1
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Dell M, Tran MA, Capper MJ, Sundaram S, Fiedler J, Koehnke J, Hellmich UA, Hertweck C. Trapping of a Polyketide Synthase Module after C-C Bond Formation Reveals Transient Acyl Carrier Domain Interactions. Angew Chem Int Ed Engl 2024; 63:e202315850. [PMID: 38134222 DOI: 10.1002/anie.202315850] [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: 10/19/2023] [Revised: 12/19/2023] [Accepted: 12/21/2023] [Indexed: 12/24/2023]
Abstract
Modular polyketide synthases (PKSs) are giant assembly lines that produce an impressive range of biologically active compounds. However, our understanding of the structural dynamics of these megasynthases, specifically the delivery of acyl carrier protein (ACP)-bound building blocks to the catalytic site of the ketosynthase (KS) domain, remains severely limited. Using a multipronged structural approach, we report details of the inter-domain interactions after C-C bond formation in a chain-branching module of the rhizoxin PKS. Mechanism-based crosslinking of an engineered module was achieved using a synthetic substrate surrogate that serves as a Michael acceptor. The crosslinked protein allowed us to identify an asymmetric state of the dimeric protein complex upon C-C bond formation by cryo-electron microscopy (cryo-EM). The possible existence of two ACP binding sites, one of them a potential "parking position" for substrate loading, was also indicated by AlphaFold2 predictions. NMR spectroscopy showed that a transient complex is formed in solution, independent of the linker domains, and photochemical crosslinking/mass spectrometry of the standalone domains allowed us to pinpoint the interdomain interaction sites. The structural insights into a branching PKS module arrested after C-C bond formation allows a better understanding of domain dynamics and provides valuable information for the rational design of modular assembly lines.
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Affiliation(s)
- Maria Dell
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology (HKI), 07745, Jena, Germany
| | - Mai Anh Tran
- Institute of Organic Chemistry and Macromolecular Chemistry, Friedrich Schiller University Jena, 07743, Jena, Germany
| | - Michael J Capper
- School of Chemistry, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Srividhya Sundaram
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology (HKI), 07745, Jena, Germany
| | - Jonas Fiedler
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology (HKI), 07745, Jena, Germany
| | - Jesko Koehnke
- School of Chemistry, University of Glasgow, Glasgow, G12 8QQ, UK
- Institute of Food Chemistry, Leibniz University Hannover, 30167, Hannover, Germany
| | - Ute A Hellmich
- Institute of Organic Chemistry and Macromolecular Chemistry, Friedrich Schiller University Jena, 07743, Jena, Germany
- Center for Biomolecular Magnetic Resonance (BMRZ), Goethe-University Frankfurt, 60438, Frankfurt am Main, Germany
- Cluster of Excellence Balance of the Microverse, Friedrich Schiller University Jena, Jena, Germany
- Faculty of Biological Sciences, Friedrich Schiller University Jena, 07743, Jena, Germany
| | - Christian Hertweck
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology (HKI), 07745, Jena, Germany
- Cluster of Excellence Balance of the Microverse, Friedrich Schiller University Jena, Jena, Germany
- Faculty of Biological Sciences, Friedrich Schiller University Jena, 07743, Jena, Germany
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2
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Lin YC, Ren P, Webb LJ. AMOEBA Force Field Predicts Accurate Hydrogen Bond Counts of Nitriles in SNase by Revealing Water-Protein Interaction in Vibrational Absorption Frequencies. J Phys Chem B 2023; 127:5609-5619. [PMID: 37339399 PMCID: PMC10851345 DOI: 10.1021/acs.jpcb.3c02060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/22/2023]
Abstract
Precisely quantifying the magnitude and direction of electric fields in proteins has long been an outstanding challenge in understanding biological functions. Nitrile vibrational Stark effect probes have been shown to be minimally disruptive to the protein structure and can be better direct reporters of local electrostatic field in the native state of a protein than other measures such as pKa shifts of titratable residues. However, interpretations of the connection between measured vibrational energy and electric field rely on the accurate molecular understanding of interactions of the nitrile group and its environment, particularly from hydrogen bonding. In this work, we compared the extent of hydrogen bonding calculated in two common force fields, the fixed charge force field Amber03 and polarizable force field AMOEBA, at 10 locations of cyanocysteine (CNC) in staphylococcal nuclease (SNase) against the experimental nitrile absorption frequency in terms of full width at half-maximum (FWHM) and frequency temperature line slope (FTLS). We observed that the number of hydrogen bonds correlated well in AMOEBA trajectories with respect to both the FWHM (r = 0.88) and the FTLS (r = -0.85), whereas the correlation of Amber03 trajectories was less reliable because the Amber03 force field predicted more hydrogen bonds in some mutants. Moreover, we demonstrated that contributions from the interactions between CNC and nearby water molecules were significant in AMOEBA trajectories but were not predicted by Amber03. We conclude that although the nitrile absorption peak shape could be qualitatively predicted by the fixed charge Amber03 force field, the detailed electrostatic environment measured by the nitrile probe in terms of the extent of hydrogen bonding could only be accurately observed in the AMOEBA trajectories, where the permanent dipole, quadrupole, and dipole-induced-dipole polarizable interactions were all taken into account. The significance of this finding to the goal of accurately predicting electric fields in complex biomolecular environments is discussed.
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Affiliation(s)
- Yu-Chun Lin
- Department of Chemistry, Texas Materials Institute, and Interdisciplinary Life Sciences Program, The University of Texas at Austin, 105 E 24th St. STOP A5300, Austin, TX, 78712, USA
| | - Pengyu Ren
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Lauren J. Webb
- Department of Chemistry, Texas Materials Institute, and Interdisciplinary Life Sciences Program, The University of Texas at Austin, 105 E 24th St. STOP A5300, Austin, TX, 78712, USA
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3
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Ruppert M, Creon A, Tidow H, Huse N. Population Dynamics of Stretching Excitations of p-Azido-phenylalanine Incorporated in Calmodulin-Peptide Complexes. J Phys Chem B 2022; 126:368-375. [PMID: 34990136 DOI: 10.1021/acs.jpcb.1c06775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We genetically incorporated the unnatural amino acid p-azido-phenylalanine (AzF) into the ubiquitous Ca2+ sensor protein calmodulin (CaM) in complex with different peptides to explore the response of the azido stretching line shape to varying binding motifs with femtosecond infrared spectroscopy. The dynamic response of the azido stretching mode varies in different CaM-peptide complexes. We model these dynamics as coherent excitations of Fermi resonances and extract a lifetime of the azido stretching vibration of about 1 ps. The resulting model parameters are commensurate with the linear infrared absorption lineshapes which suggests that the conformation-sensitive vibrational lineshape could be composed of Fermi resonances that differ between the protein-peptide complexes.
