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Phanumartwiwath A, Kesornpun C, Chokchaichamnankit D, Khongmanee A, Diskul-Na-Ayudthaya P, Ruangjaroon T, Srisomsap C, Kittakoop P, Svasti J, Ruchirawat S. Protein Modification via Nitrile Oxide- Dehydroalanine Cycloaddition: Formation of Isoxazoline Ring on the Protein Backbone. Chembiochem 2023; 24:e202300268. [PMID: 37199473 DOI: 10.1002/cbic.202300268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 04/26/2023] [Accepted: 05/18/2023] [Indexed: 05/19/2023]
Abstract
Here we describe a novel catalyst-free 1,3-dipolar cycloaddition bioconjugation approach for chemical modification of proteins. The dehydroalanine (Dha)-containing protein reacts with nitrile oxides generated in situ through 1,3-dipolar cycloaddition in fully aqueous-buffered systems. This leads to the formation of a new isoxazoline ring at a pre-defined site (Dha) of the protein. Furthermore, the 1-pyrene isoxazoline-installed annexin V acts as a fluorescent probe, which successfully labels the outer cellular membranes of human cholangiocarcinoma (HuCCA-1) cells for detection of apoptosis.
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Affiliation(s)
- Anuchit Phanumartwiwath
- College of Public Health Sciences, Chulalongkorn University, Phyathai Road, Bangkok, 10330, Thailand
- Chemical Biology Program, Chulabhorn Graduate Institute, Kamphaeng Phet6 Road, Lak Si, Bangkok, 10210, Thailand
- Centre of Excellence on Environmental Health and Toxicology (EHT), CHE, Ministry of Education, Bangkok, 10400, Thailand
| | - Chatchai Kesornpun
- Chulabhorn Research Institute, Kamphaeng Phet6 Road, Lak Si, Bangkok, 10210, Thailand
| | | | - Amnart Khongmanee
- Chulabhorn Research Institute, Kamphaeng Phet6 Road, Lak Si, Bangkok, 10210, Thailand
| | | | - Theetat Ruangjaroon
- Chulabhorn Research Institute, Kamphaeng Phet6 Road, Lak Si, Bangkok, 10210, Thailand
| | - Chantragan Srisomsap
- Chulabhorn Research Institute, Kamphaeng Phet6 Road, Lak Si, Bangkok, 10210, Thailand
| | - Prasat Kittakoop
- Chemical Biology Program, Chulabhorn Graduate Institute, Kamphaeng Phet6 Road, Lak Si, Bangkok, 10210, Thailand
- Centre of Excellence on Environmental Health and Toxicology (EHT), CHE, Ministry of Education, Bangkok, 10400, Thailand
| | - Jisnuson Svasti
- Chulabhorn Research Institute, Kamphaeng Phet6 Road, Lak Si, Bangkok, 10210, Thailand
- Applied Biological Sciences Program, Chulabhorn Graduate Institute, Kamphaeng Phet6 Road, Lak Si, Bangkok, 10210, Thailand
| | - Somsak Ruchirawat
- Chemical Biology Program, Chulabhorn Graduate Institute, Kamphaeng Phet6 Road, Lak Si, Bangkok, 10210, Thailand
- Centre of Excellence on Environmental Health and Toxicology (EHT), CHE, Ministry of Education, Bangkok, 10400, Thailand
- Chulabhorn Research Institute, Kamphaeng Phet6 Road, Lak Si, Bangkok, 10210, Thailand
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2
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Ahmed K, Chotana GA, Faisal A, Zaib Saleem RS. Chemical Synthesis of Selenium-containing Peptides. Mini Rev Med Chem 2022:MRMC-EPUB-125875. [PMID: 36029080 DOI: 10.2174/1389557522666220826140910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 05/09/2022] [Accepted: 05/27/2022] [Indexed: 11/22/2022]
Abstract
Selenium (Se), a semi-metallic element has chemical properties similar to sulfur, however because of its comparatively low electronegativity as well as large atomic radius than sulfur. These features bestow selenium-containing compounds with extraordinary reactivity, sensitivity, and potential for several applications like chemical alteration, protein engineering, chemical (semi)synthesis, etc. Organoselenium chemistry is emerging fastly, however, the examples of effective incorporation of Se into the peptides are relatively scarce. Providentially, there is a drastic interest in the synthesis and application of selenoproteins and selenium-containing peptides over the last few decades. In this minireview, the synthetic methodologies of selenium-containing peptides and a brief description of their chemistry and biological activities are summarized. These methodologies enable access to various natural and unnatural selenium-containing peptides that have been used in a range of applications from modulating protein characteristics to structure-activity relationship (SAR) studies for applications in nutraceuticals and drug development. This review aims at the audience interested in learning about the synthesis as well as will open new dimensions for their future research by aiding in the design of biologically interesting selenium-containing peptides.
