1
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Crow RS, Shaw CG, Grayfer L, Smith LC. Recombinant SpTransformer proteins are functionally diverse for binding and phagocytosis by three subtypes of sea urchin phagocytes. Front Immunol 2024; 15:1372904. [PMID: 38742116 PMCID: PMC11089230 DOI: 10.3389/fimmu.2024.1372904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Accepted: 03/29/2024] [Indexed: 05/16/2024] Open
Abstract
Introduction The California purple sea urchin, Strongylocentrotus purpuratus, relies solely on an innate immune system to combat the many pathogens in the marine environment. One aspect of their molecular defenses is the SpTransformer (SpTrf) gene family that is upregulated in response to immune challenge. The gene sequences are highly variable both within and among animals and likely encode thousands of SpTrf isoforms within the sea urchin population. The native SpTrf proteins bind foreign targets and augment phagocytosis of a marine Vibrio. A recombinant (r)SpTrf-E1-Ec protein produced by E. coli also binds Vibrio but does not augment phagocytosis. Methods To address the question of whether other rSpTrf isoforms function as opsonins and augment phagocytosis, six rSpTrf proteins were expressed in insect cells. Results The rSpTrf proteins are larger than expected, are glycosylated, and one dimerized irreversibly. Each rSpTrf protein cross-linked to inert magnetic beads (rSpTrf::beads) results in different levels of surface binding and phagocytosis by phagocytes. Initial analysis shows that significantly more rSpTrf::beads associate with cells compared to control BSA::beads. Binding specificity was verified by pre-incubating the rSpTrf::beads with antibodies, which reduces the association with phagocytes. The different rSpTrf::beads show significant differences for cell surface binding and phagocytosis by phagocytes. Furthermore, there are differences among the three distinct types of phagocytes that show specific vs. constitutive binding and phagocytosis. Conclusion These findings illustrate the complexity and effectiveness of the sea urchin innate immune system driven by the natSpTrf proteins and the phagocyte cell populations that act to neutralize a wide range of foreign pathogens.
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Affiliation(s)
| | | | | | - L Courtney Smith
- Department of Biological Sciences, George Washington University, Washington, DC, United States
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2
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Barela Hudgell MA, Momtaz F, Jafri A, Alekseyev MA, Smith LC. Local Genomic Instability of the SpTransformer Gene Family in the Purple Sea Urchin Inferred from BAC Insert Deletions. Genes (Basel) 2024; 15:222. [PMID: 38397211 PMCID: PMC10887614 DOI: 10.3390/genes15020222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Revised: 02/02/2024] [Accepted: 02/05/2024] [Indexed: 02/25/2024] Open
Abstract
The SpTransformer (SpTrf) gene family in the purple sea urchin, Strongylocentrotus purpuratus, encodes immune response proteins. The genes are clustered, surrounded by short tandem repeats, and some are present in genomic segmental duplications. The genes share regions of sequence and include repeats in the coding exon. This complex structure is consistent with putative local genomic instability. Instability of the SpTrf gene cluster was tested by 10 days of growth of Escherichia coli harboring bacterial artificial chromosome (BAC) clones of sea urchin genomic DNA with inserts containing SpTrf genes. After the growth period, the BAC DNA inserts were analyzed for size and SpTrf gene content. Clones with multiple SpTrf genes showed a variety of deletions, including loss of one, most, or all genes from the cluster. Alternatively, a BAC insert with a single SpTrf gene was stable. BAC insert instability is consistent with variations in the gene family composition among sea urchins, the types of SpTrf genes in the family, and a reduction in the gene copy number in single coelomocytes. Based on the sequence variability among SpTrf genes within and among sea urchins, local genomic instability of the family may be important for driving sequence diversity in this gene family that would be of benefit to sea urchins in their arms race with marine microbes.