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Affiliation(s)
- Matthias Ruppert
- Hamburg Advanced Research Centre for Bioorganic Chemistry, Institute for Nanostructure and Solid-State Physics, Department of Physics, and Center for Free-Electron Laser Science, University of Hamburg, Luruper Chaussee 149, D-22761 Hamburg, Germany
| | - Anne Creon
- Hamburg Advanced Research Centre for Bioorganic Chemistry, Institute for Nanostructure and Solid-State Physics, Department of Physics, and Center for Free-Electron Laser Science, University of Hamburg, Luruper Chaussee 149, D-22761 Hamburg, Germany.,Hamburg Advanced Research Centre for Bioorganic Chemistry, Institute for Biochemistry and Molecular Biology, Department of Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, D-20146 Hamburg, Germany
| | - Henning Tidow
- Hamburg Advanced Research Centre for Bioorganic Chemistry, Institute for Biochemistry and Molecular Biology, Department of Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, D-20146 Hamburg, Germany.,The Hamburg Centre for Ultrafast Imaging, University of Hamburg, Luruper Chaussee, 149, D-22761 Hamburg, Germany
| | - Nils Huse
- Hamburg Advanced Research Centre for Bioorganic Chemistry, Institute for Nanostructure and Solid-State Physics, Department of Physics, and Center for Free-Electron Laser Science, University of Hamburg, Luruper Chaussee 149, D-22761 Hamburg, Germany.,The Hamburg Centre for Ultrafast Imaging, University of Hamburg, Luruper Chaussee, 149, D-22761 Hamburg, Germany
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4
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Hamrick GS, Londergan CH, Charkoudian LK. Heterologous Expression, Purification, and Characterization of Type II Polyketide Synthase Acyl Carrier Proteins. Methods Mol Biol 2022; 2489:239-267. [PMID: 35524054 PMCID: PMC9373356 DOI: 10.1007/978-1-0716-2273-5_13] [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] [Indexed: 06/14/2023]
Abstract
The enzymes that comprise type II polyketide synthases (PKSs) are powerful biocatalysts that, once well-understood and strategically applied, could enable cost-effective and sustainable access to a range of pharmaceutically relevant molecules. Progress toward this goal hinges on gaining ample access to materials for in vitro characterizations and structural analysis of the components of these synthases. A central component of PKSs is the acyl carrier protein (ACP), which serves as a hub during the biosynthesis of type II polyketides. Herein, we share methods for accessing type II PKS ACPs via heterologous expression in E. coli . We also share how the installation of reactive and site-specific spectroscopic probes can be leveraged to study the conformational dynamics and interactions of type II PKS ACPs.
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5
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Singh BK, Biswas R, Basak A, Das AK. Mycobacterial crypto-AcpM as a tool to investigate the consequence of drug binding on its key FAS II partner enzyme HadAB. Biochim Biophys Acta Gen Subj 2021; 1865:129964. [PMID: 34252514 DOI: 10.1016/j.bbagen.2021.129964] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 06/20/2021] [Accepted: 07/06/2021] [Indexed: 01/18/2023]
Abstract
Background Mycobacterial FASII pathway is governed by the Protein-Protein Interaction mediated dynamics existent between Acyl Carrier Protein and its partner enzymes. The dehydratase HadAB, involved in the third step of FASII synthesis has remained a key target of drugs like Thiacetazone (TAC) and its consequence on AcpM binding is yet to be deciphered. Owing to the transient nature of these interactions, analysing their implications as a drug target has been exhausting. Methods In this context, we have developed an in vitro method to study the effect of thiocarbamide-containing compounds, TAC and SPA0355 (a thiourea analogue) against mycobacterial HadAB. Additionally, by utilizing crypto-ACP (NBD-tagged Acyl Carrier Protein) as a tool of our choice, we attempted at exploring the effect of TAC and SPA0355 on mycobacterial HadAB. Results SPA0355 behaves at par with TAC and undergoes activation in the presence of monooxygenase EthA thus, bringing about a covalent modification in HadA subunit of HadAB. The crypto-ACP method provides insights into the altered substrate housing capability in HadAB associated with the impediment of its AcpM mediated functionality; an outcome attributed to the repercussions associated with the binding of the aforementioned thiourea compounds. Conclusion This investigation has assisted in unveiling a two-step mechanism undertaken by AcpM for interacting with its corresponding partner protein during acyl chain transfer. General significance This study highlights the alterations brought about by drug binding in the interplay between ACP and HadAB. Additionally, this work for the first time establishes the role of SPA0355 as a promising drug candidate against dehydratase HadAB.
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Affiliation(s)
- Bina K Singh
- School of Biosciences, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Rupam Biswas
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Amit Basak
- School of Biosciences, Indian Institute of Technology Kharagpur, Kharagpur 721302, India; Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Amit K Das
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India.
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6
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Steric occlusion regulates proximal interactions of acyl carrier protein domain in fungal fatty acid synthase. Commun Biol 2020; 3:274. [PMID: 32471977 PMCID: PMC7260205 DOI: 10.1038/s42003-020-0997-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 05/06/2020] [Indexed: 11/26/2022] Open
Abstract
The acyl carrier protein (ACP) domain shuttles substrates and reaction intermediates in type I fungal fatty acid synthases via transient protein-protein interactions. Here, using electron cryo-microscopy (cryoEM), we report the structure of a fungal FAS stalled at the dehydration reaction, which precedes the final enoyl reduction in the fatty acid biosynthesis cycle. This conformation revealed multiple contact sites between ACP and the dehydratase (DH) and enoyl reductase (ER) domains that occluded the ACP binding to the adjacent ER domain. Our data suggests a minimal path from the DH to the ER reaction site that requires minute changes in the coordinates of the structured N- and C- termini of the ACP domain. Lou and Mazhab-Jafari report the structure of a fungal fatty acid synthase stalled at the dehydration reaction, which precedes the final enoyl reduction in the fatty acid biosynthesis cycle. This study suggests that the binding of acyl carrier protein domain to its proximal dehydratase and enoyl reductase domains in fatty acid synthase is mutually exclusive.
