1
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Gomez AM, Brewer RC, Moon JS, Acharya S, Kongpachith S, Wang Q, Jahanbani S, Wong HH, Lanz TV, Love ZZ, Min-Oo G, Niedziela-Majka A, Robinson WH. Anti-Citrullinated Protein Antibodies With Multiple Specificities Ameliorate Collagen Antibody-Induced Arthritis in a Time-Dependent Manner. Arthritis Rheumatol 2024; 76:181-191. [PMID: 37610274 DOI: 10.1002/art.42679] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 06/23/2023] [Accepted: 08/17/2023] [Indexed: 08/24/2023]
Abstract
OBJECTIVE Anti-citrullinated protein antibodies (ACPAs) are highly specific for rheumatoid arthritis (RA) and have long been regarded as pathogenic. Despite substantial in vitro evidence supporting this claim, reports investigating the proinflammatory effects of ACPAs in animal models of arthritis are rare and include mixed results. Here, we sequenced the plasmablast antibody repertoire of a patient with RA and functionally characterized the encoded ACPAs. METHODS We expressed ACPAs from the antibody repertoire of a patient with RA and characterized their autoantigen specificities on antigen arrays and enzyme-linked immunosorbent assays. Binding affinities were estimated by bio-layer interferometry. Select ACPAs (n = 9) were tested in the collagen antibody-induced arthritis (CAIA) mouse model to evaluate their effects on joint inflammation. RESULTS Recombinant ACPAs bound preferentially and with high affinity (nanomolar range) to citrullinated (cit) autoantigens (primarily histones and fibrinogen) and to auto-cit peptidylarginine deiminase 4 (PAD4). ACPAs were grouped for in vivo testing based on their predominant cit-antigen specificities. Unexpectedly, injections of recombinant ACPAs significantly reduced paw thickness and arthritis severity in CAIA mice as compared with isotype-matched control antibodies (P ≤ 0.001). Bone erosion, synovitis, and cartilage damage were also significantly reduced (P ≤ 0.01). This amelioration of CAIA was observed for all the ACPAs tested and was independent of cit-PAD4 and cit-fibrinogen specificities. Furthermore, disease amelioration was more prominent when ACPAs were injected at earlier stages of CAIA than at later phases of the model. CONCLUSION Recombinant patient-derived ACPAs ameliorated CAIA. Their antiinflammatory effects were more preventive than therapeutic. This study highlights a potential protective role for ACPAs in arthritis.
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Affiliation(s)
- Alejandro M Gomez
- Stanford University School of Medicine, Stanford, and VA Palo Alto Health Care System, Palo Alto, California
| | - R Camille Brewer
- Stanford University School of Medicine, Stanford, and VA Palo Alto Health Care System, Palo Alto, California
| | - Jae-Seung Moon
- Stanford University School of Medicine, Stanford, and VA Palo Alto Health Care System, Palo Alto, California
| | - Suman Acharya
- Stanford University School of Medicine, Stanford, and VA Palo Alto Health Care System, Palo Alto, California
| | - Sarah Kongpachith
- Stanford University School of Medicine, Stanford, and VA Palo Alto Health Care System, Palo Alto, California
| | - Qian Wang
- Stanford University School of Medicine, Stanford, and VA Palo Alto Health Care System, Palo Alto, California
| | - Shaghayegh Jahanbani
- Stanford University School of Medicine, Stanford, and VA Palo Alto Health Care System, Palo Alto, California
| | - Heidi H Wong
- Stanford University School of Medicine, Stanford, and VA Palo Alto Health Care System, Palo Alto, California
| | - Tobias V Lanz
- Stanford University School of Medicine, Stanford, and VA Palo Alto Health Care System, Palo Alto, California
| | - Zelda Z Love
- Stanford University School of Medicine, Stanford, and VA Palo Alto Health Care System, Palo Alto, California
| | | | | | - William H Robinson
- Stanford University School of Medicine, Stanford, and VA Palo Alto Health Care System, Palo Alto, California
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2
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Mackman RL, Kalla RV, Babusis D, Pitts J, Barrett KT, Chun K, Du Pont V, Rodriguez L, Moshiri J, Xu Y, Lee M, Lee G, Bleier B, Nguyen AQ, O'Keefe BM, Ambrosi A, Cook M, Yu J, Dempah KE, Bunyan E, Riola NC, Lu X, Liu R, Davie A, Hsiang TY, Dearing J, Vermillion M, Gale M, Niedziela-Majka A, Feng JY, Hedskog C, Bilello JP, Subramanian R, Cihlar T. Discovery of GS-5245 (Obeldesivir), an Oral Prodrug of Nucleoside GS-441524 That Exhibits Antiviral Efficacy in SARS-CoV-2-Infected African Green Monkeys. J Med Chem 2023; 66:11701-11717. [PMID: 37596939 DOI: 10.1021/acs.jmedchem.3c00750] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/21/2023]
Abstract
Remdesivir 1 is an phosphoramidate prodrug that releases the monophosphate of nucleoside GS-441524 (2) into lung cells, thereby forming the bioactive triphosphate 2-NTP. 2-NTP, an analog of ATP, inhibits the SARS-CoV-2 RNA-dependent RNA polymerase replication and transcription of viral RNA. Strong clinical results for 1 have prompted interest in oral approaches to generate 2-NTP. Here, we describe the discovery of a 5'-isobutyryl ester prodrug of 2 (GS-5245, Obeldesivir, 3) that has low cellular cytotoxicity and 3-7-fold improved oral delivery of 2 in monkeys. Prodrug 3 is cleaved presystemically to provide high systemic exposures of 2 that overcome its less efficient metabolism to 2-NTP, leading to strong SARS-CoV-2 antiviral efficacy in an African green monkey infection model. Exposure-based SARS-CoV-2 efficacy relationships resulted in an estimated clinical dose of 350-400 mg twice daily. Importantly, all SARS-CoV-2 variants remain susceptible to 2, which supports development of 3 as a promising COVID-19 treatment.
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Affiliation(s)
- Richard L Mackman
- Medicinal Chemistry, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
| | - Rao V Kalla
- Medicinal Chemistry, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
| | - Darius Babusis
- Drug Metabolism, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
| | - Jared Pitts
- Discovery Virology, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
| | - Kimberly T Barrett
- Formulation and Process Development, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
| | - Kwon Chun
- Medicinal Chemistry, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
| | - Venice Du Pont
- Discovery Virology, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
| | - Lauren Rodriguez
- Clinical Virology, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
| | - Jasmine Moshiri
- Clinical Virology, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
| | - Yili Xu
- Biochemistry, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
| | - Michael Lee
- Biology, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
| | - Gary Lee
- Biology, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
| | - Blake Bleier
- Formulation and Process Development, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
| | - Anh-Quan Nguyen
- Formulation and Process Development, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
| | - B Michael O'Keefe
- Process Chemistry, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
| | - Andrea Ambrosi
- Process Chemistry, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
| | - Meredith Cook
- Process Chemistry, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
| | - Joy Yu
- Process Chemistry, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
| | - Kassibla Elodie Dempah
- Process Development, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
| | - Elaine Bunyan
- Process Development, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
| | - Nicholas C Riola
- Discovery Virology, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
| | - Xianghan Lu
- Discovery Virology, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
| | - Renmeng Liu
- Drug Metabolism, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
| | - Ashley Davie
- Drug Metabolism, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
| | - Tien-Ying Hsiang
- Center for Innate Immunity and Immune Disease, Department of Immunology, School of Medicine, University of Washington, Seattle, Washington 98109 United States
| | - Justin Dearing
- Lovelace Biomedical Research Institute, 2425 Ridgecrest Drive Southeast, Albuquerque, New Mexico 87108 United States
| | - Meghan Vermillion
- Lovelace Biomedical Research Institute, 2425 Ridgecrest Drive Southeast, Albuquerque, New Mexico 87108 United States
| | - Michael Gale
- Center for Innate Immunity and Immune Disease, Department of Immunology, School of Medicine, University of Washington, Seattle, Washington 98109 United States
| | - Anita Niedziela-Majka
- Biology, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
| | - Joy Y Feng
- Biochemistry, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
| | - Charlotte Hedskog
- Clinical Virology, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
| | - John P Bilello
- Discovery Virology, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
| | - Raju Subramanian
- Drug Metabolism, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
| | - Tomas Cihlar
- Discovery Virology, Gilead Sciences Incorporated, 333 Lakeside Drive, Foster City, California 94404 United States
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3
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Farand J, Kropf JE, Blomgren P, Xu J, Schmitt AC, Newby ZE, Wang T, Murakami E, Barauskas O, Sudhamsu J, Feng JY, Niedziela-Majka A, Schultz BE, Schwartz K, Viatchenko-Karpinski S, Kornyeyev D, Kashishian A, Fan P, Chen X, Lansdon EB, Ports MO, Currie KS, Watkins WJ, Notte GT. Discovery of Potent and Selective MTH1 Inhibitors for Oncology: Enabling Rapid Target (In)Validation. ACS Med Chem Lett 2020; 11:358-364. [PMID: 32184970 DOI: 10.1021/acsmedchemlett.9b00420] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 11/12/2019] [Indexed: 02/07/2023] Open
Abstract
We describe the discovery of three structurally differentiated potent and selective MTH1 inhibitors and their subsequent use to investigate MTH1 as an oncology target, culminating in target (in)validation. Tetrahydronaphthyridine 5 was rapidly identified as a highly potent MTH1 inhibitor (IC50 = 0.043 nM). Cocrystallization of 5 with MTH1 revealed the ligand in a Φ-cis-N-(pyridin-2-yl)acetamide conformation enabling a key intramolecular hydrogen bond and polar interactions with residues Gly34 and Asp120. Modification of literature compound TH287 with O- and N-linked aryl and alkyl aryl substituents led to the discovery of potent pyrimidine-2,4,6-triamine 25 (IC50 = 0.49 nM). Triazolopyridine 32 emerged as a highly selective lead compound with a suitable in vitro profile and desirable pharmacokinetic properties in rat. Elucidation of the DNA damage response, cell viability, and intracellular concentrations of oxo-NTPs (oxidized nucleoside triphosphates) as a function of MTH1 knockdown and/or small molecule inhibition was studied. Based on our findings, we were unable to provide evidence to further pursue MTH1 as an oncology target.
