1
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Yan Y, Shetty M, Harding HP, George G, Zyryanova A, Labbé K, Mafi A, Hao Q, Sidrauski C, Ron D. Substrate recruitment via eIF2γ enhances catalytic efficiency of a holophosphatase that terminates the integrated stress response. Proc Natl Acad Sci U S A 2024; 121:e2320013121. [PMID: 38547060 PMCID: PMC10998612 DOI: 10.1073/pnas.2320013121] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Accepted: 02/16/2024] [Indexed: 04/02/2024] Open
Abstract
Dephosphorylation of pSer51 of the α subunit of translation initiation factor 2 (eIF2αP) terminates signaling in the integrated stress response (ISR). A trimeric mammalian holophosphatase comprised of a protein phosphatase 1 (PP1) catalytic subunit, the conserved C-terminally located ~70 amino acid core of a substrate-specific regulatory subunit (PPP1R15A/GADD34 or PPP1R15B/CReP) and G-actin (an essential cofactor) efficiently dephosphorylate eIF2αP in vitro. Unlike their viral or invertebrate counterparts, with whom they share the conserved 70 residue core, the mammalian PPP1R15s are large proteins of more than 600 residues. Genetic and cellular observations point to a functional role for regions outside the conserved core of mammalian PPP1R15A in dephosphorylating its natural substrate, the eIF2 trimer. We have combined deep learning technology, all-atom molecular dynamics simulations, X-ray crystallography, and biochemistry to uncover binding of the γ subunit of eIF2 to a short helical peptide repeated four times in the functionally important N terminus of human PPP1R15A that extends past its conserved core. Binding entails insertion of Phe and Trp residues that project from one face of an α-helix formed by the conserved repeats of PPP1R15A into a hydrophobic groove exposed on the surface of eIF2γ in the eIF2 trimer. Replacing these conserved Phe and Trp residues with Ala compromises PPP1R15A function in cells and in vitro. These findings suggest mechanisms by which contacts between a distant subunit of eIF2 and elements of PPP1R15A distant to the holophosphatase active site contribute to dephosphorylation of eIF2αP by the core PPP1R15 holophosphatase and to efficient termination of the ISR in mammals.
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Affiliation(s)
- Yahui Yan
- Cambridge Institute for Medical Research, Department of Clinical Biochemistry, University of Cambridge, CambridgeCB2 0XY, United Kingdom
| | - Maithili Shetty
- Cambridge Institute for Medical Research, Department of Clinical Biochemistry, University of Cambridge, CambridgeCB2 0XY, United Kingdom
| | - Heather P. Harding
- Cambridge Institute for Medical Research, Department of Clinical Biochemistry, University of Cambridge, CambridgeCB2 0XY, United Kingdom
| | - Ginto George
- Cambridge Institute for Medical Research, Department of Clinical Biochemistry, University of Cambridge, CambridgeCB2 0XY, United Kingdom
| | - Alisa Zyryanova
- Cambridge Institute for Medical Research, Department of Clinical Biochemistry, University of Cambridge, CambridgeCB2 0XY, United Kingdom
| | | | | | - Qi Hao
- Calico Life Sciences, South San Francisco, CA94080
| | | | - David Ron
- Cambridge Institute for Medical Research, Department of Clinical Biochemistry, University of Cambridge, CambridgeCB2 0XY, United Kingdom
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2
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Wang JCK, Baddock HT, Mafi A, Foe IT, Bratkowski M, Lin TY, Jensvold ZD, Preciado López M, Stokoe D, Eaton D, Hao Q, Nile AH. Structure of the p53 degradation complex from HPV16. Nat Commun 2024; 15:1842. [PMID: 38418456 PMCID: PMC10902388 DOI: 10.1038/s41467-024-45920-w] [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: 05/04/2023] [Accepted: 02/06/2024] [Indexed: 03/01/2024] Open
Abstract
Human papillomavirus (HPV) is a significant contributor to the global cancer burden, and its carcinogenic activity is facilitated in part by the HPV early protein 6 (E6), which interacts with the E3-ligase E6AP, also known as UBE3A, to promote degradation of the tumor suppressor, p53. In this study, we present a single-particle cryoEM structure of the full-length E6AP protein in complex with HPV16 E6 (16E6) and p53, determined at a resolution of ~3.3 Å. Our structure reveals extensive protein-protein interactions between 16E6 and E6AP, explaining their picomolar binding affinity. These findings shed light on the molecular basis of the ternary complex, which has been pursued as a potential therapeutic target for HPV-driven cervical, anal, and oropharyngeal cancers over the last two decades. Understanding the structural and mechanistic underpinnings of this complex is crucial for developing effective therapies to combat HPV-induced cancers. Our findings may help to explain why previous attempts to disrupt this complex have failed to generate therapeutic modalities and suggest that current strategies should be reevaluated.
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Affiliation(s)
- John C K Wang
- Calico Life Sciences LLC, 1170 Veterans Blvd, South San Francisco, CA, 94080, USA
| | - Hannah T Baddock
- Calico Life Sciences LLC, 1170 Veterans Blvd, South San Francisco, CA, 94080, USA
| | - Amirhossein Mafi
- Calico Life Sciences LLC, 1170 Veterans Blvd, South San Francisco, CA, 94080, USA
| | - Ian T Foe
- Calico Life Sciences LLC, 1170 Veterans Blvd, South San Francisco, CA, 94080, USA
| | - Matthew Bratkowski
- Calico Life Sciences LLC, 1170 Veterans Blvd, South San Francisco, CA, 94080, USA
| | - Ting-Yu Lin
- Calico Life Sciences LLC, 1170 Veterans Blvd, South San Francisco, CA, 94080, USA
| | - Zena D Jensvold
- Calico Life Sciences LLC, 1170 Veterans Blvd, South San Francisco, CA, 94080, USA
| | | | - David Stokoe
- Calico Life Sciences LLC, 1170 Veterans Blvd, South San Francisco, CA, 94080, USA
| | - Dan Eaton
- Calico Life Sciences LLC, 1170 Veterans Blvd, South San Francisco, CA, 94080, USA
| | - Qi Hao
- Calico Life Sciences LLC, 1170 Veterans Blvd, South San Francisco, CA, 94080, USA.
| | - Aaron H Nile
- Calico Life Sciences LLC, 1170 Veterans Blvd, South San Francisco, CA, 94080, USA.