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7
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Structural Characterization of an ACP from Thermotoga maritima: Insights into Hyperthermal Adaptation. Int J Mol Sci 2020; 21:ijms21072600. [PMID: 32283632 PMCID: PMC7178038 DOI: 10.3390/ijms21072600] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 04/06/2020] [Accepted: 04/07/2020] [Indexed: 12/30/2022] Open
Abstract
Thermotoga maritima, a deep-branching hyperthermophilic bacterium, expresses an extraordinarily stable Thermotoga maritima acyl carrier protein (Tm-ACP) that functions as a carrier in the fatty acid synthesis system at near-boiling aqueous environments. Here, to understand the hyperthermal adaptation of Tm-ACP, we investigated the structure and dynamics of Tm-ACP by nuclear magnetic resonance (NMR) spectroscopy. The melting temperature of Tm-ACP (101.4 °C) far exceeds that of other ACPs, owing to extensive ionic interactions and tight hydrophobic packing. The D59 residue, which replaces Pro/Ser of other ACPs, mediates ionic clustering between helices III and IV. This creates a wide pocket entrance to facilitate the accommodation of long acyl chains required for hyperthermal adaptation of the T. maritima cell membrane. Tm-ACP is revealed to be the first ACP that harbor an amide proton hyperprotected against hydrogen/deuterium exchange for I15. The hydrophobic interactions mediated by I15 appear to be the key driving forces of the global folding process of Tm-ACP. Our findings provide insights into the structural basis of the hyperthermal adaptation of ACP, which might have allowed T. maritima to survive in hot ancient oceans.
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8
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First JT, Novelli ET, Webb LJ. Beyond pKa: Experiments and Simulations of Nitrile Vibrational Probes in Staphylococcal Nuclease Show the Importance of Local Interactions. J Phys Chem B 2020; 124:3387-3399. [DOI: 10.1021/acs.jpcb.0c00747] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jeremy T. First
- Department of Chemistry, Texas Materials Institute, and Institute for Cell and Molecular Biology The University of Texas at Austin 105 East 24th Street STOP A5300, Austin, Texas 78712-1224, United States
| | - Elisa T. Novelli
- Department of Chemistry, Texas Materials Institute, and Institute for Cell and Molecular Biology The University of Texas at Austin 105 East 24th Street STOP A5300, Austin, Texas 78712-1224, United States
| | - Lauren J. Webb
- Department of Chemistry, Texas Materials Institute, and Institute for Cell and Molecular Biology The University of Texas at Austin 105 East 24th Street STOP A5300, Austin, Texas 78712-1224, United States
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9
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Acheampong KK, Kokona B, Braun GA, Jacobsen DR, Johnson KA, Charkoudian LK. Colorimetric Assay Reports on Acyl Carrier Protein Interactions. Sci Rep 2019; 9:15589. [PMID: 31666546 PMCID: PMC6821831 DOI: 10.1038/s41598-019-51554-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2019] [Accepted: 09/25/2019] [Indexed: 01/15/2023] Open
Abstract
The ability to produce new molecules of potential pharmaceutical relevance via combinatorial biosynthesis hinges on improving our understanding of acyl-carrier protein (ACP)-protein interactions. However, the weak and transient nature of these interactions makes them difficult to study using traditional spectroscopic approaches. Herein we report that converting the terminal thiol of the E. coli ACP 4'-phosphopantetheine arm into a mixed disulfide with 2-nitro-5-thiobenzoate ion (TNB-) activates this site to form a selective covalent cross-link with the active site cysteine of a cognate ketoacyl synthase (KS). The concomitant release of TNB2-, which absorbs at 412 nm, provides a visual and quantitative measure of mechanistically relevant ACP-KS interactions. The colorimetric assay can propel the engineering of biosynthetic routes to novel chemical diversity by providing a high-throughput screen for functional hybrid ACP-KS partnerships as well as the discovery of novel antimicrobial agents by enabling the rapid identification of small molecule inhibitors of ACP-KS interactions.
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Affiliation(s)
- Kofi K Acheampong
- Department of Chemistry, Haverford College, Haverford, PA, 19041-1391, USA
| | - Bashkim Kokona
- Department of Chemistry, Haverford College, Haverford, PA, 19041-1391, USA
| | - Gabriel A Braun
- Department of Chemistry, Haverford College, Haverford, PA, 19041-1391, USA
| | | | - Karl A Johnson
- Department of Biology, Haverford College, Haverford, PA, 19041-1391, USA.
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10
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Gulick AM, Aldrich CC. Trapping interactions between catalytic domains and carrier proteins of modular biosynthetic enzymes with chemical probes. Nat Prod Rep 2019; 35:1156-1184. [PMID: 30046790 DOI: 10.1039/c8np00044a] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Covering: up to early 2018 The Nonribosomal Peptide Synthetases (NRPSs) and Polyketide Synthases (PKSs) are families of modular enzymes that produce a tremendous diversity of natural products, with antibacterial, antifungal, immunosuppressive, and anticancer activities. Both enzymes utilize a fascinating modular architecture in which the synthetic intermediates are covalently attached to a peptidyl- or acyl-carrier protein that is delivered to catalytic domains for natural product elongation, modification, and termination. An investigation of the structural mechanism therefore requires trapping the often transient interactions between the carrier and catalytic domains. Many novel chemical probes have been produced to enable the structural and functional investigation of multidomain NRPS and PKS structures. This review will describe the design and implementation of the chemical tools that have proven to be useful in biochemical and biophysical studies of these natural product biosynthetic enzymes.
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Affiliation(s)
- Andrew M Gulick
- University at Buffalo, Department of Structural Biology, Jacobs School of Medicine and Biomedical Sciences, 955 Main St, Buffalo, NY 14203, USA.
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11
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Biswas R, Singh BK, Dutta D, Das PK, Maiti MK, Basak A, Das AK. Decrypting the oscillating nature of the 4'-phosphopantetheine arm in acyl carrier protein AcpM of Mycobacterium tuberculosis. FEBS Lett 2019; 593:622-633. [PMID: 30847903 DOI: 10.1002/1873-3468.13339] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Revised: 02/04/2019] [Accepted: 02/11/2019] [Indexed: 12/28/2022]
Abstract
In Mycobacterium tuberculosis, acyl carrier protein (AcpM)-mediated fatty acid synthase type II is integral for the synthesis of mycolic acids. AcpM, designated as an atypical ACP, comprises of a putative 33 amino acid long C-terminal extension which is distinctive in nature. Here, we aimed at devising an 'easy-to-go' method for the generation of crypto-AcpM loaded with a solvatochromic probe 7-Nitrobenz-2-oxa-1,3-diazol-4-yl, which is linked to the 4'-phosphopantetheine (Ppant) prosthetic group of AcpM. The crypto-AcpM, coupled with fluorescence spectroscopy and molecular dynamics simulation studies, was employed to explore the elusive dynamics of Ppant arm in AcpM. This investigation establishes the role of the flexible C-terminal extension of AcpM in regulating the prosthetic group sequestration ability by modulating the 'Asp-Ser-Leu' motif.