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Affiliation(s)
- Megan A. Barela Hudgell
- Department of Biological Sciences, George Washington University, Washington, DC 20052, USA; (M.A.B.H.); (F.M.)
| | - Farhana Momtaz
- Department of Biological Sciences, George Washington University, Washington, DC 20052, USA; (M.A.B.H.); (F.M.)
| | - Abiha Jafri
- Department of Biological Sciences, George Washington University, Washington, DC 20052, USA; (M.A.B.H.); (F.M.)
| | - Max A. Alekseyev
- Department of Mathematics and the Computational Biology Institute, George Washington University, Washington, DC 20052, USA;
| | - L. Courtney Smith
- Department of Biological Sciences, George Washington University, Washington, DC 20052, USA; (M.A.B.H.); (F.M.)
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3
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Barela Hudgell MA, Smith LC. Sequence Diversity, Locus Structure, and Evolutionary History of the SpTransformer Genes in the Sea Urchin Genome. Front Immunol 2021; 12:744783. [PMID: 34867968 PMCID: PMC8634487 DOI: 10.3389/fimmu.2021.744783] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 10/12/2021] [Indexed: 11/13/2022] Open
Abstract
The generation of large immune gene families is often driven by evolutionary pressure exerted on host genomes by their pathogens, which has been described as the immunological arms race. The SpTransformer (SpTrf) gene family from the California purple sea urchin, Strongylocentrotus purpuratus, is upregulated upon immune challenge and encodes the SpTrf proteins that interact with pathogens during an immune response. Native SpTrf proteins bind both bacteria and yeast, and augment phagocytosis of a marine Vibrio, while a recombinant SpTrf protein (rSpTrf-E1) binds a subset of pathogens and a range of pathogen associated molecular patterns. In the sequenced sea urchin genome, there are four SpTrf gene clusters for a total of 17 genes. Here, we report an in-depth analysis of these genes to understand the sequence complexities of this family, its genomic structure, and to derive a putative evolutionary history for the formation of the gene clusters. We report a detailed characterization of gene structure including the intron type and UTRs with conserved transcriptional start sites, the start codon and multiple stop codons, and locations of polyadenylation signals. Phylogenetic and percent mismatch analyses of the genes and the intergenic regions allowed us to predict the last common ancestral SpTrf gene and a theoretical evolutionary history of the gene family. The appearance of the gene clusters from the theoretical ancestral gene may have been driven by multiple duplication and deletion events of regions containing SpTrf genes. Duplications and ectopic insertion events, indels, and point mutations in the exons likely resulted in the extant genes and family structure. This theoretical evolutionary history is consistent with the involvement of these genes in the arms race in responses to pathogens and suggests that the diversification of these genes and their encoded proteins have been selected for based on the survival benefits of pathogen binding and host protection.
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Affiliation(s)
| | - L. Courtney Smith
- Department of Biological Sciences, George Washington University, Washington, DC, United States
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4
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The Diverse Transformer (Trf) Protein Family in the Sea Urchin Paracentrotus lividus Acts through a Collaboration between Cellular and Humoral Immune Effector Arms. Int J Mol Sci 2021; 22:ijms22136639. [PMID: 34206148 PMCID: PMC8268236 DOI: 10.3390/ijms22136639] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 06/15/2021] [Accepted: 06/15/2021] [Indexed: 01/06/2023] Open
Abstract
Sea urchins are long-living marine invertebrates with a complex innate immune system, which includes expanded families of immune receptors. A central immune gene family in sea urchins encodes the Transformer (Trf) proteins. The Trf family has been studied mainly in the purple sea urchin Strongylocentrotus purpuratus. Here, we explore this protein family in the Mediterranean Sea urchin Paracentrotus lividus. The PlTrf genes and predicted proteins are highly diverse and show a typical Trf size range and structure. Coelomocytes and cell-free coelomic fluid from P. lividus contain different PlTrf protein repertoires with a shared subset, that bind specifically to E. coli. Using FACS, we identified five different P. lividus coelomocyte sub-populations with cell surface PlTrf protein expression. The relative abundance of the PlTrf-positive cells increases sharply following immune challenge with E. coli, but not following challenge with LPS or the sea urchin pathogen, Vibrio penaeicida. Phagocytosis of E. coli by P. lividus phagocytes is mediated through the cell-free coelomic fluid and is inhibited by blocking PlTrf activity with anti-SpTrf antibodies. Together, our results suggest a collaboration between cellular and humoral PlTrf-mediated effector arms in the P. lividus specific immune response to pathogens.
