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Marine Natural Products in Clinical Use. Mar Drugs 2022; 20:md20080528. [PMID: 36005531 PMCID: PMC9410185 DOI: 10.3390/md20080528] [Citation(s) in RCA: 39] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Revised: 08/05/2022] [Accepted: 08/12/2022] [Indexed: 12/11/2022] Open
Abstract
Marine natural products are potent and promising sources of drugs among other natural products of plant, animal, and microbial origin. To date, 20 drugs from marine sources are in clinical use. Most approved marine compounds are antineoplastic, but some are also used for chronic neuropathic pain, for heparin overdosage, as haptens and vaccine carriers, and for omega-3 fatty-acid supplementation in the diet. Marine drugs have diverse structural characteristics and mechanisms of action. A considerable increase in the number of marine drugs approved for clinical use has occurred in the past few decades, which may be attributed to increasing research on marine compounds in laboratories across the world. In the present manuscript, we comprehensively studied all marine drugs that have been successfully used in the clinic. Researchers and clinicians are hopeful to discover many more drugs, as a large number of marine natural compounds are being investigated in preclinical and clinical studies.
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Gurale BP, He Y, Cui X, Dinh H, Dhawane AN, Lucchi NW, Udhayakumar V, Iyer SS. Toward the Development of the Next Generation of a Rapid Diagnostic Test: Synthesis of Glycophosphatidylinositol (GPI) Analogues of Plasmodium falciparum and Immunological Characterization. Bioconjug Chem 2016; 27:2886-2899. [PMID: 27792303 DOI: 10.1021/acs.bioconjchem.6b00542] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A large number of proteins in malaria parasites are anchored using glycophosphatidylinositols (GPIs) with lipid tails. These GPIs are structurally distinct from human GPIs. Plasmodium falciparum GPIs have been considered as potential vaccine candidates because these molecules are involved in inducing inflammatory responses in human hosts, and natural anti-GPI antibody responses have been shown to be associated with protection against severe disease. GPIs can also be considered as targets for rapid diagnostic tests. Because isolation of native GPIs in large quantities is challenging, development of synthetic GPI molecules can facilitate further exploration of GPI molecules for diagnostics. Here, we report synthesis and immunological characterization of a panel of malaria-specific GPI analogues. A total of three GPI analogues were chemically synthesized and conjugated to a carrier protein to immunize and generate antibodies in rabbits. The rabbit immune sera showed reactivity with synthetic GPIs and native GPIs extracted from P. falciparum parasite, as determined by Luminex and ELISA methods.
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Affiliation(s)
- Bharat P Gurale
- Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, 788 Petit Science Center , 161 Jesse Hill Jr. Drive, Atlanta, Georgia 30302, United States
| | - Yun He
- Atlanta Research and Education Foundation , Atlanta, Georgia 30329, United States
| | - Xikai Cui
- Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, 788 Petit Science Center , 161 Jesse Hill Jr. Drive, Atlanta, Georgia 30302, United States
| | - Hieu Dinh
- Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, 788 Petit Science Center , 161 Jesse Hill Jr. Drive, Atlanta, Georgia 30302, United States
| | - Abasaheb N Dhawane
- Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, 788 Petit Science Center , 161 Jesse Hill Jr. Drive, Atlanta, Georgia 30302, United States
| | - Naomi W Lucchi
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers of Disease Control and Prevention , Atlanta, Georgia 30329, United States
| | - Venkatachalam Udhayakumar
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers of Disease Control and Prevention , Atlanta, Georgia 30329, United States
| | - Suri S Iyer
- Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, 788 Petit Science Center , 161 Jesse Hill Jr. Drive, Atlanta, Georgia 30302, United States
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Wu J, Cunningham AL, Dehghani F, Diefenbach RJ. Comparison of Haliotis rubra hemocyanin isoforms 1 and 2. GENE REPORTS 2016. [DOI: 10.1016/j.genrep.2016.04.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Markl J. Evolution of molluscan hemocyanin structures. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2013; 1834:1840-52. [PMID: 23454609 DOI: 10.1016/j.bbapap.2013.02.020] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2012] [Revised: 02/12/2013] [Accepted: 02/13/2013] [Indexed: 11/17/2022]
Abstract
Hemocyanin transports oxygen in the hemolymph of many molluscs and arthropods and is therefore a central physiological factor in these animals. Molluscan hemocyanin molecules are oligomers composed of many protein subunits that in turn encompass subsets of distinct functional units. The structure and evolution of molluscan hemocyanin have been studied for decades, but it required the recent progress in DNA sequencing, X-ray crystallography and 3D electron microscopy to produce a detailed view of their structure and evolution. The basic quaternary structure is a cylindrical decamer 35nm in diameter, consisting of wall and collar (typically at one end of the cylinder). Depending on the animal species, decamers, didecamers and multidecamers occur in the hemolymph. Whereas the wall architecture of the decamer seems to be invariant, four different types of collar have been identified in different molluscan taxa. Correspondingly, there exist four subunit types that differ in their collar functional units and range from 350 to 550kDa. Thus, molluscan hemocyanin subunits are among the largest polypeptides in nature. In this report, recent 3D reconstructions are used to explain and visualize the different functional units, subunits and quaternary structures of molluscan hemocyanins. Moreover, on the basis of DNA analyses and structural considerations, their possible evolution is traced. This article is part of a Special Issue entitled: Oxygen Binding and Sensing Proteins.
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Affiliation(s)
- Jürgen Markl
- Institute of Zoology, Johannes Gutenberg University, Mainz, Germany.
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Jaenicke E, Büchler K, Decker H, Markl J, Schröder GF. The refined structure of functional unit h of keyhole limpet hemocyanin (KLH1-h) reveals disulfide bridges. IUBMB Life 2011; 63:183-7. [PMID: 21445849 DOI: 10.1002/iub.435] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Hemocyanins are multimeric oxygen-transport proteins in the hemolymph of many arthropods and mollusks. The overall molecular architecture of arthropod and molluscan hemocyanin is very different, although they possess a similar binuclear type 3 copper center to bind oxygen in a side-on conformation. Gastropod hemocyanin is a 35 nm cylindrical didecamer (2 × 10-mer) based on a 400 kDa subunit. The latter is subdivided into eight paralogous "functional units" (FU-a to FU-h), each with an active site. FU-a to FU-f contribute to the cylinder wall, whereas FU-g and FU-h form the internal collar complex. Atomic structures of FU-e and FU-g, and a 9 Å cryoEM structure of the 8 MDa didecamer are available. Recently, the structure of keyhole limpet hemocyanin FU-h (KLH1-h) was presented as a C(α) -trace at 4 Å resolution. Unlike the other seven FU types, FU-h contains an additional C-terminal domain with a cupredoxin-like fold. Because of the resolution limit of 4 Å, in some loops, the course of the protein backbone could not be established with high certainty yet. Here, we present a refined atomic structure of FU-h (KLH1-h) obtained from low-resolution refinement, which unambiguously establishes the course of the polypeptide backbone and reveals the disulfide bridges as well as the orientation of bulky amino acids.
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Affiliation(s)
- Elmar Jaenicke
- Institut für Molekulare Biophysik, Johannes Gutenberg-Universität, Jakob Welder Weg 26, Mainz, Germany.
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Gesheva V, Idakieva K, Kerekov N, Nikolova K, Mihaylova N, Doumanova L, Tchorbanov A. Marine gastropod hemocyanins as adjuvants of non-conjugated bacterial and viral proteins. FISH & SHELLFISH IMMUNOLOGY 2011; 30:135-142. [PMID: 20887791 DOI: 10.1016/j.fsi.2010.09.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Revised: 09/21/2010] [Accepted: 09/21/2010] [Indexed: 05/29/2023]
Abstract
Killed viral vaccines and bacterial toxoids are weakly immunogenic. Numerous compounds are under evaluation as immunological adjuvants and peptide-carriers to improve the immune response. The hemocyanins, giant extracellular copper proteins in the blood of many mollusks, are widely used as immune stimulants. In the present study we investigated the adjuvant properties of hemocyanins isolated from marine gastropods Rapana thomasiana and Megathura crenulata. An immunization with Influenza vaccine or tetanus toxoid combined with Rapana thomasiana hemocyanin (RtH) and Keyhole limpet hemocyanin (KLH) in mice induced an anti-influenza cytotoxic response lasting at least 5 months and an antibody response to viral proteins. The IgG antibody response to the tetanus toxoid (TT) combined with RtH or KLH was comparable to the response of the toxoid in complete Freund's adjuvant. The results obtained demonstrate that the both hemocyanins are acceptable as potential bio-adjuvants for subunit vaccines.
