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Croll TI, Andersen GR. Re-evaluation of low-resolution crystal structures via interactive molecular-dynamics flexible fitting (iMDFF): a case study in complement C4. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2016; 72:1006-16. [PMID: 27599733 DOI: 10.1107/s2059798316012201] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 07/27/2016] [Indexed: 11/10/2022]
Abstract
While the rapid proliferation of high-resolution structures in the Protein Data Bank provides a rich set of templates for starting models, it remains the case that a great many structures both past and present are built at least in part by hand-threading through low-resolution and/or weak electron density. With current model-building tools this task can be challenging, and the de facto standard for acceptable error rates (in the form of atomic clashes and unfavourable backbone and side-chain conformations) in structures based on data with dmax not exceeding 3.5 Å reflects this. When combined with other factors such as model bias, these residual errors can conspire to make more serious errors in the protein fold difficult or impossible to detect. The three recently published 3.6-4.2 Å resolution structures of complement C4 (PDB entries 4fxg, 4fxk and 4xam) rank in the top quartile of structures of comparable resolution both in terms of Rfree and MolProbity score, yet, as shown here, contain register errors in six β-strands. By applying a molecular-dynamics force field that explicitly models interatomic forces and hence excludes most physically impossible conformations, the recently developed interactive molecular-dynamics flexible fitting (iMDFF) approach significantly reduces the complexity of the conformational space to be searched during manual rebuilding. This substantially improves the rate of detection and correction of register errors, and allows user-guided model building in maps with a resolution lower than 3.5 Å to converge to solutions with a stereochemical quality comparable to atomic resolution structures. Here, iMDFF has been used to individually correct and re-refine these three structures to MolProbity scores of <1.7, and strategies for working with such challenging data sets are suggested. Notably, the improved model allowed the resolution for complement C4b to be extended from 4.2 to 3.5 Å as demonstrated by paired refinement.
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Affiliation(s)
- Tristan Ian Croll
- Institute of Health and Biomedical Innovation, Queensland University of Technology, GPO Box 2434, Brisbane, QLD 4001, Australia
| | - Gregers Rom Andersen
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10C, 8000 Aarhus, Denmark
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2
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Kanan Y, Al-Ubaidi MR. Identification of Tyrosine O Sulfated Proteins in Cow Retina and the 661W Cell Line. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 854:649-54. [PMID: 26427471 DOI: 10.1007/978-3-319-17121-0_86] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Lack of tyrosine O Sulfation compromises both rod and cone electroretinographic responses emphasizing the importance of this post-translational modification for vision. To identify tyrosine sulfated proteins in retina, cow retinal lysates were subjected to immunoaffinity purification using an anti-sulfotyrosine antibody. The tyrosine sulfated proteins were eluted from the column using a sulfotyrosine pentapeptide and identified using mass spectrometry. Similarly, tyrosine sulfated proteins secreted by the 661W cell line were identified. Proteins identified were vitronectin, fibronectin, fibulin 2, nidogen, collagen V alpha 2, complement component 3 and C4 and fibrinogen beta. All proteins were subjected to analysis by 'Sulfinator' to determine potential sulfated tyrosines.
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Affiliation(s)
- Yogita Kanan
- Departments of Cell Biology, University of Oklahoma Health Sciences Center, 73104, Oklahoma City, OK, USA.
| | - Muayyad R Al-Ubaidi
- Departments of Cell Biology, University of Oklahoma Health Sciences Center, 73104, Oklahoma City, OK, USA.
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3
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Mortensen S, Kidmose RT, Petersen SV, Szilágyi Á, Prohászka Z, Andersen GR. Structural Basis for the Function of Complement Component C4 within the Classical and Lectin Pathways of Complement. THE JOURNAL OF IMMUNOLOGY 2015; 194:5488-96. [PMID: 25911760 DOI: 10.4049/jimmunol.1500087] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 03/22/2015] [Indexed: 11/19/2022]
Abstract
Complement component C4 is a central protein in the classical and lectin pathways within the complement system. During activation of complement, its major fragment C4b becomes covalently attached to the surface of pathogens and altered self-tissue, where it acts as an opsonin marking the surface for removal. Moreover, C4b provides a platform for assembly of the proteolytically active convertases that mediate downstream complement activation by cleavage of C3 and C5. In this article, we present the crystal and solution structures of the 195-kDa C4b. Our results provide the molecular details of the rearrangement accompanying C4 cleavage and suggest intramolecular flexibility of C4b. The conformations of C4b and its paralogue C3b are shown to be remarkably conserved, suggesting that the convertases from the classical and alternative pathways are likely to share their overall architecture and mode of substrate recognition. We propose an overall molecular model for the classical pathway C5 convertase in complex with C5, suggesting that C3b increases the affinity for the substrate by inducing conformational changes in C4b rather than a direct interaction with C5. C4b-specific features revealed by our structural studies are probably involved in the assembly of the classical pathway C3/C5 convertases and C4b binding to regulators.