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5
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Balakirev ES. Trans-Species Polymorphism in Mitochondrial Genome of Camarodont Sea Urchins. Genes (Basel) 2019; 10:E592. [PMID: 31387337 PMCID: PMC6723515 DOI: 10.3390/genes10080592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 07/30/2019] [Accepted: 08/02/2019] [Indexed: 11/16/2022] Open
Abstract
Mitochondrial (mt) genomes of the sea urchins Strongylocentrotus intermedius and Mesocentrotus nudus demonstrate the identical patterns of intraspecific length variability of the ND6 gene, consisting of 489 bp (S variant) and 498 bp (L variant), respectively. For both species, the ND6 length difference is due to the 488A>G substitution, which changes the stop codon TAG in S variant for a tryptophan codon TGG in L variant and elongates the corresponding ND6 protein by three additional amino acids, Trp-Leu-Trp. The phylogenetic analysis based on mt genomes of sea urchins and related echinoderm groups from GenBank has shown the S and L ND6 variants as shared among the camarodont sea urchins; the rest of the echinoderms demonstrate the S variant only. The data suggest that the ND6 488A>G substitution can be the first example of the trans-species polymorphism in sea urchins, persisting at least since the time of the Odontophora diversification at the Eocene/Oligocene boundary (approximately 34 million years ago), which was characterized by an abrupt climate change and significant global ocean cooling. Alternative hypotheses, including the convergent RNA editing and/or codon reassignment, are not supported by direct comparisons of the ND6 gene sequences with the corresponding transcripts using the basic local alignment search tool (BLAST) of full sea urchin transcriptomes.
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Affiliation(s)
- Evgeniy S Balakirev
- National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, 17 Palchevsky Street, 690041 Vladivostok, Russia.
- School of Biomedicine, Far Eastern Federal University, 8 Sukhanov Street, 690950 Vladivostok, Russia.
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6
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Oren M, Rosental B, Hawley TS, Kim GY, Agronin J, Reynolds CR, Grayfer L, Smith LC. Individual Sea Urchin Coelomocytes Undergo Somatic Immune Gene Diversification. Front Immunol 2019; 10:1298. [PMID: 31244844 PMCID: PMC6563789 DOI: 10.3389/fimmu.2019.01298] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 05/21/2019] [Indexed: 12/19/2022] Open
Abstract
The adaptive immune response in jawed vertebrates is marked by the ability to diversify somatically specific immune receptor genes. Somatic recombination and hypermutation of gene segments are used to generate extensive repertoires of T and B cell receptors. In contrast, jawless vertebrates utilize a distinct diversification system based on copy choice to assemble their variable lymphocyte receptors. To date, very little evidence for somatic immune gene diversification has been reported in invertebrate species. Here we show that the SpTransformer (SpTrf ; formerly Sp185/333) immune effector gene family members from individual coelomocytes from purple sea urchins undergo somatic diversification by means of gene deletions, duplications, and acquisitions of single nucleotide polymorphisms. While sperm cells from an individual sea urchin have identical SpTrf gene repertoires, single cells from two distinct coelomocyte subpopulations from the same sea urchin exhibit significant variation in the SpTrf gene repertoires. Moreover, the highly diverse gene sequences derived from single coelomocytes are all in-frame, suggesting that an unknown mechanism(s) driving these somatic changes involve stringent selection or correction processes for expression of productive SpTrf transcripts. Together, our findings infer somatic immune gene diversification strategy in an invertebrate.