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Affiliation(s)
- Vera Gesheva
- The Stephan Angeloff Institute of Microbiology, Bulgarian Academy of Sciences, Acad G Bonchev Str 26, 1113 Sofia, Bulgaria
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Lieb B, Gebauer W, Gatsogiannis C, Depoix F, Hellmann N, Harasewych MG, Strong EE, Markl J. Molluscan mega-hemocyanin: an ancient oxygen carrier tuned by a ~550 kDa polypeptide. Front Zool 2010; 7:14. [PMID: 20465844 PMCID: PMC2881123 DOI: 10.1186/1742-9994-7-14] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2010] [Accepted: 05/13/2010] [Indexed: 11/10/2022] Open
Abstract
Background The allosteric respiratory protein hemocyanin occurs in gastropods as tubular di-, tri- and multimers of a 35 × 18 nm, ring-like decamer with a collar complex at one opening. The decamer comprises five subunit dimers. The subunit, a 400 kDa polypeptide, is a concatenation of eight paralogous functional units. Their exact topology within the quaternary structure has recently been solved by 3D electron microscopy, providing a molecular model of an entire didecamer (two conjoined decamers). Here we study keyhole limpet hemocyanin (KLH2) tridecamers to unravel the exact association mode of the third decamer. Moreover, we introduce and describe a more complex type of hemocyanin tridecamer discovered in fresh/brackish-water cerithioid snails (Leptoxis, Melanoides, Terebralia). Results The "typical" KLH2 tridecamer is partially hollow, whereas the cerithioid tridecamer is almost completely filled with material; it was therefore termed "mega-hemocyanin". In both types, the staggering angle between adjoining decamers is 36°. The cerithioid tridecamer comprises two typical decamers based on the canonical 400 kDa subunit, flanking a central "mega-decamer" composed of ten unique ~550 kDa subunits. The additional ~150 kDa per subunit substantially enlarge the internal collar complex. Preliminary oxygen binding measurements indicate a moderate hemocyanin oxygen affinity in Leptoxis (p50 ~9 mmHg), and a very high affinity in Melanoides (~3 mmHg) and Terebralia (~2 mmHg). Species-specific and individual variation in the proportions of the two subunit types was also observed, leading to differences in the oligomeric states found in the hemolymph. Conclusions In cerithioid hemocyanin tridecamers ("mega-hemocyanin") the collar complex of the central decamer is substantially enlarged and modified. The preliminary O2 binding curves indicate that there are species-specific functional differences in the cerithioid mega-hemocyanins which might reflect different physiological tolerances of these gill-breathing animals. The observed differential expression of the two subunit types of mega-hemocyanin might allow individual respiratory acclimatization. We hypothesize that mega-hemocyanin is a key character supporting the adaptive radiation and invasive capacity of cerithioid snails.
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Affiliation(s)
- Bernhard Lieb
- Institute of Zoology, Johannes Gutenberg University, 55099 Mainz, Germany.
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Varshney A, Ahmad B, Rabbani G, Kumar V, Yadav S, Khan RH. Acid-induced unfolding of didecameric keyhole limpet hemocyanin: detection and characterizations of decameric and tetrameric intermediate states. Amino Acids 2010; 39:899-910. [DOI: 10.1007/s00726-010-0524-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2009] [Accepted: 02/10/2010] [Indexed: 10/19/2022]
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Gatsogiannis C, Markl J. Keyhole limpet hemocyanin: 9-A CryoEM structure and molecular model of the KLH1 didecamer reveal the interfaces and intricate topology of the 160 functional units. J Mol Biol 2008; 385:963-83. [PMID: 19013468 DOI: 10.1016/j.jmb.2008.10.080] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2008] [Revised: 10/19/2008] [Accepted: 10/29/2008] [Indexed: 10/21/2022]
Abstract
Hemocyanins are blue copper-containing respiratory proteins in the hemolymph of many arthropods and molluscs. Molluscan hemocyanins are decamers, didecamers, or multidecamers of a 340- to 400-kDa polypeptide subunit containing seven or eight globular functional units (FUs; FU-a to FU-h), each with an oxygen-binding site. The decamers are short 35-nm hollow cylinders, with their lumen narrowed by a collar complex. Our recently published 9-A cryo-electron microscopy/crystal structure hybrid model of a 3.4-MDa cephalopod hemocyanin decamer [Nautilus pompilius hemocyanin (NpH)] revealed the pathway of the seven-FU subunit (340 kDa), 15 types of inter-FU interface, and an asymmetric collar consisting of five "arcs" (FU-g pairs). We now present a comparable hybrid model of an 8-MDa gastropod hemocyanin didecamer assembled from two asymmetric decamers [isoform keyhole limpet hemocyanin (KLH) 1 of the established immunogen KLH]. Compared to NpH, the KLH1 subunit (400 kDa) is C-terminally elongated by FU-h, which is further extended by a unique tail domain. We have found that the wall-and-arc structure of the KLH1 decamer is very similar to that of NpH. We have traced the subunit pathway and how it continues from KLH1-g to KLH1-h to form an annulus of five "slabs" (FU-h pairs) at one cylinder edge. The 15 types of inter-FU interface detected in NpH are also present in KLH1. Moreover, we have identified one arc/slab interface, two slab/slab interfaces, five slab/wall interfaces, and four decamer/decamer interfaces. The 27 interfaces are described on the basis of two subunit conformers, yielding an asymmetric homodimer. Six protrusions from the cryo-electron microscopy structure per subunit are associated with putative attachment sites for N-linked glycans, indicating a total of 120 sugar trees in KLH1. Also, putative binding sites for divalent cations have been detected. In conclusion, the present 9-A data on KLH1 confirm and substantially broaden our recent analysis of the smaller cephalopod hemocyanin and essentially solve the gastropod hemocyanin structure.
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Dolashki A, Velkova L, Atanasov B, Voelter W, Stevanovic S, Schwarz H, Di Muro P, Dolashka-Angelova P. Reversibility and “pH–T phase diagrams” of Rapana venosa hemocyanin and its structural subunits. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2008; 1784:1617-24. [DOI: 10.1016/j.bbapap.2008.06.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2008] [Revised: 06/03/2008] [Accepted: 06/05/2008] [Indexed: 11/29/2022]
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Mizutani Y, Tsuge S, Shiogama K, Shimomura R, Kamoshida S, Inada KI, Tsutsumi Y. Enzyme-labeled antigen method: histochemical detection of antigen-specific antibody-producing cells in tissue sections of rats immunized with horseradish peroxidase, ovalbumin, or keyhole limpet hemocyanin. J Histochem Cytochem 2008; 57:101-11. [PMID: 18765837 DOI: 10.1369/jhc.2008.952259] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The enzyme-labeled antigen method is a histochemical technique that visualizes antigen-specific antibody-producing cells in tissue sections, originally documented in 1968. In this study, we attempted to reemerge this hidden but potentially useful method in rat models immunized with horseradish peroxidase (HRP), ovalbumin (OA), or keyhole limpet hemocyanin (KLH). After repeated immunization in footpads, popliteal, groin, and axillary lymph nodes and spleen were sampled. Paraformaldehyde-prefixed frozen sections were incubated with HRP, biotinylated OA, or biotinylated KLH. Proteinase K pretreatment and the secondary use of HPR-labeled streptavidin were applied in the latter two situations. Plasma cells producing antigen-specific antibodies were visualized. Proportions of antigen-specific antibody-producing cells in total plasma cells shown with the immunoperoxidase method for rat immunoglobulins were evaluated. The percentage of antigen-specific plasma cells reached approximately 50% of total plasma cells in the regional lymph nodes. The specificity was confirmed by (a) negativity in non-immune rat tissue, (b) negativity with indifferent antigen probes, and (c) abolishment of the reactivity with the corresponding rat serum. In buffered formalin-fixed, paraffin-embedded tissues, fewer plasma cells were labeled for HRP and KLH antibody reactivity after strong proteolysis and prolonged incubation. Expectedly, this method allows us to observe antigen-specific antibody-producing cells under varied pathological conditions.
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Affiliation(s)
- Yasuyoshi Mizutani
- Department of Pathology, Fujita Health University School of Medicine, Toyoake, Japan
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Abstract
For almost four decades, the scanning transmission electron microscope (STEM) has made significant contributions to structural biology by providing accurate determinations of the molecular masses of large protein assemblies that have arbitrary shapes and sizes. Nevertheless, STEM mass mapping has been implemented in very few laboratories, most of which have employed cold field-emission gun (FEG) electron sources operating at acceleration voltages of 100 kV and lower. Here we show that a 300 kV commercial transmission electron microscope (TEM) equipped with a thermally assisted Shottky FEG can also provide accurate STEM mass measurements. Using the recently published database of elastic-scattering cross sections from the National Institute of Standards and Technology, we show that the measured absolute mass values for tobacco mosaic virus and limpet hemocyanin didecamers agree with the known values to within better than 10%. Applying the established approach, whereby tobacco mosaic virus is added to a specimen as a calibration standard, we find that the measured molecular weight of the hemocyanin assemblies agrees with the known value to within 3%. This accuracy is achievable although only a very small fraction ( approximately 0.002) of the incident probe current of 300 kV electrons is scattered onto the annular dark-field STEM detector. FEG TEMs operating at intermediate voltages (200-400 kV) are becoming common tools for determining the structure of frozen hydrated protein assemblies. The ability to perform mass determination with the same instrument can provide important complementary information about the numbers of subunits comprising the protein assemblies whose structure is being studied.
