sites in the yeast Saccharomyces cerevisiae, based on a discrete state-space model or hidden Markov model. Comparison of predicted sites with experimentally verified 3'-processing sites indicates good agreement. All predicted or known yeast genes were analyzed to find probable 3'-processing sites. Known alternative 3'-processing sites, both within the 3'-untranslated region and within the protein coding sequence were successfully identified, leading to the possibility of prediction of previously unknown alternative sites. The lack of an apparent 3'-processing site calls into question the validity of some predicted genes. This is specifically investigated for predicted genes with overlapping coding sequences.
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Affiliation(s)
- Joel H Graber
- Center for Advanced Biotechnology, Boston University, 36 Cummington Street, Boston, MA 02215, USA.
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46
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Scott DJ, Grossmann JG, Tame JRH, Byron O, Wilson KS, Otto BR. Low resolution solution structure of the Apo form of Escherichia coli haemoglobin protease Hbp. J Mol Biol 2002; 315:1179-87. [PMID: 11827485 DOI: 10.1006/jmbi.2001.5306] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have studied the solution properties of the apo form of the haemoglobin protease or "haemoglobinase", Hbp, a principal component of an important iron acquisition system in pathogenic Escherichia coli. Experimental determination of secondary structure content from circular dichroism (CD) spectroscopy, obtained using synchrotron light, showed that the protein contains predominately beta-sheets in agreement with secondary structure prediction from the primary sequence. Next, the size and shape of the protein were probed using analytical ultracentrifugation (AUC) and small angle X-ray scattering (SAXS). These showed that Hbp is a monomer, with an extended conformation. Using ab initio reconstruction methods we have produced a model of Hbp, which shows that the protein adopts an extended crescent-shaped conformation. Analysis of the resulting model gives hydrodynamic parameters in good agreement with those observed experimentally. Thus we are able to construct a hydrodynamically rigorous model of apo-Hbp in solution, not only giving a greater level of confidence to the results of the SAXS reconstruction methods, but providing the first three-dimensional view of this intriguing molecule.
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Affiliation(s)
- David J Scott
- York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, YO10 5DD, UK.
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47
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Zuniga FA, Shi G, Haller JF, Rubashkin A, Flynn DR, Iserovich P, Fischbarg J. A three-dimensional model of the human facilitative glucose transporter Glut1. J Biol Chem 2001; 276:44970-5. [PMID: 11571301 DOI: 10.1074/jbc.m107350200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The human facilitative transporter Glut1 is the major glucose transporter present in all human cells, has a central role in metabolism, and is an archetype of the superfamily of major protein facilitators. Here we describe a three-dimensional structure of Glut1 based on helical packing schemes proposed for lactose permease and Glut1 and predictions of secondary structure, and refined using energy minimization, molecular dynamics simulations, and quality and environmental scores. The Ramachandran scores and the stereochemical quality of the structure obtained were as good as those for the known structures of the KcsA K(+) channel and aquaporin 1. We found two channels in Glut1. One of them traverses the structure completely, and is lined by many residues known to be solvent-accessible. Since it is delimited by the QLS motif and by several well conserved residues, it may serve as the substrate transport pathway. To validate our structure, we determined the distance between these channels and all the residues for which mutations are known. From the locations of sugar transporter signatures, motifs, and residues important to the transport function, we find that this Glut1 structure is consistent with mutagenesis and biochemical studies. It also accounts for functional deficits in seven pathogenic mutants.
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Affiliation(s)
- F A Zuniga
- Department of Physiology, College of Physicians & Surgeons, Columbia University, New York, New York 10032, USA
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49
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Eichenmüller B, Ahrens DP, Li Q, Suprenant KA. Saturable binding of the echinoderm microtubule-associated protein (EMAP) on microtubules, but not filamentous actin or vimentin filaments. CELL MOTILITY AND THE CYTOSKELETON 2001; 50:161-72. [PMID: 11807937 DOI: 10.1002/cm.10002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The echinoderm microtubule-associated protein (EMAP) is a 75-kDa, WD-repeat protein associated with the mitotic spindle apparatus. To understand EMAP's biological role, it is important to determine its affinity for microtubules (MTs) and other cytoskeletal components. To accomplish this goal, we utilized a low-cost, bubble-column bioreactor to express EMAP as a hexahistidine fusion (6his) protein in baculovirus-infected insect cells. After optimizing cell growth conditions, up to 30 mg of EMAP was obtained in the soluble cell lysate from a 1-liter culture. EMAP was purified to homogeneity in a two-step process that included immobilized metal-affinity chromatography (IMAC) and anion-exchange chromatography. In vitro binding studies on cytoskeletal components were performed with the 6his-EMAP. EMAP bound to MTs, but not actin or vimentin filaments, with an intrinsic dissociation constant of 0.18 microM and binding stoichiometry of 0.7 mol EMAP per mol tubulin heterodimer. In addition, we show that a strong MT binding domain resides in the 137 amino acid, NH(2)-terminus of EMAP and a weaker binding site in the WD-domain. Previous work has shown that the EMAP concentration in the sea urchin egg is over 4 microM. Together, these results show that there is sufficient EMAP in the egg to regulate the assembly of a large pool of maternally stored tubulin.
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Affiliation(s)
- B Eichenmüller
- Department of Molecular Biosciences, University of Kansas, Lawrence 66045, USA
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50
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Bertola F, Manigand C, Picard P, Goetz M, Schmitter JM, Precigoux G. N-Terminal domain of HTLV-I integrase. Complexation and conformational studies of the zinc finger. J Pept Sci 2001; 7:588-97. [PMID: 11763363 DOI: 10.1002/psc.356] [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: 12/21/2022]
Abstract
The HTLV-I integrase N-terminal domain [50-residue peptide (IN50)], and a 35-residue truncated peptide formed by residues 9-43 (IN35) have been synthesized by solid-phase peptide synthesis. Formation of the 50-residue zinc finger type structure through a HHCC motif has been proved by UV-visible absorption spectroscopy. Its stability was demonstrated by an original method using RP-HPLC. Similar experiments performed on the 35-residue peptide showed that the truncation does not prevent zinc complex formation but rather that it significantly influences its stability. As evidenced by CD spectroscopy, the 50-residue zinc finger is unordered in aqueous solution but adopts a partially helical conformation when trifluoroethanol is added. These results are in agreement with our secondary structure predictions and demonstrate that the HTLV-I integrase N-terminal domain is likely to be composed of an helical region (residues 28-42) and a beta-strand (residues 20-23), associated with a HHCC zinc-binding motif. Size-exclusion chromatography showed that the structured zinc finger dimerizes through the helical region.
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Affiliation(s)
- F Bertola
- Unité de Biophysique Structurale, UMR 5471 CNRS, Université Bordeaux, France
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