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Affiliation(s)
- Kainat Ahmed
- Department of Chemistry and Chemical Engineering, SBASSE, Lahore University of Management Sciences, Sector-U, DHA, Lahore-54792, Pakistan
| | - Ghayoor Abbas Chotana
- Department of Chemistry and Chemical Engineering, SBASSE, Lahore University of Management Sciences, Sector-U, DHA, Lahore-54792, Pakistan
| | - Amir Faisal
- Department of Biology, SBASSE, Lahore University of Management Sciences, Sector-U, DHA, Lahore-54792, Pakistan
| | - Rahman Shah Zaib Saleem
- Department of Chemistry and Chemical Engineering, SBASSE, Lahore University of Management Sciences, Sector-U, DHA, Lahore-54792, Pakistan
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3
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Harel O, Jbara M. Posttranslational Chemical Mutagenesis Methods to Insert Posttranslational Modifications into Recombinant Proteins. Molecules 2022; 27:4389. [PMID: 35889261 DOI: 10.3390/molecules27144389] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2022] [Revised: 06/27/2022] [Accepted: 07/06/2022] [Indexed: 11/17/2022]
Abstract
Posttranslational modifications (PTMs) dramatically expand the functional diversity of the proteome. The precise addition and removal of PTMs appears to modulate protein structure and function and control key regulatory processes in living systems. Deciphering how particular PTMs affect protein activity is a current frontier in biology and medicine. The large number of PTMs which can appear in several distinct positions, states, and combinations makes preparing such complex analogs using conventional biological and chemical tools challenging. Strategies to access homogeneous and precisely modified proteins with desired PTMs at selected sites and in feasible quantities are critical to interpreting their molecular code. Here, we summarize recent advances in posttranslational chemical mutagenesis and late-stage functionalization chemistry to transfer novel PTM mimicry into recombinant proteins with emphasis on novel transformations.
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4
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Lenartowicz P, Beelen M, Makowski M, Wanat W, Dziuk B, Kafarski P. Synthesis of Tetrapeptides Containing Dehydroalanine, Dehydrophenylalanine and Oxazole as Building Blocks for Construction of Foldamers and Bioinspired Catalysts. Molecules 2022; 27:2611. [PMID: 35565962 DOI: 10.3390/molecules27092611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 04/14/2022] [Accepted: 04/15/2022] [Indexed: 11/17/2022]
Abstract
The incorporation of dehydroamino acid or fragments of oxazole into peptide chain is accompanied by a distorted three-dimensional structure and additionally enables the introduction of non-typical side-chain substituents. Thus, such compounds could be building blocks for obtaining novel foldamers and/or artificial enzymes (artzymes). In this paper, effective synthetic procedures leading to such building blocks-tetrapeptides containing glycyldehydroalanine, glycyldehydrophenylalanine, and glycyloxazole subunits-are described. Peptides containing serine were used as substrates for their conversion into peptides containing dehydroalanine and aminomethyloxazole-4-carboxylic acid while considering possible requirements for the introduction of these fragments into long-chain peptides at the last steps of synthesis.
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5
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Miller RM, Knoener RA, Benner BE, Frey BL, Scalf M, Shortreed MR, Sherer NM, Smith LM. Discovery of Dehydroamino Acid Residues in the Capsid and Matrix Structural Proteins of HIV-1. J Proteome Res 2022; 21:993-1001. [PMID: 35192358 PMCID: PMC8976760 DOI: 10.1021/acs.jproteome.1c00867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Human immunodeficiency virus type 1 (HIV-1) remains a deadly infectious disease despite existing antiretroviral therapies. A comprehensive understanding of the specific mechanisms of viral infectivity remains elusive and currently limits the development of new and effective therapies. Through in-depth proteomic analysis of HIV-1 virions, we discovered the novel post-translational modification of highly conserved residues within the viral matrix and capsid proteins to the dehydroamino acids, dehydroalanine and dehydrobutyrine. We further confirmed their presence by labeling the reactive alkene, characteristic of dehydroamino acids, with glutathione via Michael addition. Dehydroamino acids are rare, understudied, and have been observed mainly in select bacterial and fungal species. Until now, they have not been observed in HIV proteins. We hypothesize that these residues are important in viral particle maturation and could provide valuable insight into HIV infectivity mechanisms.
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Affiliation(s)
- Rachel M Miller
- Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Rachel A Knoener
- Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706, United States.,McArdle Laboratory for Cancer Research and Institute for Molecular Virology, University of Wisconsin, Madison, Wisconsin 53705, United States
| | - Bayleigh E Benner
- McArdle Laboratory for Cancer Research and Institute for Molecular Virology, University of Wisconsin, Madison, Wisconsin 53705, United States
| | - Brian L Frey
- Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Mark Scalf
- Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Michael R Shortreed
- Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Nathan M Sherer
- McArdle Laboratory for Cancer Research and Institute for Molecular Virology, University of Wisconsin, Madison, Wisconsin 53705, United States
| | - Lloyd M Smith
- Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706, United States
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6
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Lai KY, Galan SRG, Zeng Y, Zhou TH, He C, Raj R, Riedl J, Liu S, Chooi KP, Garg N, Zeng M, Jones LH, Hutchings GJ, Mohammed S, Nair SK, Chen J, Davis BG, van der Donk WA. LanCLs add glutathione to dehydroamino acids generated at phosphorylated sites in the proteome. Cell 2021; 184:2680-2695.e26. [PMID: 33932340 DOI: 10.1016/j.cell.2021.04.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 01/22/2021] [Accepted: 03/31/2021] [Indexed: 12/13/2022]
Abstract
Enzyme-mediated damage repair or mitigation, while common for nucleic acids, is rare for proteins. Examples of protein damage are elimination of phosphorylated Ser/Thr to dehydroalanine/dehydrobutyrine (Dha/Dhb) in pathogenesis and aging. Bacterial LanC enzymes use Dha/Dhb to form carbon-sulfur linkages in antimicrobial peptides, but the functions of eukaryotic LanC-like (LanCL) counterparts are unknown. We show that LanCLs catalyze the addition of glutathione to Dha/Dhb in proteins, driving irreversible C-glutathionylation. Chemo-enzymatic methods were developed to site-selectively incorporate Dha/Dhb at phospho-regulated sites in kinases. In human MAPK-MEK1, such "elimination damage" generated aberrantly activated kinases, which were deactivated by LanCL-mediated C-glutathionylation. Surveys of endogenous proteins bearing damage from elimination (the eliminylome) also suggest it is a source of electrophilic reactivity. LanCLs thus remove these reactive electrophiles and their potentially dysregulatory effects from the proteome. As knockout of LanCL in mice can result in premature death, repair of this kind of protein damage appears important physiologically.