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Affiliation(s)
- Alioscka A Sousa
- National Institute of Biomedical Imaging and Bioengineering, Bethesda, MD 20892, USA
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Bergmann S, Markl J, Lieb B. The first complete cDNA sequence of the hemocyanin from a bivalve, the protobranch Nucula nucleus. J Mol Evol 2007; 64:500-10. [PMID: 17476452 DOI: 10.1007/s00239-006-0036-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2006] [Accepted: 01/30/2007] [Indexed: 10/23/2022]
Abstract
By cDNA sequencing we have achieved the first, and complete, hemocyanin sequence of a bivalve (Nucula nucleus). This extracellular oxygen-binding protein consists of two immunologically distinguishable isoforms, here termed NnH1 and NnH2. They share a mean sequence identity of 61%, both contain a linear arrangement of eight paralogous, ca.50-kDa functional units (FUs a-h), and in both isoforms the C-terminal FU-h possesses an extension of ca. 100 amino acids. The cDNA of NnH1 comprises 11,090 bp, subdivided into a 5'utr of 75 bp, a 3'utr of 791 bp, and an open reading frame for a signal peptide of 19 amino acids plus a polypeptide of 3389 amino acids (Mr = 385 kDa). The cDNA of NnH2 comprises 10,849 bp, subdivided into a 5'utr of 47 bp, a 3'utr of 647 bp, and an open reading frame for a signal peptide of 16 amino acids plus a polypeptide of 3369 amino acids (Mr = 387 kDa). In contrast to other molluscan hemocyanins, which are highly glycosylated, the bivalve hemocyanin sequence exhibits only four potential N-glycosylation sites, and within both isoforms a peculiar indel is present, surrounding the highly conserved copper-binding site CuA. Phylogenetic analyses of NnH1 and NnH2, compared to the known hemocyanin sequences of gastropods and cephalopods, reveal a statistically sound closer relationship between gastropod and protobranch hemocyanin than to cephalopod hemocyanin. Assuming a molecular clock, the last common ancestor of protobranch and gastropods lived 494 million +/- 50 million years ago, in conformity with fossil records from the late Cambrian.
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Affiliation(s)
- Sandra Bergmann
- Institute of Zoology, Johannes Gutenberg University, 55099 Mainz, Germany
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Bergmann S, Lieb B, Ruth P, Markl J. The Hemocyanin from a Living Fossil, the Cephalopod Nautilus pompilius: Protein Structure, Gene Organization, and Evolution. J Mol Evol 2006; 62:362-74. [PMID: 16501879 DOI: 10.1007/s00239-005-0160-x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2005] [Accepted: 10/03/2005] [Indexed: 10/25/2022]
Abstract
By electron microscopic and immunobiochemical analyses we have confirmed earlier evidence that Nautilus pompilius hemocyanin (NpH) is a ring-like decamer (M(r) = approximately 3.5 million), assembled from 10 identical copies of an approximately 350-kDa polypeptide. This subunit in turn is substructured into seven sequential covalently linked functional units of approximately 50 kDa each (FUs a-g). We have cloned and sequenced the cDNA encoding the complete polypeptide; it comprises 9198 bp and is subdivided into a 5' UTR of 58 bp, a 3' UTR of 365 bp, and an open reading frame for a signal peptide of 21 amino acids plus a polypeptide of 2903 amino acids (M(r) = 335,881). According to sequence alignments, the seven FUs of Nautilus hemocyanin directly correspond to the seven FU types of the previously sequenced hemocyanin "OdH" from the cephalopod Octopus dofleini. Thirteen potential N-glycosylation sites are distributed among the seven Nautilus hemocyanin FUs; the structural consequences of putatively attached glycans are discussed on the basis of the published X-ray structure for an Octopus dofleini and a Rapana thomasiana FU. Moreover, the complete gene structure of Nautilus hemocyanin was analyzed; it resembles that of Octopus hemocyanin with respect to linker introns but shows two internal introns that differ in position from the three internal introns of the Octopus hemocyanin gene. Multiple sequence alignments allowed calculation of a rather robust phylogenetic tree and a statistically firm molecular clock. This reveals that the last common ancestor of Nautilus and Octopus lived 415 +/- 24 million years ago, in close agreement with fossil records from the early Devonian.
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Affiliation(s)
- Sandra Bergmann
- Institute of Zoology, Johannes Gutenberg University, Mainz, Germany
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Streit K, Jackson D, Degnan BM, Lieb B. Developmental expression of two Haliotis asinina hemocyanin isoforms. Differentiation 2005; 73:341-9. [PMID: 16219038 DOI: 10.1111/j.1432-0436.2005.00035.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Hemocyanins are large copper-containing respiratory proteins that play a role in oxygen transport in many molluscs. In some species only one hemocyanin isoform is present while in others two are expressed. The physiological relevance of these isoforms is unclear and the developmental and tissue-specific expression of hemocyanin genes is largely unknown. Here we show that two hemocyanin genes in the gastropod Haliotis asinina, which encode H. asinina hemocyanin (HaH1) and HaH2 isoforms, are developmentally expressed. These genes initially are expressed in a small number of mesenchyme cells at trochophore and pre-torsional veliger stages, with HaH1 expression slightly preceding HaH2. These cells largely are localized to the visceral mass, although a small number of cells are present in head and foot regions. Following metamorphosis the isoforms show overlapping as well as isoform-specific expression profiles, suggesting some degree of isoform-specific function.
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Affiliation(s)
- Klaus Streit
- Institute of Zoology, Johannes Gutenberg University, D-55099 Mainz, Germany
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16
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Lieb B, Boisguérin V, Gebauer W, Markl J. cDNA Sequence, Protein Structure, and Evolution of the Single Hemocyanin from Aplysia californica, an Opisthobranch Gastropod. J Mol Evol 2004; 59:536-45. [PMID: 15638465 DOI: 10.1007/s00239-004-2646-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
By protein immunobiochemistry and cDNA sequencing, we have found only a single hemocyanin polypeptide in an opisthobranch gastropod, the sea hare Aplysia californica, which contrasts with previously studied prosobranch gastropods, which express two distinct isoforms of this extracellular respiratory protein. We have cloned and sequenced the cDNA encoding the complete polypeptide of Aplysia californica hemocyanin (AcH). The cDNA comprises 11,433 bp, encompassing a 5'UTR of 77 bp, a 3'UTR of 1057 bp, and an open reading frame for a signal peptide of 20 amino acids plus a polypeptide of 3412 amino acids (Mr ca. 387 kDa). This polypeptide is the subunit of the cylindrical native hemocyanin (Mr ca. 8 MDa). It comprises eight different functional units (FUs: a, b, c, d, e, f, g, h) that have been identified immunobiochemically after limited proteolysis of AcH purified from the hemolymph. Each FU shows a highly conserved copper-A and copper-B site for reversible oxygen binding. FU AcH-h carries a specific C-terminal extension of ca. 100 amino acids that include two cysteines that may be utilized for disulfide bridge formation. Potential N-glycosylation sites are present in six FUs but lacking in AcH-b and AcH-c. On the basis of multiple sequence alignments, phylogenetic trees and a statistically firm molecular clock were calculated. The latter suggests that the last common ancestor of Haliotis and Aplysia lived 373+/-47 million years ago, in convincing agreement with fossil records from the early Devonian. However, the gene duplication yielding the two distinct hemocyanin isoforms found today in Haliotis tuberculata occurred 343+/-43 million years ago.