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Affiliation(s)
- Julie Farand
- Gilead Sciences, Inc. 333 Lakeside Drive, Foster City, California 94404, United States
| | - Jeffrey E. Kropf
- Gilead Sciences, Inc. 199 East Blaine Street, Seattle, Washington 98102, United States
| | - Peter Blomgren
- Gilead Sciences, Inc. 199 East Blaine Street, Seattle, Washington 98102, United States
| | - Jianjun Xu
- Gilead Sciences, Inc. 199 East Blaine Street, Seattle, Washington 98102, United States
| | - Aaron C. Schmitt
- Gilead Sciences, Inc. 199 East Blaine Street, Seattle, Washington 98102, United States
| | - Zachary E. Newby
- Gilead Sciences, Inc. 333 Lakeside Drive, Foster City, California 94404, United States
| | - Ting Wang
- Gilead Sciences, Inc. 333 Lakeside Drive, Foster City, California 94404, United States
| | - Eisuke Murakami
- Gilead Sciences, Inc. 333 Lakeside Drive, Foster City, California 94404, United States
| | - Ona Barauskas
- Gilead Sciences, Inc. 333 Lakeside Drive, Foster City, California 94404, United States
| | - Jawahar Sudhamsu
- Gilead Sciences, Inc. 333 Lakeside Drive, Foster City, California 94404, United States
| | - Joy Y. Feng
- Gilead Sciences, Inc. 333 Lakeside Drive, Foster City, California 94404, United States
| | - Anita Niedziela-Majka
- Gilead Sciences, Inc. 333 Lakeside Drive, Foster City, California 94404, United States
| | - Brian E. Schultz
- Gilead Sciences, Inc. 333 Lakeside Drive, Foster City, California 94404, United States
| | - Karen Schwartz
- Gilead Sciences, Inc. 333 Lakeside Drive, Foster City, California 94404, United States
| | | | - Dmytro Kornyeyev
- Gilead Sciences, Inc. 333 Lakeside Drive, Foster City, California 94404, United States
| | - Adam Kashishian
- Gilead Sciences, Inc. 199 East Blaine Street, Seattle, Washington 98102, United States
| | - Peidong Fan
- Gilead Sciences, Inc. 333 Lakeside Drive, Foster City, California 94404, United States
| | - Xiaowu Chen
- Gilead Sciences, Inc. 333 Lakeside Drive, Foster City, California 94404, United States
| | - Eric B. Lansdon
- Gilead Sciences, Inc. 333 Lakeside Drive, Foster City, California 94404, United States
| | - Michael O. Ports
- Gilead Sciences, Inc. 199 East Blaine Street, Seattle, Washington 98102, United States
| | - Kevin S. Currie
- Gilead Sciences, Inc. 199 East Blaine Street, Seattle, Washington 98102, United States
| | - William J. Watkins
- Gilead Sciences, Inc. 333 Lakeside Drive, Foster City, California 94404, United States
| | - Gregory T. Notte
- Gilead Sciences, Inc. 333 Lakeside Drive, Foster City, California 94404, United States
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4
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Sperandio D, Aktoudianakis V, Babaoglu K, Chen X, Elbel K, Chin G, Corkey B, Du J, Jiang B, Kobayashi T, Mackman R, Martinez R, Yang H, Zablocki J, Kusam S, Jordan K, Webb H, Bates JG, Lad L, Mish M, Niedziela-Majka A, Metobo S, Sapre A, Hung M, Jin D, Fung W, Kan E, Eisenberg G, Larson N, Newby ZER, Lansdon E, Tay C, Neve RM, Shevick SL, Breckenridge DG. Structure-guided discovery of a novel, potent, and orally bioavailable 3,5-dimethylisoxazole aryl-benzimidazole BET bromodomain inhibitor. Bioorg Med Chem 2018; 27:457-469. [PMID: 30606676 DOI: 10.1016/j.bmc.2018.11.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [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: 07/26/2018] [Revised: 11/05/2018] [Accepted: 11/13/2018] [Indexed: 12/12/2022]
Abstract
The bromodomain and extra-terminal (BET) family of proteins, consisting of the bromodomains containing protein 2 (BRD2), BRD3, BRD4, and the testis-specific BRDT, are key epigenetic regulators of gene transcription and has emerged as an attractive target for anticancer therapy. Herein, we describe the discovery of a novel potent BET bromodomain inhibitor, using a systematic structure-based approach focused on improving potency, metabolic stability, and permeability. The optimized dimethylisoxazole aryl-benzimidazole inhibitor exhibited high potency towards BRD4 and related BET proteins in biochemical and cell-based assays and inhibited tumor growth in two proof-of-concept preclinical animal models.
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Affiliation(s)
- David Sperandio
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA.
| | - Vangelis Aktoudianakis
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Kerim Babaoglu
- Department of Structural Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Xiaowu Chen
- Department of Structural Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Kristyna Elbel
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Gregory Chin
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Britton Corkey
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Jinfa Du
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Bob Jiang
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Tetsuya Kobayashi
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Richard Mackman
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Ruben Martinez
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Hai Yang
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Jeff Zablocki
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Saritha Kusam
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Kim Jordan
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Heather Webb
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Jamie G Bates
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Latesh Lad
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Michael Mish
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Anita Niedziela-Majka
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Sammy Metobo
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Annapurna Sapre
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Magdeleine Hung
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Debi Jin
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Wanchi Fung
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Elaine Kan
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Gene Eisenberg
- Department of Drug Metabolism, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Nate Larson
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Zachary E R Newby
- Department of Structural Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Eric Lansdon
- Department of Structural Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Chin Tay
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Richard M Neve
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Sophia L Shevick
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - David G Breckenridge
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
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5
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Ordabayev YA, Nguyen B, Niedziela-Majka A, Lohman TM. Regulation of UvrD Helicase Activity by MutL. J Mol Biol 2018; 430:4260-4274. [PMID: 30171840 DOI: 10.1016/j.jmb.2018.08.022] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [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: 06/05/2018] [Revised: 08/03/2018] [Accepted: 08/23/2018] [Indexed: 11/18/2022]
Abstract
Escherichia coli UvrD is a superfamily 1 helicase/translocase involved in multiple DNA metabolic processes including methyl-directed mismatch DNA repair. Although a UvrD monomer can translocate along single-stranded DNA, a UvrD dimer is needed for processive helicase activity in vitro. E. coli MutL, a regulatory protein involved in methyl-directed mismatch repair, stimulates UvrD helicase activity; however, the mechanism is not well understood. Using single-molecule fluorescence and ensemble approaches, we find that a single MutL dimer can activate latent UvrD monomer helicase activity. However, we also find that MutL stimulates UvrD dimer helicase activity. We further find that MutL enhances the DNA-unwinding processivity of UvrD. Hence, MutL acts as a processivity factor by binding to and presumably moving along with UvrD to facilitate DNA unwinding.
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Affiliation(s)
- Yerdos A Ordabayev
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, 660 S. Euclid Ave., Box 8231, St. Louis, MO 63110, United States
| | - Binh Nguyen
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, 660 S. Euclid Ave., Box 8231, St. Louis, MO 63110, United States
| | - Anita Niedziela-Majka
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, 660 S. Euclid Ave., Box 8231, St. Louis, MO 63110, United States
| | - Timothy M Lohman
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, 660 S. Euclid Ave., Box 8231, St. Louis, MO 63110, United States.
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6
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Ordabayev Y, Nguyen B, Niedziela-Majka A, Lohman T. Regulation of UvrD Helicase Activity by MutL. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.2455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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7
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Xing W, Barauskas O, Kirschberg T, Niedziela-Majka A, Clarke M, Birkus G, Weissburg P, Liu X, Schultz BE, Sakowicz R, Kwon H, Feng JY. Biochemical characterization of recombinant influenza A polymerase heterotrimer complex: Endonuclease activity and evaluation of inhibitors. PLoS One 2017; 12:e0181969. [PMID: 28809961 PMCID: PMC5557545 DOI: 10.1371/journal.pone.0181969] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 07/10/2017] [Indexed: 12/23/2022] Open
Abstract
Influenza polymerase is a heterotrimer composed of polymerase acidic protein A (PA) and basic proteins 1 (PB1) and 2 (PB2). The endonuclease active site, located in the PA subunit, cleaves host mRNA to prime viral mRNA transcription, and is essential for viral replication. To date, the human influenza A endonuclease activity has only been studied on the truncated active-site containing N-terminal domain of PA (PAN) or full-length PA in the absence of PB1 or PB2. In this study, we characterized the endonuclease activity of recombinant proteins of influenza A/PR8 containing full length PA, PA/PB1 dimer, and PA/PB1/PB2 trimer, observing 8.3-, 265-, and 142-fold higher activity than PAN, respectively. Using the PA/PB1/PB2 trimer, we developed a robust endonuclease assay with a synthetic fluorogenic RNA substrate. The observed Km (150 ± 11 nM) and kcat [(1.4 ± 0.2) x 10-3s-1] values were consistent with previous reports using virion-derived replication complex. Two known influenza endonuclease phenylbutanoic acid inhibitors showed IC50 values of 10–20 nM, demonstrating the utility of this system for future high throughput screening.
