scholarly journals Diversity and complexity of the large surface protein family in the compacted genomes of various Pneumocystis species

2019 ◽  
Author(s):  
Liang Ma ◽  
Zehua Chen ◽  
Da Wei Huang ◽  
Ousmane H. Cissé ◽  
Jamie L. Rothenburger ◽  
...  
Keyword(s):  
Antigenic Variation ◽  
Life Stage ◽  
Surface Protein ◽  
Opportunistic Pathogen ◽  
Surface Proteins ◽  
Surface Glycoprotein ◽  
Mammalian Host ◽  
Expression Site ◽  
Phylogeny And Evolution ◽  
Major Surface

AbstractPneumocystis, a major opportunistic pathogen in patients with a broad range of immunodeficiencies, contains abundant surface proteins encoded by a multi-copy gene family, termed the major surface glycoprotein (Msg) gene superfamily. This superfamily has been identified in all Pneumocystis species characterized to date, highlighting its important role in Pneumocystis biology. In this report, through a comprehensive and in-depth characterization of 459 msg genes from 7 Pneumocystis species, we demonstrate, for the first time, the phylogeny and evolution of conserved domains in Msg proteins, and provide detailed description of the classification, unique characteristics and phylogenetic relatedness of five Msg families. We further describe the relative expression levels of individual msg families in two rodent Pneumocystis species, the substantial variability of the msg repertoires in P. carinii from laboratory and wild rats, and the distinct features of the expression site for the classic msg genes in Pneumocystis from 8 mammalian host species. Our analysis suggests a wide variety of functions for this superfamily, not only conferring antigenic variation to allow immune evasion but also mediating life-stage development, optimizing cell mobility and adhesion, and adapting to specific host niches or environmental conditions. This study provides a rich source of information that lays the foundation for the continued experimental exploration of the functions of the Msg superfamily in Pneumocystis biology.

scholarly journals Antigenic Variation of Anaplasma Marginale: Major Surface Protein 2 Diversity during Cyclic Transmission between Ticks and Cattle

2001 ◽  
Vol 69 (5) ◽  
pp. 3057-3066 ◽  
Author(s):  
A. F. Barbet ◽  
Jooyoung Yi ◽  
Anna Lundgren ◽  
B. R. McEwen ◽  
E. F. Blouin ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Salivary Glands ◽  
Antigenic Variation ◽  
Hypervariable Region ◽  
Surface Protein ◽  
Genomic Expression ◽  
Major Surface Protein ◽  
Expression Site ◽  
Major Surface ◽  
Tick Salivary Glands

ABSTRACT The rickettsial pathogen Anaplasma marginale expresses a variable immunodominant outer membrane protein, major surface protein 2 (MSP2), involved in antigenic variation and long-term persistence of the organism in carrier animals. MSP2 contains a central hypervariable region of about 100 amino acids that encodes immunogenic B-cell epitopes that induce variant-specific antibodies during infection. Previously, we have shown that MSP2 is encoded on a polycistronic mRNA transcript in erythrocyte stages of A. marginale and defined the structure of the genomic expression site for this transcript. In this study, we show that the same expression site is utilized in stages of A. marginale infecting tick salivary glands. We also analyzed the variability of this genomic expression site in Oklahoma strain A. marginale transmitted from in vitro cultures to cattle and between cattle and ticks. The structure of the expression site and flanking regions was conserved except for sequence that encoded the MSP2 hypervariable region. At least three different MSP2 variants were encoded in each A. marginalepopulation. The major sequence variants did not change on passage ofA. marginale between culture, acute erythrocyte stage infections, and tick salivary glands but did change during persistent infections of cattle. The variant types found in tick salivary glands most closely resembled those present in bovine blood at the time of acquisition of infection, whether infection was acquired from an acute or from a persistent rickettsemia. These variations in structure of an expression site for a major, immunoprotective outer membrane protein have important implications for vaccine development and for obtaining an improved understanding of the mechanisms of persistence of ehrlichial infections in humans, domestic animals, and reservoir hosts.

Mutational and functional analysis of the Leishmania surface metalloproteinase GP63: similarities to matrix metalloproteinases

Parasitology ◽  
1994 ◽  
Vol 108 (S1) ◽  
pp. S29-S36 ◽  
Author(s):  
W. R. McMaster ◽  
C. J. Morrison ◽  
M. H. Macdonald ◽  
P. B. Joshi
Keyword(s):  
Matrix Metalloproteinases ◽  
Life Stage ◽  
Expression System ◽  
Baculovirus Expression System ◽  
Site Directed Mutagenesis ◽  
Surface Glycoprotein ◽  
Proteinase Activity ◽  
Mammalian Host ◽  
Targeted Gene Deletion ◽  
Major Surface