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Affiliation(s)
- Kuan-Yu Lai
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Sébastien R G Galan
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield, Oxford OX1 3TA, UK
| | - Yibo Zeng
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield, Oxford OX1 3TA, UK; UK Catalysis Hub, Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell, Oxford OX11 0FA, UK; The Rosalind Franklin Institute, Oxfordshire OX11 0FA, UK
| | - Tianhui Hina Zhou
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Chang He
- Department of Chemistry and Howard Hughes Medical Institute, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Ritu Raj
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield, Oxford OX1 3TA, UK
| | - Jitka Riedl
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield, Oxford OX1 3TA, UK
| | - Shi Liu
- Department of Chemistry and Howard Hughes Medical Institute, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - K Phin Chooi
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield, Oxford OX1 3TA, UK
| | - Neha Garg
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Min Zeng
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Lyn H Jones
- Dana-Farber Cancer Institute, 360 Longwood Avenue, Boston, MA 02115, USA
| | - Graham J Hutchings
- UK Catalysis Hub, Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell, Oxford OX11 0FA, UK; Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Cardiff CF10 3AT, UK
| | - Shabaz Mohammed
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield, Oxford OX1 3TA, UK; The Rosalind Franklin Institute, Oxfordshire OX11 0FA, UK
| | - Satish K Nair
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Jie Chen
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
| | - Benjamin G Davis
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield, Oxford OX1 3TA, UK; The Rosalind Franklin Institute, Oxfordshire OX11 0FA, UK.
| | - Wilfred A van der Donk
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Department of Chemistry and Howard Hughes Medical Institute, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
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7
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Qiao Y, Yu G, Leeuwon SZ, Liu WR. Site-Specific Conversion of Cysteine in a Protein to Dehydroalanine Using 2-Nitro-5-thiocyanatobenzoic Acid. Molecules 2021; 26:2619. [PMID: 33947165 PMCID: PMC8125731 DOI: 10.3390/molecules26092619] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 04/26/2021] [Accepted: 04/27/2021] [Indexed: 01/21/2023] Open
Abstract
Dehydroalanine exists natively in certain proteins and can also be chemically made from the protein cysteine. As a strong Michael acceptor, dehydroalanine in proteins has been explored to undergo reactions with different thiolate reagents for making close analogues of post-translational modifications (PTMs), including a variety of lysine PTMs. The chemical reagent 2-nitro-5-thiocyanatobenzoic acid (NTCB) selectively modifies cysteine to form S-cyano-cysteine, in which the S-Cβ bond is highly polarized. We explored the labile nature of this bond for triggering E2 elimination to generate dehydroalanine. Our results indicated that when cysteine is at the flexible C-terminal end of a protein, the dehydroalanine formation is highly effective. We produced ubiquitin and ubiquitin-like proteins with a C-terminal dehydroalanine residue with high yields. When cysteine is located at an internal region of a protein, the efficiency of the reaction varies with mainly hydrolysis products observed. Dehydroalanine in proteins such as ubiquitin and ubiquitin-like proteins can serve as probes for studying pathways involving ubiquitin and ubiquitin-like proteins and it is also a starting point to generate proteins with many PTM analogues; therefore, we believe that this NTCB-triggered dehydroalanine formation method will find broad applications in studying ubiquitin and ubiquitin-like protein pathways and the functional annotation of many PTMs in proteins such as histones.
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Affiliation(s)
- Yuchen Qiao
- The Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX 77843, USA; (Y.Q.); (G.Y.); (S.Z.L.)
| | - Ge Yu
- The Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX 77843, USA; (Y.Q.); (G.Y.); (S.Z.L.)
| | - Sunshine Z. Leeuwon
- The Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX 77843, USA; (Y.Q.); (G.Y.); (S.Z.L.)
| | - Wenshe Ray Liu
- The Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX 77843, USA; (Y.Q.); (G.Y.); (S.Z.L.)