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Affiliation(s)
- Weimei Xing
- Gilead Sciences, Inc., Foster City, California, United States of America
| | - Ona Barauskas
- Gilead Sciences, Inc., Foster City, California, United States of America
| | | | | | - Michael Clarke
- Gilead Sciences, Inc., Foster City, California, United States of America
| | - Gabriel Birkus
- Gilead Sciences, Inc., Foster City, California, United States of America
| | - Perry Weissburg
- Gilead Sciences, Inc., Foster City, California, United States of America
| | - Xiaohong Liu
- Gilead Sciences, Inc., Foster City, California, United States of America
| | - Brian E. Schultz
- Gilead Sciences, Inc., Foster City, California, United States of America
| | - Roman Sakowicz
- Gilead Sciences, Inc., Foster City, California, United States of America
| | - HyockJoo Kwon
- Gilead Sciences, Inc., Foster City, California, United States of America
- * E-mail: (HJK); (JYF)
| | - Joy Y. Feng
- Gilead Sciences, Inc., Foster City, California, United States of America
- * E-mail: (HJK); (JYF)
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8
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Niedziela-Majka A, Hinman K, Voigt J, Hung M, Post A, Sakowicz R. A Rapid Biochemical Assay to Measure Small Molecules Binding to Pregnane Xenobiotic Receptors from Human, Dog and Rat. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.2902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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9
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Kwon HJ, Xing W, Chan K, Niedziela-Majka A, Brendza KM, Kirschberg T, Kato D, Link JO, Cheng G, Liu X, Sakowicz R. Direct binding of ledipasvir to HCV NS5A: mechanism of resistance to an HCV antiviral agent. PLoS One 2015; 10:e0122844. [PMID: 25856426 PMCID: PMC4391872 DOI: 10.1371/journal.pone.0122844] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 02/19/2015] [Indexed: 01/01/2023] Open
Abstract
Ledipasvir, a direct acting antiviral agent (DAA) targeting the Hepatitis C Virus NS5A protein, exhibits picomolar activity in replicon cells. While its mechanism of action is unclear, mutations that confer resistance to ledipasvir in HCV replicon cells are located in NS5A, suggesting that NS5A is the direct target of ledipasvir. To date co-precipitation and cross-linking experiments in replicon or NS5A transfected cells have not conclusively shown a direct, specific interaction between NS5A and ledipasvir. Using recombinant, full length NS5A, we show that ledipasvir binds directly, with high affinity and specificity, to NS5A. Ledipasvir binding to recombinant NS5A is saturable with a dissociation constant in the low nanomolar range. A mutant form of NS5A (Y93H) that confers resistance to ledipasvir shows diminished binding to ledipasvir. The current study shows that ledipasvir inhibits NS5A through direct binding and that resistance to ledipasvir is the result of a reduction in binding affinity to NS5A mutants.
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Affiliation(s)
- Hyock Joo Kwon
- Gilead Sciences, Inc., Foster City, California, United States of America
- * E-mail:
| | - Weimei Xing
- Gilead Sciences, Inc., Foster City, California, United States of America
| | - Katie Chan
- Gilead Sciences, Inc., Foster City, California, United States of America
| | | | | | | | - Darryl Kato
- Gilead Sciences, Inc., Foster City, California, United States of America
| | - John O. Link
- Gilead Sciences, Inc., Foster City, California, United States of America
| | - Guofeng Cheng
- Gilead Sciences, Inc., Foster City, California, United States of America
| | - Xiaohong Liu
- Gilead Sciences, Inc., Foster City, California, United States of America
| | - Roman Sakowicz
- Gilead Sciences, Inc., Foster City, California, United States of America
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10
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Lad L, Clancy S, Koditek D, Wong MH, Jin D, Niedziela-Majka A, Papalia GA, Hung M, Yant S, Somoza JR, Hu E, Chou C, Tse W, Halcomb R, Sakowicz R, Pagratis N. Functional label-free assays for characterizing the in vitro mechanism of action of small molecule modulators of capsid assembly. Biochemistry 2015; 54:2240-8. [PMID: 25774576 DOI: 10.1021/acs.biochem.5b00151] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [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
HIV capsid protein is an important target for antiviral drug design. High-throughput screening campaigns have identified two classes of compounds (PF74 and BI64) that directly target HIV capsid, resulting in antiviral activity against HIV-1 and HIV-2 laboratory strains. Using recombinant proteins, we developed a suite of label-free assays to mechanistically understand how these compounds modulate capsid activity. PF74 preferentially binds to the preassembled hexameric capsid form and prevents disruption of higher-order capsid structures by stabilizing capsid intersubunit interactions. BI64 binds only the monomeric capsid and locks the protein in the assembly incompetent monomeric form by disrupting capsid intersubunit interactions. We also used these assays to characterize the interaction between capsid and the host protein cleavage and polyadenylation specific factor 6 (CPSF6). Consistent with recently published results, our assays revealed CPSF6 activates capsid polymerization and preferentially binds to the preassembled hexameric capsid form similar to the small molecule compound, PF74. Furthermore, these label-free assays provide a robust method for facilitating the identification of a different class of small molecule modulators of capsid function.
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Affiliation(s)
- Latesh Lad
- Gilead Sciences, 333 Lakeside Drive, Foster City, California 94404, United States
| | - Sheila Clancy
- Gilead Sciences, 333 Lakeside Drive, Foster City, California 94404, United States
| | - David Koditek
- Gilead Sciences, 333 Lakeside Drive, Foster City, California 94404, United States
| | - Melanie H Wong
- Gilead Sciences, 333 Lakeside Drive, Foster City, California 94404, United States
| | - Debi Jin
- Gilead Sciences, 333 Lakeside Drive, Foster City, California 94404, United States
| | | | - Giuseppe A Papalia
- Gilead Sciences, 333 Lakeside Drive, Foster City, California 94404, United States
| | - Magdeleine Hung
- Gilead Sciences, 333 Lakeside Drive, Foster City, California 94404, United States
| | - Stephen Yant
- Gilead Sciences, 333 Lakeside Drive, Foster City, California 94404, United States
| | - John R Somoza
- Gilead Sciences, 333 Lakeside Drive, Foster City, California 94404, United States
| | - Eric Hu
- Gilead Sciences, 333 Lakeside Drive, Foster City, California 94404, United States
| | - Chienhung Chou
- Gilead Sciences, 333 Lakeside Drive, Foster City, California 94404, United States
| | - Winston Tse
- Gilead Sciences, 333 Lakeside Drive, Foster City, California 94404, United States
| | - Randall Halcomb
- Gilead Sciences, 333 Lakeside Drive, Foster City, California 94404, United States
| | - Roman Sakowicz
- Gilead Sciences, 333 Lakeside Drive, Foster City, California 94404, United States
| | - Nikos Pagratis
- Gilead Sciences, 333 Lakeside Drive, Foster City, California 94404, United States
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11
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Niedziela-Majka A, Kan E, Weissburg P, Mehra U, Sellers S, Sakowicz R. High-Throughput Screening of Formulations to Optimize the Thermal Stability of a Therapeutic Monoclonal Antibody. ACTA ACUST UNITED AC 2014; 20:552-9. [DOI: 10.1177/1087057114557781] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Monoclonal antibodies (mAbs) are an important class of biotherapeutics. Successful development of a mAb depends not only on its biological activity but also on its physicochemical properties, such as homogeneity and stability. mAb stability is affected by its formulation. Among the many techniques used to study the stability of mAbs, differential scanning fluorimetry (DSF) offers both excellent throughput and minimal material consumption. DSF measures the temperature of the protein unfolding transition (Tm) based on the change in fluorescence intensity of the environmentally sensitive dye SYPRO Orange. With DSF adapted to a 96-well plate format, we have shown that low-pH or high-salt concentrations decrease the thermal stability of mAb1, whereas some excipients, such as sucrose, polysorbate 80, and sodium phosphate, increase its stability. The basal fluorescence of SYPRO Orange was enhanced by the presence of detergents, limiting the use of this approach to diluted detergent solutions. Throughput of DSF can be increased further with the use of a 384-well plate. DSF thermograms are in good agreement with the melting profiles obtained by differential scanning calorimetry (DSC). The Tms determined by DSF and DSC were well correlated, with the former being on average lower by 3 °C.
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Affiliation(s)
| | - Elaine Kan
- Gilead Sciences, Inc., Foster City, CA, USA
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12
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Phillips B, Cai R, Delaney W, Du Z, Ji M, Jin H, Lee J, Li J, Niedziela-Majka A, Mish M, Pyun HJ, Saugier J, Tirunagari N, Wang J, Yang H, Wu Q, Sheng C, Zonte C. Highly potent HCV NS4B inhibitors with activity against multiple genotypes. J Med Chem 2014; 57:2161-6. [PMID: 24512292 DOI: 10.1021/jm401646w] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The exploration of novel inhibitors of the HCV NS4B protein that are based on a 2-oxadiazoloquinoline scaffold is described. Optimization to incorporate activity across genotypes led to a potent new series with broad activity, of which inhibitor 1 displayed the following EC50 values: 1a, 0.08 nM; 1b, 0.10 nM; 2a, 3 nM; 2b, 0.6 nM, 3a, 3.7 nM; 4a, 0.9 nM; 6a, 3.1 nM.