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3
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Ye X, Zhang P, Tao J, Wang JCK, Mafi A, Grob NM, Quartararo AJ, Baddock HT, Chan LJG, McAllister FE, Foe I, Loas A, Eaton DL, Hao Q, Nile AH, Pentelute BL. Discovery of reactive peptide inhibitors of human papillomavirus oncoprotein E6. Chem Sci 2023; 14:12484-12497. [PMID: 38020382 PMCID: PMC10646941 DOI: 10.1039/d3sc02782a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 08/22/2023] [Indexed: 12/01/2023] Open
Abstract
Human papillomavirus (HPV) infections account for nearly all cervical cancer cases, which is the fourth most common cancer in women worldwide. High-risk variants, including HPV16, drive tumorigenesis in part by promoting the degradation of the tumor suppressor p53. This degradation is mediated by the HPV early protein 6 (E6), which recruits the E3 ubiquitin ligase E6AP and redirects its activity towards ubiquitinating p53. Targeting the protein interaction interface between HPV E6 and E6AP is a promising modality to mitigate HPV-mediated degradation of p53. In this study, we designed a covalent peptide inhibitor, termed reactide, that mimics the E6AP LXXLL binding motif by selectively targeting cysteine 58 in HPV16 E6 with quantitative conversion. This reactide provides a starting point in the development of covalent peptidomimetic inhibitors for intervention against HPV-driven cancers.
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Affiliation(s)
- Xiyun Ye
- Department of Chemistry, Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge MA 02139 USA
| | - Peiyuan Zhang
- Department of Chemistry, Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge MA 02139 USA
| | - Jason Tao
- Department of Chemistry, Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge MA 02139 USA
| | - John C K Wang
- Calico Life Sciences LLC 1170 Veterans Boulevard South San Francisco CA 94080 USA
| | - Amirhossein Mafi
- Calico Life Sciences LLC 1170 Veterans Boulevard South San Francisco CA 94080 USA
| | - Nathalie M Grob
- Department of Chemistry, Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge MA 02139 USA
| | - Anthony J Quartararo
- Department of Chemistry, Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge MA 02139 USA
| | - Hannah T Baddock
- Calico Life Sciences LLC 1170 Veterans Boulevard South San Francisco CA 94080 USA
| | - Leanne J G Chan
- Calico Life Sciences LLC 1170 Veterans Boulevard South San Francisco CA 94080 USA
| | - Fiona E McAllister
- Calico Life Sciences LLC 1170 Veterans Boulevard South San Francisco CA 94080 USA
| | - Ian Foe
- Calico Life Sciences LLC 1170 Veterans Boulevard South San Francisco CA 94080 USA
| | - Andrei Loas
- Department of Chemistry, Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge MA 02139 USA
| | - Dan L Eaton
- Calico Life Sciences LLC 1170 Veterans Boulevard South San Francisco CA 94080 USA
| | - Qi Hao
- Calico Life Sciences LLC 1170 Veterans Boulevard South San Francisco CA 94080 USA
| | - Aaron H Nile
- Calico Life Sciences LLC 1170 Veterans Boulevard South San Francisco CA 94080 USA
| | - Bradley L Pentelute
- Department of Chemistry, Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge MA 02139 USA
- The Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology 500 Main Street Cambridge MA 02142 USA
- Center for Environmental Health Sciences, Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge MA 02139 USA
- Broad Institute of MIT and Harvard 415 Main Street Cambridge MA 02142 USA
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4
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Sridar J, Mafi A, Judge RA, Xu J, Kong KA, Wang JCK, Stoll VS, Koukos G, Simon RJ, Eaton D, Bratkowski M, Hao Q. Cryo-EM structure of human PAPP-A2 and mechanism of substrate recognition. Commun Chem 2023; 6:234. [PMID: 37898658 PMCID: PMC10613257 DOI: 10.1038/s42004-023-01032-y] [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: 05/05/2023] [Accepted: 10/18/2023] [Indexed: 10/30/2023] Open
Abstract
Pregnancy-Associated Plasma Protein A isoforms, PAPP-A and PAPP-A2, are metalloproteases that cleave insulin-like growth factor binding proteins (IGFBPs) to modulate insulin-like growth factor signaling. The structures of homodimeric PAPP-A in complex with IGFBP5 anchor peptide, and inhibitor proteins STC2 and proMBP have been recently reported. Here, we present the single-particle cryo-EM structure of the monomeric, N-terminal LG, MP, and the M1 domains (with the exception of LNR1/2) of human PAPP-A2 to 3.13 Å resolution. Our structure together with functional studies provides insight into a previously reported patient mutation that inactivates PAPP-A2 in a distal region of the protein. Using a combinational approach, we suggest that PAPP-A2 recognizes IGFBP5 in a similar manner as PAPP-A and show that PAPP-A2 cleaves IGFBP5 less efficiently due to differences in the M2 domain. Overall, our studies characterize the cleavage mechanism of IGFBP5 by PAPP-A2 and shed light onto key differences with its paralog PAPP-A.
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Affiliation(s)
- Janani Sridar
- Calico Life Sciences LLC, South San Francisco, CA, 94080, USA
| | | | | | - Jun Xu
- Calico Life Sciences LLC, South San Francisco, CA, 94080, USA
| | - Kailyn A Kong
- Calico Life Sciences LLC, South San Francisco, CA, 94080, USA
| | - John C K Wang
- Calico Life Sciences LLC, South San Francisco, CA, 94080, USA
| | | | - Georgios Koukos
- Calico Life Sciences LLC, South San Francisco, CA, 94080, USA
| | - Reyna J Simon
- Calico Life Sciences LLC, South San Francisco, CA, 94080, USA
| | - Dan Eaton
- Calico Life Sciences LLC, South San Francisco, CA, 94080, USA
| | | | - Qi Hao
- Calico Life Sciences LLC, South San Francisco, CA, 94080, USA.
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5
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Mafi A, Kim SK, Goddard WA. The dynamics of agonist-β 2-adrenergic receptor activation induced by binding of GDP-bound Gs protein. Nat Chem 2023:10.1038/s41557-023-01238-6. [PMID: 37349378 DOI: 10.1038/s41557-023-01238-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 05/12/2023] [Indexed: 06/24/2023]
Abstract
There is considerable uncertainty about the mechanism by which the β2-adrenergic receptor (β2AR) is activated. Here we use molecular metadynamics computations to predict the mechanism by which an agonist induces the activation of the β2AR and its cognate Gs protein. We found that binding agonist alone to the inactive β2AR does not break the ionic lock and hence does not drive the β2AR towards the activated conformation. However, we found that attaching the inactive Gs protein to the agonist-bound inactive β2AR (containing the ionic lock) leads to partial insertion of Gαs-α5 into the core of β2AR, which breaks the ionic lock, leading to activation of the Gs protein coupled to β2AR. Upon activation, the Gαs protein undergoes a remarkable opening of the GDP binding pocket, making the GDP available for exchange or release. Concomitantly, Gαs-α5 undergoes a remarkable expansion in the β2AR cytoplasmic region after the ionic lock is broken, inducing TM6 to displace outward by ~5 Å from TM3.