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, TX 77843, USA
- Molecular & Cellular Medicine Department, College of Medicine, Texas A&M University, College Station, TX 77843, USA
- Institute of Biosciences and Technology and Department of Translational Medical Sciences, College of Medicine, Texas A&M University, Houston, TX 77030, USA
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de Vries RH, Viel JH, Kuipers OP, Roelfes G. Rapid and Selective Chemical Editing of Ribosomally Synthesized and Post-Translationally Modified Peptides (RiPPs) via Cu II -Catalyzed β-Borylation of Dehydroamino Acids. Angew Chem Int Ed Engl 2021; 60:3946-3950. [PMID: 33185967 PMCID: PMC7898795 DOI: 10.1002/anie.202011460] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Indexed: 12/22/2022]
Abstract
We report the fast and selective chemical editing of ribosomally synthesized and post-translationally modified peptides (RiPPs) by β-borylation of dehydroalanine (Dha) residues. The thiopeptide thiostrepton was modified efficiently using CuII -catalysis under mild conditions and 1D/2D NMR of the purified product showed site-selective borylation of the terminal Dha residues. Using similar conditions, the thiopeptide nosiheptide, lanthipeptide nisin Z, and protein SUMO_G98Dha were also modified efficiently. Borylated thiostrepton showed an up to 84-fold increase in water solubility, and minimum inhibitory concentration (MIC) assays showed that antimicrobial activity was maintained in thiostrepton and nosiheptide. The introduced boronic-acid functionalities were shown to be valuable handles for chemical mutagenesis and in a reversible click reaction with triols for the pH-controlled labeling of RiPPs.
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Affiliation(s)
- Reinder H. de Vries
- Stratingh Institute for ChemistryUniversity of GroningenNijenborgh 49747AGGroningenThe Netherlands
| | - Jakob H. Viel
- Department of Molecular GeneticsGroningen Biomolecular Sciences and Biotechnology InstituteUniversity of GroningenNijenborgh 79747AGGroningenThe Netherlands
| | - Oscar P. Kuipers
- Department of Molecular GeneticsGroningen Biomolecular Sciences and Biotechnology InstituteUniversity of GroningenNijenborgh 79747AGGroningenThe Netherlands
| | - Gerard Roelfes
- Stratingh Institute for ChemistryUniversity of GroningenNijenborgh 49747AGGroningenThe Netherlands
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9
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Lindstedt PR, Taylor RJ, Bernardes GJL, Vendruscolo M. Facile Installation of Post-translational Modifications on the Tau Protein via Chemical Mutagenesis. ACS Chem Neurosci 2021; 12:557-561. [PMID: 33464820 DOI: 10.1021/acschemneuro.0c00761] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Post-translational modifications of proteins are ubiquitous in living organisms, as they enable an accurate control of the interactions of these macromolecules. For mechanistic studies, it would be highly advantageous to be able to produce in vitro post-translationally modified proteins with site-specificity. Here, we demonstrate one facile way to achieve this goal through the use of post-translational chemical mutagenesis. We illustrate this approach by performing site-specific phosphorylation and methylation of tau, a protein that stabilizes microtubules and whose aggregation is closely linked with Alzheimer's disease. We then verify the effects of the post-translational modifications on the ability of tau to control microtubule polymerization, revealing in particular an unexpected role for phosphorylation at S199, which is outside the microtubule-binding region of tau. These results show how the chemical mutagenesis approach that we present enables the systematic analysis of site-specific post-translational modifications of a key protein involved in the pathogenesis of Alzheimer's disease.
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Affiliation(s)
- Philip R. Lindstedt
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, CB2 1EW Cambridge, United Kingdom
| | - Ross J. Taylor
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, CB2 1EW Cambridge, United Kingdom
| | - Gonçalo J. L. Bernardes
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, CB2 1EW Cambridge, United Kingdom
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Michele Vendruscolo
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, CB2 1EW Cambridge, United Kingdom
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van Lier RCW, de Bruijn AD, Roelfes G. A Water-Soluble Iridium Photocatalyst for Chemical Modification of Dehydroalanines in Peptides and Proteins. Chemistry 2020; 27:1430-1437. [PMID: 32896943 PMCID: PMC7898865 DOI: 10.1002/chem.202002599] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 09/04/2020] [Indexed: 12/27/2022]
Abstract
Dehydroalanine (Dha) residues are attractive noncanonical amino acids that occur naturally in ribosomally synthesised and post-translationally modified peptides (RiPPs). Dha residues are attractive targets for selective late-stage modification of these complex biomolecules. In this work, we show the selective photocatalytic modification of dehydroalanine residues in the antimicrobial peptide nisin and in the proteins small ubiquitin-like modifier (SUMO) and superfolder green fluorescent protein (sfGFP). For this purpose, a new water-soluble iridium(III) photoredox catalyst was used. The design and synthesis of this new photocatalyst, [Ir(dF(CF3 )ppy)2 (dNMe3 bpy)]Cl3 , is presented. In contrast to commonly used iridium photocatalysts, this complex is highly water soluble and allows peptides and proteins to be modified in water and aqueous solvents under physiologically relevant conditions, with short reaction times and with low reagent and catalyst loadings. This work suggests that photoredox catalysis using this newly designed catalyst is a promising strategy to modify dehydroalanine-containing natural products and thus could have great potential for novel bioconjugation strategies.