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Affiliation(s)
- Bernhard Lieb
- Institute of Zoology, Johannes Gutenberg University, D-55128 Mainz, Germany
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17
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De Ioannes P, Moltedo B, Oliva H, Pacheco R, Faunes F, De Ioannes AE, Becker MI. Hemocyanin of the Molluscan Concholepas concholepas Exhibits an Unusual Heterodecameric Array of Subunits. J Biol Chem 2004; 279:26134-42. [PMID: 15075320 DOI: 10.1074/jbc.m400903200] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We describe here the structure of the hemocyanin from the Chilean gastropod Concholepas concholepas (CCH), emphasizing some attributes that make it interesting among molluscan hemocyanins. CCH exhibits a predominant didecameric structure as revealed by electron microscopy and a size of 8 MDa by gel filtration, and, in contrast with other mollusc hemocyanins, its stabilization does not require additional Ca(2+) and/or Mg(2+) in the medium. Polyacrylamide gel electrophoresis studies, analyses by a MonoQ FPLC column, and Western blots with specific monoclonal antibodies showed that CCH is made by two subunits noncovalently linked, named CCH-A and CCH-B, with molecular masses of 405 and 350 kDa, respectively. Interestingly, one of the subunits undergoes changes within the macromolecule; we demonstrated that CCH-A has an autocleavage site that under reducing conditions is cleaved to yield two polypeptides, CCH-A1 (300 kDa) and CCH-A2 (108 kDa), whereas CCH-B remains unchanged. The CCH-A nick occurs at 4 degrees C, increases at 37 degrees C, and is not inhibited by the addition of protease inhibitors and/or divalent cations. Since the CCH structure is a heterodimer, we investigated whether subunits would be either intermingled, forming heterodecamers, or assembled as two homogeneous decamers. Light scattering and electron microscope studies of the in vitro reassociation of purified CCH subunits demonstrated that the sole addition of Mg(2+) is needed for its reassembly into the native decameric molecule; no homodecamer reorganization was found with either CCH-A or CCH-B subunits alone. Our evidence showed that C. concholepas hemocyanin is an unusual example of heterodecameric organization.
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Affiliation(s)
- Pablo De Ioannes
- Department of Research and Development, BIOSONDA Corp., Avenida Alcalde Eduardo Castillo Velasco 2902, Santiago 7750269, Chile
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Hartmann H, Bongers A, Decker H. Small-angle X-ray Scattering-based Three-dimensional Reconstruction of the Immunogen KLH1 Reveals Different Oxygen-dependent Conformations. J Biol Chem 2004; 279:2841-5. [PMID: 14573592 DOI: 10.1074/jbc.m308959200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
For decades the respiratory protein keyhole limpet hemocyanin (KLH1) from the marine gastropod Megathura crenulata has been used widely as a potent immunostimulant, useful hapten carrier, and valuable agent in the treatment of bladder carcinoma. Although much information on the immunological properties of KLH1 is available, biochemical and structural data are still incomplete. Small-angle x-ray scattering revealed the existence of two conformations, an oxy state being slightly more compact than the deoxy state. Based on small-angle scattering curves, a newly developed Monte Carlo algorithm delivered a surface representation of proteins. The massive changes of the surfaces of reconstructed didecameric KLH1 molecules are explained as a twist of the two non-covalently associated decameric half-molecules. Upon oxygenation, the KLH1 molecule becomes longer and skinnier. This study provides the first real evidence how a molluscan hemocyanin changes conformation during an allosteric transition.
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Affiliation(s)
- Hermann Hartmann
- Institut für Molekulare Biophysik, Universität Mainz, D-55099 Mainz, Germany.
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Dolashka-Angelova P, Schwarz H, Dolashki A, Stevanovic S, Fecker M, Saeed M, Voelter W. Oligomeric stability of Rapana venosa hemocyanin (RvH) and its structural subunits. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1646:77-85. [PMID: 12637014 DOI: 10.1016/s1570-9639(02)00549-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The two structural subunits RvH1 and RvH2 were separated after overnight dialysis of Rapana venosa Hc against 130 mM Gly/NaOH buffer, pH 9.6, on an ion exchange column Hiload 26/10 Sepharose Q using a fast performance liquid chromatography (FPLC) system. The reassociation characteristics of these two RvH isoforms and the native molecule were studied in buffers with different pH values and concentrations of Ca(2+) and Mg(2+). Reassociation of mixed RvH subunits was performed over a period of several days using a stabilizing buffer (SB) of pH 7.0 containing different concentrations of Ca(2+) and Mg(2+) ions. After 2 days of dialysis, an RvH subunit mixture of didecamers and multidecamers was observed in the presence of 100 mM CaCl(2) and MgCl(2), though RvH1 and RvH2 are biochemically and immunologically different and have also different dissociation properties. The reassociation, performed at pH 9.6 with 2 mM CaCl(2) and MgCl(2) at 4 degrees C over a period of one to several weeks, led to the formation of decameric oligomers, while didecamers formed predominantly in the SB at pH 7.0. Higher concentrations of calcium and magnesium ions led to a more rapid reassociation of RvH1 resulting in long stable multidecamers and helical tubules, which were stable and slowly dissociated into shorter multidecamers and decamers at higher pH values. The reassociation of the RvH2 structural subunit in the same buffers processed slowly and yielded didecamers, shorter tubule polymers and long multidecamers which are less stable at higher pH values. The stability of RvH isoforms under varying ionic conditions is compared with the stability of keyhole limpet (KLH, Megathura crenulata) hemocyanin (KLH) and Haliotis tuberculata hemocyanin (HtH) isoforms. The process of dissociation and reassociation is connected with changes of the fluorescence intensity at 600 nm, which can be explained by differences in opalescence of the solutions of these two isoforms. The solutions of longer tubule polymers and multidecamers of RvH1 show a higher opalescence compared to the solutions of shorter helical tubules and multidecamers of RvH2.
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Kurokawa T, Wuhrer M, Lochnit G, Geyer H, Markl J, Geyer R. Hemocyanin from the keyhole limpet Megathura crenulata (KLH) carries a novel type of N-glycans with Gal(beta1-6)Man-motifs. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:5459-73. [PMID: 12423344 DOI: 10.1046/j.1432-1033.2002.03244.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Keyhole limpet (Megathura crenulata) hemocyanin (KLH), an extracellular respiratory protein, is widely used as hapten carrier and immune stimulant. Although it is generally accepted that the sugar constituents of this glycoprotein are likely to be implicated in the antigenicity and biomedical properties of KLH, knowledge of its carbohydrate structure is still limited. Therefore, we have investigated the N-linked oligosaccharides of KLH. Glycan chains were enzymatically liberated from tryptic glycopeptides, pyridylaminated and separated by two-dimensional HPLC. Only neutral oligosaccharides were obtained and characterized by carbohydrate constituent and methylation analyses, MALDI-TOF-MS, ESI-ion trap-MS and sequential exoglycosidase digestion. The results revealed that KLH is carrying high mannose-type glycans and truncated sugar chains derived thereof. As a characteristic feature, a number of the studied N-glycans contained a Gal(beta1-6)Man-unit which has not been found in glycoprotein-N-glycans so far. Hence, our studies demonstrate that this marine mollusk glycoprotein is characterized by a unique oligosaccharide pattern comprising, in part, novel structural elements.
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Affiliation(s)
- Tomofumi Kurokawa
- Pharmaceutical Discovery Center, Pharmaceutical Research Division, Takeda Chemical Industries, Ltd, Osaka, Japan
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21
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Oliva H, Moltedo B, De Ioannes P, Faunes F, De Ioannes AE, Becker MI. Monoclonal antibodies to molluskan hemocyanin from Concholepas concholepas demonstrate common and specific epitopes among subunits. HYBRIDOMA AND HYBRIDOMICS 2002; 21:365-74. [PMID: 12470479 DOI: 10.1089/153685902761022715] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We studied the reactivity of mouse monoclonal antibodies (MAbs) against the hemocyanin from the Chilean marine gastropod Concholepas concholepas (CCH). This protein has been successfully used as a carrier to produce antibodies to haptens and peptides. All MAbs (13) belonging to IgG subclass exhibit dissociation constants (K(d)) from 1 x 10(-7) M to 1 x 10(-9) M. MAbs were characterized by enzyme-linked immunosorbant assay (ELISA) using CCH treated with different procedures, including dissociation into CCH-A and CCH-B subunits, Western blot, enzymatic digestion, chemical deglycosylation, and thermal denaturation. MAbs were classified into three categories, according to subunit specificity by ELISA. The epitope distribution shows that CCH subunits display common epitopes (group I, 5 MAbs, 1H5, 2A8, 3A5, 3B3, and 3E3), as well as specific epitopes for CCH-A subunits (group II, 3 MAbs, 1B8, 4D8, and 8E5) and for CCH-B subunits (group III, 5 MAbs, 1A4, 1E4, 2H10, 3B7, and 7B4). The results can be summarized as follows: (1). six antibodies react with thermal denatured CCH, suggesting that they recognize linear epitopes, whereas seven recognize conformational epitopes; (2). oxidation of carbohydrate moieties does not affect the binding of the MAbs; (3). enzymatic digestion of CCH decreases the reactivity of all antibodies irrespective of the protease used (elastase or trypsin); (4). bringing together the above data, in addition to epitopic complementarity analysis, we identified 12 different epitopes on the CCH molecule recognized by these MAbs. The anti-CCH MAbs presented here can be useful tools to understand the subunit organization of the CCH and its complex structure, which can explain its immunogenic and immunostimulating properties in mammals.