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Affiliation(s)
- Amirhossein Mafi
- Materials and Process Simulation Center, Caltech, Pasadena, CA, USA
- California Institute of Technology, Pasadena, CA, USA
| | - Soo-Kyung Kim
- Materials and Process Simulation Center, Caltech, Pasadena, CA, USA
- California Institute of Technology, Pasadena, CA, USA
| | - William A Goddard
- Materials and Process Simulation Center, Caltech, Pasadena, CA, USA.
- California Institute of Technology, Pasadena, CA, USA.
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6
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Nag A, Mafi A, Das S, Yu MB, Alvarez-Villalonga B, Kim SK, Su Y, Goddard WA, Heath JR. Stereochemical engineering yields a multifunctional peptide macrocycle inhibitor of Akt2 by fine-tuning macrocycle-cell membrane interactions. Commun Chem 2023; 6:95. [PMID: 37202473 DOI: 10.1038/s42004-023-00890-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 04/26/2023] [Indexed: 05/20/2023] Open
Abstract
Macrocycle peptides are promising constructs for imaging and inhibiting extracellular, and cell membrane proteins, but their use for targeting intracellular proteins is typically limited by poor cell penetration. We report the development of a cell-penetrant high-affinity peptide ligand targeted to the phosphorylated Ser474 epitope of the (active) Akt2 kinase. This peptide can function as an allosteric inhibitor, an immunoprecipitation reagent, and a live cell immunohistochemical staining reagent. Two cell penetrant stereoisomers were prepared and shown to exhibit similar target binding affinities and hydrophobic character but 2-3-fold different rates of cell penetration. Experimental and computational studies resolved that the ligands' difference in cell penetration could be assigned to their differential interactions with cholesterol in the membrane. These results expand the tool kit for designing new chiral-based cell-penetrant ligands.
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Affiliation(s)
- Arundhati Nag
- California Institute of Technology, Pasadena, CA, USA
- Clark University, Worcester, MA, USA
| | - Amirhossein Mafi
- Materials and Process Simulation Center (139-74), California Institute of Technology, Pasadena, CA, USA
| | - Samir Das
- California Institute of Technology, Pasadena, CA, USA
- Clark University, Worcester, MA, USA
| | - Mary Beth Yu
- California Institute of Technology, Pasadena, CA, USA
| | | | - Soo-Kyung Kim
- Materials and Process Simulation Center (139-74), California Institute of Technology, Pasadena, CA, USA
| | - Yapeng Su
- California Institute of Technology, Pasadena, CA, USA
- Institute for Systems Biology, Seattle, WA, USA
| | - William A Goddard
- Materials and Process Simulation Center (139-74), California Institute of Technology, Pasadena, CA, USA
| | - James R Heath
- California Institute of Technology, Pasadena, CA, USA.
- Institute for Systems Biology, Seattle, WA, USA.
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7
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Sharma VK, Yang X, Kim SK, Mafi A, Saiz-Sanchez D, Villanueva-Anguita P, Xiao L, Inoue A, Goddard WA, Loh YP, Toulabi L. Correction to: Novel interaction between neurotrophic factor-α1/carboxypeptidase E and serotonin receptor, 5-HTR1E, protects human neurons against oxidative/neuroexcitotoxic stress via β-arrestin/ERK signaling. Cell Mol Life Sci 2023; 80:65. [PMID: 36808009 PMCID: PMC9941249 DOI: 10.1007/s00018-023-04711-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/26/2023] [Indexed: 02/23/2023]
Affiliation(s)
- Vinay Kumar Sharma
- Section on Cellular Neurobiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, 49, Convent Drive, Bldg 49, Rm 6A-10, Bethesda, MD 20892 USA
| | - Xuyu Yang
- Section on Cellular Neurobiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, 49, Convent Drive, Bldg 49, Rm 6A-10, Bethesda, MD 20892 USA
| | - Soo-Kyung Kim
- Materials and Process Simulation Center, California Institute of Technology, Pasedena, CA 91125 USA
| | - Amirhossein Mafi
- Materials and Process Simulation Center, California Institute of Technology, Pasedena, CA 91125 USA
| | - Daniel Saiz-Sanchez
- Neuroplasticity and Neurodegeneration Laboratory, Medical School, Regional Center for Biomedical Research, University of Castilla-La Mancha, 13071 Ciudad Real, Spain
| | - Patricia Villanueva-Anguita
- Neuroplasticity and Neurodegeneration Laboratory, Medical School, Regional Center for Biomedical Research, University of Castilla-La Mancha, 13071 Ciudad Real, Spain
| | - Lan Xiao
- Section on Cellular Neurobiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, 49, Convent Drive, Bldg 49, Rm 6A-10, Bethesda, MD 20892 USA
| | - Asuka Inoue
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi 980-8578 Japan
| | - William A. Goddard
- Materials and Process Simulation Center, California Institute of Technology, Pasedena, CA 91125 USA
| | - Y. Peng Loh
- Section on Cellular Neurobiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, 49, Convent Drive, Bldg 49, Rm 6A-10, Bethesda, MD 20892 USA
| | - Leila Toulabi
- Section on Cellular Neurobiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, 49, Convent Drive, Bldg 49, Rm 6A-10, Bethesda, MD 20892 USA
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8
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Judge RA, Sridar J, Tunyasuvunakool K, Jain R, Wang JCK, Ouch C, Xu J, Mafi A, Nile AH, Remarcik C, Smith CL, Ghosh C, Xu C, Stoll V, Jumper J, Singh AH, Eaton D, Hao Q. Author Correction: Structure of the PAPP-A BP5 complex reveals mechanism of substrate recognition. Nat Commun 2022; 13:5694. [PMID: 36171222 PMCID: PMC9519949 DOI: 10.1038/s41467-022-33522-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Affiliation(s)
| | - Janani Sridar
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | | | - Rinku Jain
- AbbVie, 1 North Waukegan Road, North Chicago, IL, USA
| | - John C K Wang
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | - Christna Ouch
- Department of Biochemistry & Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Jun Xu
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | | | - Aaron H Nile
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | | | | | - Crystal Ghosh
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | - Chen Xu
- Department of Biochemistry & Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Vincent Stoll
- AbbVie, 1 North Waukegan Road, North Chicago, IL, USA
| | | | - Amoolya H Singh
- Calico Life Sciences LLC, South San Francisco, CA, USA.,GRAIL, Menlo Park, CA, USA
| | - Dan Eaton
- Calico Life Sciences LLC, South San Francisco, CA, USA.
| | - Qi Hao
- Calico Life Sciences LLC, South San Francisco, CA, USA.