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Affiliation(s)
- Roos C W van Lier
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
| | - A Dowine de Bruijn
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
| | - Gerard Roelfes
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
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Nord C, Levenfors JJ, Bjerketorp J, Sahlberg C, Guss B, Öberg B, Broberg A. Antibacterial Isoquinoline Alkaloids from the Fungus Penicillium Spathulatum Em19. Molecules 2019; 24:E4616. [PMID: 31861067 DOI: 10.3390/molecules24244616] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 12/12/2019] [Accepted: 12/13/2019] [Indexed: 01/21/2023] Open
Abstract
In the search for new microbial antibacterial secondary metabolites, two new compounds (1 and 2) were isolated from culture broths of Penicillium spathulatum Em19. Structure determination by nuclear magnetic resonance and mass spectrometry identified the compounds as 6,7-dihydroxy-5,10-dihydropyrrolo[1,2-b]isoquinoline-3-carboxylic acid (1, spathullin A) and 5,10-dihydropyrrolo[1,2-b]isoquinoline-6,7-diol (2, spathullin B). The two compounds displayed activity against both Gram-negative and -positive bacteria, including Escherichia coli, Acinetobacter baumannii, Enterobacter cloacae, Klebsiella pneumonia, Pseudomonas aeruginosa, and Staphylococcus aureus. Compound 2 was more potent than 1 against all tested pathogens, with minimal inhibitory concentrations down to 1 µg/mL (5 µM) against S. aureus, but 2 was also more cytotoxic than 1 (50% inhibitory concentrations 112 and 11 µM for compounds 1 and 2, respectively, towards Huh7 cells). Based on stable isotope labelling experiments and a literature comparison, the biosynthesis of 1 was suggested to proceed from cysteine, tyrosine and methionine via a non-ribosomal peptides synthase like enzyme complex, whereas compound 2 was formed spontaneously from 1 by decarboxylation. Compound 1 was also easily oxidized to the 1,2-benzoquinone 3. Due to the instability of compound 1 and the toxicity of 2, the compounds are of low interest as possible future antibacterial drugs.
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Abstract
A mild, metal-free, regioselective carbofluorination of dehydroalanine derivatives has been developed. Alkyl radicals resulting from visible-light photoredox catalysis engage in a radical conjugate addition to dehydroalanine, with subsequent fluorination of the newly generated radical to afford an α-fluoro-α-amino acid. By using a highly oxidizing organic photocatalyst, this process incorporates non-stabilized primary, secondary, and tertiary alkyl radicals derived from commercially available alkyltrifluoroborates to furnish a wide range of fluorinated unnatural amino acids.
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Affiliation(s)
- Jaehoon Sim
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, United States
| | - Mark W. Campbell
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, United States
| | - Gary A. Molander
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, United States
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13
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Abstract
Dehydroalanine (Dha) and dehydrobutyrine (Dhb) are remarkably versatile non-canonical amino acids often found in antimicrobial peptides. This work presents the selective modification of Dha and Dhb in antimicrobial peptides through photocatalytic activation of organoborates under the influence of visible light. Ir(dF(CF3 )ppy)2 (dtbbpy)PF6 was used as a photoredox catalyst in aqueous solutions for the modification of thiostrepton and nisin. The mild conditions and high selectivity for the dehydrated residues show that photoredox catalysis is a promising tool for the modification of peptide-derived natural products.
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Affiliation(s)
- A. Dowine de Bruijn
- Stratingh Institute for ChemistryUniversity of GroningenNijenborgh 49747AGGroningenThe Netherlands
| | - Gerard Roelfes
- Stratingh Institute for ChemistryUniversity of GroningenNijenborgh 49747AGGroningenThe Netherlands
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de Bruijn AD, Roelfes G. Catalytic Modification of Dehydroalanine in Peptides and Proteins by Palladium-Mediated Cross-Coupling. Chemistry 2018; 24:12728-12733. [PMID: 29923249 PMCID: PMC6146911 DOI: 10.1002/chem.201802846] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 06/18/2018] [Indexed: 11/16/2022]
Abstract
Dehydroalanine (Dha) is a remarkably versatile non‐canonical amino acid often found in antimicrobial peptides. Herein, we present the catalytic modification of Dha by a palladium‐mediated cross‐coupling reaction. By using Pd(EDTA)(OAc)2 as water‐soluble catalyst, a variety of arylboronic acids was coupled to the dehydrated residues in proteins and peptides, such as Nisin. The cross‐coupling reaction gave both the Heck product, in which the sp2‐hybridisation of the α‐carbon is retained, as well as the conjugated addition product. The reaction can be performed under mild aqueous conditions, which makes this method an attractive addition to the palette of bio‐orthogonal catalytic methods.
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Affiliation(s)
- A Dowine de Bruijn
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747, AG, Groningen, The Netherlands
| | - Gerard Roelfes
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747, AG, Groningen, The Netherlands
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15
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Meledin R, Mali SM, Kleifeld O, Brik A. Activity-Based Probes Developed by Applying a Sequential Dehydroalanine Formation Strategy to Expressed Proteins Reveal a Potential α-Globin-Modulating Deubiquitinase. Angew Chem Int Ed Engl 2018. [PMID: 29527788 DOI: 10.1002/anie.201800032] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
We report a general and novel semisynthetic strategy for the preparation of ubiquitinated protein-activity-based probes on the basis of sequential dehydroalanine formation on expressed proteins. We applied this approach to construct a physiologically and therapeutically relevant ubiquitinated α-globin probe, which was used for the enrichment and proteomic identification of α-globin-modulating deubiquitinases. We found USP15 as a potential deubiquitinase for the modulation of α-globin, an excess of which aggravates β-thalassemia symptoms. This development opens new opportunities for activity-based-probe design to shed light on the important aspects underlying ubiquitination and deubiquitination in health and disease.