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Affiliation(s)
- Sofia Mortensen
- Department of Molecular Biology and Genetics, Aarhus University, DK-8000 Aarhus, Denmark
| | - Rune T Kidmose
- Department of Molecular Biology and Genetics, Aarhus University, DK-8000 Aarhus, Denmark
| | - Steen V Petersen
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus, Denmark; and
| | - Ágnes Szilágyi
- 3rd Department of Internal Medicine, Semmelweis University, Budapest 1125, Hungary
| | - Zoltan Prohászka
- 3rd Department of Internal Medicine, Semmelweis University, Budapest 1125, Hungary
| | - Gregers R Andersen
- Department of Molecular Biology and Genetics, Aarhus University, DK-8000 Aarhus, Denmark;
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4
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Ludeman JP, Stone MJ. The structural role of receptor tyrosine sulfation in chemokine recognition. Br J Pharmacol 2014; 171:1167-79. [PMID: 24116930 DOI: 10.1111/bph.12455] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Revised: 09/10/2013] [Accepted: 09/30/2013] [Indexed: 12/22/2022] Open
Abstract
Tyrosine sulfation is a post-translational modification of secreted and transmembrane proteins, including many GPCRs such as chemokine receptors. Most chemokine receptors contain several potentially sulfated tyrosine residues in their extracellular N-terminal regions, the initial binding site for chemokine ligands. Sulfation of these receptors increases chemokine binding affinity and potency. Although receptor sulfation is heterogeneous, insights into the molecular basis of sulfotyrosine (sTyr) recognition have been obtained using purified, homogeneous sulfopeptides corresponding to the N-termini of chemokine receptors. Receptor sTyr residues bind to a shallow cleft defined by the N-loop and β3-strand elements of cognate chemokines. Tyrosine sulfation enhances the affinity of receptor peptides for cognate chemokines in a manner dependent on the position of sulfation. Moreover, tyrosine sulfation can alter the selectivity of receptor peptides among several cognate chemokines for the same receptor. Finally, binding to receptor sulfopeptides can modulate the oligomerization state of chemokines, thereby influencing the ability of a chemokine to activate its receptor. These results increase the motivation to investigate the structural basis by which tyrosine sulfation modulates chemokine receptor activity and the biological consequences of this functional modulation.
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Affiliation(s)
- Justin P Ludeman
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic., Australia
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5
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Kanan Y, Siefert JC, Kinter M, Al-Ubaidi MR. Complement factor H, vitronectin, and opticin are tyrosine-sulfated proteins of the retinal pigment epithelium. PLoS One 2014; 9:e105409. [PMID: 25136834 PMCID: PMC4138151 DOI: 10.1371/journal.pone.0105409] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 07/23/2014] [Indexed: 01/09/2023] Open
Abstract
Lack of tyrosine sulfation of ocular proteins results in disorganized photoreceptor structure and drastically reduced visual function, demonstrating the importance of this post-translational modification to vision. To understand the role that tyrosine sulfation plays in the function of ocular proteins, we identified some tyrosine-sulfated proteins in the retinal pigment epithelium using two independent methods, immuno-affinity column purification with an anti-sulfotyrosine specific antibody and computer-based sequence analysis of retinal pigment epithelium secretome by means of the prediction program Sulfinator. Radioactive labeling followed by thin layer electrophoresis revealed that three proteins, vitronectin, opticin, and complement factor H (CFH), were post-translationally modified by tyrosine sulfation. The identification of vitronectin and CFH as tyrosine-sulfated proteins is significant, since both are deposited in drusen in the eyes of patients with age-related macular degeneration (AMD). Furthermore, mutations in CFH have been determined to be a major risk factor in the development of AMD. Future studies that seek to understand the role of CFH in the development of AMD should take into account the role that tyrosine sulfation plays in the interaction of this protein with its partners, and examine whether modulating sulfation provides a potential therapeutic target.
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Affiliation(s)
- Yogita Kanan
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
| | - Joseph C. Siefert
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
| | - Michael Kinter
- Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
- Free Radical Biology and Aging Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, United States of America
| | - Muayyad R. Al-Ubaidi
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
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6
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Improved detection of intact tyrosine sulfate-containing peptides by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry in linear negative ion mode. Int J Biochem Cell Biol 2009; 42:174-9. [PMID: 19857600 DOI: 10.1016/j.biocel.2009.10.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2009] [Revised: 09/28/2009] [Accepted: 10/14/2009] [Indexed: 12/15/2022]
Abstract
Sulfation of tyrosine residues is a common post-translational modification, but detecting and quantitating this modification poses challenges due to lability of the sulfate group. The goal of our studies was to determine how best to detect and to assess the stoichiometry of this modification using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS). Sulfated and nonsulfated forms of peptides-hirudin(55-65), caerulein, and cholecystokinin octapeptide and phosphorylated and nonphosphorylated pp60-c-src (521-533)-were analyzed using several matrices: sinapinic acid (SA), 2,5-dihydroxybenzoic acid (DBA), and cyano-4-hydroxycinnamic acid (CHCA). Intact sulfated peptides were difficult to detect using positive ion mode; peptides were observed as desulfated ions. Phosphorylated peptide was stable and was detected in positive and negative ion modes. Detection of sulfated peptides improved with: (1) Analysis in negative ion mode, (2) Decreased laser power, (3) Matrix selection: DBA>/=SA>CHCA. In negative ion mode, desorption/ionization of sulfated peptide was equivalent or more efficient than nonsulfated peptide, depending on conditions of analysis. Examination of a tryptic digest of alpha(2)-antiplasmin detected the single site of sulfation in negative ion mode but not in positive ion mode. We conclude that improved detection of sulfated peptides can be achieved in negative ion mode. Dual analysis in positive and negative ion modes serves as a potential means of identifying peptides with labile modifications such as sulfation and distinguishing them from phosphorylation.
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7
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Hoffhines AJ, Damoc E, Bridges KG, Leary JA, Moore KL. Detection and purification of tyrosine-sulfated proteins using a novel anti-sulfotyrosine monoclonal antibody. J Biol Chem 2006; 281:37877-87. [PMID: 17046811 PMCID: PMC1764208 DOI: 10.1074/jbc.m609398200] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein tyrosine O-sulfation is a post-translational modification mediated by one of two Golgi tyrosylprotein sulfotransferases (TPST1 and TPST2) that catalyze the transfer of sulfate to tyrosine residues in secreted and transmembrane proteins. Tyrosine sulfation plays a role in protein-protein interactions in several well defined systems. Although dozens of tyrosine-sulfated proteins are known, many more are likely to exist and await description. Advancing our understanding of the importance of tyrosine sulfation in biological systems requires the development of new tools for the detection and study of tyrosine-sulfated proteins. We have developed a novel anti-sulfotyrosine monoclonal antibody (called PSG2) that binds with high affinity and exquisite specificity to sulfotyrosine residues in peptides and proteins independently of sequence context. We show that it can detect tyrosine-sulfated proteins in complex biological samples and can be used as a probe to assess the role of tyrosine sulfation in protein function. We also demonstrate the utility of PSG2 in the purification of tyrosine-sulfated proteins from crude tissue samples. Finally, Western blot analysis using PSG2 showed that certain sperm/epididymal proteins are undersulfated in Tpst2(-/-) mice. This indicates that TPST1 and TPST2 have distinct macromolecular substrate specificities and provides clues as to the molecular mechanism of the infertility of Tpst2(-/-) males. PSG2 should be widely applicable for identification of tyrosine-sulfated proteins in other systems and organisms.