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9
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Judge RA, Sridar J, Tunyasunvunakool K, Jain R, Wang JCK, Ouch C, Xu J, Mafi A, Nile AH, Remarcik C, Smith CL, Ghosh C, Xu C, Stoll V, Jumper J, Singh AH, Eaton D, Hao Q. Structure of the PAPP-A BP5 complex reveals mechanism of substrate recognition. Nat Commun 2022; 13:5500. [PMID: 36127359 PMCID: PMC9489782 DOI: 10.1038/s41467-022-33175-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 09/03/2022] [Indexed: 11/09/2022] Open
Abstract
Insulin-like growth factor (IGF) signaling is highly conserved and tightly regulated by proteases including Pregnancy-Associated Plasma Protein A (PAPP-A). PAPP-A and its paralog PAPP-A2 are metalloproteases that mediate IGF bioavailability through cleavage of IGF binding proteins (IGFBPs). Here, we present single-particle cryo-EM structures of the catalytically inactive mutant PAPP-A (E483A) in complex with a peptide from its substrate IGFBP5 (PAPP-ABP5) and also in its substrate-free form, by leveraging the power of AlphaFold to generate a high quality predicted model as a starting template. We show that PAPP-A is a flexible trans-dimer that binds IGFBP5 via a 25-amino acid anchor peptide which extends into the metalloprotease active site. This unique IGFBP5 anchor peptide that mediates the specific PAPP-A-IGFBP5 interaction is not found in other PAPP-A substrates. Additionally, we illustrate the critical role of the PAPP-A central domain as it mediates both IGFBP5 recognition and trans-dimerization. We further demonstrate that PAPP-A trans-dimer formation and distal inter-domain interactions are both required for efficient proteolysis of IGFBP4, but dispensable for IGFBP5 cleavage. Together the structural and biochemical studies reveal the mechanism of PAPP-A substrate binding and selectivity.
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Affiliation(s)
| | - Janani Sridar
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | | | - Rinku Jain
- AbbVie, 1 North Waukegan Road, North Chicago, IL, USA
| | - John C K Wang
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | - Christna Ouch
- Department of Biochemistry & Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Jun Xu
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | | | - Aaron H Nile
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | | | | | - Crystal Ghosh
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | - Chen Xu
- Department of Biochemistry & Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Vincent Stoll
- AbbVie, 1 North Waukegan Road, North Chicago, IL, USA
| | | | - Amoolya H Singh
- Calico Life Sciences LLC, South San Francisco, CA, USA.,GRAIL, Menlo Park, CA, USA
| | - Dan Eaton
- Calico Life Sciences LLC, South San Francisco, CA, USA.
| | - Qi Hao
- Calico Life Sciences LLC, South San Francisco, CA, USA.
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10
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Abstract
G protein–coupled receptors (GPCRs) activate cellular responses ranging from odorants to neurotransmitters. Binding an agonist leads to activation of a heterotrimeric G protein (GP) that stimulates external signaling. Unfortunately, the mechanism remains unknown. We show for 15 class A GPCRs, including opioids, adrenergics, adenosines, chemokines, muscarinics, cannabinoids, serotonins, and dopamines, that interaction of an inactive GP, including Gs, Gi, Go, G11, and Gq, to the inactive GPCR, containing the intracellular ionic lock between transmembrane (TM) helices 3 and 6, evolves exothermically to form a precoupled GPCR-GP complex with an opened TM3-TM6 and the GP-α5 helix partially inserted into the GPCR but not activated. We show that binding of agonist to this precoupled GPCR-GP complex causes the Gα protein to open into its active form, with the guanosine diphosphate exposed for signaling. This GP-first paradigm provides a strategy for developing selective agonists for GPCRs since it is the pharmacophore for the precoupled GPCR-GP complex that should be used to design drugs.
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Affiliation(s)
- Amirhossein Mafi
- Materials and Process Simulation Center, California Institute of Technology, Pasadena, CA 91125
| | - Soo-Kyung Kim
- Materials and Process Simulation Center, California Institute of Technology, Pasadena, CA 91125
| | - William A. Goddard
- Materials and Process Simulation Center, California Institute of Technology, Pasadena, CA 91125
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11
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Sharma VK, Yang X, Kim SK, Mafi A, Saiz-Sanchez D, Villanueva-Anguita P, Xiao L, Inoue A, Goddard WA, Loh YP. Novel interaction between neurotrophic factor-α1/carboxypeptidase E and serotonin receptor, 5-HTR1E, protects human neurons against oxidative/neuroexcitotoxic stress via β-arrestin/ERK signaling. Cell Mol Life Sci 2021; 79:24. [PMID: 34966948 PMCID: PMC8732845 DOI: 10.1007/s00018-021-04021-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [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: 07/26/2021] [Revised: 10/14/2021] [Accepted: 11/01/2021] [Indexed: 12/18/2022]
Abstract
Protecting neurons from death during oxidative and neuroexcitotoxic stress is key for preventing cognitive dysfunction. We uncovered a novel neuroprotective mechanism involving interaction between neurotrophic factor-α1 (NF-α1/carboxypeptidase E, CPE) and human 5-HTR1E, a G protein-coupled serotonin receptor with no previously known neurological function. Co-immunoprecipitation and pull-down assays confirmed interaction between NFα1/CPE and 5-HTR1E and 125I NF-α1/CPE-binding studies demonstrated saturable, high-affinity binding to 5-HTR1E in stably transfected HEK293 cells (Kd = 13.82 nM). Treatment of 5-HTR1E stable cells with NF-α1/CPE increased pERK 1/2 and pCREB levels which prevented a decrease in pro-survival protein, BCL2, during H2O2-induced oxidative stress. Cell survival assay in β-arrestin Knockout HEK293 cells showed that the NF-α1/CPE-5-HTR1E-mediated protection against oxidative stress was β-arrestin-dependent. Molecular dynamics studies revealed that NF-α1/CPE interacts with 5-HTR1E via 3 salt bridges, stabilized by several hydrogen bonds, independent of the serotonin pocket. Furthermore, after phosphorylating the C-terminal tail and intracellular loop 3 (ICL3) of NF-α1/CPE-5-HTR1E, it recruited β-arrestin1 by forming numerous salt bridges and hydrogen bonds to ICL2 and ICL3, leading to activation of β-arrestin1. Immunofluorescence studies showed 5-HTR1E and NF-α1/CPE are highly expressed and co-localized on cell surface of human hippocampal neurons. Importantly, knock-down of 5-HTR1E in human primary neurons diminished the NF-α1/CPE-mediated protection of these neurons against oxidative stress and glutamate neurotoxicity-induced cell death. Thus, NF-α1/CPE uniquely interacts with serotonin receptor 5-HTR1E to activate the β-arrestin/ERK/CREB/BCL2 pathway to mediate stress-induced neuroprotection.
