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Wu D, Guo M, Robinson CV. Connecting single-nucleotide polymorphisms, glycosylation status, and interactions of plasma serine protease inhibitors. Chem 2023; 9:665-681. [PMID: 38455847 PMCID: PMC10914678 DOI: 10.1016/j.chempr.2022.11.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 10/06/2022] [Accepted: 11/22/2022] [Indexed: 12/23/2022]
Abstract
Understanding the combined impacts of genetic variances and post-translational modifications requires new approaches. Here, we delineate proteoforms of plasma serine protease inhibitors and relate specific proteoforms to their interactions in complexes through the use of native mass spectrometry (MS). First, we dissect the proteoform repertoire of an acute-phase plasma protein, serine protease inhibitor A1 (SERPINA1), resolving four SERPINA1 variants (M1V, M1A, M2, and M3) with common single-nucleotide polymorphisms (SNPs). Investigating the glycosylation status of these variants and their ability to form complexes with a serine protease, elastase, we find that fucosylation stabilizes the interaction of the SERPINA1 M1V variant through its core fucosylation on Asn271. In contrast, antennary fucosylation on Asn271 destabilizes SERPINA1-elastase interactions. We unveil the same opposing effects of core and antennary fucosylation on SERPINA3 interactions with chymotrypsin. Together, our native MS results highlight the modulating effects of fucosylation with different linkages on glycoprotein interactions.
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Affiliation(s)
- Di Wu
- Department of Chemistry, University of Oxford, Oxford OX1 3QZ, UK
- Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford OX1 3QU, UK
| | - Manman Guo
- Botnar Research Centre, NIHR Biomedical Research Unit Oxford, Nuffield Department of Musculoskeletal Sciences, University of Oxford, Oxford OX3 7LD, UK
| | - Carol V. Robinson
- Department of Chemistry, University of Oxford, Oxford OX1 3QZ, UK
- Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford OX1 3QU, UK
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2
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Sun W, Grassi P, Engström Å, Sooriyaarachchi S, Ubhayasekera W, Hreinsson J, Wånggren K, Clark GF, Dell A, Schedin-Weiss S. N-glycans of human protein C inhibitor: tissue-specific expression and function. PLoS One 2011; 6:e29011. [PMID: 22205989 PMCID: PMC3242763 DOI: 10.1371/journal.pone.0029011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Accepted: 11/18/2011] [Indexed: 02/01/2023] Open
Abstract
Protein C inhibitor (PCI) is a serpin type of serine protease inhibitor that is found in many tissues and fluids in human, including blood plasma, seminal plasma and urine. This inhibitor displays an unusually broad protease specificity compared with other serpins. Previous studies have shown that the N-glycan(s) and the NH2-terminus affect some blood-related functions of PCI. In this study, we have for the first time determined the N-glycan profile of seminal plasma PCI, by mass spectrometry. The N-glycan structures differed markedly compared with those of both blood-derived and urinary PCI, providing evidence that the N-glycans of PCI are expressed in a tissue-specific manner. The most abundant structure (m/z 2592.9) had a composition of Fuc3Hex5HexNAc4, consistent with a core fucosylated bi-antennary glycan with terminal Lewisx. A major serine protease in semen, prostate specific antigen (PSA), was used to evaluate the effects of N-glycans and the NH2-terminus on a PCI function related to the reproductive tract. Second-order rate constants for PSA inhibition by PCI were 4.3±0.2 and 4.1±0.5 M−1s−1 for the natural full-length PCI and a form lacking six amino acids at the NH2-terminus, respectively, whereas these constants were 4.8±0.1 and 29±7 M−1s−1 for the corresponding PNGase F-treated forms. The 7–8-fold higher rate constants obtained when both the N-glycans and the NH2-terminus had been removed suggest that these structures jointly affect the rate of PSA inhibition, presumably by together hindering conformational changes of PCI required to bind to the catalytic pocket of PSA.