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Affiliation(s)
- Harold Oliva
- Department of Research and Development, BIOSONDA Corp, Eduardo Castillo Velasco 2902, Santiago, Chile
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22
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Gebauer W, Robin Harris J, Markl J. Topology of the 10 subunits within the decamer of KLH, the hemocyanin of the marine gastropod Megathura crenulata. J Struct Biol 2002; 139:153-9. [PMID: 12457845 DOI: 10.1016/s1047-8477(02)00591-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Immunoelectron microscopy has been performed using negatively stained immune complexes of keyhole limpet hemocyanin isoform 1 (KLH1) decamers and a functional unit-specific monoclonal antibody anti-KLH1-c1. The antibody links hemocyanin molecules at both the collar and the collarless edge of the decamer, indicating a peripheral localization of functional units c. In isoform 2 (KLH2) the positions of functional units c have been identified with the peanut agglutinin (PNA), which has previously been shown to exclusively bind to KLH2-c. Ferritin linked to PNA was used to visualize labeled molecules electron microscopically. The pattern of labeling also indicates a peripheral localization of the c functional units. The data presented in this paper support only one of two possible models for the subunit orientation within the hemocyanin decamer.
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Behrens JW, Elias JP, Taylor HH, Weber RE. The archaeogastropod mollusc Haliotis iris: tissue and blood metabolites and allosteric regulation of haemocyanin function. J Exp Biol 2002; 205:253-63. [PMID: 11821491 DOI: 10.1242/jeb.205.2.253] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
We investigated divalent cation and anaerobic end-product concentrations and the interactive effects of these substances and pH on haemocyanin oxygen-binding (Hc-O2) in the New Zealand abalone Haliotis iris. During 24 h of environmental hypoxia (emersion), d-lactate and tauropine accumulated in the foot and shell adductor muscles and in the haemolymph of the aorta, the pedal sinus and adductor muscle lacunae, whereas l-lactate was not detected. Intramuscular and haemolymph d-lactate concentrations were similar, but tauropine accumulated to much higher levels in muscle tissues. Repeated disturbance and short-term exposure to air over 3 h induced no accumulation of d- or l-lactate and no change in [Ca2+], [Mg2+], pH and O2-binding properties of the native haemolymph.
The haemolymph showed a low Hc-O2 affinity, a large reverse Bohr effect and marked cooperativity. Dialysis increased Hc-O2 affinity, obliterated cooperativity and decreased the pH-sensitivity of O2 binding. Replacing Mg2+ and Ca2+ restored the native O2-binding properties and the reverse Bohr shift. l- and d-lactate exerted minor modulatory effects on O2-affinity. At in vivo concentrations of Mg2+ and Ca2+, the cooperativity is dependent largely on Mg2+, which modulates the O2 association equilibrium constants of both the high-affinity (KR) and the low-affinity (KT) states (increasing and decreasing, respectively). This allosteric mechanism contrasts with that encountered in other haemocyanins and haemoglobins. The functional properties of H. iris haemocyanin suggest that high rates of O2 delivery to the tissues are not a priority but are consistent with the provision of a large O2 reserve for facultatively anaerobic tissues during internal hypoxia associated with clamping to the substratum.
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Affiliation(s)
- Jane W Behrens
- Department of Zoophysiology, Institute Biological Sciences, University of Aarhus, DK 8000 Aarhus, Denmark
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Idakieva K, Schwarz H, Genov N, Voelter W, Stoeva S. Rapana thomasiana hemocyanin (RtH): dissociation and reassociation behavior of two isoforms, RtH1 and RtH2. Micron 2001; 33:7-14. [PMID: 11473809 DOI: 10.1016/s0968-4328(00)00099-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Rapana thomasiana hemocyanin (RtH) is a mixture of two hemocyanin isoforms, termed RtH1 and RtH2. The two subunit types, purified by ion exchange chromatography, were used for macromolecular reassociation studies. In vitro reassociation was achieved with Tris-saline stabilizing buffer at pH 7.4, containing 100mM calcium and magnesium chloride at 4 degrees C. The relatively slow progress of reassociation was monitored, and the different oligomeric forms of RtH1 and RtH2 were studied by transmission electron microscopy, using samples negatively stained with 1% (w/v) uranyl acetate or 5% (w/v) ammonium molybdate containing 1% (w/v) trehalose at pH 7.0. The two subunits reassociate to produce characteristic didecamers, oligomeric and polymeric forms depending on the dissociated material and the reassociation conditions (i.e. divalent ion concentration, duration). In contrast to the didecamers of the freshly isolated RtH preparations, RtH1 and RtH2 show after 2 weeks' reassociation a clear tendency to generate multidecameric structures. The behavior of the native RtH1 and RtH2 during reassociation in the presence of 100mM calcium and magnesium chloride corresponds to the reported common oligomerization characteristics of KLH1/HtH1 and KLH2/HtH2, respectively. It is important to note that during the reassociation of the RtH isoforms: (I) no smaller diameter tubular polymers (ca. 25-27nm) were formed from the subunits as well as from the decamers; (II) multidecamers with one or more 'nucleating' didecamers were detected in addition to the multidecamers, composed of didecamers with associated decamers at one or both ends.
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Affiliation(s)
- K Idakieva
- Institute of Organic Chemistry, Bulgarian Academy of Sciences, Akad. G. Bonchev-Str. bl.9, 1113, Sofia, Bulgaria
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25
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Jones DS, Cockerill KA, Gamino CA, Hammaker JR, Hayag MS, Iverson GM, Linnik MD, McNeeley PA, Tedder ME, Ton-Nu HT, Victoria EJ. Synthesis of LJP 993, a multivalent conjugate of the N-terminal domain of beta2GPI and suppression of an anti-beta2GPI immune response. Bioconjug Chem 2001; 12:1012-20. [PMID: 11716694 DOI: 10.1021/bc015512x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
LJP 993, a tetravalent conjugate of the amino-terminal domain (domain 1) of beta2GPI, was synthesized, and studies were carried out to explore the ability of LJP 993 to bind anti-beta2GPI antibodies and to function as a B cell toleragen. Domain 1 was expressed in Pichia pastoris, and the N-terminus was site-specifically modified by a transamination reaction converting the N-terminal glycine to a glyoxyl group. A tetravalent platform was synthesized with linkers that terminate in aminooxy groups. This was accomplished by preparing an ethylene glycol-based heterobifunctional linker that contains both a Boc-protected aminooxy group and a free primary amine. The linker was used to modify a tetravalent platform molecule by reacting the amino groups on the linker with 4-nitrophenyl carbonate esters on the platform to provide a linker-modified platform, and the Boc protecting groups were removed to provide a tetravalent aminooxy platform. Glyoxylated domain 1 was attached to the platform to provide LJP 993 by formation of oxime bonds. The protein domains of LJP 993 retain activity as evidenced by the ability of LJP 993 to bind to anti-beta2GPI antibodies. Dissociation constants (Kd) for domain 1 and LJP 993 bound to immobilized affinity-purified anti-beta2GPI antibodies from autoimmune thrombosis patients were determined using surface plasmon resonance. An immunized mouse model was developed to test the ability of LJP 993 to act as a toleragen. A thiol containing domain 1 analogue was expressed in insect cells using the baculovirus expression system, and it was used to prepare an immunogenic conjugate of domain 1 and maleimide-derivatized keyhole limpet hemocyanin (KLH). Mice were immunized with the KLH conjugate, and spleen cells were harvested from the immunized mice. The cells were incubated with various concentrations of LJP 993 and transferred to mice whose immune systems had been compromised by irradiation. The hosts were then boosted with the KLH-domain 1 conjugate, and after 7 days their antibody levels were measured. Host mice receiving cells that were treated with LJP 993 produced significantly lower amounts of anti-domain 1 antibodies than controls which received untreated cells, indicative of B cell tolerance.
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Affiliation(s)
- D S Jones
- La Jolla Pharmaceutical Company, 6455 Nancy Ridge Drive, San Diego, California 92121, USA.
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26
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Harris JR, Hoeger U, Adrian M. Transmission electron microscopical studies on some haemolymph proteins from the marine polychaete Nereis virens. Micron 2001; 32:599-613. [PMID: 11166580 DOI: 10.1016/s0968-4328(00)00051-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The hexagonal bilayer haemoglobin molecule from Nereis virens has been investigated in a comparative study using several different negative stain electron microscopical specimen preparations (i.e. by conventional adsorption to continuous carbon support films, by the negative staining-carbon film technique and by negative staining across the holes of holey carbon support films with air-drying and rapid freezing/cryo-negative staining). The benefits and limitations of these different approaches are indicated, with the overall conclusion that negative staining with ammonium molybdate across holes creates the best possibilities for molecular imaging, and also has the potential for the creation of two-dimensional (2D) crystals/arrays at the fluid-air interface. Of the different negative staining procedures presented, cryo-negative staining reveals the greatest details of N. virens haemoglobin. This is exemplified by the direct visualisation of the central linker-assembly within the haemoglobin molecule, a structural feature less clearly defined by the other negative staining techniques. A discoidal lipoprotein molecule (diameter 30-60nm; thickness ca 8nm) has been detected in N. virens, which represents the first documented account of an annelid haemolymph lipoprotein. The biological implications of this lipoprotein for lipid transport remain to be established. The presence of a low concentration of ferritin molecules in N. virens haemolymph is also shown, assisted by the formation of small 2D ferritin arrays in negatively stained specimens prepared across holes.