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Affiliation(s)
- Adam J. Hoffhines
- From the Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Eugen Damoc
- Genome Center, Departments of Chemistry and Molecular Cell Biology, University of California, Davis, California 94616
| | | | - Julie A. Leary
- Genome Center, Departments of Chemistry and Molecular Cell Biology, University of California, Davis, California 94616
| | - Kevin L. Moore
- From the Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
- From the Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104
- Oklahoma Center for Medical Glycobiology, Oklahoma City, Oklahoma 73104
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8
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Mishiro E, Sakakibara Y, Liu MC, Suiko M. Differential enzymatic characteristics and tissue-specific expression of human TPST-1 and TPST-2. J Biochem 2006; 140:731-7. [PMID: 17028309 DOI: 10.1093/jb/mvj206] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Protein tyrosine sulfation is emerging as a widespread post-translational modification in multicellular eukaryotes. The responsible enzyme, named tyrosylprotein sulfotransferase (TPST), catalyzes the sulfate transfer from 3'-phosphoadenosine 5'-phosphosulfate to tyrosine residues of proteins. Two distinct TPSTs, designated TPST-1 and TPST-2, had previously been identified. In the present study, we cloned human TPST-1 and TPST-2 expressed and characterized the recombinant enzymes using peptide substrates. These enzymes displayed distinct acidic pH optima and stimulatory effects of Mn(2+). Additionally, the activity of TPST-2, but not TPST-1, was stimulated in the presence of Mg(2+). Compared with TPST-2, TPST-1 displayed considerably lower K(m) and V(max) for the majority of the tested peptide substrates, implying their differential substrate specificity. Quantitative real-time PCR analysis showed that although the two TPSTs were co-expressed in all 20 human tissues examined, the levels of expression of TPST-1 and TPST-2 varied significantly among different tissues. These latter findings may imply distinct physiological functions of TPST-1 and TPST-2.
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Affiliation(s)
- Emi Mishiro
- Department of Biochemistry and Applied Biosciences, Faculty of Agriculture, University of Miyazaki, Miyazaki 889-2192
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9
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Goettsch S, Badea RA, Mueller JW, Wotzlaw C, Schoelermann B, Schulz L, Rabiller M, Bayer P, Hartmann-Fatu C. Human TPST1 Transmembrane Domain Triggers Enzyme Dimerisation and Localisation to the Golgi Compartment. J Mol Biol 2006; 361:436-49. [PMID: 16859706 DOI: 10.1016/j.jmb.2006.06.023] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2006] [Revised: 06/06/2006] [Accepted: 06/08/2006] [Indexed: 10/24/2022]
Abstract
TPST1 is a human tyrosylprotein sulfotransferase that uses 3'phosphoadenosine-5'phosphosulfate (PAPS) to transfer the sulfate moiety to proteins predominantly designated for secretion. To achieve a general understanding of the cellular role of human tyrosine-directed sulfotransferases, we investigated targeting, structure and posttranslational modification of TPST1. Golgi localisation of the enzyme in COS-7 and HeLa cells was visualised by fluorescence imaging techniques. PNGase treatment and mutational studies determined that TPST1 bears N-linked glycosyl residues exclusively at position Asn60 and Asn262. By alanine mutation of these asparagine residues, we could determine that the N-linked oligosaccharides do not have an influence on Golgi retention of TPST1. In concert with N and C-terminal flanking residues, the transmembrane domain of TPST1 was determined to act in targeting and retention of the enzyme to the trans-Golgi compartment. This domain exhibits a pronounced secondary structure in a lipid environment. Further in vivo FRET studies using the transmembrane domain suggest that the human tyrosylprotein sulfotransferase may be functional as homodimer/oligomer in the trans-Golgi compartment.
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Affiliation(s)
- Sandra Goettsch
- Department of Structural and Medicinal Biochemistry, University of Duisburg-Essen and Centre for Medicinal Biotechnology, Universitätsstr. 2-5, 45117 Essen, Germany
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10
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Yu CY, Chung EK, Yang Y, Blanchong CA, Jacobsen N, Saxena K, Yang Z, Miller W, Varga L, Fust G. Dancing with complement C4 and the RP-C4-CYP21-TNX (RCCX) modules of the major histocompatibility complex. ACTA ACUST UNITED AC 2004; 75:217-92. [PMID: 14604014 DOI: 10.1016/s0079-6603(03)75007-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The number of the complement component C4 genes varies from 2 to 8 in a diploid genome among different human individuals. Three quarters of the C4 genes in Caucasian populations have the endogenous retrovirus, HERV-K(C4), in the ninth intron. The remainder does not. The C4 serum proteins are highly polymorphic and their concentrations vary from 100 to approximately 1000 microg/ml. There are two distinct classes of C4 protein, C4A and C4B, which have diversified to fulfill (a) the opsonization/immunoclearance purposes and (b) the well-known complement function in the killing of microbes by lysis and neutralization, respectively. Many infectious and autoimmune diseases are associated with complete or partial deficiency of C4A and/or C4B. The adverse effects of high C4 gene dosages, however, are just emerging, as the concepts of human C4 genetics are revised and accurate techniques are applied to distinguish partial deficiencies from differential expression caused by unequal C4A and C4B gene dosages and gene sizes. This review attempts to dissect the sophisticated genetics of complement C4A and C4B. The emphases are on the qualitative and quantitative diversities of C4 genotypes and phenotypes. The many allotypic variants and the processed products of human and mouse C4 proteins are described. The modular variation of C4 genes together with the serine/threonine nuclear kinase gene RP, the steroid 21-hydroxylase CYP21, and extracellular matrix protein TNX (RCCX modules) are investigated for the effects on homogenization of C4 protein polymorphisms, and on the unequal genetic crossovers that knocked out the functions of CYP21 and/or TNX. Furthermore, the influence of the endogenous retrovirus HERV-K(C4) on C4 gene expression and the dispersal of HERV-K(C4) family members in the human genome are discussed.