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Affiliation(s)
- Vinay Kumar Sharma
- Section on Cellular Neurobiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, 49, Convent Drive, Bldg 49, Rm 6A-10, Bethesda, MD, 20892, USA
| | - Xuyu Yang
- Section on Cellular Neurobiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, 49, Convent Drive, Bldg 49, Rm 6A-10, Bethesda, MD, 20892, USA
| | - Soo-Kyung Kim
- Materials and Process Simulation Center, California Institute of Technology, Pasedena, CA, 91125, USA
| | - Amirhossein Mafi
- Materials and Process Simulation Center, California Institute of Technology, Pasedena, CA, 91125, USA
| | - Daniel Saiz-Sanchez
- Neuroplasticity and Neurodegeneration Laboratory, Medical School, Regional Center for Biomedical Research, University of Castilla-La Mancha, 13071, Ciudad Real, Spain
| | - Patricia Villanueva-Anguita
- Neuroplasticity and Neurodegeneration Laboratory, Medical School, Regional Center for Biomedical Research, University of Castilla-La Mancha, 13071, Ciudad Real, Spain
| | - Lan Xiao
- Section on Cellular Neurobiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, 49, Convent Drive, Bldg 49, Rm 6A-10, Bethesda, MD, 20892, USA
| | - Asuka Inoue
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi, 980-8578, Japan
| | - William A Goddard
- Materials and Process Simulation Center, California Institute of Technology, Pasedena, CA, 91125, USA.
| | - Y Peng Loh
- Section on Cellular Neurobiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, 49, Convent Drive, Bldg 49, Rm 6A-10, Bethesda, MD, 20892, USA.
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12
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Cheng YS, Zhang T, Ma X, Pratuangtham S, Zhang GC, Ondrus AA, Mafi A, Lomenick B, Jones JJ, Ondrus AE. A proteome-wide map of 20(S)-hydroxycholesterol interactors in cell membranes. Nat Chem Biol 2021; 17:1271-1280. [PMID: 34799735 PMCID: PMC8607797 DOI: 10.1038/s41589-021-00907-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 09/25/2021] [Indexed: 12/28/2022]
Abstract
Oxysterols (OHCs) are hydroxylated cholesterol metabolites that play ubiquitous roles in health and disease. Due to the non-covalent nature of their interactions and their unique partitioning in membranes, the analysis of live-cell, proteome-wide interactions of OHCs remains an unmet challenge. Here, we present a structurally precise chemoproteomics probe for the biologically active molecule 20(S)-hydroxycholesterol (20(S)-OHC) and provide a map of its proteome-wide targets in the membranes of living cells. Our target catalog consolidates diverse OHC ontologies and demonstrates that OHC-interacting proteins cluster with specific processes in immune response and cancer. Competition experiments reveal that 20(S)-OHC is a chemo-, regio- and stereoselective ligand for the protein transmembrane protein 97 (Tmem97/the σ2 receptor), enabling us to reconstruct the 20(S)-OHC-Tmem97 binding site. Our results demonstrate that multiplexed, quantitative analysis of cellular target engagement can expose new dimensions of metabolite activity and identify actionable targets for molecular therapy.
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Affiliation(s)
- Yu-Shiuan Cheng
- Department of Chemistry, Division of Chemistry & Chemical Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Tianyi Zhang
- Department of Chemistry, Division of Chemistry & Chemical Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Xiang Ma
- Department of Chemistry, Division of Chemistry & Chemical Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Sarida Pratuangtham
- Department of Chemistry, Division of Chemistry & Chemical Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Grace C Zhang
- Department of Chemistry, Division of Chemistry & Chemical Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Alexander A Ondrus
- Mathematics Department, Northern Alberta Institute of Technology, Edmonton, Alberta, Canada
| | - Amirhossein Mafi
- Department of Chemistry, Division of Chemistry & Chemical Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Brett Lomenick
- Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, Pasadena, CA, USA
| | - Jeffrey J Jones
- Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, Pasadena, CA, USA
| | - Alison E Ondrus
- Department of Chemistry, Division of Chemistry & Chemical Engineering, California Institute of Technology, Pasadena, CA, USA.
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13
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Mafi A, Kim SK, Chou KC, Güthrie B, Goddard WA. Predicted Structure of Fully Activated Tas1R3/1R3' Homodimer Bound to G Protein and Natural Sugars: Structural Insights into G Protein Activation by a Class C Sweet Taste Homodimer with Natural Sugars. J Am Chem Soc 2021; 143:16824-16838. [PMID: 34585929 DOI: 10.1021/jacs.1c08839] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The Tas1R3 G protein-coupled receptor constitutes the main component of sweet taste sensory response in humans via forming a heterodimer with Tas1R2 or a homodimer with Tas1R3. The Tas1R3/1R3' homodimer serves as a low-affinity sweet taste receptor, stimulating gustducin G protein (GGust) signaling in the presence of a high concentration of natural sugars. This provides an additional means to detect the taste of natural sugars, thereby differentiating the flavors between natural sugars and artificial sweeteners. We report here the predicted 3D structure of active state Tas1R3/1R3' homodimer complexed with heterotrimeric GGust and sucrose. We discovered that the GGust makes ionic anchors to intracellular loops 1 and 2 of Tas1R3 while the Gα-α5 helix engages the cytoplasmic region extensively through salt bridge and hydrophobic interactions. We show that in the activation of this complex the Venus flytrap domains of the homodimer undergo a remarkable twist up to ∼100° rotation around the vertical axis to adopt a closed-closed conformation while the intracellular region relaxes to an open-open conformation. We find that binding of sucrose to the homodimer stabilizes a preactivated conformation with a largely open intracellular region that recruits and activates the GGust. Upon activation, the Gα subunit spontaneously opens up the nucleotide-binding site, making nucleotide exchange facile for signaling. This activation of GGust promotes the interdomain twist of the Venus flytrap domains. These structures and transformations could potentially be a basis for the design of new sweeteners with higher activity and less unpleasant flavors.
