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Renner B, Laskowski J, Poppelaars F, Ferreira VP, Blaine J, Antonioli AH, Hannan JP, Kovacs JM, van Kooten C, You Z, Pickering MC, Holers VM, Thurman JM. Factor H related proteins modulate complement activation on kidney cells. Kidney Int 2022; 102:1331-1344. [PMID: 36063874 PMCID: PMC9691546 DOI: 10.1016/j.kint.2022.07.035] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [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: 09/12/2021] [Revised: 07/04/2022] [Accepted: 07/27/2022] [Indexed: 01/13/2023]
Abstract
Complement activation at a particular location is determined by the balance of activating and inhibitory proteins. Factor H is a key regulator of the alternative pathway of complement, and genetic or acquired impairments in Factor H are associated with glomerular injury. The human Factor H-related proteins (FHRs) comprise a family of five proteins that are structurally related to Factor H. Variations in the genes or expression levels of the FHRs are also associated with glomerular disease, although the mechanisms of glomerular protection/injury are incompletely understood. To explore the role of the FHRs on complement regulation/dysregulation in the kidney, we expressed and purified recombinant murine FHRs (FHRs A, B, C and E). These four distinct FHRs contain binding regions with high amino acid sequence homology to binding regions within Factor H, but we observed different interactions of the FHRs with Factor H binding ligands, including heparin and C3d. There was differential binding of the FHRs to the resident kidney cell types (mesangial, glomerular endothelial, podocytes, and tubular epithelial). All four FHRs caused complement dysregulation on kidney cell surfaces in vitro, although the magnitude of the effect differed among the FHRs and also varied among the different kidney cells. However, only FHR E caused glomerular complement dysregulation when injected in vivo but did not exacerbate injury when injected into mice with ischemic acute kidney injury, an alternative pathway-mediated model. Thus, our experiments demonstrate that the FHRs have unique, and likely context-dependent, effects on the different cell types within the kidney.
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Affiliation(s)
- Brandon Renner
- Department of Medicine, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, Colorado, USA
| | - Jennifer Laskowski
- Department of Medicine, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, Colorado, USA
| | - Felix Poppelaars
- Department of Medicine, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, Colorado, USA
| | - Viviana P Ferreira
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio, USA
| | - Judith Blaine
- Department of Medicine, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, Colorado, USA
| | | | - Jonathan P Hannan
- Molecular Biophysics Program and Department of Biochemistry, University of Colorado, Boulder, Colorado, USA
| | - James M Kovacs
- Department of Chemistry and Biochemistry, University of Colorado Springs, Colorado Springs, Colorado, USA
| | - Cees van Kooten
- Department of Nephrology, Leiden University Medical Center, Leiden, the Netherlands
| | - Zhiying You
- Department of Medicine, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, Colorado, USA
| | - Matthew C Pickering
- Centre for Inflammatory Disease, Department of Immunology and Inflammation, Imperial College London, London, UK
| | - V Michael Holers
- Department of Medicine, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, Colorado, USA
| | - Joshua M Thurman
- Department of Medicine, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, Colorado, USA.
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Bricault CA, Yusim K, Seaman MS, Yoon H, Theiler J, Giorgi EE, Wagh K, Theiler M, Hraber P, Macke JP, Kreider EF, Learn GH, Hahn BH, Scheid JF, Kovacs JM, Shields JL, Lavine CL, Ghantous F, Rist M, Bayne MG, Neubauer GH, McMahan K, Peng H, Chéneau C, Jones JJ, Zeng J, Ochsenbauer C, Nkolola JP, Stephenson KE, Chen B, Gnanakaran S, Bonsignori M, Williams LD, Haynes BF, Doria-Rose N, Mascola JR, Montefiori DC, Barouch DH, Korber B. HIV-1 Neutralizing Antibody Signatures and Application to Epitope-Targeted Vaccine Design. Cell Host Microbe 2019; 26:296. [PMID: 31415756 PMCID: PMC6706656 DOI: 10.1016/j.chom.2019.07.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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Bricault CA, Yusim K, Seaman MS, Yoon H, Theiler J, Giorgi EE, Wagh K, Theiler M, Hraber P, Macke JP, Kreider EF, Learn GH, Hahn BH, Scheid JF, Kovacs JM, Shields JL, Lavine CL, Ghantous F, Rist M, Bayne MG, Neubauer GH, McMahan K, Peng H, Chéneau C, Jones JJ, Zeng J, Ochsenbauer C, Nkolola JP, Stephenson KE, Chen B, Gnanakaran S, Bonsignori M, Williams LD, Haynes BF, Doria-Rose N, Mascola JR, Montefiori DC, Barouch DH, Korber B. HIV-1 Neutralizing Antibody Signatures and Application to Epitope-Targeted Vaccine Design. Cell Host Microbe 2019; 25:59-72.e8. [PMID: 30629920 PMCID: PMC6331341 DOI: 10.1016/j.chom.2018.12.001] [Citation(s) in RCA: 90] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2018] [Revised: 07/06/2018] [Accepted: 11/14/2018] [Indexed: 12/26/2022]
Abstract
Eliciting HIV-1-specific broadly neutralizing antibodies (bNAbs) remains a challenge for vaccine development, and the potential of passively delivered bNAbs for prophylaxis and therapeutics is being explored. We used neutralization data from four large virus panels to comprehensively map viral signatures associated with bNAb sensitivity, including amino acids, hypervariable region characteristics, and clade effects across four different classes of bNAbs. The bNAb signatures defined for the variable loop 2 (V2) epitope region of HIV-1 Env were then employed to inform immunogen design in a proof-of-concept exploration of signature-based epitope targeted (SET) vaccines. V2 bNAb signature-guided mutations were introduced into Env 459C to create a trivalent vaccine, and immunization of guinea pigs with V2-SET vaccines resulted in increased breadth of NAb responses compared with Env 459C alone. These data demonstrate that bNAb signatures can be utilized to engineer HIV-1 Env vaccine immunogens capable of eliciting antibody responses with greater neutralization breadth. HIV-1 bNAb sensitivity signatures from 4 large virus panels mapped across 4 Ab classes Non-contact hypervariable region characteristics are critical for bNAb sensitivity HIV-1 Env 459C used alone as a vaccine can elicit modest tier 2 NAbs in guinea pigs V2 bNAb signature-guided modifications in 459C enhanced neutralization breadth