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Affiliation(s)
- Rupam Biswas
- Department of Biotechnology, Indian Institute of Technology, Kharagpur, India
| | - Bina Kumari Singh
- School of Biosciences, Indian Institute of Technology, Kharagpur, India
| | - Debajyoti Dutta
- Department of Biotechnology, Indian Institute of Technology, Kharagpur, India
| | - Prabir Kumar Das
- Department of Biotechnology, Indian Institute of Technology, Kharagpur, India
| | - Mrinal Kumar Maiti
- Department of Biotechnology, Indian Institute of Technology, Kharagpur, India
| | - Amit Basak
- School of Biosciences, Indian Institute of Technology, Kharagpur, India.,Department of Chemistry, Indian Institute of Technology, Kharagpur, India
| | - Amit Kumar Das
- Department of Biotechnology, Indian Institute of Technology, Kharagpur, India.,School of Biosciences, Indian Institute of Technology, Kharagpur, India
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12
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Creon A, Josts I, Niebling S, Huse N, Tidow H. Conformation-specific detection of calmodulin binding using the unnatural amino acid p-azido-phenylalanine (AzF) as an IR-sensor. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2018; 5:064701. [PMID: 30474048 PMCID: PMC6224318 DOI: 10.1063/1.5053466] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 10/22/2018] [Indexed: 05/13/2023]
Abstract
Calmodulin (CaM) is a very conserved, ubiquitous, eukaryotic protein that binds four Ca2+ ions with high affinity. It acts as a calcium sensor by translating Ca2+ signals into cellular processes such as metabolism, inflammation, immune response, memory, and muscle contraction. Calcium binding to CaM leads to conformational changes that enable Ca2+/CaM to recognize and bind various target proteins with high affinity. The binding mode and binding partners of CaM are very diverse, and a consensus binding sequence is lacking. Here, we describe an elegant system that allows conformation-specific detection of CaM-binding to its binding partners. We incorporate the unnatural amino acid p-azido-phenylalanine (AzF) in different positions of CaM and follow its unique spectral signature by infrared (IR)-spectroscopy of the azido stretching vibration. Our results suggest that the AzF vibrational probe is sensitive to the chemical environment in different CaM/CaM-binding domain (CaMBD) complexes, which allows differentiating between different binding motifs according to the spectral characteristics of the azido stretching mode. We corroborate our results with a crystal structure of AzF-labelled CaM (CaM108AzF) in complex with a binding peptide from calmodulin-dependent protein kinase IIα identifying the structural basis for the observed IR frequency shifts.
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Affiliation(s)
| | | | | | | | - Henning Tidow
- Authors to whom correspondence should be addressed: , Tel.: +49 40428381599 and , Tel.: +49 40428388984
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13
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Dalton SR, Vienneau AR, Burstein SR, Xu RJ, Linse S, Londergan CH. Cyanylated Cysteine Reports Site-Specific Changes at Protein-Protein-Binding Interfaces Without Perturbation. Biochemistry 2018; 57:3702-3712. [PMID: 29787228 PMCID: PMC6034165 DOI: 10.1021/acs.biochem.8b00283] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
![]()
To investigate the
cyanylated cysteine vibrational probe group’s
ability to report on binding-induced changes along a protein–protein
interface, the probe group was incorporated at several sites in a
peptide of the calmodulin (CaM)-binding domain of skeletal muscle
myosin light chain kinase. Isothermal titration calorimetry was used
to determine the binding thermodynamics between calmodulin and each
peptide. For all probe positions, the binding affinity was nearly
identical to that of the unlabeled peptide. The CN stretching infrared
band was collected for each peptide free in solution and bound to
calmodulin. Binding-induced shifts in the IR spectral frequencies
were correlated with estimated solvent accessibility based on molecular
dynamics simulations. This work generally suggests (1) that site-specific
incorporation of this vibrational probe group does not cause major
perturbations to its local structural environment and (2) that this
small probe group might be used quite broadly to map dynamic protein-binding
interfaces. However, site-specific perturbations due to artificial
labeling groups can be somewhat unpredictable and should be evaluated
on a site-by-site basis through complementary measurements. A fully
quantitative, simulation-based interpretation of the rich probe IR
spectra is still needed but appears to be possible given recent advances
in simulation techniques.
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Affiliation(s)
- Shannon R Dalton
- Department of Chemistry , Haverford College , 370 Lancaster Ave , Haverford , Pennsylvania 19041-1392 , United States
| | - Alice R Vienneau
- Department of Chemistry , Haverford College , 370 Lancaster Ave , Haverford , Pennsylvania 19041-1392 , United States
| | - Shana R Burstein
- Department of Chemistry , Haverford College , 370 Lancaster Ave , Haverford , Pennsylvania 19041-1392 , United States
| | - Rosalind J Xu
- Department of Chemistry , Haverford College , 370 Lancaster Ave , Haverford , Pennsylvania 19041-1392 , United States
| | - Sara Linse
- Department of Chemistry and Biochemistry , Lund University , Kemicentrum, Box 118 , 221 00 Lund , Sweden
| | - Casey H Londergan
- Department of Chemistry , Haverford College , 370 Lancaster Ave , Haverford , Pennsylvania 19041-1392 , United States
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14
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Xu RJ, Blasiak B, Cho M, Layfield JP, Londergan CH. A Direct, Quantitative Connection between Molecular Dynamics Simulations and Vibrational Probe Line Shapes. J Phys Chem Lett 2018; 9:2560-2567. [PMID: 29697984 DOI: 10.1021/acs.jpclett.8b00969] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
A quantitative connection between molecular dynamics simulations and vibrational spectroscopy of probe-labeled systems would enable direct translation of experimental data into structural and dynamical information. To constitute this connection, all-atom molecular dynamics (MD) simulations were performed for two SCN probe sites (solvent-exposed and buried) in a calmodulin-target peptide complex. Two frequency calculation approaches with substantial nonelectrostatic components, a quantum mechanics/molecular mechanics (QM/MM)-based technique and a solvatochromic fragment potential (SolEFP) approach, were used to simulate the infrared probe line shapes. While QM/MM results disagreed with experiment, SolEFP results matched experimental frequencies and line shapes and revealed the physical and dynamic bases for the observed spectroscopic behavior. The main determinant of the CN probe frequency is the exchange repulsion between the probe and its local structural neighbors, and there is a clear dynamic explanation for the relatively broad probe line shape observed at the "buried" probe site. This methodology should be widely applicable to vibrational probes in many environments.