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Affiliation(s)
- Amirhossein Mafi
- Materials and Process Simulation Center (139-74), California Institute of Technology, Pasadena, California 91125, United States
| | - Soo-Kyung Kim
- Materials and Process Simulation Center (139-74), California Institute of Technology, Pasadena, California 91125, United States
| | - Keng C Chou
- Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
| | - Brian Güthrie
- Cargill Global Food Research, Wayzata, Minnesota 55391, United States
| | - William A Goddard
- Materials and Process Simulation Center (139-74), California Institute of Technology, Pasadena, California 91125, United States
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14
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Mafi A, Purohit R, Vielmas E, Lauinger AR, Lam B, Cheng YS, Zhang T, Huang Y, Kim SK, Goddard WA, Ondrus AE. Hedgehog proteins create a dynamic cholesterol interface. PLoS One 2021; 16:e0246814. [PMID: 33630857 PMCID: PMC7906309 DOI: 10.1371/journal.pone.0246814] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 01/26/2021] [Indexed: 12/27/2022] Open
Abstract
During formation of the Hedgehog (Hh) signaling proteins, cooperative activities of the Hedgehog INTein (Hint) fold and Sterol Recognition Region (SRR) couple autoproteolysis to cholesterol ligation. The cholesteroylated Hh morphogens play essential roles in embryogenesis, tissue regeneration, and tumorigenesis. Despite the centrality of cholesterol in Hh function, the full structure of the Hint-SRR ("Hog") domain that attaches cholesterol to the last residue of the active Hh morphogen remains enigmatic. In this work, we combine molecular dynamics simulations, photoaffinity crosslinking, and mutagenesis assays to model cholesterolysis intermediates in the human Sonic Hedgehog (hSHH) protein. Our results provide evidence for a hydrophobic Hint-SRR interface that forms a dynamic, non-covalent cholesterol-Hog complex. Using these models, we suggest a unified mechanism by which Hh proteins can recruit, sequester, and orient cholesterol, and offer a molecular basis for the effects of disease-causing hSHH mutations.
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Affiliation(s)
- Amirhossein Mafi
- Department of Chemistry, Division of Chemistry & Chemical Engineering, California Institute of Technology, Pasadena, California, United States of America
| | - Rahul Purohit
- Department of Chemistry, Division of Chemistry & Chemical Engineering, California Institute of Technology, Pasadena, California, United States of America
| | - Erika Vielmas
- Department of Chemistry, Division of Chemistry & Chemical Engineering, California Institute of Technology, Pasadena, California, United States of America
| | - Alexa R. Lauinger
- Department of Chemistry, Division of Chemistry & Chemical Engineering, California Institute of Technology, Pasadena, California, United States of America
| | - Brandon Lam
- Department of Chemistry, Division of Chemistry & Chemical Engineering, California Institute of Technology, Pasadena, California, United States of America
| | - Yu-Shiuan Cheng
- Department of Chemistry, Division of Chemistry & Chemical Engineering, California Institute of Technology, Pasadena, California, United States of America
| | - Tianyi Zhang
- Department of Chemistry, Division of Chemistry & Chemical Engineering, California Institute of Technology, Pasadena, California, United States of America
| | - Yiran Huang
- Department of Chemistry, Division of Chemistry & Chemical Engineering, California Institute of Technology, Pasadena, California, United States of America
| | - Soo-Kyung Kim
- Department of Chemistry, Division of Chemistry & Chemical Engineering, California Institute of Technology, Pasadena, California, United States of America
| | - William A. Goddard
- Department of Chemistry, Division of Chemistry & Chemical Engineering, California Institute of Technology, Pasadena, California, United States of America
- * E-mail: (AEO); (WAG)
| | - Alison E. Ondrus
- Department of Chemistry, Division of Chemistry & Chemical Engineering, California Institute of Technology, Pasadena, California, United States of America
- * E-mail: (AEO); (WAG)
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15
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Soniat M, Tesfaye M, Mafi A, Brooks DJ, Humphrey ND, Weng L, Merinov B, Goddard WA, Weber AZ, Houle FA. Permeation of CO
2
and N
2
through glassy poly(dimethyl phenylene) oxide under steady‐ and presteady‐state conditions. Journal of Polymer Science 2020. [DOI: 10.1002/pol.20200053] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Marielle Soniat
- Joint Center for Artificial PhotosynthesisLawrence Berkeley National Laboratory Berkeley California
- Chemical Sciences DivisionLawrence Berkeley National Laboratory Berkeley California
| | - Meron Tesfaye
- Energy Storage and Distributed Resources DivisionLawrence Berkeley National Laboratory Berkeley California
- Department of Chemical and Biomolecular EngineeringUniversity of California Berkeley California
| | - Amirhossein Mafi
- Materials and Process Simulation Center (MSC), Beckman InstituteCalifornia Institute of Technology Pasadena California
| | - Daniel J. Brooks
- Materials and Process Simulation Center (MSC), Beckman InstituteCalifornia Institute of Technology Pasadena California
| | - Nicholas D. Humphrey
- Materials and Process Simulation Center (MSC), Beckman InstituteCalifornia Institute of Technology Pasadena California
| | - Lien‐Chun Weng
- Joint Center for Artificial PhotosynthesisLawrence Berkeley National Laboratory Berkeley California
- Department of Chemical and Biomolecular EngineeringUniversity of California Berkeley California
| | - Boris Merinov
- Materials and Process Simulation Center (MSC), Beckman InstituteCalifornia Institute of Technology Pasadena California
| | - William A. Goddard
- Materials and Process Simulation Center (MSC), Beckman InstituteCalifornia Institute of Technology Pasadena California
| | - Adam Z. Weber
- Joint Center for Artificial PhotosynthesisLawrence Berkeley National Laboratory Berkeley California
- Energy Storage and Distributed Resources DivisionLawrence Berkeley National Laboratory Berkeley California
| | - Frances A. Houle
- Joint Center for Artificial PhotosynthesisLawrence Berkeley National Laboratory Berkeley California
- Chemical Sciences DivisionLawrence Berkeley National Laboratory Berkeley California
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16