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Affiliation(s)
- Barton Phillips
- Gilead Sciences , 333 Lakeside Drive, Foster City, California 94404, United States
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13
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Boyce SE, Tirunagari N, Niedziela-Majka A, Perry J, Wong M, Kan E, Lagpacan L, Barauskas O, Hung M, Fenaux M, Appleby T, Watkins WJ, Schmitz U, Sakowicz R. Structural and regulatory elements of HCV NS5B polymerase--β-loop and C-terminal tail--are required for activity of allosteric thumb site II inhibitors. PLoS One 2014; 9:e84808. [PMID: 24416288 PMCID: PMC3886995 DOI: 10.1371/journal.pone.0084808] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 11/19/2013] [Indexed: 01/01/2023] Open
Abstract
Elucidation of the mechanism of action of the HCV NS5B polymerase thumb site II inhibitors has presented a challenge. Current opinion holds that these allosteric inhibitors stabilize the closed, inactive enzyme conformation, but how this inhibition is accomplished mechanistically is not well understood. Here, using a panel of NS5B proteins with mutations in key regulatory motifs of NS5B – the C-terminal tail and β-loop – in conjunction with a diverse set of NS5B allosteric inhibitors, we show that thumb site II inhibitors possess a distinct mechanism of action. A combination of enzyme activity studies and direct binding assays reveals that these inhibitors require both regulatory elements to maintain the polymerase inhibitory activity. Removal of either element has little impact on the binding affinity of thumb site II inhibitors, but significantly reduces their potency. NS5B in complex with a thumb site II inhibitor displays a characteristic melting profile that suggests stabilization not only of the thumb domain but also the whole polymerase. Successive truncations of the C-terminal tail and/or removal of the β-loop lead to progressive destabilization of the protein. Furthermore, the thermal unfolding transitions characteristic for thumb site II inhibitor – NS5B complex are absent in the inhibitor – bound constructs in which interactions between C-terminal tail and β-loop are abolished, pointing to the pivotal role of both regulatory elements in communication between domains. Taken together, a comprehensive picture of inhibition by compounds binding to thumb site II emerges: inhibitor binding provides stabilization of the entire polymerase in an inactive, closed conformation, propagated via coupled interactions between the C-terminal tail and β-loop.
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Affiliation(s)
- Sarah E. Boyce
- Gilead Sciences Inc., Foster City, California, United States of America
| | - Neeraj Tirunagari
- Gilead Sciences Inc., Foster City, California, United States of America
| | | | - Jason Perry
- Gilead Sciences Inc., Foster City, California, United States of America
| | - Melanie Wong
- Gilead Sciences Inc., Foster City, California, United States of America
| | - Elaine Kan
- Gilead Sciences Inc., Foster City, California, United States of America
| | - Leanna Lagpacan
- Gilead Sciences Inc., Foster City, California, United States of America
| | - Ona Barauskas
- Gilead Sciences Inc., Foster City, California, United States of America
| | - Magdeleine Hung
- Gilead Sciences Inc., Foster City, California, United States of America
| | - Martijn Fenaux
- Gilead Sciences Inc., Foster City, California, United States of America
| | - Todd Appleby
- Gilead Sciences Inc., Foster City, California, United States of America
| | | | - Uli Schmitz
- Gilead Sciences Inc., Foster City, California, United States of America
| | - Roman Sakowicz
- Gilead Sciences Inc., Foster City, California, United States of America
- * E-mail:
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14
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Niedziela-Majka A, Boyce SE, Tirunagari N, Perry J, Wong M, Kan E, Lagpacan L, Barauskas O, Hung M, Fenaux M, Appleby T, Watkins WJ, Schmitz U, Sakowicz R. Regulatory Elements of HCV NS5B Polymerase - β -Loop and C-Terminal Tail - are Required for Activity of Allosteric Thumb Site II Inhibitors. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.1537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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15
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Kan E, Niedziela-Majka A, Weissburg P, Sellers S, Sakowicz R. High Throughput Screening of Formulations to Optimize the Thermal Stability of Therapeutic Monoclonal Antibody. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.2661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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16
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Hung M, Niedziela-Majka A, Jin D, Wong M, Leavitt S, Brendza KM, Liu X, Sakowicz R. Large-scale functional purification of recombinant HIV-1 capsid. PLoS One 2013; 8:e58035. [PMID: 23472130 PMCID: PMC3589475 DOI: 10.1371/journal.pone.0058035] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 01/27/2013] [Indexed: 01/21/2023] Open
Abstract
During human immunodeficiency virus type-1 (HIV-1) virion maturation, capsid proteins undergo a major rearrangement to form a conical core that protects the viral nucleoprotein complexes. Mutations in the capsid sequence that alter the stability of the capsid core are deleterious to viral infectivity and replication. Recently, capsid assembly has become an attractive target for the development of a new generation of anti-retroviral agents. Drug screening efforts and subsequent structural and mechanistic studies require gram quantities of active, homogeneous and pure protein. Conventional means of laboratory purification of Escherichia coli expressed recombinant capsid protein rely on column chromatography steps that are not amenable to large-scale production. Here we present a function-based purification of wild-type and quadruple mutant capsid proteins, which relies on the inherent propensity of capsid protein to polymerize and depolymerize. This method does not require the packing of sizable chromatography columns and can generate double-digit gram quantities of functionally and biochemically well-behaved proteins with greater than 98% purity. We have used the purified capsid protein to characterize two known assembly inhibitors in our in-house developed polymerization assay and to measure their binding affinities. Our capsid purification procedure provides a robust method for purifying large quantities of a key protein in the HIV-1 life cycle, facilitating identification of the next generation anti-HIV agents.
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Affiliation(s)
- Magdeleine Hung
- Gilead Sciences Inc., Foster City, California, United States of America
| | | | - Debi Jin
- Gilead Sciences Inc., Foster City, California, United States of America
| | - Melanie Wong
- Gilead Sciences Inc., Foster City, California, United States of America
| | - Stephanie Leavitt
- Gilead Sciences Inc., Foster City, California, United States of America
| | | | - Xiaohong Liu
- Gilead Sciences Inc., Foster City, California, United States of America
| | - Roman Sakowicz
- Gilead Sciences Inc., Foster City, California, United States of America
- * E-mail:
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17
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Niedziela-Majka A, Lad L, Chisholm JW, Lagpacan L, Schwartz K, Hung M, Jin D, Fung W, Brendza KM, Liu X, Pagratis N, Sakowicz R. Lipid-sensing high-throughput ApoA-I assays. ACTA ACUST UNITED AC 2012; 17:1050-61. [PMID: 22811478 DOI: 10.1177/1087057112451923] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Apolipoprotein A-I (ApoA-I), a primary protein component of high-density lipoprotein (HDL), plays an important role in cholesterol metabolism mediating the formation of HDL and the efflux of cellular cholesterol from macrophage foam cells in arterial walls. Lipidation of ApoA-I is mediated by adenosine triphosphate (ATP) binding cassette A1 (ABCA1). Insufficient ABCA1 activity may lead to increased risk of atherosclerosis due to reduced HDL formation and cholesterol efflux. The standard radioactive assay for measuring cholesterol transport to ApoA-I has low throughput and poor dynamic range, and it fails to measure phospholipid transfer. We describe the development of two sensitive, nonradioactive high-throughput assays that report on the lipidation of ApoA-I: a homogeneous assay based on time-resolved fluorescence resonance energy transfer (TR-FRET) and a discontinuous assay that uses the label-free Epic platform. The TR-FRET assay employs HiLyte Fluor 647-labeled ApoA-I with N-terminal biotin bound to streptavidin-terbium. When fluorescent ApoA-I was incorporated into HDL, TR-FRET decreased proportionally to the increase in the ratio of lipids to ApoA-I, demonstrating that the assay was sensitive to the amount of lipid bound to ApoA-I. In the Epic assay, biotinylated ApoA-I was captured on a streptavidin-coated biosensor. Measured resonant wavelength shift was proportional to the amount of lipids associated with ApoA-I, indicating that the assay senses ApoA-I lipidation.
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18
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Tsiang M, Niedziela-Majka A, Hung M, Jin D, Hu E, Yant S, Samuel D, Liu X, Sakowicz R. A trimer of dimers is the basic building block for human immunodeficiency virus-1 capsid assembly. Biochemistry 2012; 51:4416-28. [PMID: 22564075 DOI: 10.1021/bi300052h] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Human immunodeficiency virus-1 (HIV-1) capsid protein (CA) has become a target of antiviral drug design in recent years. The recognition that binding of small molecules to the CA protein can result in the perturbation of capsid assembly or disassembly has led to mathematical modeling of the process. Although a number of capsid assembly models have been developed using biophysical parameters of the CA protein obtained experimentally, there is currently no model of CA polymerization that can be practically used to analyze in vitro CA polymerization data to facilitate drug discovery. Herein, we describe an equilibrium model of CA polymerization for the kinetic analysis of in vitro assembly of CA into polymer tubes. This new mathematical model has been used to assess whether a triangular trimer of dimers rather than a hexagonal hexamer can be the basic capsomere building block of CA polymer. The model allowed us to quantify for the first time the affinity for each of the four crucial interfaces involved in the polymerization process and indicated that the trimerization of CA dimers is a relatively slow step in CA polymerization in vitro. For wild-type CA, these four interfaces include the interface between two monomers of a CA dimer (K(D) = 6.6 μM), the interface between any two dimers within a CA trimer of dimers (K(D) = 32 nM), and two types of interfaces between neighboring trimers of dimers, either within the same ring around the perimeter of the polymer tube (K(D) = 438 nM) or from two adjacent rings (K(D) = 147 nM). A comparative analysis of the interface dissociation constants between wild-type and two mutant CA proteins, cross-linked hexamer (A14C/E45C/W184A/M185A) and A14C/E45C, yielded results that are consistent with the trimer of dimers with a triangular geometry being the capsomere building block involved in CA polymer growth. This work provides additional insights into the mechanism of HIV-1 CA assembly and may prove useful in elucidating how small molecule CA binding agents may disturb this essential step in the HIV-1 life cycle.