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Affiliation(s)
- Wei Sun
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Paola Grassi
- Division of Molecular Biosciences, Imperial College London, London, United Kingdom
| | - Åke Engström
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | | | - Wimal Ubhayasekera
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Julius Hreinsson
- Department of Women's and Children's Health, Uppsala University Hospital, Uppsala, Sweden
| | - Kjell Wånggren
- Department of Women's and Children's Health, Uppsala University Hospital, Uppsala, Sweden
| | - Gary F. Clark
- Department of Obstetrics, Gynecology and Women's Health, University of Missouri, Columbia, Missouri, United States of America
| | - Anne Dell
- Division of Molecular Biosciences, Imperial College London, London, United Kingdom
| | - Sophia Schedin-Weiss
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
- * E-mail:
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3
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Sun W, Parry S, Ubhayasekera W, Engström A, Dell A, Schedin-Weiss S. Further insight into the roles of the glycans attached to human blood protein C inhibitor. Biochem Biophys Res Commun 2010; 403:198-202. [PMID: 21056543 DOI: 10.1016/j.bbrc.2010.11.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Accepted: 11/01/2010] [Indexed: 10/18/2022]
Abstract
Protein C inhibitor (PCI) is a 57-kDa glycoprotein that exists in many tissues and secretions in human. As a member of the serpin superfamily of proteins it displays unusually broad protease specificity. PCI is implicated in the regulation of a wide range of processes, including blood coagulation, fertilization, prevention of tumors and pathogen defence. It has been reported that PCI isolated from human blood plasma is highly heterogeneous, and that this heterogeneity is caused by differences in N-glycan structures, N-glycosylation occupancy, and the presence of two forms that differ by the presence or absence of 6 amino acids at the amino-terminus. In this study we have verified that such heterogeneity exists in PCI purified from single individuals, and that individuals of two different ethnicities possess a similar PCI pattern, verifying that the micro-heterogeneity is conserved among humans. Furthermore, we have provided experimental evidence that PCI in both individuals is O-glycosylated on Thr20 with a core type 1 O-glycan, which is mostly NeuAcGalGalNAc. Modeling suggested that the O-glycan attachment site is located in proximity to several ligand-binding sites of the inhibitor.
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Affiliation(s)
- Wei Sun
- Department of Medical Biochemistry and Microbiology, Uppsala University, Box 582, Uppsala SE-751 23, Sweden
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4
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Sun W, Parry S, Panico M, Morris HR, Kjellberg M, Engström A, Dell A, Schedin-Weiss S. N-glycans and the N terminus of protein C inhibitor affect the cofactor-enhanced rates of thrombin inhibition. J Biol Chem 2008; 283:18601-11. [PMID: 18467335 DOI: 10.1074/jbc.m800608200] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein C inhibitor (PCI) is a serine protease inhibitor, displaying broad protease specificity, found in blood and other tissues. In blood, it is capable of inhibiting both procoagulant and anticoagulant proteases. Mechanisms that provide specificity to PCI remain largely unrevealed. In this study we have for the first time provided a full explanation for the marked size heterogeneity of blood-derived PCI and identified functional differences between naturally occurring PCI variants. The heterogeneity was caused by differences in N-glycan structures, N-glycosylation occupancy, and the presence of a Delta6-N-cleaved form. Bi-, tri-, and tetra-antennary complex N-glycans were identified. Fucose residues were identified both on the core GlcNAc and as parts of sialyl-Le(a/x) epitopes. Moreover, a glycan with a composition that implied a di-sialyl antenna was observed. PCI was N-glycosylated at all three potential N-glycosylation sites, Asn-230, Asn-243, and Asn-319, but a small fraction of PCI lacked the N-glycan at Asn-243. The overall removal of N-glycans affected the maximal heparin- and thrombomodulin-enhanced rates of thrombin inhibition differently in different solution conditions. In contrast, the Delta6-N-region increased both the heparin- and the thrombomodulin-enhanced rates of thrombin inhibition at all conditions examined. These results thus demonstrate that the N-linked glycans and the N-terminal region of blood-derived PCI in different ways affect the cofactor-enhanced rates of thrombin inhibition and provide information on the mechanisms by which this may be achieved. The findings are medically important, in view of the documented association of PCI with atherosclerotic plaques and the promising effect of PCI on reducing hypercoagulability states.