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Affiliation(s)
- Christine A Bricault
- Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
| | - Karina Yusim
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA; New Mexico Consortium, Los Alamos, NM 87545, USA
| | - Michael S Seaman
- Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
| | - Hyejin Yoon
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - James Theiler
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA; New Mexico Consortium, Los Alamos, NM 87545, USA
| | - Elena E Giorgi
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA; New Mexico Consortium, Los Alamos, NM 87545, USA
| | - Kshitij Wagh
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA; New Mexico Consortium, Los Alamos, NM 87545, USA
| | | | - Peter Hraber
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | | | - Edward F Kreider
- Departments of Medicine and Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Gerald H Learn
- Departments of Medicine and Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Beatrice H Hahn
- Departments of Medicine and Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Johannes F Scheid
- Massachusetts General Hospital, Boston, MA 02114, USA; Harvard Medical School, Boston, MA 02114, USA
| | - James M Kovacs
- Division of Molecular Medicine, Children's Hospital, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA; Departments of Chemistry and Biochemistry, University of Colorado, Colorado Springs, CO 80918, USA
| | - Jennifer L Shields
- Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
| | - Christy L Lavine
- Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
| | - Fadi Ghantous
- Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
| | - Michael Rist
- Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
| | - Madeleine G Bayne
- Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
| | - George H Neubauer
- Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
| | - Katherine McMahan
- Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
| | - Hanqin Peng
- Division of Molecular Medicine, Children's Hospital, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Coraline Chéneau
- Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
| | - Jennifer J Jones
- Department of Medicine and CFAR, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Jie Zeng
- Department of Medicine and CFAR, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Christina Ochsenbauer
- Department of Medicine and CFAR, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Joseph P Nkolola
- Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
| | - Kathryn E Stephenson
- Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA; Ragon Institute of Massachusetts General Hospital, MIT, and Harvard, Boston, MA 02114, USA
| | - Bing Chen
- Division of Molecular Medicine, Children's Hospital, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - S Gnanakaran
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA; New Mexico Consortium, Los Alamos, NM 87545, USA
| | - Mattia Bonsignori
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, NC 27710, USA; Department of Medicine, Duke University School of Medicine, Durham, NC 27710, USA
| | - LaTonya D Williams
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, NC 27710, USA
| | - Barton F Haynes
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, NC 27710, USA; Department of Medicine, Duke University School of Medicine, Durham, NC 27710, USA; Department of Immunology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Nicole Doria-Rose
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20814, USA
| | - John R Mascola
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20814, USA
| | - David C Montefiori
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, NC 27710, USA; Department of Surgery, Duke University School of Medicine, Durham, NC 27710, USA
| | - Dan H Barouch
- Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA; Ragon Institute of Massachusetts General Hospital, MIT, and Harvard, Boston, MA 02114, USA.
| | - Bette Korber
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA; New Mexico Consortium, Los Alamos, NM 87545, USA.
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Valderrama-Landeros L, Flores-de-Santiago F, Kovacs JM, Flores-Verdugo F. An assessment of commonly employed satellite-based remote sensors for mapping mangrove species in Mexico using an NDVI-based classification scheme. Environ Monit Assess 2017; 190:23. [PMID: 29242995 DOI: 10.1007/s10661-017-6399-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 12/05/2017] [Indexed: 06/07/2023]
Abstract
Optimizing the classification accuracy of a mangrove forest is of utmost importance for conservation practitioners. Mangrove forest mapping using satellite-based remote sensing techniques is by far the most common method of classification currently used given the logistical difficulties of field endeavors in these forested wetlands. However, there is now an abundance of options from which to choose in regards to satellite sensors, which has led to substantially different estimations of mangrove forest location and extent with particular concern for degraded systems. The objective of this study was to assess the accuracy of mangrove forest classification using different remotely sensed data sources (i.e., Landsat-8, SPOT-5, Sentinel-2, and WorldView-2) for a system located along the Pacific coast of Mexico. Specifically, we examined a stressed semiarid mangrove forest which offers a variety of conditions such as dead areas, degraded stands, healthy mangroves, and very dense mangrove island formations. The results indicated that Landsat-8 (30 m per pixel) had the lowest overall accuracy at 64% and that WorldView-2 (1.6 m per pixel) had the highest at 93%. Moreover, the SPOT-5 and the Sentinel-2 classifications (10 m per pixel) were very similar having accuracies of 75 and 78%, respectively. In comparison to WorldView-2, the other sensors overestimated the extent of Laguncularia racemosa and underestimated the extent of Rhizophora mangle. When considering such type of sensors, the higher spatial resolution can be particularly important in mapping small mangrove islands that often occur in degraded mangrove systems.