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Affiliation(s)
- J R Harris
- Institute of Zoology, University of Mainz, D-55099 Mainz, Germany.
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27
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Harris JR, Scheffler D, Gebauer W, Lehnert R, Markl J. Haliotis tuberculata hemocyanin (HtH): analysis of oligomeric stability of HtH1 and HtH2, and comparison with keyhole limpet hemocyanin KLH1 and KLH2. Micron 2000; 31:613-22. [PMID: 10838022 DOI: 10.1016/s0968-4328(99)00145-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The multimeric/higher oligomeric states of the two isoforms of Haliotis tuberculata hemocyanin (HtH1 and HtH2) have been assessed by transmission electron microscopy (TEM) of negatively stained specimens, for comparison with previously published structural data from keyhole limpet hemocyanin (KLH1 and KLH2) [see Harris, J.R., Gebauer, W., Guderian, F.U., Markl, J., 1997a. Keyhole limpet hemocyanin (KLH), I: Reassociation from Immucothel followed by separation of KLH1 and KLH2. Micron, 28, 31-41; Harris, J.R., Gebauer, W., Söhngen, S.M., Nermut, M.V., Markl, J., 1997b. Keyhole limpet hemocyanin (KLH). II: Characteristic reassociation properties of purified KLH1 and KLH2. Micron, 28, 43-56; Harris, J.R., Gebauer, W., Adrian, M., Markl, J., 1998. Keyhole limpet hemocyanin (KLH): Slow in vitro reassociation of KLH1 and KLH2 from Immucothel. Micron, 29, 329-339]. In purified samples of both HtH isoforms, the hollow cylindrical ca 8MDa didecamer predominates together with a small number of decamers, but tri- and longer multidecamers are detectable only in the HtH2. The stability of the two HtH isoforms under varying ionic conditions have been monitored, thereby enabling conditions for the production of stable decamers to be established. The ability of these decamers to reform multimers in the presence of 10 and 100mM concentrations of calcium and magnesium ions in Tris-HCl buffer (pH 7.4), and also of individual HtH1 and HtH2 subunits (produced by pH 9.6 dissociation in glycine-NaOH buffer), to reassociate in the presence of calcium and magnesium ions, has been assessed. For the HtH1 decamers, the predominant multimeric product is the didecamer at 10 and 100mM calcium and magnesium concentrations, whereas for the HtH2 decamers, large numbers of multidecamers are produced, with the reaction proceeding more completely at the higher calcium and magnesium concentration. With the HtH1 subunit, reassociation in the presence of 10 and 100mM calcium and magnesium ions yielded an almost 100% conversion into didecamers, whereas the HtH2 subunit produced a mixture containing large numbers of short multidecamers and relatively few didecamers, together with a considerable number of smaller diameter helical/tubular polymers. The association properties of the HtH1 and HtH2 decamers, and the subunit reassociation, firmly indicate the integrity and structural competency of the protein under the experimental conditions used. Data on the association of KLH2 decamers is also presented, which together with previously published data on the association KLH1 decamers and the reassociation of KLH1 and KLH2 subunits, enables a detailed comparison of the two hemocyanin isoforms from both molluscan species to be made. Biochemical manipulation of the oligomer states and the subunit reassociation of molluscan hemocyanins can usefully be assessed by the study of negatively stained TEM specimens.
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Affiliation(s)
- J R Harris
- Institute of Zoology, University of Mainz, Germany.
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28
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Massover WH, Marsh P. Light atom derivatives of structure-preserving sugars are unconventional negative stains. Ultramicroscopy 2000; 85:107-21. [PMID: 11014484 DOI: 10.1016/s0304-3991(00)00048-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Although glucose and certain other sugars are known to greatly reduce distortion and denaturation of proteins during drying, use of this monosaccharide as an experimental negative stain does not permit imaging of lattice periodicities in test specimens of thin catalase crystals. However, the potassium and sodium salts of several forms of monophosphorylated glucose (200 mM), diphosphorylated glucose, monosulfated glucose, maltose-1-phosphate, and trehalose-6-phosphate, all dry into a glassy layer and scatter transmitted electrons sufficiently to show the 86 A major periods in catalase crystals. Glucose-6-phosphate provides sufficient image contrast at concentrations from 2 mM (=0.067%) to 500 mM (= 16.8%). Underfocusing increases visualization of the periodic lattice, indicating a large contribution of phase contrast to these images. Upon exposure to the electron beam, thicker regions of derivatized saccharides or pure glucose develop bubbling; this redistribution of dried stain largely can be precluded by imaging with low-dose exposures. Power spectra of images of catalase crystals contained within 200 mM disodium glucose-6-phosphate show that periodic information can be recorded to 21 A; some individual features of dipotassium glucose-6-phosphate distribution within the protein lattice have a measured width of around 5 A. The experimental results demonstrate that structure-preserving mono- and di-saccharides also serve successfully as negative stains after they are coupled to light atom scatterers.
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Affiliation(s)
- W H Massover
- Department of Anatomy and Cell Biology, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark 07103, USA.
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29
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Idakieva K, Stoeva S, Pervanova K, Genov N, Voelter W. Arrangement of functional units within the Rapana thomasiana hemocyanin subunit RtH2. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1479:175-84. [PMID: 11004539 DOI: 10.1016/s0167-4838(00)00053-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
For the determination of the number and linear sequential arrangement of functional units (FUs) within the polypeptide chain of the Rapana hemocyanin subunit RtH2, a panel of mono-, di-, tri- and penta-FU fragments was generated by limited proteolysis of the purified subunit with four different enzymes. The individual cleavage products were isolated, characterized by SDS-PAGE and N-terminally sequenced. Most of the information about the FU sequential arrangement within RtH2 was obtained after limited proteolysis of the subunit with plasmin. Overall correlation of the data revealed the sequential order of the eight FUs within the polypeptide chain of RtH2, termed RtH2-a to RtH2-h. The sites, most sensitive to proteolytic cleavage with plasmin, are located at the C-terminus, between the FUs ef, fg and gh. A second main cleavage site was observed between the FUs cd. Endoproteinase GluC hydrolyzes these sites, too, but produces exclusively a mixture of mono-, di- and tri-FU fragments. The most stable fragments, the trimer abc and the dimer gh, are found in all cleavage mixtures of RtH2 studied. RtH2-h is compared with the corresponding h-FUs of the gastropodan hemocyanins of Pila leopoldvillensis, Helix pomatia, Megathura crenulata and Haliotis tuberculata, and a remarkable similarity is observed between them: an increased M(r) of approximately 65000 instead of approximately 50000, estimated for an average FU, suggesting that the sequence of RtH2-h is elongated by about 95 amino acid residues at the C-terminal part of the molecule, as found for beta(c)-HpH, HtH1 and HtH2.
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Affiliation(s)
- K Idakieva
- Institute of Organic Chemistry, Bulgarian Academy of Sciences, Sofia, Bulgaria
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Meissner U, Dube P, Harris JR, Stark H, Markl J. Structure of a molluscan hemocyanin didecamer (HtH1 from Haliotis tuberculata) at 12 A resolution by cryoelectron microscopy. J Mol Biol 2000; 298:21-34. [PMID: 10756103 DOI: 10.1006/jmbi.2000.3631] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A 12 A resolution three-dimensional density map of the Haliotis tuberculata hemocyanin type 1 (HtH1) didecamer has been obtained by cryoelectron microscopy of unstained molecules and angular reconstitution. The dyad symmetry of the 8 MDa D5 HtH1 didecamer, formed by the pairing of two asymmetric 4 MDa ring-like C5 decamers, is emphasised. The major and minor surface helical grooves of the didecamer are well defined, in agreement with earlier data on molluscan hemocyanins. The location of the obliquely orientated repeating unit, a subunit dimer, within the decamer has been defined. Following interactive extraction of this dimer, several new structural features of the dimer and of the subunit have now emerged with improved detail. The subunit dimer possesses pseudo 2-fold symmetry, resulting from the steric arrangement of the wall domains/functional units (FUs-abcdef) of the two subunits. The arc and collar FUs (g and h) depart from this inherent 2-fold symmetry and are thereby responsible for the asymmetry of the C5 decamer, with the internalised collar/arc complex at one edge of the decamer. The FU heterodimers forming the wall morphological units have a hollow centre, and thus create a series of repeating channels that extend within the wall through all three tiers of the decamer. The connections between the wall and the arc are defined with improved clarity, and evidence is provided to indicate that the arc and collar FU pairs have a homodimeric composition (gg and hh, respectively). Two possibilities for the subunit path within the subunit dimer are presented, which correlate with the available structural, immunolabelling and protease cleavage data from HtH1 and other molluscan hemocyanins.