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Affiliation(s)
- Manuel Tsiang
- Gilead Sciences, Foster City, California 94404, United States.
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19
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Tsiang M, Jones GS, Niedziela-Majka A, Kan E, Lansdon EB, Huang W, Hung M, Samuel D, Novikov N, Xu Y, Mitchell M, Guo H, Babaoglu K, Liu X, Geleziunas R, Sakowicz R. New class of HIV-1 integrase (IN) inhibitors with a dual mode of action. J Biol Chem 2012; 287:21189-203. [PMID: 22535962 DOI: 10.1074/jbc.m112.347534] [Citation(s) in RCA: 133] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
tert-Butoxy-(4-phenyl-quinolin-3-yl)-acetic acids (tBPQA) are a new class of HIV-1 integrase (IN) inhibitors that are structurally distinct from IN strand transfer inhibitors but analogous to LEDGINs. LEDGINs are a class of potent antiviral compounds that interacts with the lens epithelium-derived growth factor (LEDGF) binding pocket on IN and were identified through competition binding against LEDGF. LEDGF tethers IN to the host chromatin and enables targeted integration of viral DNA. The prevailing understanding of the antiviral mechanism of LEDGINs is that they inhibit LEDGF binding to IN, which prevents targeted integration of HIV-1. We showed that in addition to the properties already known for LEDGINs, the binding of tBPQAs to the IN dimer interface inhibits IN enzymatic activity in a LEDGF-independent manner. Using the analysis of two long terminal repeat junctions in HIV-infected cells, we showed that the inhibition by tBPQAs occurs at or prior to the viral DNA 3'-processing step. Biochemical studies revealed that this inhibition operates by compound-induced conformational changes in the IN dimer that prevent proper assembly of IN onto viral DNA. For the first time, tBPQAs were demonstrated to be allosteric inhibitors of HIV-1 IN displaying a dual mode of action: inhibition of IN-viral DNA assembly and inhibition of IN-LEDGF interaction.
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Affiliation(s)
- Manuel Tsiang
- Gilead Sciences, Inc, Foster City, California 94404, USA.
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20
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Niedziela-Majka A, Lad L, Chishom JW, Lagpacan L, Schwartz K, Hung M, Jin D, Fung W, Brendza KM, Liu X, Pagratis N, Sakowicz R. Lipid Sensing Apolipoprotein A-I for Novel High-Throughput Lipidation Assays. Biophys J 2012. [DOI: 10.1016/j.bpj.2011.11.384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022] Open
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21
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Abstract
The Escherichia coli MutL protein regulates the activity of several enzymes, including MutS, MutH, and UvrD, during methyl-directed mismatch repair of DNA. We have investigated the self-association properties of MutL and its binding to DNA using analytical sedimentation velocity and equilibrium. Self-association of MutL is quite sensitive to solution conditions. At 25 °C in Tris at pH 8.3, MutL assembles into a heterogeneous mixture of large multimers. In the presence of potassium phosphate at pH 7.4, MutL forms primarily stable dimers, with the higher-order assembly states suppressed. The weight-average sedimentation coefficient of the MutL dimer in this buffer ( ̅s(20,w)) is equal to 5.20 ± 0.08 S, suggesting a highly asymmetric dimer (f/f(o) = 1.58 ± 0.02). Upon binding the nonhydrolyzable ATP analogue, AMPPNP/Mg(2+), the MutL dimer becomes more compact ( ̅s(20,w) = 5.71 ± 0.08 S; f/f(o) = 1.45 ± 0.02), probably reflecting reorganization of the N-terminal ATPase domains. A MutL dimer binds to an 18 bp duplex with a 3'-(dT(20)) single-stranded flanking region, with apparent affinity in the micromolar range. AMPPNP binding to MutL increases its affinity for DNA by a factor of ∼10. These results indicate that the presence of phosphate minimizes further MutL oligomerization beyond a dimer and that differences in solution conditions likely explain apparent discrepancies in previous studies of MutL assembly.
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Affiliation(s)
- Anita Niedziela-Majka
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, 660 South Euclid Avenue, Box 8231, St. Louis, Missouri 63110-1093, USA
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22
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Jia H, Korolev S, Niedziela-Majka A, Maluf NK, Gauss GH, Myong S, Ha T, Waksman G, Lohman TM. Rotations of the 2B sub-domain of E. coli UvrD helicase/translocase coupled to nucleotide and DNA binding. J Mol Biol 2011; 411:633-48. [PMID: 21704638 DOI: 10.1016/j.jmb.2011.06.019] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Revised: 06/06/2011] [Accepted: 06/13/2011] [Indexed: 10/18/2022]
Abstract
Escherichia coli UvrD is a superfamily 1 DNA helicase and single-stranded DNA (ssDNA) translocase that functions in DNA repair and plasmid replication and as an anti-recombinase by removing RecA protein from ssDNA. UvrD couples ATP binding and hydrolysis to unwind double-stranded DNA and translocate along ssDNA with 3'-to-5' directionality. Although a UvrD monomer is able to translocate along ssDNA rapidly and processively, DNA helicase activity in vitro requires a minimum of a UvrD dimer. Previous crystal structures of UvrD bound to a ssDNA/duplex DNA junction show that its 2B sub-domain exists in a "closed" state and interacts with the duplex DNA. Here, we report a crystal structure of an apo form of UvrD in which the 2B sub-domain is in an "open" state that differs by an ∼160° rotation of the 2B sub-domain. To study the rotational conformational states of the 2B sub-domain in various ligation states, we constructed a series of double-cysteine UvrD mutants and labeled them with fluorophores such that rotation of the 2B sub-domain results in changes in fluorescence resonance energy transfer. These studies show that the open and closed forms can interconvert in solution, with low salt favoring the closed conformation and high salt favoring the open conformation in the absence of DNA. Binding of UvrD to DNA and ATP binding and hydrolysis also affect the rotational conformational state of the 2B sub-domain, suggesting that 2B sub-domain rotation is coupled to the function of this nucleic acid motor enzyme.
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Affiliation(s)
- Haifeng Jia
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA
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23
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Tsiang M, Jones GS, Hung M, Samuel D, Novikov N, Mukund S, Brendza KM, Niedziela-Majka A, Jin D, Liu X, Mitchell M, Sakowicz R, Geleziunas R. Dithiothreitol causes HIV-1 integrase dimer dissociation while agents interacting with the integrase dimer interface promote dimer formation. Biochemistry 2011; 50:1567-81. [PMID: 21222490 DOI: 10.1021/bi101504w] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
We have developed a homogeneous time-resolved fluorescence resonance energy transfer (FRET)-based assay that detects the formation of HIV-1 integrase (IN) dimers. The assay utilizes IN monomers that express two different epitope tags that are recognized by their respective antibodies, coupled to distinct fluorophores. Surprisingly, we found that dithiothreitol (DTT), a reducing agent essential for in vitro enzymatic activity of IN, weakened the interaction between IN monomers. This effect of DTT on IN is dependent on its thiol groups, since the related chemical threitol, which contains hydroxyls in place of thiols, had no effect on IN dimer formation. By studying mutants of IN, we determined that cysteines in IN appear to be dispensable for the dimer dissociation effect of DTT. Peptides derived from the IN binding domain (IBD) of lens epithelium derived growth factor/transcriptional coactivator p75 (LEDGF), a cellular cofactor that interacts with the IN dimer interface, were tested in this IN dimerization assay. These peptides, which compete with LEDGF for binding to IN, displayed an intriguing equilibrium binding dose-response curve characterized by a plateau rising to a peak, then descending to a second plateau. Mathematical modeling of this binding system revealed that these LEDGF-derived peptides promote IN dimerization and block subunit exchange between IN dimers. This dose-response behavior was also observed with a small molecule that interacts with the IN dimer interface and inhibits LEDGF binding to IN. In conclusion, this novel IN dimerization assay revealed that peptide and small molecule inhibitors of the IN-LEDGF interaction also stabilize IN dimers and promote their formation.
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Affiliation(s)
- Manuel Tsiang
- Gilead Sciences, 333 Lakeside Drive, Foster City, California 94404, United States.
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24
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Park J, Myong S, Niedziela-Majka A, Lee KS, Yu J, Lohman TM, Ha T. PcrA helicase dismantles RecA filaments by reeling in DNA in uniform steps. Cell 2010; 142:544-55. [PMID: 20723756 DOI: 10.1016/j.cell.2010.07.016] [Citation(s) in RCA: 136] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2008] [Revised: 02/02/2010] [Accepted: 07/08/2010] [Indexed: 10/19/2022]
Abstract
Translocation of helicase-like proteins on nucleic acids underlies key cellular functions. However, it is still unclear how translocation can drive removal of DNA-bound proteins, and basic properties like the elementary step size remain controversial. Using single-molecule fluorescence analysis on a prototypical superfamily 1 helicase, Bacillus stearothermophilus PcrA, we discovered that PcrA preferentially translocates on the DNA lagging strand instead of unwinding the template duplex. PcrA anchors itself to the template duplex using the 2B subdomain and reels in the lagging strand, extruding a single-stranded loop. Static disorder limited previous ensemble studies of a PcrA stepping mechanism. Here, highly repetitive looping revealed that PcrA translocates in uniform steps of 1 nt. This reeling-in activity requires the open conformation of PcrA and can rapidly dismantle a preformed RecA filament even at low PcrA concentrations, suggesting a mode of action for eliminating potentially deleterious recombination intermediates.