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Affiliation(s)
- Rosalind J Xu
- Department of Chemistry , Haverford College , Haverford , Pennsylvania , United States
| | - Bartosz Blasiak
- Department of Physical and Quantum Chemistry, Faculty of Chemistry , Wrocław University of Science and Technology , Wybrzeże Wyspiańskiego 27 , 50-370 Wrocław , Poland
| | - Minhaeng Cho
- Center for Molecular Spectroscopy and Dynamics , Institute for Basic Science (IBS) , Seoul 02841 , Republic of Korea
- Department of Chemistry , Korea University , Seoul 02841 , Republic of Korea
| | - Joshua P Layfield
- Department of Chemistry , St. Thomas University , Minneapolis , Minnesota , United States
| | - Casey H Londergan
- Department of Chemistry , Haverford College , Haverford , Pennsylvania , United States
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15
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Kelly KL, Dalton SR, Wai RB, Ramchandani K, Xu RJ, Linse S, Londergan CH. Conformational Ensembles of Calmodulin Revealed by Nonperturbing Site-Specific Vibrational Probe Groups. J Phys Chem A 2018; 122:2947-2955. [PMID: 29400461 PMCID: PMC5867645 DOI: 10.1021/acs.jpca.8b00475] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
![]()
Seven native residues on the regulatory
protein calmodulin, including
three key methionine residues, were replaced (one by one) by the vibrational
probe amino acid cyanylated cysteine, which has a unique CN stretching
vibration that reports on its local environment. Almost no perturbation
was caused by this probe at any of the seven sites, as reported by
CD spectra of calcium-bound and apo calmodulin and
binding thermodynamics for the formation of a complex between calmodulin
and a canonical target peptide from skeletal muscle myosin light chain
kinase measured by isothermal titration. The surprising lack of perturbation
suggests that this probe group could be applied directly in many protein–protein
binding interfaces. The infrared absorption bands for the probe groups
reported many dramatic changes in the probes’ local environments
as CaM went from apo- to calcium-saturated to target
peptide-bound conditions, including large frequency shifts and a variety
of line shapes from narrow (interpreted as a rigid and invariant local
environment) to symmetric to broad and asymmetric (likely from multiple
coexisting and dynamically exchanging structures). The fast intrinsic
time scale of infrared spectroscopy means that the line shapes report
directly on site-specific details of calmodulin’s variable
structural distribution. Though quantitative interpretation of the
probe line shapes depends on a direct connection between simulated
ensembles and experimental data that does not yet exist, formation
of such a connection to data such as that reported here would provide
a new way to evaluate conformational ensembles from data that directly
contains the structural distribution. The calmodulin probe sites developed
here will also be useful in evaluating the binding mode of calmodulin
with many uncharacterized regulatory targets.
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Affiliation(s)
- Kristen L Kelly
- Department of Chemistry , Haverford College , Haverford , Pennsylvania 19041 , United States
| | - Shannon R Dalton
- Department of Chemistry , Haverford College , Haverford , Pennsylvania 19041 , United States
| | - Rebecca B Wai
- Department of Chemistry , Haverford College , Haverford , Pennsylvania 19041 , United States
| | - Kanika Ramchandani
- Department of Chemistry , Haverford College , Haverford , Pennsylvania 19041 , United States
| | - Rosalind J Xu
- Department of Chemistry , Haverford College , Haverford , Pennsylvania 19041 , United States
| | - Sara Linse
- Department of Biochemistry and Structural Biology , Lund University , 221 00 Lund , Sweden
| | - Casey H Londergan
- Department of Chemistry , Haverford College , Haverford , Pennsylvania 19041 , United States
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16
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Lee G, Kossowska D, Lim J, Kim S, Han H, Kwak K, Cho M. Cyanamide as an Infrared Reporter: Comparison of Vibrational Properties between Nitriles Bonded to N and C Atoms. J Phys Chem B 2018. [DOI: 10.1021/acs.jpcb.8b00887] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Giseong Lee
- Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Dorota Kossowska
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Seoul 02841, Korea
- Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Joonhyung Lim
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Seoul 02841, Korea
- Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Soobin Kim
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Seoul 02841, Korea
| | - Hogyu Han
- Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Kyungwon Kwak
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Seoul 02841, Korea
- Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Minhaeng Cho
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Seoul 02841, Korea
- Department of Chemistry, Korea University, Seoul 02841, Korea
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17
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Wang J, Wang C, Song K, Wen J. Metabolic network model guided engineering ethylmalonyl-CoA pathway to improve ascomycin production in Streptomyces hygroscopicus var. ascomyceticus. Microb Cell Fact 2017; 16:169. [PMID: 28974216 PMCID: PMC5627430 DOI: 10.1186/s12934-017-0787-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 09/26/2017] [Indexed: 12/22/2022] Open
Abstract
Background Ascomycin is a 23-membered polyketide macrolide with high immunosuppressant and antifungal activity. As the lower production in bio-fermentation, global metabolic analysis is required to further explore its biosynthetic network and determine the key limiting steps for rationally engineering. To achieve this goal, an engineering approach guided by a metabolic network model was implemented to better understand ascomycin biosynthesis and improve its production. Results The metabolic conservation of Streptomyces species was first investigated by comparing the metabolic enzymes of Streptomyces coelicolor A3(2) with those of 31 Streptomyces strains, the results showed that more than 72% of the examined proteins had high sequence similarity with counterparts in every surveyed strain. And it was found that metabolic reactions are more highly conserved than the enzymes themselves because of its lower diversity of metabolic functions than that of genes. The main source of the observed metabolic differences was from the diversity of secondary metabolism. According to the high conservation of primary metabolic reactions in Streptomyces species, the metabolic network model of Streptomyces hygroscopicus var. ascomyceticus was constructed based on the latest reported metabolic model of S. coelicolor A3(2) and validated experimentally. By coupling with flux balance analysis and using minimization of metabolic adjustment algorithm, potential targets for ascomycin overproduction were predicted. Since several of the preferred targets were highly associated with ethylmalonyl-CoA biosynthesis, two target genes hcd (encoding 3-hydroxybutyryl-CoA dehydrogenase) and ccr (encoding crotonyl-CoA carboxylase/reductase) were selected for overexpression in S. hygroscopicus var. ascomyceticus FS35. Both the mutants HA-Hcd and HA-Ccr showed higher ascomycin titer, which was consistent with the model predictions. Furthermore, the combined effects of the two genes were evaluated and the strain HA-Hcd-Ccr with hcd and ccr overexpression exhibited the highest ascomycin production (up to 438.95 mg/L), 1.43-folds improvement than that of the parent strain FS35 (305.56 mg/L). Conclusions The successful constructing and experimental validation of the metabolic model of S. hygroscopicus var. ascomyceticus showed that the general metabolic network model of Streptomyces species could be used to analyze the intracellular metabolism and predict the potential key limiting steps for target metabolites overproduction. The corresponding overexpression strains of the two identified genes (hcd and ccr) using the constructed model all displayed higher ascomycin titer. The strategy for yield improvement developed here could also be extended to the improvement of other secondary metabolites in Streptomyces species. Electronic supplementary material The online version of this article (doi:10.1186/s12934-017-0787-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Junhua Wang
- Key Laboratory of System Bioengineering (Tianjin University), Ministry of Education, Tianjin, 300072, People's Republic of China.,SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, People's Republic of China
| | - Cheng Wang
- Key Laboratory of System Bioengineering (Tianjin University), Ministry of Education, Tianjin, 300072, People's Republic of China.,SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, People's Republic of China
| | - Kejing Song
- Key Laboratory of System Bioengineering (Tianjin University), Ministry of Education, Tianjin, 300072, People's Republic of China.,SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, People's Republic of China
| | - Jianping Wen
- Key Laboratory of System Bioengineering (Tianjin University), Ministry of Education, Tianjin, 300072, People's Republic of China. .,SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, People's Republic of China.