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Affiliation(s)
- U Meissner
- Institute of Zoology, University of Mainz, D-55099, Germany
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Lieb B, Altenhein B, Markl J. The sequence of a gastropod hemocyanin (HtH1 from Haliotis tuberculata). J Biol Chem 2000; 275:5675-81. [PMID: 10681551 DOI: 10.1074/jbc.275.8.5675] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The eight functional units (FUs), a-h, of the hemocyanin isoform HtH1 from Haliotis tuberculata (Prosobranchia, Archaeogastropoda) have been sequenced via cDNA, which provides the first complete primary structure of a gastropod hemocyanin subunit. With 3404 amino acids (392 kDa) it is the largest polypeptide sequence ever obtained for a respiratory protein. The cDNA comprises 10,758 base pairs and includes the coding regions for a short signal peptide, the eight different functional units, a 3'-untranslated region of 478 base pairs, and a poly(A) tail. The predicted protein contains 13 potential sites for N-linked carbohydrates (one for HtH1-a, none for HtH1-c, and two each for the other six functional units). Multiple sequence alignments show that the fragment HtH1-abcdefg is structurally equivalent to the seven-FU subunit from Octopus hemocyanin, which is fundamental to our understanding of the quaternary structures of both hemocyanins. Using the fossil record of the gastropod-cephalopod split to calibrate a molecular clock, the origin of the molluscan hemocyanin from a single-FU protein was calculated as 753 +/- 68 million years ago. This fits recent paleontological evidence for the existence of rather large mollusc-like species in the late Precambrian.
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Affiliation(s)
- B Lieb
- Institute of Zoology, Johannes Gutenberg University of Mainz, D-55099 Mainz, Germany
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Gebauer W, Harris JR, Geisthardt G, Markl J. Keyhole limpet hemocyanin type 2 (KLH2): detection and immunolocalization of a labile functional unit h. J Struct Biol 1999; 128:280-6. [PMID: 10633067 DOI: 10.1006/jsbi.1999.4198] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Keyhole limpet hemocyanin (KLH) is a mixture of two hemocyanin isoforms, termed KLH1 and KLH2. Within KLH1 eight oxygen-binding functional units (FUs), 1-a to 1-h, have been identified, in contrast to KLH2, which was previously thought to be organized in seven FUs (2-a to 2-g). By limited proteolysis of KLH2 subunits, isolation of the polypeptide fragments, and N-terminal sequencing, we have now identified an eighth FU of type h, with a molecular mass of 43 kDa. This is unusually small for a FU h from a gastropodan hemocyanin. It is also shown that KLH2 didecamers can be split into a stable and homogeneous population of decamers by dialysis against 50 mM Tris/HCl, pH 7.5, in the absence of divalent cations. Electron microscopic immunolocalization using a specific monoclonal antibody reveals that FU KLH2-h is located at the collar of the decamer.
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Affiliation(s)
- W Gebauer
- Institute of Zoology, University of Mainz, Mainz, D-55099, Germany.
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Abstract
In this review we present a broad survey of fundamental scientific and medically applied studies on keyhole limpet hemocyanin (KLH). Commencing with the biochemistry of KLH, information on the biosynthesis and biological role of this copper-containing respiratory protein in the marine gastropod Megathura crenulata is provided. The established methods for the purification of the two isoforms of KLH (KLH1 and KLH2) are then covered, followed by detailed accounts of the molecular mass determination, functional unit (FU) structure, carbohydrate content, immunological analysis and recent aspects of the molecular genetics of KLH. The transmission electron microscope (TEM) has contributed significantly to the understanding of KLH structure, primarily from negatively stained images. We give a brief account of TEM studies on the native KLH oligomers, the experimental manipulation of the oligomeric states, together with immunolabelling data and studies on subunit reassociation. The field of cellular immunology has provided much relevant biomedical information on KLH and has led to the expansion of use of KLH in experimental immunology and clinically as an immunotherapeutic agent; this area is presented in some detail. The major clinical use of KLH is specifically for the treatment of bladder carcinoma, with efficacy probably due to a cross-reacting carbohydrate epitope. KLH also has considerable possibilities for the treatment of other carcinomas, in particular the epithelially derived adenocarciomas, when used as a carrier for carcinoma ganglioside and mucin-like epitopes. The widespread use of KLH as a hapten carrier and generalised vaccine component represent other major on-going aspects of KLH research, together with its use for the diagnosis of Schistosomiasis, drug assay and the treatment of drug addiction. Immune competence testing, assessment of stress and the understanding of inflammatory conditions are other areas where KLH is also making a useful contribution to medical research.
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Affiliation(s)
- J R Harris
- Institute of Zoology, University of Mainz, Germany.
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Gebauer W, Stoeva S, Voelter W, Dainese E, Salvato B, Beltramini M, Markl J. Hemocyanin subunit organization of the gastropod Rapana thomasiana. Arch Biochem Biophys 1999; 372:128-34. [PMID: 10562425 DOI: 10.1006/abbi.1999.1478] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
RtH1 and RtH2, the two hemocyanin isoforms of the prosobranch gastropod Rapana thomasiana, have been purified by anion-exchange chromatography and studied by SDS-PAGE and immunoelectrophoresis. Both subunit types are built up of eight functional units (FUs). Under reducing conditions subunit RtH2 splits into two fragments, RtH2-a-f and RtH2-gh, suggesting the presence of a disulfide bridge between FU2-f and FU2-g. By proteolytic cleavage of the subunits into three-, two-, and single-FU fragments, purification of fragments by HPLC, N-terminal sequencing of the peptides, and crossed-line immunoelectrophoresis, FUs-a-h of RtH2 and FU-a, FU-d, FU-e, and FU-f of RtH1 were identified and correlated to the eight-FUs pattern of immunoelectrophoresis. FU-a, FU-e, and FU-f of RtH1 and RtH2 are very closely related immunologically. RtH1 and RtH2 both correspond immunologically to KLH2, one of the two hemocyanin isoforms of the prosobranch gastropod Megathura crenulata.
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Affiliation(s)
- W Gebauer
- Institute of Zoology, University of Mainz, Mainz, Germany.
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Stoeva S, Schütz J, Gebauer W, Hundsdörfer T, Manz C, Markl J, Voelter W. Primary structure and unusual carbohydrate moiety of functional unit 2-c of keyhole limpet hemocyanin (KLH). BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1435:94-109. [PMID: 10561541 DOI: 10.1016/s0167-4838(99)00198-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The complete amino acid sequence of the Megathura crenulata hemocyanin functional unit KLH2-c was determined by direct sequencing and matrix-assisted laser desorption ionization mass spectrometry of the protein, and of peptides obtained by cleavage with EndoLysC proteinase, chymotrypsin and cyanogen bromide. This is the first complete primary structure of a functional unit c from a gastropod hemocyanin. KLH2-c consists of 420 amino acid residues. Circular dichroism spectra indicated approx. 31% beta-sheet and 29% alpha-helix contents. A multiple sequence alignment with other molluscan hemocyanin functional units revealed average identities between 41 and 49%, but 55% in case of Octopus hemocyanin functional unit c which is the structural equivalent to KLH2-c. KLH2-c has a molecular mass of approx. 48 kDa as calculated from its sequence and a measured mass of approx. 56 kDa; the mass difference is attributed to the sugar side chains usually decorating molluscan hemocyanin. However, inspection of the sequence of KLH2-c revealed no potential N-linked carbohydrate attachment sites, and this was supported by its inability to bind concanavalin A. Also KLH1-c was unreactive, whereas most, if not all, other functional units of KLH1 and KLH2 reacted positively to this lectin. On the other hand, peanut agglutinin specifically binds KLH2-c, indicating the presence of O-glycosidically linked carbohydrates in this functional unit. This contrasts to all other KLH functional units (including KLH1-c), which lack O-linked glycosides. The present results are discussed in view of the recent X-ray structure of the functional unit g from Octopus hemocyanin, and a published record of the Thomsen Friedenreich tumor antigenic epitope in KLH.
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Affiliation(s)
- S Stoeva
- Abteilung für Physikalische Biochemie, Physiologisch-chemisches Institut der Universität Tübingen, Hoppe-Seyler-Str. 4, D-72076, Tübingen, Germany.