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Affiliation(s)
- C Yung Yu
- Center for Molecular and Human Genetics, Columbus Children's Research Institute, 700 Children's Drive, Columbus, OH 43205-2696, USA
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11
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Gao J, Choe H, Bota D, Wright PL, Gerard C, Gerard NP. Sulfation of tyrosine 174 in the human C3a receptor is essential for binding of C3a anaphylatoxin. J Biol Chem 2003; 278:37902-8. [PMID: 12871936 DOI: 10.1074/jbc.m306061200] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The complement anaphylatoxin C3a and its cellular seven-transmembrane segment receptor, C3aR, are implicated in a variety of pathological inflammatory processes. C3aR is a G-protein-coupled receptor with an exceptionally large second extracellular loop of 172 amino acids. Previously reported deletion studies have shown that at least part of this region plays a critical role in binding C3a. Our data now demonstrate that five tyrosines in the second extracellular loop of the C3aR are posttranslationally modified by the addition of sulfate. Blocking sulfation by mutation of tyrosine to phenylalanine at positions 184, 188, 317, and/or 318 does not affect ligand binding or signal transduction. However, when tyrosine 174 is mutated to phenylalanine, binding of native C3a is completely blocked. This variant efficiently mobilizes calcium in response to synthetic C3a agonist peptides, but not to native C3a. This finding is consistent with a two-site model of ligand association typical of many peptide ligand-receptor interactions and identifies sulfotyrosine 174 as the critical C3a docking site. Tyrosine sulfation in the amino-terminal extracellular domain has been shown to be important in several other seven-transmembrane segment receptors. Our data now demonstrate that tyrosine sulfate in other extracellular domains can function for ligand interactions as well.
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Affiliation(s)
- Jinming Gao
- Perlmutter Laboratory, Children's Hospital, Boston, Massachusetts 02115, USA
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12
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Abstract
The sulfonation of endogenous molecules is a pervasive biological phenomenon that is not always easily understood, and although it is increasingly recognized as a function of fundamental importance, there remain areas in which significant cognizance is still lacking or at most minimal. This is particularly true in the field of endocrinology, in which the sulfoconjugation of hormones is a widespread occurrence that is only partially, if at all, appreciated. In the realm of steroid/sterol sulfoconjugation, the discovery of a novel gene that utilizes an alternative exon 1 to encode for two sulfotransferase isoforms, one of which sulfonates cholesterol and the other pregnenolone, has been an important advance. This is significant because cholesterol sulfate plays a crucial role in physiological systems such as keratinocyte differentiation and development of the skin barrier, and pregnenolone sulfate is now acknowledged as an important neurosteroid. The sulfonation of thyroglobulin and thyroid hormones has been extensively investigated and, although this transformation is better understood, there remain areas of incomplete comprehension. The sulfonation of catecholamines is a prevalent modification that has been extensively studied but, unfortunately, remains poorly understood. The sulfonation of pituitary glycoprotein hormones, especially LH and TSH, does not affect binding to their cognate receptors; however, sulfonation does play an important role in their plasma clearance, which indirectly has a significant effect on biological activity. On the other hand, the sulfonation of distinct neuroendocrine peptides does have a profound influence on receptor binding and, thus, a direct effect on biological activity. The sulfonation of specific extracellular structures plays an essential role in the binding and signaling of a large family of extracellular growth factors. In summary, sulfonation is a ubiquitous posttranslational modification of hormones and extracellular components that can lead to dramatic structural changes in affected molecules, the biological significance of which is now beginning to be appreciated.
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Affiliation(s)
- Charles A Strott
- Section on Steroid Regulation, Endocrinology and Reproduction Research Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-4510, USA.
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13
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Dong J, Ye P, Schade AJ, Gao S, Romo GM, Turner NT, McIntire LV, López JA. Tyrosine sulfation of glycoprotein I(b)alpha. Role of electrostatic interactions in von Willebrand factor binding. J Biol Chem 2001; 276:16690-4. [PMID: 11279169 DOI: 10.1074/jbc.m101035200] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glycoprotein I(b)alpha (GP I(b)alpha), the ligand binding subunit of the platelet glycoprotein Ib-IX-V complex, is sulfated on three tyrosine residues (Tyr-276, Tyr-278, and Tyr-279). This posttranslational modification is known to be critical for von Willebrand factor (vWF) binding; yet it remains unclear whether it provides a specific structure or merely contributes negative charges. To investigate this issue, we constructed cell lines expressing GP I(b)alpha polypeptides with the three tyrosine residues converted to either Glu or Phe and studied the ability of these mutants to bind vWF in the presence of modulators or shear stress. The mutants were expressed normally on the cell surface as GP Ib-IX complexes, with the conformation of the ligand-binding domain preserved, as judged by the binding of conformation-sensitive monoclonal antibodies. In contrast to their normal expression, both mutants were functionally abnormal. Cells expressing the Phe mutant failed to bind vWF in the presence of either ristocetin or botrocetin. These cells adhered to and rolled on immobilized vWF only when their surface receptor density was increased to twice the level that supported adhesion of cells expressing the wild-type receptor and even then only 20% as many rolled and rolled significantly faster than wild-type cells. Cells expressing the Glu mutant, on the other hand, were normal with respect to ristocetin-induced vWF binding and adhesion to immobilized vWF but were markedly defective in botrocetin-induced vWF binding. These results indicate that GP I(b)alpha tyrosine sulfation influences the interaction of this polypeptide with vWF primarily by contributing negative charges under physiological conditions and when the interaction is induced by ristocetin but contributes a specific structure to the botrocetin-induced interaction.