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18
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Thiele GAR, Friedman CP, Tsai KJS, Beld J, Londergan CH, Charkoudian LK. Acyl Carrier Protein Cyanylation Delivers a Ketoacyl Synthase-Carrier Protein Cross-Link. Biochemistry 2017; 56:2533-2536. [PMID: 28448715 DOI: 10.1021/acs.biochem.7b00219] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Acyl carrier proteins (ACPs) are central hubs in polyketide and fatty acid biosynthetic pathways, but the fast motions of the ACP's phosphopantetheine (Ppant) arm make its conformational dynamics difficult to capture using traditional spectroscopic approaches. Here we report that converting the terminal thiol of Escherichia coli ACP's Ppant arm into a thiocyanate activates this site to form a selective cross-link with the active site cysteine of its partner ketoacyl synthase (FabF). The reaction releases a cyanide anion, which can be detected by infrared spectroscopy. This represents a practical and generalizable method for obtaining and visualizing ACP-protein complexes relevant to biocatalysis and will be valuable in future structural and engineering studies.
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Affiliation(s)
- Grace A R Thiele
- Department of Chemistry, Haverford College , Haverford, Pennsylvania 19041-1392, United States
| | - Connie P Friedman
- Department of Chemistry, Haverford College , Haverford, Pennsylvania 19041-1392, United States
| | - Kathleen J S Tsai
- Department of Chemistry, Haverford College , Haverford, Pennsylvania 19041-1392, United States
| | - Joris Beld
- Department of Microbiology and Immunology, Drexel University College of Medicine , 245 North 15th Street, Philadelphia, Pennsylvania 19102, United States
| | - Casey H Londergan
- Department of Chemistry, Haverford College , Haverford, Pennsylvania 19041-1392, United States
| | - Louise K Charkoudian
- Department of Chemistry, Haverford College , Haverford, Pennsylvania 19041-1392, United States
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19
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Błasiak B, Londergan CH, Webb LJ, Cho M. Vibrational Probes: From Small Molecule Solvatochromism Theory and Experiments to Applications in Complex Systems. Acc Chem Res 2017; 50:968-976. [PMID: 28345879 DOI: 10.1021/acs.accounts.7b00002] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The vibrational frequency of a chosen normal mode is one of the most accurately measurable spectroscopic properties of molecules in condensed phases. Accordingly, infrared absorption and Raman scattering spectroscopy have provided valuable information on both distributions and ensemble-average values of molecular vibrational frequencies, and these frequencies are now routinely used to investigate structure, conformation, and even absolute configuration of chemical and biological molecules of interest. Recent advancements in coherent time-domain nonlinear vibrational spectroscopy have allowed the study of heterogeneous distributions of local structures and thermally driven ultrafast fluctuations of vibrational frequencies. To fully utilize IR probe functional groups for quantitative bioassays, a variety of biological and chemical techniques have been developed to site-specifically introduce vibrational probe groups into proteins and nucleic acids. These IR-probe-labeled biomolecules and chemically reactive systems are subject to linear and nonlinear vibrational spectroscopic investigations and provide information on the local electric field, conformational changes, site-site protein contacts, and/or function-defining features of biomolecules. A rapidly expanding library of data from such experiments requires an interpretive method with atom-level chemical accuracy. However, despite prolonged efforts to develop an all-encompassing theory for describing vibrational solvatochromism and electrochromism as well as dynamic fluctuations of instantaneous vibrational frequencies, purely empirical and highly approximate theoretical models have often been used to interpret experimental results. They are, in many cases, based on the simple assumption that the vibrational frequency of an IR reporter is solely dictated by electric potential or field distribution around the vibrational chromophore. Such simplified description of vibrational solvatochromism generally referred to as vibrational Stark effect theory has been considered to be quite appealing and, even in some cases, e.g., carbonyl stretch modes in amide, ester, ketone, and carbonate compounds or proteins, it works quantitatively well, which makes it highly useful in determining the strength of local electric field around the IR chromophore. However, noting that the vibrational frequency shift results from changes of solute-solvent intermolecular interaction potential along its normal coordinate, Pauli exclusion repulsion, polarization, charge transfer, and dispersion interactions, in addition to the electrostatic interaction between distributed charges of both vibrational chromophore and solvent molecules, are to be properly included in the theoretical description of vibrational solvatochromism. Since the electrostatic and nonelectrostatic intermolecular interaction components have distinctively different distance and orientation dependences, they affect the solvatochromic vibrational properties in a completely different manner. Over the past few years, we have developed a systematic approach to simulating vibrational solvatochromic data based on the effective fragment potential approach, one of the most accurate and rigorous theories on intermolecular interactions. We have further elucidated the interplay of local electric field with the general vibrational solvatochromism of small IR probes in either solvents or complicated biological systems, with emphasis on contributions from non-Coulombic intermolecular interactions to vibrational frequency shifts and fluctuations. With its rigorous foundation and close relation to quantitative interpretation of experimental data, this and related theoretical approaches and experiments will be of use in studying and quantifying the structure and dynamics of biomolecules with unprecedented time and spatial resolution when combined with time-resolved vibrational spectroscopy and chemically sensitive vibrational imaging techniques.