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Mafi A, Abbina S, Kalathottukaren MT, Morrissey JH, Haynes C, Kizhakkedathu JN, Pfaendtner J, Chou KC. Design of Polyphosphate Inhibitors: A Molecular Dynamics Investigation on Polyethylene Glycol-Linked Cationic Binding Groups. Biomacromolecules 2018. [PMID: 29539260 DOI: 10.1021/acs.biomac.8b00327] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Inorganic polyphosphate (polyP) released by human platelets has recently been shown to activate blood clotting and identified as a potential target for the development of novel antithrombotics. Recent studies have shown that polymers with cationic binding groups (CBGs) inhibit polyP and attenuate thrombosis. However, a good molecular-level understanding of the binding mechanism is lacking for further drug development. While molecular dynamics (MD) simulation can provide molecule-level information, the time scale required to simulate these large biomacromolecules makes classical MD simulation impractical. To overcome this challenge, we employed metadynamics simulations with both all-atom and coarse-grained force fields. The force field parameters for polyethylene glycol (PEG) conjugated CBGs and polyP were developed to carry out coarse-grained MD simulations, which enabled simulations of these large biomacromolecules in a reasonable time scale. We found that the length of the PEG tail does not impact the interaction between the (PEG) n-CBG and polyP. As expected, increasing the number of the charged tertiary amine groups in the head group strengthens its binding to polyP. Our simulation shows that (PEG) n-CBG initially form aggregates, mostly with the PEG in the core and the hydrophilic CBG groups pointing toward water; then the aggregates approach the polyP and sandwich the polyP to form a complex. We found that the binding of (PEG) n-CBG remains intact against various lengths of polyP. Binding thermodynamics for two of the (PEG) n-CBG/polyP systems simulated were measured by isothermal titration calorimetry to confirm the key finding of the simulations that the length PEG tail does not influence ligand binding to polyP.
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Affiliation(s)
- Amirhossein Mafi
- Department of Chemistry , University of British Columbia , Vancouver , BC V6T 1Z1 , Canada
| | | | | | - James H Morrissey
- Department of Biological Chemistry , University of Michigan Medical School , Ann Arbor , Michigan 48109 , United States
| | | | | | - Jim Pfaendtner
- Department of Chemical Engineering , University of Washington , Seattle , Washington 98195 , United States
| | - Keng C Chou
- Department of Chemistry , University of British Columbia , Vancouver , BC V6T 1Z1 , Canada
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17
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Abstract
The mechanism of complex formation between surfactants and polyelectrolytes with the same charge on the water surface was investigated using molecular dynamics simulations and phase-sensitive sum-frequency generation vibrational spectroscopy. Although complex formation between highly charged surfactants and polyelectrolytes of the same charge is generally expected to be prohibited by the electrostatic repulsive force, our study shows that it is possible to form thermodynamically stable complexes when excess ions are present in the solution. We found that anionic partially hydrolyzed polyacrylamide (HPAM) could interact with anionic sodium dodecyl sulfate (SDS) on a water surface in the presence of salts. With excess Na+ ions in the solution, the charge screening effect allows HPAM to weakly interact with SDS via hydrogen bonds. In the presence of divalent Ca2+ ions, the surfactant and the polymer are strongly coupled by forming Ca2+ ion bridges and hydrogen bonds. Our calculation shows that the presence of Ca2+ ions creates a steep binding energy of ∼30 kJ/mol near the water surface. These results were qualitatively verified using phase-sensitive sum-frequency generation vibrational spectroscopy.
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Affiliation(s)
- Amirhossein Mafi
- Department of Chemistry, University of British Columbia , Vancouver, British Columbia V6T 1Z1, Canada
- Department of Chemical and Biological Engineering, University of British Columbia , Vancouver, British Columbia V6T 1Z3, Canada
| | - Dan Hu
- Department of Chemistry, University of British Columbia , Vancouver, British Columbia V6T 1Z1, Canada
| | - Keng C Chou
- Department of Chemistry, University of British Columbia , Vancouver, British Columbia V6T 1Z1, Canada
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18
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Hajjeh R, Mafi A. The growing threat of antibiotic resistance in the Eastern Mediterranean Region - what does it take to control it? East Mediterr Health J 2016; 22:701-702. [PMID: 27966773 DOI: 10.26719/2016.22.9.701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- R Hajjeh
- Department of Communicable Diseases Control and Prevention, WHO Regional Office for the Eastern Mediterranean, Cairo, Egypt
| | - A Mafi
- Department of Communicable Diseases Control and Prevention, WHO Regional Office for the Eastern Mediterranean, Cairo, Egypt
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19
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Abstract
We carried out a combined study using surface tension, phase-sensitive frequency generation (SFG) vibrational spectroscopy, and MD simulations to investigate the industrially relevant zwitterionic surfactant N-dodecyl-N, N-dimethyl-3-ammonio-1-propanesulfonate (DDAPS) on water surface. The SFG Im(χ(2)) spectra showed that the interaction between DDAPS and water was different from those between biologically relevant zwitterionic phospholipids and water. While zwitterionic phospholipids were found to be anionic-like and flipped water molecules with their OHs pointing toward the air, DDAPS oriented water molecules with their OHs mostly pointing toward the liquid water. We built a new force field for the MD simulation which produced the correct surface tension of water with various DDPAS coverage. The MD simulation showed that the head groups of DDPAS were nearly parallel to the water surface. When the surface coverage of DDPAS was increased, the averaged tilting angle of DDPAS's tails decreased, but it had little effect on the orientation of the headgroup. The sulfobetaine zwitterionic surfactant was found to be more cationic-like because the positively charged group was more capable of orienting interfacial water.