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Affiliation(s)
- L Valderrama-Landeros
- Subcoordinación de Percepción Remota, Comisión Nacional Para el Conocimiento y Uso de la Biodiversidad (CONABIO), 4903 Liga Periférico-Insurgentes Sur, 14010, Tlalpan, CDMX, Mexico
| | - F Flores-de-Santiago
- Instituto de Ciencias del Mar y Limnología, Unidad Académica Procesos Oceánicos y Costeros, Universidad Nacional Autónoma de México, A.P. 70-305, Av. Universidad 3000, Ciudad Universitaria, 04510, Coyoacán, CDMX, Mexico.
| | - J M Kovacs
- Department of Geography, Nipissing University, 100 College Dr, North Bay, ON, P1B 8L7, Canada
| | - F Flores-Verdugo
- Instituto de Ciencias del Mar y Limnología, Unidad Académica Mazatlán, Universidad Nacional Autónoma de México, Av. Joel Montes Camarena s/n, 82040, Mazatlán, SIN, Mexico
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Chen J, Kovacs JM, Peng H, Rits-Volloch S, Lu J, Park D, Zablowsky E, Seaman MS, Chen B. HIV-1 ENVELOPE. Effect of the cytoplasmic domain on antigenic characteristics of HIV-1 envelope glycoprotein. Science 2015; 349:191-5. [PMID: 26113642 DOI: 10.1126/science.aaa9804] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 06/08/2015] [Indexed: 12/20/2022]
Abstract
A major goal for HIV-1 vaccine development is the production of an immunogen to mimic native, functional HIV-1 envelope trimeric spikes (Env) on the virion surface. We lack a reliable description of a native, functional trimer, however, because of inherent instability and heterogeneity in most preparations. We describe here two conformationally homogeneous Envs derived from difficult-to-neutralize primary isolates. All their non-neutralizing epitopes are fully concealed and independent of their proteolytic processing. Most broadly neutralizing antibodies (bnAbs) recognize these native trimers. Truncation of their cytoplasmic tail has little effect on membrane fusion, but it diminishes binding to trimer-specific bnAbs while exposing non-neutralizing epitopes. These results yield a more accurate antigenic picture than hitherto possible of a genuinely untriggered and functional HIV-1 Env; they can guide effective vaccine development.
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Affiliation(s)
- Jia Chen
- Division of Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA. Department of Pediatrics, Harvard Medical School, 3 Blackfan Street, Boston, MA 02115, USA
| | - James M Kovacs
- Division of Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA. Department of Pediatrics, Harvard Medical School, 3 Blackfan Street, Boston, MA 02115, USA
| | - Hanqin Peng
- Division of Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Sophia Rits-Volloch
- Division of Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Jianming Lu
- Codex BioSolutions, Inc., 401 Professional Drive, Gaithersburg, MD 20879, USA
| | - Donghyun Park
- Division of Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Elise Zablowsky
- Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02215, USA
| | - Michael S Seaman
- Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02215, USA
| | - Bing Chen
- Division of Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA. Department of Pediatrics, Harvard Medical School, 3 Blackfan Street, Boston, MA 02115, USA.
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Pejawar-Gaddy S, Kovacs JM, Barouch DH, Chen B, Irvine DJ. Design of lipid nanocapsule delivery vehicles for multivalent display of recombinant Env trimers in HIV vaccination. Bioconjug Chem 2014; 25:1470-8. [PMID: 25020048 PMCID: PMC4140538 DOI: 10.1021/bc5002246] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
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Immunization strategies that elicit
antibodies capable of neutralizing
diverse virus strains will likely be an important part of a successful
vaccine against HIV. However, strategies to promote robust humoral
responses against the native intact HIV envelope trimer structure
are lacking. We recently developed chemically cross-linked lipid nanocapsules
as carriers of molecular adjuvants and encapsulated or surface-displayed
antigens, which promoted follicular helper T-cell responses and elicited
high-avidity, durable antibody responses to a candidate malaria antigen.
To apply this system to the delivery of HIV antigens, Env gp140 trimers
with terminal his-tags (gp140T-his) were anchored to the surface of
lipid nanocapsules via Ni-NTA-functionalized lipids. Initial experiments
revealed that the large (409 kDa), heavily glycosylated trimers were
capable of extracting fluid phase lipids from the membranes of nanocapsules.
Thus, liquid-ordered and/or gel-phase lipid compositions were required
to stably anchor trimers to the particle membranes. Trimer-loaded
nanocapsules combined with the clinically relevant adjuvant monophosphoryl
lipid A primed high-titer antibody responses in mice at antigen doses
ranging from 5 μg to as low as 100 ng, whereas titers dropped
more than 50-fold over the same dose range when soluble trimer was
mixed with a strong oil-in-water adjuvant comparator. Nanocapsule
immunization also broadened the number of distinct epitopes on the
HIV trimer recognized by the antibody response. These results suggest
that nanocapsules displaying HIV trimers in an oriented, multivalent
presentation can promote key aspects of the humoral response against
Env immunogens.