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Affiliation(s)
- Jeehae Park
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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25
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Khaki AR, Field C, Malik S, Niedziela-Majka A, Leavitt SA, Wang R, Hung M, Sakowicz R, Brendza KM, Fischer CJ. The macroscopic rate of nucleic acid translocation by hepatitis C virus helicase NS3h is dependent on both sugar and base moieties. J Mol Biol 2010; 400:354-78. [PMID: 20451531 DOI: 10.1016/j.jmb.2010.04.065] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2009] [Revised: 04/20/2010] [Accepted: 04/26/2010] [Indexed: 01/29/2023]
Abstract
The nonstructural protein 3 helicase (NS3h) of hepatitis C virus is a 3'-to-5' superfamily 2 RNA and DNA helicase that is essential for the replication of hepatitis C virus. We have examined the kinetic mechanism of the translocation of NS3h along single-stranded nucleic acid with bases uridylate (rU), deoxyuridylate (dU), and deoxythymidylate (dT), and have found that the macroscopic rate of translocation is dependent on both the base moiety and the sugar moiety of the nucleic acid, with approximate macroscopic translocation rates of 3 nt s(-1) (oligo(dT)), 35 nt s(-1) (oligo(dU)), and 42 nt s(-1) (oligo(rU)), respectively. We found a strong correlation between the macroscopic translocation rates and the binding affinity of the translocating NS3h protein for the respective substrates such that weaker affinity corresponded to faster translocation. The values of K(0.5) for NS3h translocation at a saturating ATP concentration are as follows: 3.3+/-0.4 microM nucleotide (poly(dT)), 27+/-2 microM nucleotide (poly(dU)), and 36+/-2 microM nucleotide (poly(rU)). Furthermore, results of the isothermal titration of NS3h with these oligonucleotides suggest that differences in TDeltaS(0) are the principal source of differences in the affinity of NS3h binding to these substrates. Interestingly, despite the differences in macroscopic translocation rates and binding affinities, the ATP coupling stoichiometries for NS3h translocation were identical for all three substrates (approximately 0.5 ATP molecule consumed per nucleotide translocated). This similar periodicity of ATP consumption implies a similar mechanism for NS3h translocation along RNA and DNA substrates.
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Affiliation(s)
- Ali R Khaki
- Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
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26
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Park J, Myong S, Niedziela-Majka A, Yu J, Lohman T, Ha T. Reeling in DNA One Base at A Time: pcrA Translocation Coupled to DNA Looping Dismantles RecA Filaments. Biophys J 2010. [DOI: 10.1016/j.bpj.2009.12.1190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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27
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Niedziela-Majka A, Chesnik MA, Tomko EJ, Lohman TM. Bacillus stearothermophilus PcrA monomer is a single-stranded DNA translocase but not a processive helicase in vitro. J Biol Chem 2007; 282:27076-27085. [PMID: 17631491 DOI: 10.1074/jbc.m704399200] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Structural studies of the Bacillus stearothermophilus PcrA protein along with biochemical studies of the single-stranded (ss) DNA translocation activity of PcrA monomers have led to the suggestion that a PcrA monomer possesses processive helicase activity in vitro. Yet definitive studies testing whether the PcrA monomer possesses processive helicase activity have not been performed. Here we show, using single turnover kinetic methods, that monomers of PcrA are able to translocate along ssDNA, in the 3' to 5' direction, rapidly and processively, whereas these same monomers display no detectable helicase activity under the same solution conditions in vitro. The PcrA monomer ssDNA translocation activity, although necessary, is not sufficient for processive helicase activity, and thus the translocase and helicase activities of PcrA are separable. These results also suggest that the helicase activity of PcrA needs to be activated either by self-assembly or through interactions with accessory proteins. This same behavior is displayed by both the Escherichia coli Rep and UvrD monomers. Hence, all three of these SF1 enzymes are ssDNA translocases as monomers but do not display processive helicase activity in vitro unless activated. The fact that the translocase and helicase activities are separable suggests that each activity may be used for different functions in vivo.
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Affiliation(s)
- Anita Niedziela-Majka
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110-1093
| | - Marla A Chesnik
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110-1093
| | - Eric J Tomko
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110-1093
| | - Timothy M Lohman
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110-1093.
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28
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Tomko EJ, Fischer CJ, Niedziela-Majka A, Lohman TM. A nonuniform stepping mechanism for E. coli UvrD monomer translocation along single-stranded DNA. Mol Cell 2007; 26:335-47. [PMID: 17499041 PMCID: PMC2041850 DOI: 10.1016/j.molcel.2007.03.024] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2006] [Revised: 03/15/2007] [Accepted: 03/30/2007] [Indexed: 10/23/2022]
Abstract
E. coli UvrD is an SF1 helicase involved in several DNA metabolic processes. Although a UvrD dimer is needed for helicase activity, a monomer can translocate with 3' to 5' directionality along single-stranded DNA, and this ATP-dependent translocation is likely involved in RecA displacement. In order to understand how the monomeric translocase functions, we have combined fluorescence stopped-flow kinetic methods with recently developed analysis methods to determine the kinetic mechanism, including ATP coupling stoichiometry, for UvrD monomer translocation along ssDNA. Our results suggest that the macroscopic rate of UvrD monomer translocation is not limited by each ATPase cycle but rather by a slow step (pause) in each translocation cycle that occurs after four to five rapid 1 nt translocation steps, with each rapid step coupled to hydrolysis of one ATP. These results suggest a nonuniform stepping mechanism that differs from either a Brownian motor or previous structure-based inchworm mechanisms.
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Affiliation(s)
| | | | | | - Timothy M. Lohman
- *Address correspondence to: T. M. Lohman, Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, 660 S. Euclid, St. Louis, MO 63110, 314-362-4393, FAX: 314-362-7183,
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29
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Majka J, Niedziela-Majka A, Burgers PMJ. The checkpoint clamp activates Mec1 kinase during initiation of the DNA damage checkpoint. Mol Cell 2007; 24:891-901. [PMID: 17189191 PMCID: PMC1850967 DOI: 10.1016/j.molcel.2006.11.027] [Citation(s) in RCA: 144] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2006] [Revised: 11/17/2006] [Accepted: 11/30/2006] [Indexed: 11/22/2022]
Abstract
Yeast Mec1/Ddc2 protein kinase, the ortholog of human ATR/ATRIP, plays a central role in the DNA damage checkpoint. The PCNA-like clamp Rad17/Mec3/Ddc1 (the 9-1-1 complex in human) and its loader Rad24-RFC are also essential components of this signal transduction pathway. Here we have studied the role of the clamp in regulating Mec1, and we delineate how the signal generated by DNA lesions is transduced to the Rad53 effector kinase. The checkpoint clamp greatly activates the kinase activity of Mec1, but only if the clamp is appropriately loaded upon partial duplex DNA. Activated Mec1 phosphorylates the Ddc1 and Mec3 subunits of the clamp, the Rad24 subunit of the loader, and the Rpa1 and Rpa2 subunits of RPA. Phosphorylation of Rad53, and of human PHAS-1, a nonspecific target, also requires a properly loaded clamp. Phosphorylation and binding studies with individual clamp subunits indicate that the Ddc1 subunit mediates the functional interactions with Mec1.
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30
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Niedziela-Majka A, Heyduk T. Escherichia coli RNA polymerase contacts outside the -10 promoter element are not essential for promoter melting. J Biol Chem 2005; 280:38219-27. [PMID: 16169843 DOI: 10.1074/jbc.m507984200] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We examined the relative affinity of model promoter constructs for binding Escherichia coli RNA polymerase (RNAP) holoenzyme. Model promoter constructs were designed to mimic DNA structures characteristic for different steps of transcription initiation. DNA duplexes in which a chemical cross-link was introduced just downstream from -10 hexamer to prevent DNA melting upon RNAP binding were used to mimic RNAP-promoter contacts in a closed complex. Fork junction DNA molecules with double-stranded/single-stranded junction between -11 and -10 position were used to study interactions of RNA polymerase with DNA in open complex. The -35 and -10 promoter regions were found to be equally important for the initial RNAP binding. The recognition of -35 promoter region was independent of structural context of the model promoter fragment. In contrast, free energy of RNAP binding to -10 hexamer was highly dependent on DNA structure. The relative importance of -10 region for sequence-specific interaction with the polymerase was the lowest for constructs mimicking closed complex and the highest for the constructs mimicking open complex. The relative importance of region -10 was also dependent on the presence of -35 consensus element indicating a communication between different DNA binding determinants of polymerase during open complex formation. Short double-stranded promoter fragments comprising only -35 and -10 or only -10 consensus elements underwent melting in a complex with polymerase indicating that the core of promoter melting activity of the polymerase is localized to a very small subset of all promoter-polymerase contacts.
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Affiliation(s)
- Anita Niedziela-Majka
- Edward A. Doisy Department of Biochemistry and Molecular Biology, St. Louis University Medical School, St. Louis, Missouri 63104, USA
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31
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Brendza KM, Cheng W, Fischer CJ, Chesnik MA, Niedziela-Majka A, Lohman TM. Autoinhibition of Escherichia coli Rep monomer helicase activity by its 2B subdomain. Proc Natl Acad Sci U S A 2005; 102:10076-81. [PMID: 16009938 PMCID: PMC1177377 DOI: 10.1073/pnas.0502886102] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
DNA helicases catalyze separation of double-helical DNA into its complementary single strands, a process essential for DNA replication, recombination, and repair. The Escherichia coli Rep protein, a superfamily 1 DNA helicase, functions in DNA replication restart and is required for replication of several bacteriophages. Monomers of Rep do not display helicase activity in vitro; in fact, DNA unwinding requires Rep dimerization. Here we show that removal of the 2B subdomain of Rep to form RepDelta2B activates monomer helicase activity, albeit with limited processivity. Although both full length Rep and RepDelta2B monomers can translocate with 3' to 5' directionality along single-stranded DNA, the 2B subdomain inhibits the helicase activity of full length Rep. This suggests an autoregulatory mechanism for Rep helicase, which may apply to other nonhexameric helicases, whereby helicase activity is regulated by the rotational conformational state of the 2B subdomain; formation of a Rep dimer may relieve autoinhibition by altering the 2B subdomain orientation.