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Affiliation(s)
- J Dong
- Division of Thrombosis Research, Department of Medicine, Baylor College of Medicine, Houston, Texas 77030, USA
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14
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Blanchong CA, Chung EK, Rupert KL, Yang Y, Yang Z, Zhou B, Moulds JM, Yu CY. Genetic, structural and functional diversities of human complement components C4A and C4B and their mouse homologues, Slp and C4. Int Immunopharmacol 2001; 1:365-92. [PMID: 11367523 DOI: 10.1016/s1567-5769(01)00019-4] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The complement protein C4 is a non-enzymatic component of the C3 and C5 convertases and thus essential for the propagation of the classical complement pathway. The covalent binding of C4 to immunoglobulins and immune complexes (IC) also enhances the solubilization of immune aggregates, and the clearance of IC through complement receptor one (CR1) on erythrocytes. Human C4 is the most polymorphic protein of the complement system. In this review, we summarize the current concepts on the 1-2-3 loci model of C4A and C4B genes in the population, factors affecting the expression levels of C4 transcripts and proteins, and the structural, functional and serological diversities of the C4A and C4B proteins. The diversities and polymorphisms of the mouse homologues Slp and C4 proteins are described and contrasted with their human homologues. The human C4 genes are located in the MHC class III region on chromosome 6. Each human C4 gene consists of 41 exons coding for a 5.4-kb transcript. The long gene is 20.6 kb and the short gene is 14.2 kb. In the Caucasian population 55% of the MHC haplotypes have the 2-locus, C4A-C4B configurations and 45% have an unequal number of C4A and C4B genes. Moreover, three-quarters of C4 genes harbor the 6.4 kb endogenous retrovirus HERV-K(C4) in the intron 9 of the long genes. Duplication of a C4 gene always concurs with its adjacent genes RP, CYP21 and TNX, which together form a genetic unit termed an RCCX module. Monomodular, bimodular and trimodular RCCX structures with 1, 2 and 3 complement C4 genes have frequencies of 17%, 69% and 14%, respectively. Partial deficiencies of C4A and C4B, primarily due to the presence of monomodular haplotypes and homo-expression of C4A proteins from bimodular structures, have a combined frequency of 31.6%. Multiple structural isoforms of each C4A and C4B allotype exist in the circulation because of the imperfect and incomplete proteolytic processing of the precursor protein to form the beta-alpha-gamma structures. Immunofixation experiments of C4A and C4B demonstrate > 41 allotypes in the two classes of proteins. A compilation of polymorphic sites from limited C4 sequences revealed the presence of 24 polymophic residues, mostly clustered C-terminal to the thioester bond within the C4d region of the alpha-chain. The covalent binding affinities of the thioester carbonyl group of C4A and C4B appear to be modulated by four isotypic residues at positions 1101, 1102, 1105 and 1106. Site directed mutagenesis experiments revealed that D1106 is responsible for the effective binding of C4A to form amide bonds with immune aggregates or protein antigens, and H1106 of C4B catalyzes the transacylation of the thioester carbonyl group to form ester bonds with carbohydrate antigens. The expression of C4 is inducible or enhanced by gamma-interferon. The liver is the main organ that synthesizes and secretes C4A and C4B to the circulation but there are many extra-hepatic sites producing moderate quantities of C4 for local defense. The plasma protein levels of C4A and C4B are mainly determined by the corresponding gene dosage. However, C4B proteins encoded by monomodular short genes may have relatively higher concentrations than those from long C4A genes. The 5' regulatory sequence of a C4 gene contains a Spl site, three E-boxes but no TATA box. The sequences beyond--1524 nt may be completely different as the C4 genes at RCCX module I have RPI-specific sequences, while those at Modules II, III and IV have TNXA-specific sequences. The remarkable genetic diversity of human C4A and C4B probably promotes the exchange of genetic information to create and maintain the quantitative and qualitative variations of C4A and C4B proteins in the population, as driven by the selection pressure against a great variety of microbes. An undesirable accompanying byproduct of this phenomenon is the inherent deleterious recombinations among the RCCX constituents leading to autoimmune and genetic disorders.
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Affiliation(s)
- C A Blanchong
- Children's Research Institute, 700 Children's Drive, Columbus, OH 43205-2696, USA
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15
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Kehoe JW, Bertozzi CR. Tyrosine sulfation: a modulator of extracellular protein-protein interactions. CHEMISTRY & BIOLOGY 2000; 7:R57-61. [PMID: 10712936 DOI: 10.1016/s1074-5521(00)00093-4] [Citation(s) in RCA: 196] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Tyrosine sulfation is a post-translational modification of many secreted and membrane-bound proteins. Its biological roles have been unclear. Recent work has implicated tyrosine sulfate as a determinant of protein-protein interactions involved in leukocyte adhesion, hemostasis and chemokine signaling.
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Affiliation(s)
- J W Kehoe
- Departments of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
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16
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Ouyang YB, Moore KL. Molecular cloning and expression of human and mouse tyrosylprotein sulfotransferase-2 and a tyrosylprotein sulfotransferase homologue in Caenorhabditis elegans. J Biol Chem 1998; 273:24770-4. [PMID: 9733778 DOI: 10.1074/jbc.273.38.24770] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Tyrosine O-sulfation, a common post-translational modification in eukaryotes, is mediated by Golgi enzymes that catalyze the transfer of the sulfuryl group from 3'-phosphoadenosine 5'-phosphosulfate to tyrosine residues in polypeptides. We recently isolated cDNAs encoding human and mouse tyrosylprotein sulfotransferase-1 (Ouyang, Y. B., Lane, W. S., and Moore, K. L. (1998) Proc. Natl. Acad. Sci. U. S. A. 95, 2896-2901). Here we report the isolation of cDNAs encoding a second tyrosylprotein sulfotransferase (TPST), designated TPST-2. The human and mouse TPST-2 cDNAs predict type II transmembrane proteins of 377 and 376 amino acid residues, respectively. The cDNAs encode functional N-glycosylated enzymes when expressed in mammalian cells. In addition, preliminary analysis indicates that TPST-1 and TPST-2 have distinct specificities toward peptide substrates. The human TPST-2 gene is on chromosome 22q12.1, and the mouse gene is in the central region of chromosome 5. We have also identified a cDNA that encodes a TPST in the nematode Caenorhabditis elegans that maps to the right arm of chromosome III. Thus, we have identified two new members of a class of membrane-bound sulfotransferases that catalyze tyrosine O-sulfation. These enzymes may catalyze tyrosine O-sulfation of a variety of protein substrates involved in diverse physiologic functions.