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Affiliation(s)
- Bartosz Błasiak
- Center
of Molecular Spectroscopy and Dynamics, Institute of Basic Science (IBS), 145
Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
- Department
of Chemistry, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Casey H. Londergan
- Department
of Chemistry, Haverford College, Haverford, Pennsylvania 19041-1392, United States
| | - Lauren J. Webb
- Department
of Chemistry, Center for Nano- and Molecular Science and Technology,
and Institute for Cell and Molecular Biology, The University of Texas at Austin, 105
E. 24th Street, STOP A5300, Austin, Texas 78712, United States
| | - Minhaeng Cho
- Center
of Molecular Spectroscopy and Dynamics, Institute of Basic Science (IBS), 145
Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
- Department
of Chemistry, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
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20
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Adhikary R, Zimmermann J, Romesberg FE. Transparent Window Vibrational Probes for the Characterization of Proteins With High Structural and Temporal Resolution. Chem Rev 2017; 117:1927-1969. [DOI: 10.1021/acs.chemrev.6b00625] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Ramkrishna Adhikary
- Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037, United States
| | - Jörg Zimmermann
- Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037, United States
| | - Floyd E. Romesberg
- Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037, United States
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21
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Ahmed IA, Gai F. Simple method to introduce an ester infrared probe into proteins. Protein Sci 2017; 26:375-381. [PMID: 27813296 DOI: 10.1002/pro.3076] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 10/25/2016] [Accepted: 10/28/2016] [Indexed: 01/09/2023]
Abstract
The ester carbonyl stretching vibration has recently been shown to be a sensitive and convenient infrared (IR) probe of protein electrostatics due to the linear dependence of its frequency on local electric field. While an ester moiety can be easily incorporated into peptides via solid-phase synthesis, currently there is no method available to site-specifically incorporate it into a large protein. Herein, we show that it is possible to use a cysteine alkylation reaction to achieve this goal and demonstrate the feasibility of this simple method by successfully incorporating a methyl ester group (CH2 COOCH3 ) into a model peptide (YGGCGG), two amyloid-forming peptides derived from the insulin B chain and Aβ, and bovine serum albumin (BSA). IR results obtained with those peptide and protein systems further confirm the utility of this vibrational probe in monitoring, for example, the structural integrity of amyloid fibrils and ligand binding-induced changes in protein local hydration status.
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Affiliation(s)
- Ismail A Ahmed
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania, 19104
| | - Feng Gai
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania, 19104
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22
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Maj M, Ahn C, Błasiak B, Kwak K, Han H, Cho M. Isonitrile as an Ultrasensitive Infrared Reporter of Hydrogen-Bonding Structure and Dynamics. J Phys Chem B 2016; 120:10167-10180. [DOI: 10.1021/acs.jpcb.6b04319] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Michał Maj
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic
Science (IBS) and ‡Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Changwoo Ahn
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic
Science (IBS) and ‡Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Bartosz Błasiak
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic
Science (IBS) and ‡Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Kyungwon Kwak
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic
Science (IBS) and ‡Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Hogyu Han
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic
Science (IBS) and ‡Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Minhaeng Cho
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic
Science (IBS) and ‡Department of Chemistry, Korea University, Seoul 02841, Korea
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23
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Dong X, Bailey CD, Williams C, Crosby J, Simpson TJ, Willis CL, Crump MP. Recognition of extended linear and cyclised polyketide mimics by a type II acyl carrier protein. Chem Sci 2016; 7:1779-1785. [PMID: 28936328 PMCID: PMC5595124 DOI: 10.1039/c5sc03864b] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 12/08/2015] [Indexed: 12/02/2022] Open
Abstract
Polyketides are secondary metabolites which display both valuable pharmaceutical and agrochemical properties. Biosynthesis is performed by polyketide synthases (PKSs), and the acyl carrier protein (ACP), a small acidic protein, that transports the growing polyketide chain and is essential for activity. Here we report the synthesis of two aromatic probes and a linear octaketide mimic that have been tethered to actinorhodin ACP. These experiments were aimed at probing the ACP's capacity to sequester a non-polar versus a phenolic aromatic ring (that more closely mimics a polyketide intermediate) as well as investigations with extended polyketide chain surrogates. The binding of these mimics has been assessed using high-resolution solution NMR studies and high-resolution structure determination. These results reveal that surprisingly a PKS ACP is able to bind and sequester a bulky non-polar substrate containing an aromatic ring in a fatty acid type binding mode, but the introduction of even a small degree of polarity favours a markedly different association at a surface site that is distinct from that employed by fatty acid ACPs.
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Affiliation(s)
- Xu Dong
- School of Chemistry , University of Bristol , Cantock's Close , Bristol , BS8 1TS , UK . ;
| | - Christopher D Bailey
- School of Chemistry , University of Bristol , Cantock's Close , Bristol , BS8 1TS , UK . ;
| | - Christopher Williams
- School of Chemistry , University of Bristol , Cantock's Close , Bristol , BS8 1TS , UK . ;
| | - John Crosby
- School of Chemistry , University of Bristol , Cantock's Close , Bristol , BS8 1TS , UK . ;
| | - Thomas J Simpson
- School of Chemistry , University of Bristol , Cantock's Close , Bristol , BS8 1TS , UK . ;
| | - Christine L Willis
- School of Chemistry , University of Bristol , Cantock's Close , Bristol , BS8 1TS , UK . ;
| | - Matthew P Crump
- School of Chemistry , University of Bristol , Cantock's Close , Bristol , BS8 1TS , UK . ;
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24
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Sticky swinging arm dynamics: studies of an acyl carrier protein domain from the mycolactone polyketide synthase. Biochem J 2016; 473:1097-110. [PMID: 26920023 PMCID: PMC4847154 DOI: 10.1042/bcj20160041] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 02/18/2016] [Indexed: 11/17/2022]
Abstract
When covalently linked to an acyl carrier protein (ACP) and loaded with acyl substrate-mimics, some 4′-phosphopantetheine prosthetic group arms swing freely, whereas others stick to the protein surface, suggesting a possible mode of interaction with enzyme domains during polyketide biosynthesis. Type I modular polyketide synthases (PKSs) produce polyketide natural products by passing a growing acyl substrate chain between a series of enzyme domains housed within a gigantic multifunctional polypeptide assembly. Throughout each round of chain extension and modification reactions, the substrate stays covalently linked to an acyl carrier protein (ACP) domain. In the present study we report on the solution structure and dynamics of an ACP domain excised from MLSA2, module 9 of the PKS system that constructs the macrolactone ring of the toxin mycolactone, cause of the tropical disease Buruli ulcer. After modification of apo ACP with 4′-phosphopantetheine (Ppant) to create the holo form, 15N nuclear spin relaxation and paramagnetic relaxation enhancement (PRE) experiments suggest that the prosthetic group swings freely. The minimal chemical shift perturbations displayed by Ppant-attached C3 and C4 acyl chains imply that these substrate-mimics remain exposed to solvent at the end of a flexible Ppant arm. By contrast, hexanoyl and octanoyl chains yield much larger chemical shift perturbations, indicating that they interact with the surface of the domain. The solution structure of octanoyl-ACP shows the Ppant arm bending to allow the acyl chain to nestle into a nonpolar pocket, whereas the prosthetic group itself remains largely solvent exposed. Although the highly reduced octanoyl group is not a natural substrate for the ACP from MLSA2, similar presentation modes would permit partner enzyme domains to recognize an acyl group while it is bound to the surface of its carrier protein, allowing simultaneous interactions with both the substrate and the ACP.