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Affiliation(s)
- Katherine M Brendza
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA
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32
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Simeonov MF, Bieber Urbauer RJ, Gilmore JM, Adelman K, Brody EN, Niedziela-Majka A, Minakhin L, Heyduk T, Urbauer JL. Characterization of the interactions between the bacteriophage T4 AsiA protein and RNA polymerase. Biochemistry 2003; 42:7717-26. [PMID: 12820881 DOI: 10.1021/bi0340797] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The anti-sigma factor AsiA effects a change in promoter specificity of the Escherichia coli RNA polymerase via interactions with two conserved regions of the sigma(70) subunit, denoted 4.1 and 4.2. Free AsiA is a symmetrical homodimer. Here, we show that AsiA is monomeric when bound to sigma(70) and that a subset of the residues that contribute to the homodimer interface also contributes to the interface with sigma(70). AsiA interacts primarily with C-terminal sections of regions 4.1 and 4.2, which show remarkable sequence similarity. An AsiA monomer can simultaneously, and apparently cooperatively, bind both isolated regions 4.1 and 4.2 at preferred, distinct subsites, whereas region 4.1 alone or region 4.2 alone can interact with either subsite. These results suggest structural and functional plasticity in the interaction of AsiA with sigma(70) and support the notion of discrete roles for regions 4.1 and 4.2 in transcription regulation by AsiA. Furthermore, we show that AsiA inhibits recognition of the -35 consensus promoter element by region 4 of sigma(70) indirectly, as the residues on region 4 responsible for AsiA binding are distinct from those involved in DNA binding. Finally, we show that AsiA must directly disrupt the interaction of region 4 with the RNA polymerase beta subunit flap domain, resulting in a distance change between region 2 and region 4 of sigma(70). Thus, a new paradigm for transcription regulation by AsiA is emerging, whereby the distance between the DNA binding domains in sigma(70) is regulated, and promoter recognition specificity is modulated, by mediating the interactions of the sigma region 4 with the beta subunit flap domain.
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Affiliation(s)
- Mario F Simeonov
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045, USA
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33
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Minakhin L, Niedziela-Majka A, Kuznedelov K, Adelman K, Urbauer JL, Heyduk T, Severinov K. Interaction of T4 AsiA with its target sites in the RNA polymerase sigma70 subunit leads to distinct and opposite effects on transcription. J Mol Biol 2003; 326:679-90. [PMID: 12581632 DOI: 10.1016/s0022-2836(02)01442-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Bacteriophage T4 AsiA is a homodimeric protein that orchestrates a switch from the host and early viral transcription to middle viral transcription by binding to the sigma(70) subunit of Escherichia coli RNA polymerase holoenzyme (Esigma(70)) and preventing promoter complex formation on most E.coli and early T4 promoters. In addition, Esigma(70)AsiA, but not Esigma(70), is a substrate of transcription activation by T4-encoded DNA-binding protein MotA, a co-activator of transcription from middle viral promoters. The molecular determinants of sigma(70)-AsiA interaction necessary for transcription inhibition reside in the sigma(70) conserved region 4.2, which recognizes the -35 promoter consensus element. The molecular determinants of sigma(70)-AsiA interaction necessary for MotA-dependent transcription activation have not been identified. Here, we show that in the absence of sigma(70) region 4.2, AsiA interacts with sigma(70) conserved region 4.1 and activates transcription in a MotA-independent manner. Further, we show that the AsiA dimer must dissociate to interact with either region 4.2 or region 4.1 of sigma(70). We propose that MotA may co-activate transcription by restricting AsiA binding to sigma(70) region 4.1.
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Affiliation(s)
- Leonid Minakhin
- Department of Genetics, Waksman Institute of Microbiology, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
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34
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Rymarczyk G, Grad I, Rusek A, Oświecimska-Rusin K, Niedziela-Majka A, Kochman M, Ozyhar A. Purification of Drosophila melanogaster ultraspiracle protein and analysis of its A/B region-dependent dimerization behavior in vitro. Biol Chem 2003; 384:59-69. [PMID: 12674500 DOI: 10.1515/bc.2003.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Two members of the nuclear receptor superfamily, EcR (ecdysteroid receptor protein) and Usp (Ultraspiracle), heterodimerize to form a functional receptor for the steroid hormone 20-hydroxyecdysone and thus enable it to coordinate morphogenetic events during insect metamorphosis. N-terminally His-tagged Usp was overexpressed in E. coli cells as a non-truncated protein and purified to homogeneity in two chromatographic steps. It was demonstrated that the recombinant receptor specifically binds the ecdysone response element of the hsp27 gene promoter (hsp27EcRE). Moreover, a highly synergistically formed heterodimeric complex with the DNA-binding domain of EcR was observed on hsp27EcRE, but not on the native Usp response element from the chorion s15 gene promoter. Recombinant Usp forms homodimers and homotetramers in the absence of DNA, as judged from gel filtration and chemical crosslinking experiments. Truncation of its N-terminal A/B region changes molecular characteristics of Usp, considerably weakening its oligomerization potential under the same experimental conditions. This contrasts with the results obtained previously for the similarly truncated RXR--a vertebrate homolog of Usp.
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Affiliation(s)
- Grzegorz Rymarczyk
- Institute of Organic Chemistry, Biochemistry and Biotechnology, Division of Biochemistry, Wrocław University of Technology, Wybrzeze Wyspiańskiego 27, 50-370 Wrocław, Poland
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35
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Nechaev S, Yuzenkova Y, Niedziela-Majka A, Heyduk T, Severinov K. A novel bacteriophage-encoded RNA polymerase binding protein inhibits transcription initiation and abolishes transcription termination by host RNA polymerase. J Mol Biol 2002; 320:11-22. [PMID: 12079331 DOI: 10.1016/s0022-2836(02)00420-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Xp10 is a lytic bacteriophage of Xanthomonas oryzae, a Gram-negative bacterium that causes rice blight. We purified an Xp10 protein, p7, that binds to and inhibits X. oryzae RNA polymerase (RNAP). P7 is a novel 73 amino acid-long protein; it does not bind to and hence does not affect transcription by Escherichia coli RNAP. Analysis of E. coli/X. oryzae RNAP hybrids locates the p7 binding site to the largest X. oryzae RNAP subunit, beta'. Binding of p7 to X. oryzae RNAP holoenzyme prevents large conformational change that places the sigma subunit region 4 into the correct position for interaction with the -35 promoter element. As a result, open promoter complex formation on the -10/-35 class promoters is inhibited. Inhibition of promoter complex formation on the extended -10 class promoters is less efficient. The p7 protein also abolishes factor-independent transcription termination by X. oryzae RNAP by preventing the release of nascent RNA at terminators. Further physiological and mechanistic studies of this novel transcription factor should provide additional insights into its biological role and the processes of promoter recognition and transcription termination.
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Affiliation(s)
- Sergei Nechaev
- Waksman Institute for Microbiology, Rutgers, The State University, Piscataway, NJ 08854, USA
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36
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Abstract
Fluorescence resonance energy transfer (FRET) is a technique allowing measurements of atomic-scale distances in diluted solutions of macromolecules under native conditions. This feature makes FRET a powerful tool to study complicated biological assemblies. In this report we review the applications of FRET to studies of transcription initiation by Escherichia coli RNA polymerase. The versatility of FRET for studies of a large macromolecular assembly such as RNA polymerase is illustrated by examples of using FRET to address several different aspects of transcription initiation by polymerase. FRET has been used to determine the architecture of polymerase, its complex with single-stranded DNA, and the conformation of promoter fragment bound to polymerase. FRET has been also used as a binding assay to determine the thermodynamics of promoter DNA fragment binding to the polymerase. Functional conformational changes in the specificity subunit of polymerase responsible for the modulation of the promoter binding activity of the enzyme and the mechanistic aspects of the transition from the initiation to the elongation complex were also investigated.
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Affiliation(s)
- T Heyduk
- Edward A. Doisy Department of Biochemistry and Molecular Biology, St. Louis University Medical School, 1402 S. Grand Blvd., MO 63104, USA.
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37
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Kuznedelov K, Minakhin L, Niedziela-Majka A, Dove SL, Rogulja D, Nickels BE, Hochschild A, Heyduk T, Severinov K. A role for interaction of the RNA polymerase flap domain with the sigma subunit in promoter recognition. Science 2002; 295:855-7. [PMID: 11823642 DOI: 10.1126/science.1066303] [Citation(s) in RCA: 156] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
In bacteria, promoter recognition depends on the RNA polymerase sigma subunit, which combines with the catalytically proficient RNA polymerase core to form the holoenzyme. The major class of bacterial promoters is defined by two conserved elements (the -10 and -35 elements, which are 10 and 35 nucleotides upstream of the initiation point, respectively) that are contacted by sigma in the holoenzyme. We show that recognition of promoters of this class depends on the "flexible flap" domain of the RNA polymerase beta subunit. The flap interacts with conserved region 4 of sigma and triggers a conformational change that moves region 4 into the correct position for interaction with the -35 element. Because the flexible flap is evolutionarily conserved, this domain may facilitate promoter recognition by specificity factors in eukaryotes as well.