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Affiliation(s)
- Y B Ouyang
- Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
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17
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Pittman DD, Tomkinson KN, Michnick D, Selighsohn U, Kaufman RJ. Posttranslational sulfation of factor V is required for efficient thrombin cleavage and activation and for full procoagulant activity. Biochemistry 1994; 33:6952-9. [PMID: 8204629 DOI: 10.1021/bi00188a026] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Factor VIII and factor V function as cofactors in the blood coagulation cascade to accelerate the rate of activation of factor X and prothrombin, respectively. Both cofactors require proteolytic activation by either activated factor X or thrombin for functional activity. Human factor VIII and factor V expressed in mammalian cells are both modified by posttranslational sulfation of tyrosine residues. In the present study, the posttranslational addition of sulfate in factor V expressed in transfected Chinese hamster ovary (CHO) cells was demonstrated by [35S]sulfate incorporation into the thrombin-cleaved 94-kDa heavy chain and the 150-kDa activation peptide. The presence of tyrosine sulfate in recombinant factor V was confirmed by barium hydroxide hydrolysis and two-dimensional thin-layer electrophoresis. The importance of sulfation for factor V secretion and activity was evaluated by characterizing factor V expressed in Chinese hamster ovary cells grown in the presence of sodium chlorate, a potent inhibitor of posttranslational sulfation in intact cells. Increasing concentrations of sodium chlorate inhibited the incorporation of [35S]sulfate into factor V but did not inhibit the synthesis or secretion of factor V. However, the specific activity of factor V secreted in the presence of sodium chlorate was reduced 5-fold. The reduced activity was attributed to (1) slower cleavage and activation by thrombin and (2) a reduced intrinsic activity of factor Va. In contrast, sulfation of factor V did not affect the rate of activation mediated by factor Xa. These results show that sulfation of factor V is required for efficient thrombin activation but not for activation by factor Xa.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- D D Pittman
- Department of Molecular and Cellular Genetics, Genetics Institute, Cambridge, Massachusetts 02140
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18
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Desnoyers L, Thérien I, Manjunath P. Characterization of the major proteins of bovine seminal fluid by two-dimensional polyacrylamide gel electrophoresis. Mol Reprod Dev 1994; 37:425-35. [PMID: 8011327 DOI: 10.1002/mrd.1080370409] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Recently, we demonstrated that the major proteins from bovine seminal plasma BSP-A1, -A2, -A3 and -30-kDa (collectively called BSP proteins) specifically interact with choline phospholipids. These proteins coat the surface of the spermatozoa after ejaculation and are believed to play an important role in membrane modifications occurring during capacitation. In this study we determined the isoelectric point (pl) and analysed the molecular heterogeneity of BSP proteins. Total protein from bovine seminal plasma (CBSP) and purified BSP proteins were iodinated using chloramine T. Samples were reduced, denatured, separated by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), and visualized by autoradiography. Analysis of CBSP proteins demonstrated the presence of polypeptides migrating in the pH range of 3.5-7.8 and at molecular weights (M(r)) between 6 and 100 kDa. isoforms of each BSP protein were found when purified iodinated proteins were analysed by 2D-PAGE. BSP-A1 was found at a M(r) of 16.5 kDa and in the range of pl of 4.7-5.0; BSP-A2 at 16 kDa and at a pl of 4.9-5.2; BSP-A3 at 15 kDa and at a pl of 4.8-5.2, and BSP-30-kDa at 28 kDa and at a pl of 3.9-4.6. Similar results were obtained with immunolocalization of BSP proteins after Western blot using specific antibodies. The treatment of purified iodinated BSP proteins with neuraminidase increased the pl of BSP-30-kDa to 4.8-5.0 and decreased its M(r) to 25 kDa, but no change was observed for BSP-A1, -A2 and -A3. The treatment of BSP proteins with sulfatase or acid phosphatase modified neither their M(r) nor their pl. Furthermore, when CBSP proteins were separated in 2D-PAGE and the gels stained for glycoproteins with dansyl hydrazine, BSP proteins were among the major glycoproteins found in the bovine seminal plasma. In conclusion, BSP proteins are acidic and have several isoforms. Furthermore, the heterogeneity of BSP-30-kDa is mainly due to its sialic acid content.
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Affiliation(s)
- L Desnoyers
- Department of Medicine, University of Montreal, Québec, Canada
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19
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Lin W, Larsen K, Hortin G, Roth J. Recognition of substrates by tyrosylprotein sulfotransferase. Determination of affinity by acidic amino acids near the target sites. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)50666-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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20
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Abstract
Sulfation of tyrosyl residue(s) has been found to be a post-translational modification that precedes the secretion of many biologically active proteins or peptides. In the present paper, we report on the characterization of human liver tyrosylprotein sulfotransferase (TPST), the enzyme responsible for sulfation of tyrosine in proteins. Using poly Glu,Ala,Tyr (6:3:1; EAY) as the model substrate, human liver TPST was recovered in the microsomal fraction after differential centrifugation. This enzyme displayed a pH optimum of 6.4 and was stimulated approximately 2.5-fold in the presence of 0.5% non-ionic detergents, such as Lubrol-PX and Triton X-100. The divalent cation Mn2+ was required for enzymatic activity and produced maximal activation at 30 mM, whereas other divalent cations, including Mg2+ and Co2+, failed to enhance sulfoconjugation at this concentration. Using the optimized assay condition, the apparent Km for EAY was found to be approximately 1.5 microM, with significant substrate inhibition at EAY concentrations above 2 microM. The 16 amino acid peptide of the C-terminus of C4 possessed an apparent Km of approximately 2.1 microM. Using EAY as a substrate, TPST activity was measured in liver samples from ten organ donors to detect the variability of this enzyme among human subjects. The activity in the male group (1.065 +/- 0.074 pmol/min/mg) was significantly (P less than 0.005) higher than that of the female group (0.662 +/- 0.158 pmol/min/mg), suggesting that TPST activity may be regulated, in part, by sex hormones.