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25
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Abstract
Polyketides are a structurally and functionally diverse family of bioactive natural products that have found widespread application as pharmaceuticals, agrochemicals, and veterinary medicines. In bacteria complex polyketides are biosynthesized by giant multifunctional megaenzymes, termed modular polyketide synthases (PKSs), which construct their products in a highly coordinated assembly line-like fashion from a pool of simple precursor substrates. Not only is the multifaceted enzymology of PKSs a fascinating target for study, but it also presents considerable opportunities for the reengineering of these systems affording access to functionally optimized unnatural natural products. Here we provide an introductory primer to modular polyketide synthase structure and function, and highlight recent advances in the characterization and exploitation of these systems.
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Affiliation(s)
- Marisa Till
- School of Biochemistry, University of Bristol, Medical Sciences Building, University Walk, Bristol, BS8 1TD, UK
- BrisSynBio Synthetic Biology Research Centre, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol, BS8 1TQ, UK
| | - Paul R Race
- School of Biochemistry, University of Bristol, Medical Sciences Building, University Walk, Bristol, BS8 1TD, UK
- BrisSynBio Synthetic Biology Research Centre, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol, BS8 1TQ, UK
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26
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Reinvigorating natural product combinatorial biosynthesis with synthetic biology. Nat Chem Biol 2015; 11:649-59. [PMID: 26284672 DOI: 10.1038/nchembio.1893] [Citation(s) in RCA: 157] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 07/22/2015] [Indexed: 12/24/2022]
Abstract
Natural products continue to play a pivotal role in drug-discovery efforts and in the understanding if human health. The ability to extend nature's chemistry through combinatorial biosynthesis--altering functional groups, regiochemistry and scaffold backbones through the manipulation of biosynthetic enzymes--offers unique opportunities to create natural product analogs. Incorporating emerging synthetic biology techniques has the potential to further accelerate the refinement of combinatorial biosynthesis as a robust platform for the diversification of natural chemical drug leads. Two decades after the field originated, we discuss the current limitations, the realities and the state of the art of combinatorial biosynthesis, including the engineering of substrate specificity of biosynthetic enzymes and the development of heterologous expression systems for biosynthetic pathways. We also propose a new perspective for the combinatorial biosynthesis of natural products that could reinvigorate drug discovery by using synthetic biology in combination with synthetic chemistry.
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27
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Adhikary R, Zimmermann J, Dawson PE, Romesberg FE. Temperature Dependence of CN and SCN IR Absorptions Facilitates Their Interpretation and Use as Probes of Proteins. Anal Chem 2015; 87:11561-7. [DOI: 10.1021/acs.analchem.5b03437] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Ramkrishna Adhikary
- Department of Chemistry, The Scripps Research Institute, 10550 North
Torrey Pines Road, La Jolla, California 92037, United States
| | - Jörg Zimmermann
- Department of Chemistry, The Scripps Research Institute, 10550 North
Torrey Pines Road, La Jolla, California 92037, United States
| | - Philip E. Dawson
- Department of Chemistry, The Scripps Research Institute, 10550 North
Torrey Pines Road, La Jolla, California 92037, United States
| | - Floyd E. Romesberg
- Department of Chemistry, The Scripps Research Institute, 10550 North
Torrey Pines Road, La Jolla, California 92037, United States
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28
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Finzel K, Lee DJ, Burkart MD. Using modern tools to probe the structure-function relationship of fatty acid synthases. Chembiochem 2015; 16:528-547. [PMID: 25676190 PMCID: PMC4545599 DOI: 10.1002/cbic.201402578] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Indexed: 12/25/2022]
Abstract
Fatty acid biosynthesis is essential to life and represents one of the most conserved pathways in nature, preserving the same handful of chemical reactions across all species. Recent interest in the molecular details of the de novo fatty acid synthase (FAS) has been heightened by demand for renewable fuels and the emergence of multidrug-resistant bacterial strains. Central to FAS is the acyl carrier protein (ACP), a protein chaperone that shuttles the growing acyl chain between catalytic enzymes within the FAS. Human efforts to alter fatty acid biosynthesis for oil production, chemical feedstock, or antimicrobial purposes has been met with limited success, due in part to a lack of detailed molecular information behind the ACP-partner protein interactions inherent to the pathway. This review will focus on recently developed tools for the modification of ACP and analysis of protein-protein interactions, such as mechanism-based crosslinking, and the studies exploiting them. Discussion specific to each enzymatic domain will focus first on mechanism and known inhibitors, followed by available structures and known interactions with ACP. Although significant unknowns remain, new understandings of the intricacies of FAS point to future advances in manipulating this complex molecular factory.
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Affiliation(s)
- Kara Finzel
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093-0358 (USA)
| | - D. John Lee
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093-0358 (USA)
| | - Michael D. Burkart
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093-0358 (USA)
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29
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Beld J, Cang H, Burkart MD. Visualizing the chain-flipping mechanism in fatty-acid biosynthesis. Angew Chem Int Ed Engl 2014; 53:14456-61. [PMID: 25354391 PMCID: PMC4425425 DOI: 10.1002/anie.201408576] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Indexed: 11/08/2022]
Abstract
The acyl carrier protein (ACP) from fatty acid synthases sequesters elongating products within its hydrophobic core, but this dynamic mechanism remains poorly understood. We exploited solvatochromic pantetheine probes attached to ACP that fluoresce when sequestered. The addition of a catalytic partner lures the cargo out of the ACP and into the active site of the enzyme, thus enhancing fluorescence to reveal the elusive chain-flipping mechanism. This activity was confirmed by the use of a dual solvatochromic cross-linking probe and solution-phase NMR spectroscopy. The chain-flipping mechanism was visualized by single-molecule fluorescence techniques, thus demonstrating specificity between the Escherichia coli ACP and its ketoacyl synthase catalytic partner KASII.
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Affiliation(s)
- Joris Beld
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0358, USA
| | - Hu Cang
- Waitt Advanced Biophotonics Center, The Salk Institute for Biological Studies, La Jolla, California, USA
| | - Michael D. Burkart
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0358, USA
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Beld J, Cang H, Burkart MD. Visualizing the Chain-Flipping Mechanism in Fatty-Acid Biosynthesis. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201408576] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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