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Affiliation(s)
- Wei Sun
- Department of Medical Biochemistry and Microbiology, Uppsala University, Box 582, Uppsala SE-751 23, Sweden
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5
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Asanuma K, Yoshikawa T, Hayashi T, Akita N, Nakagawa N, Hamada Y, Nishioka J, Kamada H, Gabazza EC, Ido M, Uchida A, Suzuki K. Protein C inhibitor inhibits breast cancer cell growth, metastasis and angiogenesis independently of its protease inhibitory activity. Int J Cancer 2007; 121:955-65. [PMID: 17450526 DOI: 10.1002/ijc.22773] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Protein C inhibitor (PCI) regulates the anticoagulant protein C pathway and also inhibits urinary plasminogen activator (uPA), a mediator of tumor cell invasion. In the present study, we evaluated the effect of human PCI and its inactive derivatives on tumor growth and metastasis of human breast cancer (MDA-231) cells, and on angiogenesis in vivo. The invasiveness of MDA-231 cells was inhibited by recombinant intact PCI, but not by reactive site-modified PCI (R354APCI) or by the N-terminal fragment of protease-cleaved PCI (NTPCI). The in vitro invasiveness of MDA-231 cells expressing intact PCI (MDA-PCI) was significantly decreased as compared to MDA-231 cells expressing R354APCI (MDA-R354APCI) or NTPCI (MDA-NTPCI). Further, in vivo growth and metastatic potential of MDA-PCI, MDA-R354APCI and MDA-NTPCI cells in severe combined immunodeficient (SCID) mice were significantly decreased as compared to MDA-Mock cells. Angiogenesis was also significantly decreased in Matrigel implant containing MDA-PCI, MDA-R354APCI or MDA-NTPCI cells as compared to that containing MDA-Mock cells. In vivo angiogenesis in rat cornea and in vitro tube formation were also inhibited by recombinant intact PCI, R354APCI and NTPCI. Furthermore, the anti-angiogenic activity of PCI was strong as cleaved antithrombin (AT), and slightly stronger than that of plasminogen activator inhibitor (PAI)-1 and pigment epithelium-derived factor (PEDF). Overall, this study showed that, in addition to a reactive site-dependent mechanism, PCI may also regulate tumor growth and metastasis independently of its protease inhibitory activity by inhibiting angiogenesis.
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Affiliation(s)
- Kunihiro Asanuma
- Department of Molecular Pathobiology, Mie University Graduate School of Medicine, Tsu-city, Mie, Japan
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Li W, Adams TE, Kjellberg M, Stenflo J, Huntington JA. Structure of native protein C inhibitor provides insight into its multiple functions. J Biol Chem 2007; 282:13759-68. [PMID: 17337440 DOI: 10.1074/jbc.m701074200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Protein C inhibitor (PCI) is a multifunctional serpin with wide ranging protease inhibitory functions, unique cofactor binding activities, and potential non-inhibitory functions akin to the hormone-transporting serpins. To gain insight into the molecular mechanisms utilized by PCI we developed a robust expression system in Escherichia coli and solved the crystal structure of PCI in its native state. The five monomers obtained from our two crystal forms provide an NMR-like ensemble revealing regions of inherent flexibility. The reactive center loop (RCL) of PCI is long and highly flexible with no evidence of hinge region incorporation into beta-sheet A, as seen for other heparin-binding serpins. We adapted an extrinsic fluorescence method for determining dissociation constants for heparin and find that the N-terminal tail of PCI and residues adjacent to helix H are not involved in heparin binding. The minimal heparin length capable of tight binding to PCI was determined to be chains of eight monosaccharide units. A large hydrophobic pocket occupied by hydrophobic crystal contacts was found in an analogous position to the hormone-binding site in thyroxine-binding globulin. In conclusion, the data presented here provide important insights into the mechanisms by which PCI exercises its multiple inhibitory and non-inhibitory functions.