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Affiliation(s)
- Konstantin Kuznedelov
- Waksman Institute, Department of Genetics, Rutgers University, Piscataway, NJ 08854, USA
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38
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Grad I, Niedziela-Majka A, Kochman M, Ozyhar A. Analysis of Usp DNA binding domain targeting reveals critical determinants of the ecdysone receptor complex interaction with the response element. Eur J Biochem 2001; 268:3751-8. [PMID: 11432742 DOI: 10.1046/j.1432-1327.2001.02287.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The steroid hormone, 20-hydroxyecdysone (20E), directs Drosophila metamorphosis via a heterodimeric receptor formed by two members of the nuclear hormone receptors superfamily, the product of the EcR (EcR) and of the ultraspiracle (Usp) genes. Our previous study [Niedziela-Majka, A., Kochman, M., Ozyhar, A. (2000) Eur. J. Biochem. 267, 507-519] on EcR and Usp DNA-binding domains (EcRDBD and UspDBD, respectively) suggested that UspDBD may act as a specific anchor that preferentially binds the 5' half-site of the pseudo-palindromic response element from the hsp27 gene promoter and thus locates the heterocomplex in the defined orientation. Here, we analyzed in detail the determinants of the UspDBD interaction with the hsp27 element. The roles of individual amino acids in the putative DNA recognition alpha helix and the roles of the base pairs of the UspDBD target sequence have been probed by site-directed mutagenesis. The results show how the hsp27 element specifies UspDBD binding and thus the polar assembly of the UspDBD/EcRDBD heterocomplex. It is suggested how possible nucleotide deviations within the 5' half-site of the element may be used for the fine-tuning of the 20E-response element specificity and consequently the physiological response.
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Affiliation(s)
- I Grad
- Institute of Organic Chemistry, Biochemistry and Biotechnology, Division of Biochemistry, Wroclaw University of Technology, Poland
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39
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Niedziela-Majka A, Kochman M, Ozyhar A. Polarity of the ecdysone receptor complex interaction with the palindromic response element from the hsp27 gene promoter. Eur J Biochem 2000; 267:507-19. [PMID: 10632720 DOI: 10.1046/j.1432-1327.2000.01027.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The functional 20-hydroxyecdysone (20E) receptor is a heterodimer of two members of the nuclear hormone receptors superfamily; the product of the EcR (EcR) and of the ultraspiracle (Usp) genes. As most of the natural 20E-response elements are highly degenerated palindromes, we were interested in determining whether or not such asymmetric elements could dictate the defined orientation of the Usp/EcR complex. We have investigated interaction of EcR and Usp DNA-binding domains (EcRDBD and UspDBD, respectively) with the palindromic response element from the hsp27 gene promoter (hsp27pal). The hsp27pal half-sites contribute differently to the binding of the heterodimer components; the 5' half-site exhibits higher affinity for both DBDs than the 3' half-site. This observation, along with data demonstrating that UspDBD exhibits approximate fourfold higher affinity to the 5' half-site than EcRDBD, suggest that UspDBD locates the EcRDBD/UspDBD heterocomplex in the defined orientation (5'-UspDBD-EcRDBD-3') on the hsp27pal sequence. The binding polarity onto hsp27pal is accompanied by different contribution of the UspDBD and EcRDBD C-terminal sequences to the DNA-binding and heterocomplex formation. This is supported by finding that deletion of the C-terminal of EcRDBD region corresponding to the putative A-helix severely decreased binding of the EcRDBD to the hsp27pal. In contrast, UspDBD in which corresponding residues were deleted exhibited the same hsp27pal binding pattern as the wild type UspDBD. Additional truncation comprising the putative T-box, resulted in a reduced binding of the mutated UspDBD. This truncation however, still allowed effective EcRDBD/UspDBD heterodimer formation. Finally we demonstrated that perfect palindromes, composed of two hsp27pal 5' half-sites (or of the related sequence) contain all of the structural information necessary for the anisotropic UspDBD/EcRDBD heterocomplex formation. However, the perfect palindromes bind isolated homomeric DBDs as well as their heterocomplex with higher affinity than imperfect hsp27pal. This is the first report indicating that natural 20E response elements, which with one exception are degenerated palindromes, may act as functionally asymmetric elements in a manner similar to the action of direct repeats in vertebrates.
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Affiliation(s)
- A Niedziela-Majka
- Institute of Organic Chemistry, Division of Biochemistry, Wroctaw University of Technology, Poland
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Niedziela-Majka A, Rymarczyk G, Kochman M, Ozyhar A. GST-Induced dimerization of DNA-binding domains alters characteristics of their interaction with DNA. Protein Expr Purif 1998; 14:208-20. [PMID: 9790883 DOI: 10.1006/prep.1998.0932] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The steroid hormone 20-hydroxyecdysone (20E) plays a key role in the induction and modulation of morphogenetic events throughout Drosophila melanogaster development. Two members of the nuclear receptor superfamily, the product of the EcR (EcR) and of the ultraspiracle genes (Usp), heterodimerize to form its functional receptor. To study the receptor-DNA interaction, critical for regulating 20E-dependent gene expression, it is necessary to produce large quantities of EcR and Usp DNA-binding domains. Toward this end DNA-binding domains of EcR and Usp (EcRDBD and UspDBD, respectively) were cloned and expressed in Escherichia coli as fusion proteins with glutathione S-transferase (GST). However, the results of DNA-binding studies obtained with purified GST-DBDs were found to be questionable because the fused proteins oligomerized in solution due to the presence of GST. Therefore DBDs were released from GST-chimeric proteins by thrombin cleavage and then purified by glutathione-Sepharose 4B chromatography and by gel filtration on Superdex 75 HR. The gel mobility-shift experiments showed that UspDBD exhibited higher affinity than EcRDBD toward a 20-hydroxyecdysone response element from the Drosophila hsp 27 gene (hsp 27pal). Furthermore, formation of the heterodimeric EcRDBD-UspDBD complex was observed to be synergistic when equimolar mixture of both DBDs was incubated with hsp 27pal. Surprisingly, GST-EcRDBD bound hsp 27pal with higher affinity than GST-UspDBD. This difference was accompanied by the impaired ability of the GST-DBDs to interact synergistically with hsp 27pal. This is the first report on expression and purification of the soluble DBDs of the functional ecdysteroid receptor with satisfying yields. Furthermore, our results add to the recent findings which indicate the need for caution in interpreting the activities of GST fusion proteins.
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Affiliation(s)
- A Niedziela-Majka
- Biochemistry and Biotechnology, Division of Biochemistry, Wroclaw University of Technology, Wybrzeze Wyspiańskiego 27, Wroclaw, 50-370, Poland
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Rusin A, Niedziela-Majka A, Rymarczyk G, Ozyhar A. Expression and purification of 6xHis-tagged DNA binding domains of functional ecdysteroid receptor from drosophila melanogaster. Acta Biochim Pol 1996. [DOI: 10.18388/abp.1996_4457] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Two members of the nuclear receptor superfamily, EcR and Ultraspiracle (Usp) heterodimerize to form a functional receptor for 20-hydroxyecdysone-the key ecdysteroid controlling induction and modulation of morphogenetic events through Drosophila development. In order to study aspects of receptor function and ultimately the structural basis of the ecdysteroid receptor-DNA interaction, it is necessary to produce large quantities of purified EcR and Usp DNA-binding domains. Toward this end, we have expressed the EcR DNA-binding domain and the Usp DNA-binding domain as proteins with an affinity tag consisting of six histidine residues (6xHis-EcRDBD and 6xHis-UspDBD, respectively) using the expression vector pQE-30. Under optimal conditions, elaborated in this study, bacteria can express the recombinant 6xHis-EcRDBD to the levels of 11% of total soluble proteins and the 6xHis-UspDBD to the levels of 16%. Both proteins were purified to homogeneity from the soluble protein fraction using combination of ammonium sulphate fractionation and affinity chromatography on Ni-NTA agarose. The gel mobility shift experiments demonstrated that the purified 6xHis-EcRDBD and the 6xHis-UspDBD interact specifically with an 20-hydroxyecdysone response element from the promoter region of the hsp 27 Drosophila gene.
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Rusin A, Niedziela-Majka A, Rymarczyk G, Ozyhar A. Expression and purification of 6xHis-tagged DNA binding domains of functional ecdysteroid receptor from drosophila melanogaster. Acta Biochim Pol 1996; 43:611-21. [PMID: 9104497] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Two members of the nuclear receptor superfamily, EcR and Ultraspiracle (Usp) heterodimerize to form a functional receptor for 20-hydroxyecdysone-the key ecdysteroid controlling induction and modulation of morphogenetic events through Drosophila development. In order to study aspects of receptor function and ultimately the structural basis of the ecdysteroid receptor-DNA interaction, it is necessary to produce large quantities of purified EcR and Usp DNA-binding domains. Toward this end, we have expressed the EcR DNA-binding domain and the Usp DNA-binding domain as proteins with an affinity tag consisting of six histidine residues (6xHis-EcRDBD and 6xHis-UspDBD, respectively) using the expression vector pQE-30. Under optimal conditions, elaborated in this study, bacteria can express the recombinant 6xHis-EcRDBD to the levels of 11% of total soluble proteins and the 6xHis-UspDBD to the levels of 16%. Both proteins were purified to homogeneity from the soluble protein fraction using combination of ammonium sulphate fractionation and affinity chromatography on Ni-NTA agarose. The gel mobility shift experiments demonstrated that the purified 6xHis-EcRDBD and the 6xHis-UspDBD interact specifically with an 20-hydroxyecdysone response element from the promoter region of the hsp 27 Drosophila gene.
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Affiliation(s)
- A Rusin
- Institute of Organic Chemistry, Biochemistry and Biotechnology, Technical University of Wrocław, Poland
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