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Lieb B, Altenhein B, Lehnert R, Gebauer W, Markl J. Subunit organization of the abalone Haliotis tuberculata hemocyanin type 2 (HtH2), and the cDNA sequence encoding its functional units d, e, f, g and h. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 265:134-44. [PMID: 10491167 DOI: 10.1046/j.1432-1327.1999.00694.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have developed a HPLC procedure to isolate the two different hemocyanin types (HtH1 and HtH2) of the European abalone Haliotis tuberculata. On the basis of limited proteolytic cleavage, two-dimensional immunoelectrophoresis, PAGE, N-terminal protein sequencing and cDNA sequencing, we have identified eight different 40-60-kDa functional units (FUs) in HtH2, termed HtH2-a to HtH2-h, and determined their linear arrangement within the elongated 400-kDa subunit. From a Haliotis cDNA library, we have isolated and sequenced a cDNA clone which encodes the five C-terminal FUs d, e, f, g and h of HtH2. As shown by multiple sequence alignments, defg of HtH2 correspond structurally to defg from Octopus dofleini hemocyanin. HtH2-e is the first FU of a gastropod hemocyanin to be sequenced. The new Haliotis hemocyanin sequences are compared to their counterparts in Octopus, Helix pomatia and HtH1 (from the latter, the sequences of FU-f, FU-g and FU-h have recently been determined) and discussed in relation to the recent 2.3 A X-ray structure of FU-g from Octopus hemocyanin and the 15 A three-dimensional reconstruction of the Megathura crenulata hemocyanin didecamer from electron micrographs. This data allows, for the first time, an insight into the evolution of the two functionally different hemocyanin isoforms found in marine gastropods. It appears that they evolved several hundred million years ago within the Prosobranchia, after separation of the latter from the branch leading to the Pulmonata. Moreover, as a structural explanation for the inefficiency of the type 1 hemocyanin to form multidecamers in vivo, the additional N-glycosylation sites in HtH1 compared to HtH2 are discussed.
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Affiliation(s)
- B Lieb
- Institute of Zoology, University of Mainz, Germany
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Keller H, Altenhein B, Gebauer D, Richter S, Stricker S, Markl J. Abalone (Haliotis tuberculata) hemocyanin type 1 (HtH1). Organization of the approximately 400 kDa subunit, and amino acid sequence of its functional units f, g and h. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 264:27-38. [PMID: 10447670 DOI: 10.1046/j.1432-1327.1999.00564.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have identified two separate hemocyanin types (HtH1 and HtH2) in the European abalone Haliotis tuberculata. HtH1/HtH2 hybrid molecules were not found. By selective dissociation of HtH2 we isolated HtH1 which, as revealed by electron microscopy and SDS/PAGE, is present as didecamers of a approximately 400 kDa subunit. Immunologically, HtH1 and HtH2 correspond to keyhole limpet hemocyanin (KLH)1 and KLH2, respectively, the two well-studied hemocyanin types of the closely related marine gastropod Megathura crenulata. On the basis of limited proteolytic cleavage, two-dimensional immunoelectrophoresis, SDS/PAGE and N-terminal sequencing, we identified eight different 40-60 kDa functional units in HtH1, termed HtH1-a to HtH1-h, and determined their linear arrangement within the elongated subunit. From Haliotis mantle tissue, rich in hemocyanin-producing pore cells, we isolated mRNA and constructed a cDNA library. By expression screening with HtH-specific rabbit antibodies, a cDNA clone was isolated and sequenced which codes for the three C-terminal functional units f, g and h of HtH1. Their sequences were aligned to those available from other molluscs, notably to functional unit f and functional unit g from the cephalopod Octopus dofleini. HtH1-f, which is the first sequenced functional unit of type f from a gastropod hemocyanin, corresponds to functional unit f from Octopus. Also functional unit g from Haliotis and Octopus correspond to each other. HtH1-h is a gastropod hemocyanin functional unit type which is absent in cephalopods and has not been sequenced previously. It exhibits a unique tail extension of approximately 95 amino acids, which is lacking in functional units a to g and aligns with a published peptide sequence of 48 amino acids from functional unit h of Helix pomatia hemocyanin. The new Haliotis sequences are discussed with respect to their counterparts in Octopus, the 15 A three-dimensional reconstruction of the KLH1 didecamer from electron micrographs, and the recent 2.3 A X-ray structure of functional unit g from Octopus hemocyanin.
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Affiliation(s)
- H Keller
- Institute of Zoology, Johannes Gutenberg University of Mainz, Germany
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Gebauer W, Harris JR. Controlled cleavage of KLH1 and KLH2 by the V8 protease from Staphylococcus aureus reassociation, electrophoretic and transmission electron microscopy study of peptide fragments. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 262:166-75. [PMID: 10231378 DOI: 10.1046/j.1432-1327.1999.00364.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The reassociation behaviour of protease V8-cleaved peptides from KLH1 and KLH2, the two hemocyanin isoforms from the giant keyhole limpet Megathura crenulata, has been studied by transmission electron microscopy of negatively stained specimens and SDS/PAGE. Reassociation of the complete mixture of protease cleavage products and of combinations of peptide fragments purified by HPLC was performed in the presence of 100 mm CaCl2 and 100 mm MgCl2 at pH 7.4, over a period of 1 to 4 weeks. The V8 protease splits KLH1 into peptide fragments containing the functional units abc, def, defg, defgh, g and h. This mixture of peptide fragments reassociated to form helical tubular polymers, with a diameter of approximately 25 nm. The single functional units g and h were not incorporated into the polymer. An essentially identical polymer was formed from the re-mixed HPLC-purified fragments abc, def and defg alone. As with uncleaved subunit, the tubular polymer of V8-cleaved KLH1 forms bundles. The combination of peptides def and defg led to the formation of short arc-like filamentous structures, which aggregated but showed little tendency to associate into larger polymers. The KLH1 peptide fragments abc and def alone, did not reassociate and in combination their potential to form polymers was very low. With KLH2, the V8 protease generated peptide fragments containing the functional units abc, defg, defgh and h, which in combination slowly reassociated to form a tubular polymer significantly different to that obtained from the KLH1 V8 fragments. The three-functional unit fragment abc from KLH2 showed no tendency to polymerize and the combination of peptides defg + defgh generated only disordered aggregates, with some indication of malformed tubules. The combination of biochemical and electron microscopical methods enabled the characterization of these polymers with respect to peptide composition and higher order structure.
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Affiliation(s)
- W Gebauer
- Institute of Zoology, University of Mainz, Germany.
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Harris J, Gebauer W, Adrian M, Markl J. Keyhole Limpet Hemocyanin (KLH): Slow In Vitro Reassociation of KLH1 and KLH2 from Immucothel®. Micron 1998. [DOI: 10.1016/s0968-4328(98)00019-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Stoeva S, Dolashka P, Pervanova K, Genov N, Voelter W. Multidomain Structure of the Rapana thomasiana (Gastropod) Hemocyanin Structural Subunit RHSS1. Comp Biochem Physiol B Biochem Mol Biol 1997. [DOI: 10.1016/s0305-0491(97)00284-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Orlova EV, Dube P, Harris JR, Beckman E, Zemlin F, Markl J, van Heel M. Structure of keyhole limpet hemocyanin type 1 (KLH1) at 15 A resolution by electron cryomicroscopy and angular reconstitution. J Mol Biol 1997; 271:417-37. [PMID: 9268669 DOI: 10.1006/jmbi.1997.1182] [Citation(s) in RCA: 173] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A three-dimensional reconstruction of keyhole limpet hemocyanin type 1 (KLH1) has been obtained using electron cryomicroscopy at liquid helium temperatures and single particle image processing. The use of a high-contrast embedding medium, 1% (w/v) glucose and 2% (w/v) ammonium molybdate (pH 7.0), enables high-resolution electron micrographs to be recorded close to focus, i.e. with excellent transfer of high-resolution information, while maintaining enough image contrast to localise the individual macromolecules in the images. When low-pass filtered to approximately 45 A resolution, the new 15 A resolution reconstruction is very similar to the earlier reconstructions of gastropodan hemocyanins of specimens embedded in vitreous ice. The map shows much detail and reveals many new symmetry elements in this very large cylindrical molluscan hemocyanin. The full KLH1 didecamer has D5 pointgroup symmetry, yet within the KLH1 decameric half-molecules local 2-fold axes have emerged that make the wall of the KLH1 decamer, in spite of its having an exact C5 symmetry only, resemble the D5-symmetric wall of the decameric cephalopod hemocyanins. In fact, the outside of each tier of this six-tiered gastropodan hemocyanin was found to have an approximate D5 symmetry. Local 2-fold axes also relate the "functional units" within the dimeric "morphological units" of the wall and the collar areas of the 8 MDa KLH1 molecule. Certain local-symmetry-related surface motifs may be present up to 60 times on the outside wall of this highly symmetric cylindrical hemocyanin. Keyhole limpet hemocyanin is used clinically as an immunostimulant. The very strong immune reaction elicited by this hemocyanin may be associated with its intricate hierarchy of local-symmetry components.
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Affiliation(s)
- E V Orlova
- Imperial College of Science Medicine and Technology, Department of Biochemistry, London, SW7 2AY, U.K
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