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Affiliation(s)
- Roman Meledin
- Schulich Faculty of Chemistry, Technion Israel Institute of Technology, Haifa, 3200008, Israel
| | - Sachitanand M Mali
- Schulich Faculty of Chemistry, Technion Israel Institute of Technology, Haifa, 3200008, Israel
| | - Oded Kleifeld
- Faculty of Biology, Technion Israel Institute of Technology, Haifa, 3200003, Israel
| | - Ashraf Brik
- Schulich Faculty of Chemistry, Technion Israel Institute of Technology, Haifa, 3200008, Israel
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16
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Meijer BM, Jang SM, Guerrera IC, Chhuon C, Lipecka J, Reisacher C, Baleux F, Sansonetti PJ, Muchardt C, Arbibe L. Threonine eliminylation by bacterial phosphothreonine lyases rapidly causes cross-linking of mitogen-activated protein kinase (MAPK) in live cells. J Biol Chem 2017; 292:7784-7794. [PMID: 28325837 DOI: 10.1074/jbc.m117.775940] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2016] [Revised: 03/21/2017] [Indexed: 11/06/2022] Open
Abstract
Old long-lived proteins contain dehydroalanine (Dha) and dehydrobutyrine (Dhb), two amino acids engendered by dehydration of serines and threonines, respectively. Although these residues have a suspected role in protein cross-linking and aggregation, their direct implication has yet to be determined. Here, we have taken advantage of the ability of the enteropathogen Shigella to convert the phosphothreonine residue of the pT-X-pY consensus sequence of ERK and p38 into Dhb and followed the impact of dehydration on the fate of the two MAPKs. To that end, we have generated the first antibodies recognizing Dhb-modified proteins and allowing tracing them as they form. We showed that Dhb modifications accumulate in a long-lasting manner in Shigella-infected cells, causing subsequent formation of covalent cross-links of MAPKs. Moreover, the Dhb signal correlates precisely with the activation of the Shigella type III secretion apparatus, thus evidencing injectisome activity. This observation is the first to document a causal link between Dhb formation and protein cross-linking in live cells. Detection of eliminylation is a new avenue to phosphoproteome regulation in eukaryotes that will be instrumental for the development of type III secretion inhibitors.
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Affiliation(s)
- Benoit M Meijer
- From the Team genomic plasticity and infection, Department of Immunology, Infectiology and Hematology, Institut Necker Enfants Malades, INSERM U1151, CNRS UMR 8253, 75993 Paris CEDEX 14, France.,the Université Paris Diderot, Sorbonne Paris Cité, Cellule Pasteur UPMC, 75724 Paris, France
| | - Suk Min Jang
- Institut Pasteur, Department of Biologie du Développement et Cellules Souches, Unité de Régulation Epigénétique, 75724 Paris CEDEX 15, France.,UMR3738 CNRS, 75732 Paris CEDEX 15, France
| | - Ida C Guerrera
- the Proteomic Platform Necker, PPN-3P5, Structure Fédérative de Recherche SFR Necker US24, 75015 Paris, France
| | - Cerina Chhuon
- the Proteomic Platform Necker, PPN-3P5, Structure Fédérative de Recherche SFR Necker US24, 75015 Paris, France
| | - Joanna Lipecka
- the Proteomic Platform Necker, PPN-3P5, Structure Fédérative de Recherche SFR Necker US24, 75015 Paris, France.,the CPN Proteomics Facility-3P5, Center of Psychiatry and Neuroscience, UMR INSERM 894, 75014 Paris, France
| | - Caroline Reisacher
- From the Team genomic plasticity and infection, Department of Immunology, Infectiology and Hematology, Institut Necker Enfants Malades, INSERM U1151, CNRS UMR 8253, 75993 Paris CEDEX 14, France
| | - Françoise Baleux
- the Unité de Chimie des Biomolécules, Institut Pasteur, 75015 Paris, France, and
| | - Philippe J Sansonetti
- the Unité de Pathogénie Microbienne Moléculaire, Unité INSERM U1202, Institut Pasteur, 75015 Paris, France
| | - Christian Muchardt
- Institut Pasteur, Department of Biologie du Développement et Cellules Souches, Unité de Régulation Epigénétique, 75724 Paris CEDEX 15, France.,UMR3738 CNRS, 75732 Paris CEDEX 15, France
| | - Laurence Arbibe
- From the Team genomic plasticity and infection, Department of Immunology, Infectiology and Hematology, Institut Necker Enfants Malades, INSERM U1151, CNRS UMR 8253, 75993 Paris CEDEX 14, France, .,Université Paris Descartes,75270 Paris CEDEX 06, France
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17
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Pilo AL, Peng Z, McLuckey SA. The dehydroalanine effect in the fragmentation of ions derived from polypeptides. J Mass Spectrom 2016; 51:857-866. [PMID: 27484024 PMCID: PMC5068825 DOI: 10.1002/jms.3831] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 07/27/2016] [Accepted: 07/28/2016] [Indexed: 05/11/2023]
Abstract
The fragmentation of peptides and proteins upon collision-induced dissociation (CID) is highly dependent on sequence and ion type (e.g. protonated, deprotonated, sodiated, odd electron, etc.). Some amino acids, for example aspartic acid and proline, have been found to enhance certain cleavages along the backbone. Here, we show that peptides and proteins containing dehydroalanine, a non-proteinogenic amino acid with an unsaturated side-chain, undergo enhanced cleavage of the N-Cα bond of the dehydroalanine residue to generate c- and z-ions. Because these fragment ion types are not commonly observed upon activation of positively charged even-electron species, they can be used to identify dehydroalanine residues and localize them within the peptide or protein chain. While dehydroalanine can be generated in solution, it can also be generated in the gas phase upon CID of various species. Oxidized S-alkyl cysteine residues generate dehydroalanine upon activation via highly efficient loss of the alkyl sulfenic acid. Asymmetric cleavage of disulfide bonds upon collisional activation of systems with limited proton mobility also generates dehydroalanine. Furthermore, we show that gas-phase ion/ion reactions can be used to facilitate the generation of dehydroalanine residues via, for example, oxidation of S-alkyl cysteine residues and conversion of multiply-protonated peptides to radical cations. In the latter case, loss of radical side-chains to generate dehydroalanine from some amino acids gives rise to the possibility for residue-specific backbone cleavage of polypeptide ions. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Alice L Pilo
- Department of Chemistry, Purdue University, West Lafayette, IN, 47907-2084, USA
| | - Zhou Peng
- Department of Chemistry, Purdue University, West Lafayette, IN, 47907-2084, USA
| | - Scott A McLuckey
- Department of Chemistry, Purdue University, West Lafayette, IN, 47907-2084, USA.