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Affiliation(s)
- Matan Oren
- Department of Molecular Biology, Ariel University, Ariel, Israel.,Department of Biological Sciences, The George Washington University, Washington, DC, United States
| | - Benyamin Rosental
- French Associates' Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Be'er Sheva, Israel.,Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, United States.,Department of Pathology, Hopkins Marine Station, Stanford University, Pacific Grove, CA, United States
| | - Teresa S Hawley
- Flow Cytometry Section, Research Technologies Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, United States
| | - Gi-Young Kim
- Department of Biological Sciences, The George Washington University, Washington, DC, United States.,Department of Marine Life Sciences, Jeju National University, Jeju City, South Korea
| | - Jacob Agronin
- Department of Biological Sciences, The George Washington University, Washington, DC, United States
| | - Caroline R Reynolds
- Department of Biological Sciences, The George Washington University, Washington, DC, United States
| | - Leon Grayfer
- Department of Biological Sciences, The George Washington University, Washington, DC, United States
| | - L Courtney Smith
- Department of Biological Sciences, The George Washington University, Washington, DC, United States
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7
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Chou HY, Lun CM, Smith LC. SpTransformer proteins from the purple sea urchin opsonize bacteria, augment phagocytosis, and retard bacterial growth. PLoS One 2018; 13:e0196890. [PMID: 29738524 PMCID: PMC5940198 DOI: 10.1371/journal.pone.0196890] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 04/20/2018] [Indexed: 01/05/2023] Open
Abstract
The purple sea urchin, Strongylocentrotus purpuratus, has a complex and robust immune system that is mediated by a number of multi-gene families including the SpTransformer (SpTrf) gene family (formerly Sp185/333). In response to immune challenge from bacteria and various pathogen-associated molecular patterns, the SpTrf genes are up-regulated in sea urchin phagocytes and express a diverse array of SpTrf proteins. We show here that SpTrf proteins from coelomocytes and isolated by nickel affinity (cNi-SpTrf) bind to Gram-positive and Gram-negative bacteria and to Baker's yeast, Saccharomyces cerevisiae, with saturable kinetics and specificity. cNi-SpTrf opsonization of the marine bacteria, Vibrio diazotrophicus, augments phagocytosis, however, opsonization by the recombinant protein, rSpTrf-E1, does not. Binding by cNi-SpTrf proteins retards growth rates significantly for several species of bacteria. SpTrf proteins, previously thought to be strictly membrane-associated, are secreted from phagocytes in short term cultures and bind V. diazotrophicus that are located both outside of and within phagocytes. Our results demonstrate anti-microbial activities of native SpTrf proteins and suggest variable functions among different SpTrf isoforms. Multiple isoforms may act synergistically to detect a wide array of pathogens and provide flexible and efficient host immunity.
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Affiliation(s)
- Hung-Yen Chou
- Department of Biological Sciences, George Washington University, Washington, DC, United States of America
| | - Cheng Man Lun
- Department of Biological Sciences, George Washington University, Washington, DC, United States of America
| | - L. Courtney Smith
- Department of Biological Sciences, George Washington University, Washington, DC, United States of America
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8
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Smith LC, Lun CM. The SpTransformer Gene Family (Formerly Sp185/333) in the Purple Sea Urchin and the Functional Diversity of the Anti-Pathogen rSpTransformer-E1 Protein. Front Immunol 2017; 8:725. [PMID: 28713368 PMCID: PMC5491942 DOI: 10.3389/fimmu.2017.00725] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 06/08/2017] [Indexed: 12/12/2022] Open
Abstract
The complex innate immune system of sea urchins is underpinned by several multigene families including the SpTransformer family (SpTrf; formerly Sp185/333) with estimates of ~50 members, although the family size is likely variable among individuals of Strongylocentrotus purpuratus. The genes are small with similar structure, are tightly clustered, and have several types of repeats in the second of two exons and that surround each gene. The density of repeats suggests that the genes are positioned within regions of genomic instability, which may be required to drive sequence diversification. The second exon encodes the mature protein and is composed of blocks of sequence called elements that are present in mosaics of defined element patterns and are the major source of sequence diversity. The SpTrf genes respond swiftly to immune challenge, but only a single gene is expressed per phagocyte. Many of the mRNAs appear to be edited and encode proteins with altered and/or missense sequence that are often truncated, of which some may be functional. The standard SpTrf protein structure is an N-terminal glycine-rich region, a central RGD motif, a histidine-rich region, and a C-terminal region. Function is predicted from a recombinant protein, rSpTransformer-E1 (rSpTrf-E1), which binds to Vibrio and Saccharomyces, but not to Bacillus, and binds tightly to lipopolysaccharide, β-1,3-glucan, and flagellin, but not to peptidoglycan. rSpTrf-E1 is intrinsically disordered but transforms to α helical structure in the presence of binding targets including lipopolysaccharide, which may underpin the characteristics of binding to multiple targets. SpTrf proteins associate with coelomocyte membranes, and rSpTrf-E1 binds specifically to phosphatidic acid (PA). When rSpTrf-E1 is bound to PA in liposome membranes, it induces morphological changes in liposomes that correlate with PA clustering and leakage of luminal contents, and it extracts or removes PA from the bilayer. The multitasking activities of rSpTrf-E1 infer multiple and perhaps overlapping activities for the hundreds of native SpTrf proteins that are produced by individual sea urchins. This likely generates a flexible and highly protective immune system for the sea urchin in its marine habitat that it shares with broad arrays of microbes that may be pathogens and opportunists.