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Affiliation(s)
- W H Lin
- Department of Pharmacology and Therapeutics, State University of New York School of Medicine and Biomedical Sciences, Buffalo 14214
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21
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Analysis of the substrate specificity of tyrosylprotein sulfotransferase using synthetic peptides. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)38920-3] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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22
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Gibson BW, Cohen P. Liquid secondary ion mass spectrometry of phosphorylated and sulfated peptides and proteins. Methods Enzymol 1990; 193:480-501. [PMID: 2127451 DOI: 10.1016/0076-6879(90)93434-m] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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23
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Munson R, Tolan RW. Molecular cloning, expression, and primary sequence of outer membrane protein P2 of Haemophilus influenzae type b. Infect Immun 1989; 57:88-94. [PMID: 2535836 PMCID: PMC313045 DOI: 10.1128/iai.57.1.88-94.1989] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The structural gene for the porin of Haemophilus influenzae type b, designated outer membrane protein P2, was cloned, and the DNA sequence was determined. An oligonucleotide probe generated by reverse translation of N-terminal amino acid sequence data from the purified protein was used to screen genomic DNA. The probe detected a single EcoRI fragment of approximately 1,700 base pairs which was cloned to lambda gt11 and then into M13 and partially sequenced. The derived amino acid sequence indicated that we had cloned the N-terminal portion of the P2 gene. An overlapping approximately 1,600-base-pair PvuII genomic fragment was cloned into M13, and the sequence of the remainder of the P2 gene was determined. The gene for P2 was then reconstructed under the control of the T7 promoter and expressed in Escherichia coli. The N-terminal sequence of the purified protein corresponds to residues 21 through 34 of the derived amino acid sequence. Thus, the protein is synthesized with a 20-amino-acid leader peptide. The Mr of the processed protein is 37,782, in good agreement with the estimate of 37,000 from sodium dodecyl sulfate-polyacrylamide gel electrophoresis.
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Affiliation(s)
- R Munson
- Edward Mallinckrodt Department of Pediatrics, Washington University, School of Medicine, St. Louis, Missouri
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24
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Purification of yolk protein 2 of Drosophila melanogaster and identification of its site of tyrosine sulfation. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)68127-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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25
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Munson R, Grass S. Purification, cloning, and sequence of outer membrane protein P1 of Haemophilus influenzae type b. Infect Immun 1988; 56:2235-42. [PMID: 2842261 PMCID: PMC259555 DOI: 10.1128/iai.56.9.2235-2242.1988] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Outer membrane protein P1 from Haemophilus influenzae type b MinnA was purified and partially characterized. Antiserum was generated against the purified protein and was used to immunologically screen a lamba EMBL3 genomic library prepared from strain MinnA DNA. A 4.2-kilobase-pair EcoRI-BamHI fragment containing the P1 gene was subcloned into pBR322. The recombinant protein was synthesized by Escherichia coli K-12, in which it localized to the outer membrane. The N-terminal sequence of the purified protein was determined and found to correspond to residues 23 through 36. The 22-amino-acid leader peptide had a typical structure, with two lysine residues near the amino terminus, a stretch of hydrophobic residues, and alanine residues at positions 20 and 22. The Mr of the processed protein was 47,752, which is in good agreement with the estimate of 50,000 from sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Putative -35 and -10 promoter sequences were identified upstream from the translational start site. Codon usage was examined and determined to be substantially different than the codon preference in E. coli.
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Affiliation(s)
- R Munson
- Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri 63110
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26
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Yu CY, Campbell RD, Porter RR. A structural model for the location of the Rodgers and the Chido antigenic determinants and their correlation with the human complement component C4A/C4B isotypes. Immunogenetics 1988; 27:399-405. [PMID: 2453459 DOI: 10.1007/bf00364425] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- C Y Yu
- Department of Biochemistry, University of Oxford, UK
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27
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Tyrosine O-sulfation of the fibrinogen gamma B chain in primary cultures of rat hepatocytes. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)68659-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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28
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Hortin GL, Graham JP. Sulfation of tyrosine residues does not influence secretion of alpha 2-antiplasmin or C4. Biochem Biophys Res Commun 1988; 151:417-21. [PMID: 2450539 DOI: 10.1016/0006-291x(88)90609-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Sulfation of tyrosine residues is a biosynthetic modification of many secretory proteins. The function of this modification is not known, but it has been proposed that tyrosine sulfate residues may act as sorting signals to direct proteins along the secretory pathway. We tested this hypothesis by examining the effect of sulfation inhibitors on the kinetics of secretion of proteins by HepG2 cells. The inhibitors induced no change in the rate of secretion of alpha 2-antiplasmin and C4 (fourth component of complement), both of which contain tyrosine sulfate residues. Sulfation of tyrosine residues does not contribute to secretion of these proteins.
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Affiliation(s)
- G L Hortin
- Department of Pediatrics, Washington University School of Medicine, St. Louis, MO 63110
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29
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Hortin GL, Schilling M, Graham JP. Inhibitors of the sulfation of proteins, glycoproteins, and proteoglycans. Biochem Biophys Res Commun 1988; 150:342-8. [PMID: 3422153 DOI: 10.1016/0006-291x(88)90526-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Two categories of compounds, substrates of sulfation and sulfate analogs, were tested for the ability to inhibit sulfation of macromolecules secreted by HepG2 cells. Several compounds which most effectively inhibited sulfation without toxic effects on cells were tested for their relative inhibition of sulfation of tyrosine residues (using the fourth component of complement as a model substrate), of N-linked oligosaccharides (alpha 2HS-glycoprotein as substrate), and of proteoglycans. Inhibitors decreased the sulfation of all three classes of substrate, but not always equally. Use of inhibitors from both categories in combination yielded synergistic effects, with more effective inhibition of sulfation and low toxicity. Such combinations of inhibitors should provide a valuable tool for probing the significance of the sulfation of macromolecules.