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Affiliation(s)
- Amirhossein Mafi
- Department of Chemistry, University of British Columbia , Vancouver, BC V6T 1Z1, Canada
- Department of Chemical and Biological Engineering, University of British Columbia , Vancouver, BC V6T 1Z3, Canada
| | - Dan Hu
- Department of Chemistry, University of British Columbia , Vancouver, BC V6T 1Z1, Canada
| | - Keng C Chou
- Department of Chemistry, University of British Columbia , Vancouver, BC V6T 1Z1, Canada
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20
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Affiliation(s)
- Dan Hu
- Department
of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Amirhossein Mafi
- Department
of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Department
of Chemical and Biological Engineering, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Keng C. Chou
- Department
of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
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21
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Mounts A, De La Rocque S, Fitzner J, Garcia E, Thomas H, Brown D, Schuster H, Vandemaele K, Esmat H, Eremin S, Mafi A. The early response to a novel coronavirus in the Middle East. East Mediterr Health J 2013. [DOI: 10.26719/2013.19.supp1.s19] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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22
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Mafi A, Raisi A, Aroujalian A. Computational fluid dynamics modeling of mass transfer for aroma compounds recovery from aqueous solutions by hydrophobic pervaporation. J FOOD ENG 2013. [DOI: 10.1016/j.jfoodeng.2013.04.031] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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23
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Mounts A, De La Rocque S, Fitzner J, Garcia E, Thomas HL, Brown D, Schuster H, Vandemaele K, Esmat H, Eremin S, Mafi A. The early response to a novel coronavirus in the Middle East. East Mediterr Health J 2013; 19 Suppl 1:S19-S25. [PMID: 23888791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The detection of a novel coronavirus in patients from the Arabian Peninsula in late 2012 raised serious concerns of a possible international outbreak. Ministries of health of the three affected countries invited missions from the World Health Organization to participate in a review of data and capacity to detect and respond to further cases. Recommendations were made for investigations to answer critical questions about human-to-human transmission and the geographic extent of the virus. Additional recommendations were made to improve surveillance capacity by acquiring the capacity to test for the virus and enhance syndromic surveillance. Available evidence continues to suggest an unknown animal reservoir for the virus with sporadic zoonotic transmission the primary epidemiological pattern of transmission. Human-to-human transmission, while it can occur, does not appear to be sustained in the community.
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Affiliation(s)
- A Mounts
- Global Infuenza Programme, World Health Organization, Geneva, Switzerland.
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24
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Mafi A, Raisi A, Hatam M, Aroujalian A. A mathematical model for mass transfer in hydrophobic pervaporation for organic compounds separation from aqueous solutions. J Memb Sci 2012. [DOI: 10.1016/j.memsci.2012.08.012] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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25
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Li L, Schülzgen A, Temyanko VL, Li H, Sabet S, Morrell MM, Mafi A, Moloney JV, Peyghambarian N. Investigation of modal properties of microstructured optical fibers with large depressed-index cores. Opt Lett 2005; 30:3275-7. [PMID: 16389803 DOI: 10.1364/ol.30.003275] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
We present what is, to the best of our knowledge, the first systematic study on how negative core-cladding index difference influences microstructured optical fiber's modal behavior. Single-mode lasing has been realized for short-length cladding-pumped phosphate glass microstructured fibers with large depressed-index Er(3+)-Yb(3+)-codoped cores.
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Affiliation(s)
- L Li
- College of Optical Sciences, The University of Arizona, Tucson, Arizona 85721, USA.
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26
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Li L, Schülzgen A, Temyanko VL, Qiu T, Morrell MM, Wang Q, Mafi A, Moloney JV, Peyghambarian N. Short-length microstructured phosphate glass fiber lasers with large mode areas. Opt Lett 2005; 30:1141-3. [PMID: 15943293 DOI: 10.1364/ol.30.001141] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
We report fabrication and testing of the first phosphate glass microstructured fiber lasers with large Er-Yb-codoped cores. For an 11-cm-long cladding-pumped fiber laser, more than 3 W of continuous wave output power is demonstrated, and near single-mode beam quality is obtained for an active core area larger than 400 microm2.
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Affiliation(s)
- L Li
- Optical Sciences Center, University of Arizona, Tucson, Arizona 85721, USA.
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27
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Li L, Li H, Qiu T, Temyanko VL, Morrell MM, Schülzgen A, Mafi A, Moloney JV, Peyghambarian N. 3-Dimensional thermal analysis and active cooling of short-length high-power fiber lasers. Opt Express 2005; 13:3420-3428. [PMID: 19495244 DOI: 10.1364/opex.13.003420] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A fully 3-dimensional finite element model has been developed that simulates the internal temperature distribution of short-length high-power fiber lasers. We have validated the numerical model by building a short, cladding-pumped, Er-Yb-codoped fiber laser and measuring the core temperature during laser operation. A dual-end-pumped, actively cooled, fiber laser has generated >11 W CW output power at 1535 nm from only 11.9 cm of active fiber. Simulations indicate power-scaling possibilities with improved fiber and cooling designs.
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28
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Abstract
The aim of this study was to evaluate the effect of sperm chromatin anomalies on fertilization outcome post-intracytoplasmic sperm injection (ICSI). Therefore, along with semen parameters, Chromomycin A3 (CMA3) staining for protamine deficiency, aniline blue staining for excessive histones, SDS for sperm chromatin stability and SDS + EDTA for the ability of sperm to undergo decondensation were carried out on 55 semen samples from patients referred to the Isfahan Fertility and Infertility Center for ICSI. The results showed that among the aforementioned tests and semen parameters only CMA3 showed a significant correlation with fertilization outcome post-ICSI. Patients were also grouped according to CMA3 level of <30% or >30% or fertilization rate of <50% or >50%. The results show that the mean percentage fertilization and mean percentage of CMA3 positivity is different in both groups, respectively. The area under receiver operator characteristics curve shows that CMA3 is a highly sensitive and specific test for prediction of fertilization outcome post-ICSI. In conclusion, that sperm protamine deficiency has profound effect on fertilization failure in ICSI.
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Affiliation(s)
- S Razavi
- Department of Anatomy, Isfahan University of Medical Sciences, Isfahan, Iran
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Malekafzali H, Abdollahi Z, Mafi A, Naghavi M. Community-based nutritional intervention for reducing malnutrition among children under 5 years of age in the Islamic Republic of Iran. East Mediterr Health J 2000; 6:238-45. [PMID: 11556008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
A project was conducted in a rural area in September 1994 with the aim of decreasing the incidence of protein-energy malnutrition among children under 5 years, by nutritional intervention through the primary health care system. An initial situation analysis revealed the region's resources and causes of malnutrition. Practical instruction on feeding methods, deworming, environmental sanitation, the promotion of home-grown vegetables and reinforcement of the growth monitoring programme were chosen as the routes for intervention. All indices were reassessed in the region after 1 year. Results showed that nutritional awareness had grown among mothers, and that the incidence of malnutrition had dropped from 6.5% to 1.8%, as measured against the weight-for-height index.
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Affiliation(s)
- H Malekafzali
- Faculty of Public Health, Teheran University of Medical Science, Teheran, Islamic Republic of Iran
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