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Affiliation(s)
- L Courtney Smith
- Department of Biological Sciences, George Washington University, Washington, DC, United States
| | - Cheng Man Lun
- Department of Biological Sciences, George Washington University, Washington, DC, United States
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9
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Lun CM, Samuel RL, Gillmor SD, Boyd A, Smith LC. The Recombinant Sea Urchin Immune Effector Protein, rSpTransformer-E1, Binds to Phosphatidic Acid and Deforms Membranes. Front Immunol 2017; 8:481. [PMID: 28553283 PMCID: PMC5427130 DOI: 10.3389/fimmu.2017.00481] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 04/06/2017] [Indexed: 01/11/2023] Open
Abstract
The purple sea urchin, Strongylocentrotus purpuratus, possesses a sophisticated innate immune system that functions without adaptive capabilities and responds to pathogens effectively by expressing the highly diverse SpTransformer gene family (formerly the Sp185/333 gene family). The swift gene expression response and the sequence diversity of SpTransformer cDNAs suggest that the encoded proteins have immune functions. Individual sea urchins can express up to 260 distinct SpTransformer proteins, and their diversity suggests that different versions may have different functions. Although the deduced proteins are diverse, they share an overall structure of a hydrophobic leader, a glycine-rich N-terminal region, a histidine-rich region, and a C-terminal region. Circular dichroism analysis of a recombinant SpTransformer protein, rSpTransformer-E1 (rSpTrf-E1) demonstrates that it is intrinsically disordered and transforms to α helical in the presence of buffer additives and binding targets. Although native SpTrf proteins are associated with the membranes of perinuclear vesicles in the phagocyte class of coelomocytes and are present on the surface of small phagocytes, they have no predicted transmembrane region or conserved site for glycophosphatidylinositol linkage. To determine whether native SpTrf proteins associate with phagocyte membranes through interactions with lipids, when rSpTrf-E1 is incubated with lipid-embedded nylon strips, it binds to phosphatidic acid (PA) through both the glycine-rich region and the histidine-rich region. Synthetic liposomes composed of PA and phosphatidylcholine show binding between rSpTrf-E1 and PA by fluorescence resonance energy transfer, which is associated with leakage of luminal contents suggesting changes in lipid organization and perhaps liposome lysis. Interactions with liposomes also change membrane curvature leading to liposome budding, fusion, and invagination, which is associated with PA clustering induced by rSpTrf-E1 binding. Longer incubations result in the extraction of PA from the liposomes, which form disorganized clusters. CD shows that when rSpTrf-E1 binds to PA, it changes its secondary structure from disordered to α helical. These results provide evidence for how SpTransformer proteins may associate with molecules that have exposed phosphates including PA on cell membranes and how the characteristic of protein multimerization may drive changes in the organization of membrane lipids.