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Affiliation(s)
- Sharmila Pejawar-Gaddy
- Department of Biological Engineering, #Koch Institute for Integrative Cancer Research, and ¶Department of Material Science, Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
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Thurman JM, Kulik L, Orth H, Wong M, Renner B, Sargsyan SA, Mitchell LM, Hourcade DE, Hannan JP, Kovacs JM, Coughlin B, Woodell AS, Pickering MC, Rohrer B, Holers VM. Detection of complement activation using monoclonal antibodies against C3d. J Clin Invest 2013; 123:2218-30. [PMID: 23619360 DOI: 10.1172/jci65861] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Accepted: 02/21/2013] [Indexed: 12/21/2022] Open
Abstract
During complement activation the C3 protein is cleaved, and C3 activation fragments are covalently fixed to tissues. Tissue-bound C3 fragments are a durable biomarker of tissue inflammation, and these fragments have been exploited as addressable binding ligands for targeted therapeutics and diagnostic agents. We have generated cross-reactive murine monoclonal antibodies against human and mouse C3d, the final C3 degradation fragment generated during complement activation. We developed 3 monoclonal antibodies (3d8b, 3d9a, and 3d29) that preferentially bind to the iC3b, C3dg, and C3d fragments in solution, but do not bind to intact C3 or C3b. The same 3 clones also bind to tissue-bound C3 activation fragments when injected systemically. Using mouse models of renal and ocular disease, we confirmed that, following systemic injection, the antibodies accumulated at sites of C3 fragment deposition within the glomerulus, the renal tubulointerstitium, and the posterior pole of the eye. To detect antibodies bound within the eye, we used optical imaging and observed accumulation of the antibodies within retinal lesions in a model of choroidal neovascularization (CNV). Our results demonstrate that imaging methods that use these antibodies may provide a sensitive means of detecting and monitoring complement activation-associated tissue inflammation.
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Affiliation(s)
- Joshua M Thurman
- Department of Medicine, University of Colorado School of Medicine, Aurora, Colorado 80045, USA.
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Kovacs JM, Nkolola JP, Peng H, Cheung A, Perry J, Miller CA, Seaman MS, Barouch D, Chen B. HIV-1 envelope trimer elicits higher neutralizing antibody responses than monomeric gp120. Retrovirology 2012. [PMCID: PMC3441467 DOI: 10.1186/1742-4690-9-s2-o62] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
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Nkolola JP, Kovacs JM, Korber B, Chen B, Seaman M, Barouch D. Stability and neutralization capacity of a novel mosaic HIV-1 gp140 trimer in a guinea pig model. Retrovirology 2012. [PMCID: PMC3441370 DOI: 10.1186/1742-4690-9-s2-p299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Shaw CD, Storek MJ, Young KA, Kovacs JM, Thurman JM, Holers VM, Hannan JP. Delineation of the complement receptor type 2-C3d complex by site-directed mutagenesis and molecular docking. J Mol Biol 2010; 404:697-710. [PMID: 20951140 DOI: 10.1016/j.jmb.2010.10.005] [Citation(s) in RCA: 17] [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] [Received: 08/25/2010] [Revised: 10/04/2010] [Accepted: 10/06/2010] [Indexed: 12/01/2022]
Abstract
The interactions between the complement receptor type 2 (CR2) and the C3 complement fragments C3d, C3dg, and iC3b are essential for the initiation of a normal immune response. A crystal-derived structure of the two N-terminal short consensus repeat (SCR1-2) domains of CR2 in complex with C3d has previously been elucidated. However, a number of biochemical and biophysical studies targeting both CR2 and C3d appear to be in conflict with these structural data. Previous mutagenesis and heteronuclear NMR spectroscopy studies directed toward the C3d-binding site on CR2 have indicated that the CR2-C3d cocrystal structure may represent an encounter/intermediate or nonphysiological complex. With regard to the CR2-binding site on C3d, mutagenesis studies by Isenman and coworkers [Isenman, D. E., Leung, E., Mackay, J. D., Bagby, S. & van den Elsen, J. M. H. (2010). Mutational analyses reveal that the staphylococcal immune evasion molecule Sbi and complement receptor 2 (CR2) share overlapping contact residues on C3d: Implications for the controversy regarding the CR2/C3d cocrystal structure. J. Immunol. 184, 1946-1955] have implicated an electronegative "concave" surface on C3d in the binding process. This surface is discrete from the CR2-C3d interface identified in the crystal structure. We generated a total of 18 mutations targeting the two (X-ray crystallographic- and mutagenesis-based) proposed CR2 SCR1-2 binding sites on C3d. Using ELISA analyses, we were able to assess binding of mutant forms of C3d to CR2. Mutations directed toward the concave surface of C3d result in substantially compromised CR2 binding. By contrast, targeting the CR2-C3d interface identified in the cocrystal structure and the surrounding area results in significantly lower levels of disruption in binding. Molecular modeling approaches used to investigate disparities between the biochemical data and the X-ray structure of the CR2-C3d cocrystal result in highest-scoring solutions in which CR2 SCR1-2 is docked within the concave surface of C3d.