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18
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Kim HJ, Ha S, Lee HY, Lee KJ. ROSics: chemistry and proteomics of cysteine modifications in redox biology. Mass Spectrom Rev 2015; 34:184-208. [PMID: 24916017 PMCID: PMC4340047 DOI: 10.1002/mas.21430] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2012] [Revised: 04/30/2013] [Accepted: 11/20/2013] [Indexed: 05/29/2023]
Abstract
Post-translational modifications (PTMs) occurring in proteins determine their functions and regulations. Proteomic tools are available to identify PTMs and have proved invaluable to expanding the inventory of these tools of nature that hold the keys to biological processes. Cysteine (Cys), the least abundant (1-2%) of amino acid residues, are unique in that they play key roles in maintaining stability of protein structure, participating in active sites of enzymes, regulating protein function and binding to metals, among others. Cys residues are major targets of reactive oxygen species (ROS), which are important mediators and modulators of various biological processes. It is therefore necessary to identify the Cys-containing ROS target proteins, as well as the sites and species of their PTMs. Cutting edge proteomic tools which have helped identify the PTMs at reactive Cys residues, have also revealed that Cys residues are modified in numerous ways. These modifications include formation of disulfide, thiosulfinate and thiosulfonate, oxidation to sulfenic, sulfinic, sulfonic acids and thiosulfonic acid, transformation to dehydroalanine (DHA) and serine, palmitoylation and farnesylation, formation of chemical adducts with glutathione, 4-hydroxynonenal and 15-deoxy PGJ2, and various other chemicals. We present here, a review of relevant ROS biology, possible chemical reactions of Cys residues and details of the proteomic strategies employed for rapid, efficient and sensitive identification of diverse and novel PTMs involving reactive Cys residues of redox-sensitive proteins. We propose a new name, "ROSics," for the science which describes the principles of mode of action of ROS at molecular levels.
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Affiliation(s)
- Hee-Jung Kim
- Graduate School of Pharmaceutical Sciences, College of Pharmacy, Ewha Womans UniversitySeoul, 120-750, Korea
| | - Sura Ha
- Department of Chemistry, Korea Advanced Institute of Science & Technology (KAIST)Daejeon, 305-701, Korea
| | - Hee Yoon Lee
- Department of Chemistry, Korea Advanced Institute of Science & Technology (KAIST)Daejeon, 305-701, Korea
| | - Kong-Joo Lee
- Graduate School of Pharmaceutical Sciences, College of Pharmacy, Ewha Womans UniversitySeoul, 120-750, Korea
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19
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Jewgiński M, Krzciuk-Gula J, Makowski M, Latajka R, Kafarski P. Conformation of dehydropentapeptides containing four achiral amino acid residues - controlling the role of L-valine. Beilstein J Org Chem 2014; 10:660-6. [PMID: 24778717 PMCID: PMC3999861 DOI: 10.3762/bjoc.10.58] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Accepted: 02/05/2014] [Indexed: 12/01/2022] Open
Abstract
Structural studies of pentapeptides containing an achiral block, built from two dehydroamino acid residues (ΔZPhe and ΔAla) and two glycines, as well as one chiral L-Val residue were performed using NMR spectroscopy. The key role of the L-Val residue in the generation of the secondary structure of peptides is discussed. The obtained results suggest that the strongest influence on the conformation of peptides arises from a valine residue inserted at the C-terminal position. The most ordered conformation was found for peptide Boc-Gly-ΔAla-Gly-ΔZPhe-Val-OMe (3), which adopts a right-handed helical conformation.