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Affiliation(s)
- Cheng Man Lun
- Department of Biological Sciences, George Washington University, Science and Engineering Hall, Washington, DC, USA
| | - Robin L. Samuel
- Department of Chemistry, George Washington University, Science and Engineering Hall, Washington, DC, USA
| | - Susan D. Gillmor
- Department of Chemistry, George Washington University, Science and Engineering Hall, Washington, DC, USA
| | - Anthony Boyd
- Department of Biological Sciences, George Washington University, Science and Engineering Hall, Washington, DC, USA
| | - L. Courtney Smith
- Department of Biological Sciences, George Washington University, Science and Engineering Hall, Washington, DC, USA
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10
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Lun CM, Bishop BM, Smith LC. Multitasking Immune Sp185/333 Protein, rSpTransformer-E1, and Its Recombinant Fragments Undergo Secondary Structural Transformation upon Binding Targets. THE JOURNAL OF IMMUNOLOGY 2017; 198:2957-2966. [PMID: 28242650 DOI: 10.4049/jimmunol.1601795] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 01/26/2017] [Indexed: 12/31/2022]
Abstract
The purple sea urchin, Strongylocentrotus purpuratus, expresses a diverse immune response protein family called Sp185/333. A recombinant Sp185/333 protein, previously called rSp0032, shows multitasking antipathogen binding ability, suggesting that the protein family mediates a flexible and effective immune response to multiple foreign cells. Bioinformatic analysis predicts that rSp0032 is intrinsically disordered, and its multiple binding characteristic suggests structural flexibility to adopt different conformations depending on the characteristics of the target. To address the flexibility and structural shifting hypothesis, circular dichroism analysis of rSp0032 suggests that it transforms from disordered (random coil) to α helical structure. This structural transformation may be the basis for the strong affinity between rSp0032 and several pathogen-associated molecular patterns. The N-terminal Gly-rich fragment of rSp0032 and the C-terminal His-rich fragment show unique transformations by either intensifying the α helical structure or changing from α helical to β strand depending on the solvents and molecules added to the buffer. Based on these results, we propose a name change from rSp0032 to rSpTransformer-E1 to represent its flexible structural conformations and its E1 element pattern. Given that rSpTransformer-E1 shifts its conformation in the presence of solvents and binding targets and that all Sp185/333 proteins are predicted to be disordered, many or all of these proteins may undergo structural transformation to enable multitasking binding activity toward a wide range of targets. Consequently, we also propose an overarching name change for the entire family from Sp185/333 proteins to SpTransformer proteins.
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Affiliation(s)
- Cheng Man Lun
- Department of Biological Sciences, George Washington University, Washington, DC 20052; and
| | - Barney M Bishop
- Department of Chemistry and Biochemistry, George Mason University, Manassas, VA 20110
| | - L Courtney Smith
- Department of Biological Sciences, George Washington University, Washington, DC 20052; and
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Oren M, Barela Hudgell MA, D'Allura B, Agronin J, Gross A, Podini D, Smith LC. Short tandem repeats, segmental duplications, gene deletion, and genomic instability in a rapidly diversified immune gene family. BMC Genomics 2016; 17:900. [PMID: 27829352 PMCID: PMC5103432 DOI: 10.1186/s12864-016-3241-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 11/01/2016] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Genomic regions with repetitive sequences are considered unstable and prone to swift DNA diversification processes. A highly diverse immune gene family of the sea urchin (Strongylocentrotus purpuratus), called Sp185/333, is composed of clustered genes with similar sequence as well as several types of repeats ranging in size from short tandem repeats (STRs) to large segmental duplications. This repetitive structure may have been the basis for the incorrect assembly of this gene family in the sea urchin genome sequence. Consequently, we have resolved the structure of the family and profiled the members by sequencing selected BAC clones using Illumina and PacBio approaches. RESULTS BAC insert assemblies identified 15 predicted genes that are organized into three clusters. Two of the gene clusters have almost identical flanking regions, suggesting that they may be non-matching allelic clusters residing at the same genomic locus. GA STRs surround all genes and appear in large stretches at locations of putatively deleted genes. GAT STRs are positioned at the edges of segmental duplications that include a subset of the genes. The unique locations of the STRs suggest their involvement in gene deletions and segmental duplications. Genomic profiling of the Sp185/333 gene diversity in 10 sea urchins shows that no gene repertoires are shared among individuals indicating a very high gene diversification rate for this family. CONCLUSIONS The repetitive genomic structure of the Sp185/333 family that includes STRs in strategic locations may serve as platform for a controlled mechanism which regulates the processes of gene recombination, gene conversion, duplication and deletion. The outcome is genomic instability and allelic mismatches, which may further drive the swift diversification of the Sp185/333 gene family that may improve the immune fitness of the species.