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Affiliation(s)
- Craig D Shaw
- Institute of Structural and Molecular Biology, School of Biological Sciences, King's Buildings, Mayfield Road, University of Edinburgh, Edinburgh EH9 3JR, UK
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Kovacs JM, Hannan JP, Eisenmesser EZ, Holers VM. Biophysical investigations of complement receptor 2 (CD21 and CR2)-ligand interactions reveal amino acid contacts unique to each receptor-ligand pair. J Biol Chem 2010; 285:27251-27258. [PMID: 20558730 DOI: 10.1074/jbc.m110.106617] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human complement receptor type 2 (CR2 and CD21) is a cell membrane receptor, with 15 or 16 extracellular short consensus repeats (SCRs), that promotes B lymphocyte responses and bridges innate and acquired immunity. The most distally located SCRs, SCR1-2, mediate the interaction of CR2 with its four known ligands (C3d, EBV gp350, IFNalpha, and CD23). To ascertain specific interacting residues on CR2, we utilized NMR studies wherein gp350 and IFNalpha were titrated into (15)N-labeled SCR1-2, and chemical shift changes indicative of specific inter-molecular interactions were identified. With backbone assignments made, the chemical shift changes were mapped onto the crystal structure of SCR1-2. With regard to gp350, the binding region of CR2 is primarily focused on SCR1 and the inter-SCR linker, specifically residues Asn(11), Arg(13), Ala(22), Arg(28), Ser(32), Arg(36), Lys(41), Lys(57), Tyr(64), Lys(67), Tyr(68), Arg(83), Gly(84), and Arg(89). With regard to IFNalpha, the binding is similar to the CR2-C3d interaction with specific residues being Arg(13), Tyr(16), Arg(28), Ser(42), Lys(48), Lys(50), Tyr(68), Arg(83), Gly(84), and Arg(89). We also report thermodynamic properties of each ligand-receptor pair determined using isothermal titration calorimetry. The CR2-C3d interaction was characterized as a two-mode binding interaction with K(d) values of 0.13 and 160 microm, whereas the CR2-gp350 and CR2-IFNalpha interactions were characterized as single site binding events with affinities of 0.014 and 0.035 microm, respectively. The compilation of chemical binding maps suggests specific residues on CR2 that are uniquely important in each of these three binding interactions.
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Affiliation(s)
- James M Kovacs
- Department of Medicine and Immunology, University of Colorado Denver School of Medicine, Aurora, Colorado 80045
| | - Jonathan P Hannan
- Institute of Structural and Molecular Biology, University of Edinburgh, Edinburgh EH9 3JR, Scotland, United Kingdom
| | - Elan Z Eisenmesser
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado 80045
| | - V Michael Holers
- Department of Medicine and Immunology, University of Colorado Denver School of Medicine, Aurora, Colorado 80045.
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Kovacs JM, King JML, Flores de Santiago F, Flores-Verdugo F. Evaluating the condition of a mangrove forest of the Mexican Pacific based on an estimated leaf area index mapping approach. Environ Monit Assess 2009; 157:137-149. [PMID: 19023672 DOI: 10.1007/s10661-008-0523-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2007] [Accepted: 09/11/2008] [Indexed: 05/27/2023]
Abstract
Given the alarming global rates of mangrove forest loss it is important that resource managers have access to updated information regarding both the extent and condition of their mangrove forests. Mexican mangroves in particular have been identified as experiencing an exceptional high annual rate of loss. However, conflicting studies, using remote sensing techniques, of the current state of many of these forests may be hindering all efforts to conserve and manage what remains. Focusing on one such system, the Teacapán-Agua Brava-Las Haciendas estuarine-mangrove complex of the Mexican Pacific, an attempt was made to develop a rapid method of mapping the current condition of the mangroves based on estimated LAI. Specifically, using an AccuPAR LP-80 Ceptometer, 300 indirect in situ LAI measurements were taken at various sites within the black mangrove (Avicennia germinans) dominated forests of the northern section of this system. From this sample, 225 measurements were then used to develop linear regression models based on their relationship with corresponding values derived from QuickBird very high resolution optical satellite data. Specifically, regression analyses of the in situ LAI with both the normalized difference vegetation index (NDVI) and the simple ration (SR) vegetation index revealed significant positive relationships [LAI versus NDVI (R (2) = 0.63); LAI versus SR (R (2) = 0.68)]. Moreover, using the remaining sample, further examination of standard errors and of an F test of the residual variances indicated little difference between the two models. Based on the NDVI model, a map of estimated mangrove LAI was then created. Excluding the dead mangrove areas (i.e. LAI = 0), which represented 40% of the total 30.4 km(2) of mangrove area identified in the scene, a mean estimated LAI value of 2.71 was recorded. By grouping the healthy fringe mangrove with the healthy riverine mangrove and by grouping the dwarf mangrove together with the poor condition mangrove, mean estimated LAI values of 4.66 and 2.39 were calculated, respectively. Given that the former healthy group only represents 8% of the total mangrove area examined, it is concluded that this mangrove system, considered one of the most important of the Pacific coast of the Americas, is currently experiencing a considerable state of degradation. Furthermore, based on the results of this investigation it is suggested that this approach could provide resource managers and scientists alike with a very rapid and effective method for monitoring the state of remaining mangrove forests of the Mexican Pacific and, possibly, other areas of the tropics.
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Affiliation(s)
- J M Kovacs
- Department of Geography, Nipissing University, North Bay, ON, P1B 8L7, Canada.