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Affiliation(s)
- Michał Jewgiński
- Department of Bioorganic Chemistry, Faculty of Chemistry, Wrocław University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland
| | - Joanna Krzciuk-Gula
- Department of Bioorganic Chemistry, Faculty of Chemistry, Wrocław University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland
| | - Maciej Makowski
- Faculty of Chemistry, University of Opole, Oleska 48, 45-052 Opole, Poland
| | - Rafał Latajka
- Department of Bioorganic Chemistry, Faculty of Chemistry, Wrocław University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland
| | - Paweł Kafarski
- Department of Bioorganic Chemistry, Faculty of Chemistry, Wrocław University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland
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20
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Wang SK, Weaver JD, Zhang S, Lei XG. Knockout of SOD1 promotes conversion of selenocysteine to dehydroalanine in murine hepatic GPX1 protein. Free Radic Biol Med 2011; 51:197-204. [PMID: 21420488 PMCID: PMC3109192 DOI: 10.1016/j.freeradbiomed.2011.03.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Revised: 02/22/2011] [Accepted: 03/11/2011] [Indexed: 12/23/2022]
Abstract
Se-dependent glutathione peroxidase-1 (GPX1) and Cu,Zn-superoxide dismutase (SOD1) are two major intracellular antioxidant enzymes. The purpose of this study was to elucidate the biochemical mechanisms for the 40% loss of hepatic GPX1 activity in SOD1(-/-) mice. Compared with the wild type (WT), the SOD1(-/-) mice showed no change in the total amount of GPX1 protein. However, their total enzyme protein exhibited 31 and 38% decreases (P<0.05) in the apparent k(cat) for hydrogen peroxide and tert-butylperoxide (at 2mM GSH), respectively. Most striking, mass spectrometry revealed two chemical forms of the 47th residue of GPX1: the projected native selenocysteine (Sec) and the Se-lacking dehydroalanine (DHA). The hepatic GPX1 protein of the SOD1(-/-) mice contained 38% less Sec and 77% more DHA than that of WT and showed aggravated dissociation of the tetramer structure. In conclusion, knockout of SOD1 elevated the conversion of Sec to DHA in the active site of hepatic GPX1, leading to proportional decreases in the apparent k(cat) and activity of the enzyme protein as a whole. Our data reveal a structural and kinetic mechanism for the in vivo functional dependence of GPX1 on SOD1 in mammals and provide a novel mass spectrometric method for the assay of oxidative modification of the GPX1 protein.
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Affiliation(s)
- Shi Kui Wang
- Department of Animal Science, Cornell University, Ithaca, NY 14853, USA
| | - Jeremy D. Weaver
- Department of Animal Science, Cornell University, Ithaca, NY 14853, USA
| | - Sheng Zhang
- Department of Proteomics and Mass Spectrometry Core Facility, Cornell University, Ithaca, NY 14853, USA
| | - Xin Gen Lei
- Department of Animal Science, Cornell University, Ithaca, NY 14853, USA
- Contact information of the corresponding author: Dr. X. G. Lei, Professor, Department of Animal Science, Cornell University, Ithaca, NY 14853, USA, Tel: (607)-254-4703, Fax: (607)-255-9829,
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21
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Corpet DE, Yin Y, Zhang XM, Rémésy C, Stamp D, Medline A, Thompson L, Bruce WR, Archer MC. Colonic protein fermentation and promotion of colon carcinogenesis by thermolyzed casein. Nutr Cancer 1995; 23:271-81. [PMID: 7603887 PMCID: PMC2518970 DOI: 10.1080/01635589509514381] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Thermolyzed casein is known to promote the growth of aberrant crypt foci (ACF) and colon cancer when it is fed to rats that have been initiated with azoxymethane. We speculated that the promotion was a consequence of increased colonic protein fermentation (i.e., that the thermolysis of the casein decreases its digestibility, increases the amount of protein reaching the colon, and increases colonic protein fermentation and that the potentially toxic products of this fermentation promote colon carcinogenesis). We found that the thermolysis of casein reduces its digestibility and increases colonic protein fermentation, as assessed by fecal ammonium and urinary phenol, cresol, and indol-3-ol. Thermolysis of two other proteins, soy and egg white protein, also increases colonic protein fermentation with increased fecal ammonia and urinary phenols, and thermolysis of all three proteins increases the levels of ammonia and butyric, valeric, and i-valeric acids in the cecal contents. We found, however, that the increased protein fermentation observed with thermolysis is not associated with promotion of colon carcinogenesis. With casein, the kinetics of protein fermentation with increasing thermolysis time are clearly different from the kinetics of promotion of ACF growth. The formation of the fermentation products was highest when the protein was thermolyzed for one hour, whereas promotion was highest for protein that had been thermolyzed for two or more hours. With soy and egg white, thermolysis increased colonic protein fermentation but did not promote colon carcinogenesis. Thus, although thermolysis of dietary casein increases colonic protein fermentation, products of this fermentation do not appear to be responsible for the promotion of colon carcinogenesis. Indeed, the results suggest that protein fermentation products do not play an important role in colon cancer promotion.
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Affiliation(s)
- Denis E. Corpet
- XENOBIOTIQUES, Xénobiotiques
INRA : UR1089Ecole Nationale Vétérinaire de ToulouseFR
| | | | | | | | | | | | | | - W. R. Bruce
- Department of Nutritional Sciences
University of TorontoUniversity of Toronto, Toronto, Ontario M5S 3E2,CA
| | - M. C. Archer
- Department of Nutritional Sciences
University of TorontoUniversity of Toronto, Toronto, Ontario M5S 3E2,CA
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