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Affiliation(s)
- Matan Oren
- The Department of Biological Sciences, George Washington University, Washington, DC, USA
| | - Megan A Barela Hudgell
- The Department of Biological Sciences, George Washington University, Washington, DC, USA
| | - Brian D'Allura
- The Department of Biological Sciences, George Washington University, Washington, DC, USA
- Present Address: Pennsylvania College of Optometry, Salus University, Elkins Park, PA, USA
| | - Jacob Agronin
- The Department of Biological Sciences, George Washington University, Washington, DC, USA
| | - Alexandra Gross
- The Department of Biological Sciences, George Washington University, Washington, DC, USA
| | - Daniele Podini
- Department of Forensic Sciences, George Washington University, Washington, DC, USA
| | - L Courtney Smith
- The Department of Biological Sciences, George Washington University, Washington, DC, USA.
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12
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McDowell IC, Modak TH, Lane CE, Gomez-Chiarri M. Multi-species protein similarity clustering reveals novel expanded immune gene families in the eastern oyster Crassostrea virginica. FISH & SHELLFISH IMMUNOLOGY 2016; 53:13-23. [PMID: 27033806 DOI: 10.1016/j.fsi.2016.03.157] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 03/24/2016] [Accepted: 03/24/2016] [Indexed: 06/05/2023]
Abstract
Comparative genomics research in non-model species has highlighted how invertebrate hosts possess complex diversified repertoires of immune molecules. The levels of diversification in particular immune gene families appear to differ between invertebrate lineages and even between species within lineages, reflecting differences not only in evolutionary histories, but also in life histories, environmental niches, and pathogen exposures. The goal of this research was to identify immune-related gene families experiencing high levels of diversification in eastern oysters, Crassostrea virginica. Families containing 1) transcripts differentially expressed in eastern oysters in response to bacterial challenge and 2) a larger number of transcripts compared to other species included those coding for the C1q and C-type lectin domain containing proteins (C1qDC and CTLDC), GTPase of the immune-associated proteins (GIMAP), scavenger receptors (SR), fibrinogen-C domain containing proteins (also known as FREPs), dopamine beta-hydrolase (DBH), interferon-inducible 44 (IFI44), serine protease inhibitors, apextrin, and dermatopontin. Phylogenetic analysis of two of the families significantly expanded in bivalves, IFI44 and GIMAP, showed a patchy distribution within both protostomes and deuterostomes, suggesting multiple independent losses and lineage-specific expansions. Increased availability of genomic information for a broader range of non-model species broadly distributed through vertebrate and invertebrate phyla will likely lead to improved knowledge on mechanisms of immune-gene diversification.
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A recombinant Sp185/333 protein from the purple sea urchin has multitasking binding activities towards certain microbes and PAMPs. Immunobiology 2016; 221:889-903. [PMID: 27020848 DOI: 10.1016/j.imbio.2016.03.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 03/14/2016] [Accepted: 03/17/2016] [Indexed: 11/22/2022]
Abstract
The purple sea urchin, Strongylocentrotus purpuratus, possesses a sophisticated innate immune system that responds to microbes effectively by swift expression of the highly diverse Sp185/333 gene family. The Sp185/333 proteins are predicted to have anti-pathogen functions based on inducible gene expression and their significant sequence diversity. Sp185/333 proteins are all predicted to be intrinsically disordered and do not exhibit sequence similarities to other known proteins. To test the anti-pathogen hypothesis, a recombinant Sp185/333 protein, rSp0032, was evaluated and found to exhibit specific binding to marine Vibrio diazotrophicus and to Saccharomyces cerevisiae, but not to two Bacillus species. rSp0032 also binds to LPS, β-1,3-glucan and flagellin but not to peptidoglycan. rSp0032 binding to LPS can be competed by LPS, β-1,3-glucan and flagellin but not by peptidoglycan. We speculate that the predicted intrinsically disordered structure of rSp0032 may adapt to different conformations in binding to a limited number of PAMPs and pathogens. Given that rSp0032 binds to a range of targets, and that up to 260 different Sp185/333 proteins can be expressed per individual sea urchin, this family of immune response proteins may facilitate effective host protection against a broad array of potential pathogens encountered in the marine environment.
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