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Kovacs JM, Hannan JP, Eisenmesser EZ, Holers VM. Mapping of the C3d ligand binding site on complement receptor 2 (CR2/CD21) using nuclear magnetic resonance and chemical shift analysis. J Biol Chem 2009; 284:9513-20. [PMID: 19164292 PMCID: PMC2666603 DOI: 10.1074/jbc.m808404200] [Citation(s) in RCA: 18] [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] [Received: 11/04/2008] [Revised: 01/06/2009] [Indexed: 11/06/2022] Open
Abstract
Complement receptor 2 (CR2, CD21) is a cell membrane protein, with 15 or 16 extracellular short consensus repeats (SCRs), that promotes B lymphocyte responses and bridges innate and acquired immunity. The most distally located SCRs (SCR1-2) mediate the interaction of CR2 with its four known ligands (C3d, Epstein-Barr virus gp350, interferon-alpha, and CD23). Inhibitory monoclonal antibodies against SCR1-2 block binding of all ligands. To develop ligand-specific inhibitors that would also assist in identifying residues unique to each receptor-ligand interaction, phage were selected from randomly generated libraries by panning with recombinant SCR1-2, followed by specific ligand-driven elution. Derived peptides were tested by competition ELISA. One peptide, C3dp1 (APQHLSSQYSRT) exhibited ligand-specific inhibition at midmicromolar IC(50). C3d was titrated into (15)N-labeled SCR1-2, which revealed chemical shift changes indicative of specific intermolecular interactions. With backbone assignments made, the chemical shift changes were mapped onto the crystal structure of SCR1-2. With regard to C3d, the binding surface includes regions of SCR1, SCR2, and the inter-SCR linker, specifically residues Arg(13), Tyr(16), Arg(28), Tyr(29), Ser(32), Thr(34), Lys(48), Asp(56), Lys(57), Tyr(68), Arg(83), Gly(84), Asn(101), Asn(105), and Ser(109). SCR1 and SCR2 demonstrated distinct binding modes. The CR2 binding surface incorporating SCR1 is inconsistent with a previous x-ray CR2-C3d co-crystal analysis but consistent with mutagenesis, x-ray neutron scattering, and inhibitory monoclonal antibody epitope mapping. Titration with C3dp1 yielded chemical shift changes (Arg(13), Tyr(16), Thr(34), Lys(48), Asp(56), Lys(57), Tyr(68), Arg(83), Gly(84), Asn(105), and Ser(109)) overlapping with C3d, indicating that C3dp1 interacts at the same CR2 site as C3d.
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Affiliation(s)
- James M Kovacs
- Department of Medicine, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
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Mant CT, Kovacs JM, Kim HM, Pollock DD, Hodges RS. Intrinsic amino acid side-chain hydrophilicity/hydrophobicity coefficients determined by reversed-phase high-performance liquid chromatography of model peptides: comparison with other hydrophilicity/hydrophobicity scales. Biopolymers 2009; 92:573-95. [PMID: 19795449 PMCID: PMC2792893 DOI: 10.1002/bip.21316] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [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: 11/07/2022]
Abstract
An accurate determination of the intrinsic hydrophilicity/hydrophobicity of amino acid side-chains in peptides and proteins is fundamental in understanding many area of research, including protein folding and stability, peptide and protein function, protein-protein interactions and peptide/protein oligomerization, as well as the design of protocols for purification and characterization of peptides and proteins. Our definition of intrinsic hydrophilicity/hydrophobicity of side-chains is the maximum possible hydrophilicity/hydrophobicity of side-chains in the absence of any nearest-neighbor effects and/or any conformational effects of the polypeptide chain that prevent full expression of side-chain hydrophilicity/hydrophobicity. In this review, we have compared an experimentally derived intrinsic side-chain hydrophilicity/hydrophobicity scale generated from RP-HPLC retention behavior of de novo designed synthetic model peptides at pH 2 and pH 7 with other RP-HPLC-derived scales, as well as scales generated from classic experimental and calculation-based methods of octanol/water partitioning of Nalpha-acetyl-amino-acid amides or free energy of transfer of free amino acids. Generally poor correlation was found with previous RP-HPLC-derived scales, likely due to the random nature of the peptide mixtures in terms of varying peptide size, conformation and frequency of particular amino acids. In addition, generally poor correlation with the classical approaches served to underline the importance of the presence of a polypeptide backbone when generating intrinsic values. We have shown that the intrinsic scale determined here is in full agreement with the structural characteristics of amino acid side-chains.