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Affiliation(s)
- G L Hortin
- Department of Pediatrics, Washington University School of Medicine, St. Louis, MO 63110
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30
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Bielinska M. Sulfation of the choriogonadotropin alpha subunit in human placental explants. Biochem Biophys Res Commun 1987; 148:1446-52. [PMID: 3120717 DOI: 10.1016/s0006-291x(87)80294-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Incubation of first trimester placental explants with [35S]O4 resulted in incorporation of radioactive sulfate into free and dimer forms of alpha subunit of human chorionic gonadotropin. Sulfate was not attached to N-linked oligosaccharides since it was not released by endoglycosidase F. Analysis of pronase digest revealed the presence of tyrosine-O-[35S]O4. Comparison of tryptic peptides of alpha subunit labeled with several amino acids identified the penultimate carboxyterminal peptide as the sulfation site. Since the C-terminal region of the hCG alpha plays a critical role in receptor binding of the hormone, modification in this region may regulate hormonal activity.
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Affiliation(s)
- M Bielinska
- Department of Pharmacology, Washington University School of Medicine, St. Louis, MO 63110
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31
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Kane WH, Ichinose A, Hagen FS, Davie EW. Cloning of cDNAs coding for the heavy chain region and connecting region of human factor V, a blood coagulation factor with four types of internal repeats. Biochemistry 1987; 26:6508-14. [PMID: 2827731 DOI: 10.1021/bi00394a033] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Human factor V is a high molecular weight plasma glycoprotein that participates as a cofactor in the conversion of prothrombin to thrombin by factor Xa. Prior to its participation in the coagulation cascade, factor V is converted to factor Va by thrombin generating a heavy chain and a light chain, and these two chains are held together by calcium ions. A connecting region originally located between the heavy and light chains is liberated during the activation reaction. In a previous study, a cDNA of 2970 nucleotides that codes for the carboxyl-terminal 938 amino acids of factor V was isolated and characterized from a Hep G2 cDNA library [Kane, W. H., & Davie, E. W. (1986) Proc. Natl. Acad. Sci. U.S.A. 83, 6800-6804]. This cDNA has been used to obtain additional clones from Hep G2 and human liver cDNA libraries. Furthermore, a Hep G2 cDNA library prepared with an oligonucleotide from the 5' end of these cDNAs was screened to obtain overlapping cDNA clones that code for the amino-terminal region of the molecule. The composite sequence of these clones spans 6911 nucleotides and is consistent with the size of the factor V message present in Hep G2 cells (approximately 7 kilobases). The cDNA codes for a leader sequence of 28 amino acids and a mature protein of 2196 amino acids. The amino acid sequence predicted from the cDNA was in complete agreement with 139 amino acid residues that were identified by Edman degradation of cyanogen bromide peptides isolated from the heavy chain region and connecting region of plasma factor V.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- W H Kane
- Department of Biochemistry, University of Washington, Seattle 98195
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32
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Miura N, Prentice HL, Schneider PM, Perlmutter DH. Synthesis and regulation of the two human complement C4 genes in stable transfected mouse fibroblasts. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)48236-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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33
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Hortin G, Fok K, Toren P, Strauss A. Sulfation of a tyrosine residue in the plasmin-binding domain of alpha 2-antiplasmin. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)61471-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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34
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Hortin G, Tollefsen DM, Strauss AW. Identification of two sites of sulfation of human heparin cofactor II. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(18)66637-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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35
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Kumarasamy R, Cohn DV. Sulfation of porcine parathyroid secretory protein I. Detection of tyrosine sulfate. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(18)66590-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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36
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Hortin G, Folz R, Gordon JI, Strauss AW. Characterization of sites of tyrosine sulfation in proteins and criteria for predicting their occurrence. Biochem Biophys Res Commun 1986; 141:326-33. [PMID: 3801003 DOI: 10.1016/s0006-291x(86)80372-2] [Citation(s) in RCA: 96] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
A wide variety of secretory proteins have recently been found to undergo post-translational sulfation of specific tyrosine residues. Here, amino acid sequences surrounding known sulfation sites in proteins are analyzed in order to identify factors which determine the specificity of sulfation. Several distinctive features of sulfation sites are identified, including: abundance of acidic amino acid residues, lack of basic residues, low hydropathy, absence of neighboring cysteine residues, lack of extended secondary structure. Rules are proposed for predicting likely sites of sulfation based on the amino acid sequence of a protein.
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37
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Hortin G, Chan AC, Fok KF, Strauss AW, Atkinson JP. Sequence analysis of the COOH terminus of the alpha-chain of the fourth component of human complement. Identification of the site of its extracellular cleavage. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(19)84488-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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38
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Hortin G, Strauss AW. Effects of acidotropic compounds on the secretory pathway: inhibition of secretion and processing of the third and fourth components of complement. Biochem Biophys Res Commun 1986; 136:603-9. [PMID: 3010984 DOI: 10.1016/0006-291x(86)90483-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Acidotropic compounds (also termed lysosomotropic) such as chloroquine and amantadine interfered with processing of the single-chain precursors to the third and fourth components of complement (C3 and C4) by the human hepatoma-derived cell line HepG2. When these compounds were added to culture medium, the precursors of C3 and C4 became the major secretory forms in contrast to the normal secretion of C3 and C4 as their mature forms. In addition, secretion of C3, C4, and total protein was inhibited by these compounds. Our results indicate that lysosomotropic agents, in addition to their well recognized effects on lysosomes and endosomes, inhibit functions of the secretory pathway.
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