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Affiliation(s)
- Wei Li
- Department of Haematology, Division of Structural Medicine, Thrombosis Research Unit, Cambridge Institute for Medical Research, University of Cambridge, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 2XY, United Kingdom
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7
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Hansson K, Stenflo J. Post-translational modifications in proteins involved in blood coagulation. J Thromb Haemost 2005; 3:2633-48. [PMID: 16129023 DOI: 10.1111/j.1538-7836.2005.01478.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- K Hansson
- Department of Clinical Chemistry, Lund University, University Hospital Malmö, Malmö, Sweden.
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Réhault SM, Zechmeister-Machhart M, Fortenberry YM, Malleier J, Binz NM, Cooper ST, Geiger M, Church FC. Characterization of recombinant human protein C inhibitor expressed in Escherichia coli. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2005; 1748:57-65. [PMID: 15752693 DOI: 10.1016/j.bbapap.2004.12.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2004] [Revised: 12/10/2004] [Accepted: 12/15/2004] [Indexed: 01/08/2023]
Abstract
The serine protease inhibitor (serpin) protein C inhibitor (PCI; also named plasminogen activator inhibitor-3) regulates serine proteases in hemostasis, fibrinolysis, and reproduction. The biochemical activity of PCI is not fully defined partly due to the lack of a convenient expression system for active rPCI. Using pET-15b plasmid, Ni(2+)-chelate and heparin-Sepharose affinity chromatography steps, we describe here the expression, purification and characterization of wild-type recombinant (wt-rPCI) and two inactive mutants, R354A (P1 residue) and T341R (P14 residue), expressed in Escherichia coli. Wild-type rPCI, but not the two mutants, formed a stable bimolecular complex with thrombin, activated protein C and urokinase. In the absence of heparin, wt-rPCI-thrombin, -activated protein C, and -urokinase inhibition rates were 56.7, 3.4, and 2.3 x 10(4) M(-1) min(-1), respectively, and the inhibition rates were accelerated 25-, 71-, and 265-fold in the presence of 10 mug/mL heparin for each respective inhibition reaction. The stoichiometry of inhibition (SI) for wt-rPCI-thrombin was 2.0, which is comparable to plasma-derived PCI. The present report describes for the first time the expression and characterization of recombinant PCI in a bacterial expression system and demonstrates the feasibility of using this system to obtain adequate amounts of biologically active rPCI for future structure-function studies.
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Affiliation(s)
- Sophie M Réhault
- Department of Pathology and Laboratory Medicine, Carolina Cardiovascular Biology Center, The University of North Carolina, Chapel Hill, NC 27599-7035, USA
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Huntington JA, Kjellberg M, Stenflo J. Crystal structure of protein C inhibitor provides insights into hormone binding and heparin activation. Structure 2003; 11:205-15. [PMID: 12575940 DOI: 10.1016/s0969-2126(02)00944-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Protein C inhibitor (PCI) is a member of the serpin family that has many biological functions. In blood it acts as a procoagulant, and, in the seminal vesicles, it is required for spermatogenesis. The activity of PCI is affected by heparin binding in a manner unique among the heparin binding serpins, and, in addition, PCI binds hydrophobic hormones with apparent specificity for retinoids. Here we present the 2.4 A crystallographic structure of reactive center loop (RCL) cleaved PCI. A striking feature of the structure is a two-turn N-terminal shortening of helix A, which creates a large hydrophobic pocket that docking studies indicate to be the retinoid binding site. On the basis of surface electrostatic properties, a novel mechanism for heparin activation is proposed.
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Affiliation(s)
- James A Huntington
- Department of Haematology, Division of Structural Medicine, University of Cambridge, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Hills Road, CB2 2XY, Cambridge, United Kingdom.
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