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Affiliation(s)
- Colin T. Mant
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver, School of Medicine, Aurora, CO 80045, USA
| | - James M. Kovacs
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver, School of Medicine, Aurora, CO 80045, USA
| | - Hyun-Min Kim
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver, School of Medicine, Aurora, CO 80045, USA
| | - David D. Pollock
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver, School of Medicine, Aurora, CO 80045, USA
| | - Robert S. Hodges
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver, School of Medicine, Aurora, CO 80045, USA
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Kovacs JM, Hannan JP, Holers VM. Defining CD21‐ligand interactions using ligand specific inhibitory peptides. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.1066.8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- James M Kovacs
- Medicine/ImmunologyUniversity of Colorado Denver SOMAuroraCO
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Abstract
High-performance liquid chromatography (HPLC) has proved extremely versatile over the past 25 yr for the isolation and purification of peptides varying widely in their sources, quantity and complexity. This article covers the major modes of HPLC utilized for peptides (size-exclusion, ion-exchange, and reversed-phase), as well as demonstrating the potential of a novel mixed-mode hydrophilic interaction/cation-exchange approach developed in this laboratory. In addition to the value of these HPLC modes for peptide separations, the value of various HPLC techniques for structural characterization of peptides and proteins will be addressed, e.g., assessment of oligomerization state of peptides/proteins by size-exclusion chromatography and monitoring the hydrophilicity/hydrophobicity of amphipathic alpha-helical peptides, a vital precursor for the development of novel antimicrobial peptides. The value of capillary electrophoresis for peptide separations is also demonstrated. Preparative reversed-phase chromatography purification protocols for sample loads of up to 200 mg on analytical columns and instrumentation are introduced for both peptides and recombinant proteins.
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Affiliation(s)
- Colin T Mant
- Department of Biochemistry and Molecular Genetics, University of Colorado at Denver and Health Sciences Center, Aurora, CO, USA
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Tripet B, Cepeniene D, Kovacs JM, Mant CT, Krokhin OV, Hodges RS. Requirements for prediction of peptide retention time in reversed-phase high-performance liquid chromatography: hydrophilicity/hydrophobicity of side-chains at the N- and C-termini of peptides are dramatically affected by the end-groups and location. J Chromatogr A 2006; 1141:212-25. [PMID: 17187811 PMCID: PMC2722105 DOI: 10.1016/j.chroma.2006.12.024] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [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] [Received: 08/01/2006] [Revised: 12/01/2006] [Accepted: 12/05/2006] [Indexed: 11/27/2022]
Abstract
The value of reversed-phase high-performance liquid chromatography (RP-HPLC) and the field of proteomics would be greatly enhanced by accurate prediction of retention times of peptides of known composition. The present study investigates the hydrophilicity/hydrophobicity of amino acid side-chains at the N- and C-termini of peptides while varying the functional end-groups at the termini. We substituted all 20 naturally occurring amino acids at the N- and C-termini of a model peptide sequence, where the functional end-groups were N(alpha)-acetyl-X- and N(alpha)-amino-X- at the N-terminus and -X-C(alpha)-carboxyl and -X-C(alpha)-amide at the C-terminus. Amino acid coefficients were subsequently derived from the RP-HPLC retention behaviour of these peptides and compared to each other as well as to coefficients determined in the centre of the peptide chain (internal coefficients). Coefficients generated from residues substituted at the C-terminus differed most (between the -X-C(alpha)-carboxyl and -X-C(alpha)-amide peptide series) for hydrophobic side-chains. A similar result was seen for the N(alpha)-acetyl-X- and N(alpha)-amino-X- peptide series, where the largest differences in coefficient values were observed for hydrophobic side-chains. Coefficients derived from substitutions at the C-terminus for hydrophobic amino acids were dramatically different compared to internal coefficients for hydrophobic side-chains, ranging from 17.1 min for Trp to 4.8 min for Cys. In contrast, coefficients derived from substitutions at the N-terminus showed relatively small differences from the internal coefficients. Subsequent prediction of peptide retention time, within an error of just 0.4 min, was achieved by a predictive algorithm using a combination of internal coefficients and coefficients for the C-terminal residues. For prediction of peptide retention time, the sum of the coefficients must include internal and terminal coefficients.
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Affiliation(s)
- Brian Tripet
- Department of Biochemistry and Molecular Genetics, University of Colorado at Denverand Health Sciences Center, Aurora, CO, 80045, USA
| | - Dziuleta Cepeniene
- Department of Biochemistry and Molecular Genetics, University of Colorado at Denverand Health Sciences Center, Aurora, CO, 80045, USA
| | - James M. Kovacs
- Department of Biochemistry and Molecular Genetics, University of Colorado at Denverand Health Sciences Center, Aurora, CO, 80045, USA
| | - Colin T. Mant
- Department of Biochemistry and Molecular Genetics, University of Colorado at Denverand Health Sciences Center, Aurora, CO, 80045, USA
| | - Oleg V. Krokhin
- Manitoba Centre for Proteomic and Systems Biology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Robert S. Hodges
- Department of Biochemistry and Molecular Genetics, University of Colorado at Denverand Health Sciences Center, Aurora, CO, 80045, USA
- Corresponding author. Tel.: +1 303 724 3253; fax: +1 303 724 3249. E-mail address: (R.S. Hodges)
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Kovacs JM, Mant CT, Kwok SC, Osguthorpe DJ, Hodges RS. Quantitation of the nearest-neighbour effects of amino acid side-chains that restrict conformational freedom of the polypeptide chain using reversed-phase liquid chromatography of synthetic model peptides with L- and D-amino acid substitutions. J Chromatogr A 2006; 1123:212-24. [PMID: 16712857 PMCID: PMC1976429 DOI: 10.1016/j.chroma.2006.04.092] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [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] [Received: 11/03/2005] [Revised: 04/18/2006] [Accepted: 04/28/2006] [Indexed: 10/24/2022]
Abstract
Side-chain backbone interactions (or "effects") between nearest neighbours may severely restrict the conformations accessible to a polypeptide chain and thus represent the first step in protein folding. We have quantified nearest-neighbour effects (i to i+1) in peptides through reversed-phase liquid chromatography (RP-HPLC) of model synthetic peptides, where L- and D-amino acids were substituted at the N-terminal end of the peptide sequence, adjacent to a L-Leu residue. These nearest-neighbour effects (expressed as the difference in retention times of L- and D-peptide diastereomers at pHs 2 and 7) were frequently dramatic, depending on the type of side-chain adjacent to the L-Leu residue, albeit such effects were independent of mobile phase conditions. No nearest-neighbour effects were observed when residue i is adjacent to a Gly residue. Calculation of minimum energy conformations of selected peptides supported the view that, whether a L- or D-amino acid is substituted adjacent to L-Leu, its orientation relative to this bulky Leu side-chain represents the most energetically favourable configuration. We believe that such energetically favourable, and different, configurations of L- and D-peptide diastereomers affect their respective interactions with a hydrophobic stationary phase, which are thus quantified by different RP-HPLC retention times. Side-chain hydrophilicity/hydrophobicity coefficients were generated in the presence of these nearest-neighbour effects and, despite the relative difference in such coefficients generated from peptides substituted with L- or D-amino acids, the relative difference in hydrophilicity/hydrophobicity between different amino acids in the L- or D-series is maintained. Overall, our results demonstrate that such nearest-neighbour effects can clearly restrict conformational space of an amino acid side-chain in a polypeptide chain.
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Affiliation(s)
- James M Kovacs
- Department of Biochemistry and Molecular Genetics, University of Colorado at Denver and Health Sciences Center, Aurora, CO 80045, USA
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Kovacs JM, Mant CT, Hodges RS. Determination of intrinsic hydrophilicity/hydrophobicity of amino acid side chains in peptides in the absence of nearest-neighbor or conformational effects. Biopolymers 2006; 84:283-97. [PMID: 16315143 PMCID: PMC2744689 DOI: 10.1002/bip.20417] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.1] [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] [Indexed: 11/05/2022]
Abstract
Understanding the hydrophilicity/hydrophobicity of amino acid side chains in peptides/proteins is one the most important aspects of biology. Though many hydrophilicity/hydrophobicity scales have been generated, an "intrinsic" scale has yet to be achieved. "Intrinsic" implies the maximum possible hydrophilicity/hydrophobicity of side chains in the absence of nearest-neighbor or conformational effects that would decrease the full expression of the side-chain hydrophilicity/hydrophobicity when the side chain is in a polypeptide chain. Such a scale is the fundamental starting point for determining the parameters that affect side-chain hydrophobicity and for quantifying such effects in peptides and proteins. A 10-residue peptide sequence, Ac-X-G-A-K-G-A-G-V-G-L-amide, was designed to enable the determination of the intrinsic values, where position X was substituted by all 20 naturally occurring amino acids and norvaline, norleucine, and ornithine. The coefficients were determined by reversed-phase high-performance liquid chromatography using six different mobile phase conditions involving different pH values (2, 5, and 7), ion-pairing reagents, and the presence and absence of different salts. The results show that the intrinsic hydrophilicity/hydrophobicity of amino acid side chains in peptides (proteins) is independent of pH, buffer conditions, or whether C(8) or C(18) reversed-phase columns were used for 17 side chains (Gly, Ala, Cys, Pro, Val, nVal, Leu, nLeu, Ile, Met, Tyr, Phe, Trp, Ser, Thr, Asn, and Gln) and dependent on pH and buffer conditions, including the type of salt or ion-pairing reagent for potentially charged side chains (Orn, Lys, His, Arg, Asp, and Glu).
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Affiliation(s)
- James M Kovacs
- Department of Biochemistry and Molecular Genetics, University of Colorado at Denver and Health Sciences Center, Aurora, 80045, USA
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Abstract
To evaluate the accounts of local fishermen, Landsat TM images (1986, 1993, 1999) were examined to assess potential losses in the mangrove forests of the Teacapán-Agua Brava lagoon system, Mexico. A binary change mask derived from image differencing of a band 4/3 ratio was employed to calculate any changes within this forested wetland. The results indicate that by 1986 approximately 18% (or 86 km2) of the mangrove area under study was either dead or in poor condition. The majority of this damage had occurred in the eastern section of the Agua Brava basin, which coincides, with the reports of the elderly fishermen. Examination of aerial photographs from 1970 revealed no adverse impacts in this area and would suggest, as postulated by the fishermen and other scientists, that modifications in environmental conditions following the opening of a canal, Cuautlá canal, in 1972 may have initiated the large-scale mortality. Although these areas of impact are still developing, the results from the satellite data indicate that the majority of the more recent changes are occurring elsewhere in the system. Obvious in the 1999 satellite data, but not so in the 1993, are large areas of mangrove degradation in the northern section of the Teacapán region. In the Agua Brava basin, the more recent transformations are appearing on the western side of the basin. Since long-term records of environmental conditions are absent, it is difficult to determine why these latest changes are occurring or even if the earlier losses were the result of the canal. Potential agents of change that have recently been observed include a hurricane, a second canal, and the uncontrolled expansion of the Cuautlá canal since 1994.
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Affiliation(s)
- J M Kovacs
- Department of Geography, Nipissing University, Ontario, Canada.
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