SUMMARYThe major surface glycoprotein of Leishmania, referred to as GP63, is a zinc metalloproteinase of 63000 Mr present on promastigotes and amastigotes from diverse species of Leishmania. GP63 shares several characteristics with the members of the matrix metalloproteinase family including degradation of at least one component of the extracellular matrix, location at the cell surface, requirement for Zn2+ for proteinase activity and inhibition of the proteinase activity by chelating agents and α2–macroglobulin. Site-directed mutagenesis of the cloned L. major GP63 genes was carried out to determine whether the proposed active site of Leishmania GP63 was homologous to those of other zinc metalloproteinases. The codon encoding the catalytic glutamic acid was modified to encode an aspartic acid and when expressed in COS–7 cells the resulting mutant GP63 had no demonstrable proteinase activity compared to wild type GP63. GP63 was predicted to be synthesized as a precursor protein containing a pro region at the NH2–terminus of GP63 implicated to be involved with the regulation of proteinase activity. As with many other proteinases, including matrix metalloproteinases, these enzymes are synthesized as latent proteinases that require activation for full proteinase activity. L. major recombinant GP63 (rGP63) has been produced in the baculovirus expression system where rGP63 was secreted as a latent proteinase. To study the activation of baculovirus rGP63, purified rGP63 was incubated with the mercurial compound, HgCl2, at concentrations previously shown to result in activation of other latent matrix degrading metalloproteinases and resulted in a significant enhancement of GP63 proteinase activity. The similarity of GP63 to the family of matrix-degrading proteinases suggests that the proteinase activity of GP63 maybe involved with the pathology of lesion formation in the mammalian host and may also be involved with the promastigote life stage in the sandfly vector. To study the functional role of GP63 proteinase, mutant strains of L. major, deficient in the expression of GP63, are currently being derived by targeted gene deletion. Using this strategy results have demonstrated the deletion of an entire L. major GP63 locus, containing in total six GP63 genes. Strategies to delete the second GP63 gene locus are developed and will determine whether deletion of both loci results in viable promastigotes. L. major strains deficient in the expression of GP63 may then be used to address the function of GP63 glycoprotein in the life cycle of Leishmania.

scholarly journals Trypanosoma brucei Interaction with Host: Mechanism of VSG Release as Target for Drug Discovery for African Trypanosomiasis

2019 ◽  
Vol 20 (6) ◽  
pp. 1484 ◽  
Author(s):  
Cláudia Moreno ◽  
Adriana Temporão ◽  
Taffarel Torres ◽  
Marcelo Sousa Silva
Keyword(s):  
Drug Discovery ◽  
Phospholipase C ◽  
Trypanosoma Brucei ◽  
Antigenic Variation ◽  
Surface Glycoprotein ◽  
Mammalian Host ◽  
African Trypanosomiasis ◽  
Variable Surface Glycoprotein ◽  
Variable Surface ◽  
Major Surface

The protozoan Trypanosoma brucei, responsible for animal and human trypanosomiasis, has a family of major surface proteases (MSPs) and phospholipase-C (PLC), both involved in some mechanisms of virulence during mammalian infections. During parasitism in the mammalian host, this protozoan is exclusively extracellular and presents a robust mechanism of antigenic variation that allows the persistence of infection. There has been incredible progress in our understanding of how variable surface glycoproteins (VSGs) are organised and expressed, and how expression is switched, particularly through recombination. The objective of this manuscript is to create a reflection about the mechanisms of antigenic variation in T. brucei, more specifically, in the process of variable surface glycoprotein (VSG) release. We firstly explore the mechanism of VSG release as a potential pathway and target for the development of anti-T. brucei drugs.

scholarly journals DNA double strand break position leads to distinct gene expression changes and regulates VSG switching pathway choice.

2021 ◽  
Author(s):  
Alix Thivolle ◽  
Ann-Kathrin Mehnert ◽  
Eliane Tihon ◽  
Emilia McLaughlin ◽  
Annick Dujeancourt-Henry ◽  
...  
Keyword(s):  
Gene Expression ◽  
Antigenic Variation ◽  
Surface Protein ◽  
Strand Break ◽  
Surface Glycoprotein ◽  
Dna Double Strand Breaks ◽  
African Trypanosomes ◽  
Distinct Gene ◽  
Active Expression ◽  
Expression Site

Antigenic variation is an immune evasion strategy used by Trypanosoma brucei that results in the periodic exchange of the surface protein coat. Underlying this process is the movement of variant surface glycoprotein genes in or out of a specialized locus known as bloodstream form expression site by homologous recombination, facilitated by blocks of repetitive sequence known as the 70-bp repeats, that provide homology for gene conversion events. DNA double strand breaks are potent drivers of antigenic variation, however where these breaks must fall to elicit a switch is not well understood. To understand how the position of a break influences antigenic variation we established a series of cell lines to study the effect of an I-SceI meganuclease break in the active expression site. We found that a DNA break within repetitive regions is not productive for VSG switching, and show that the break position leads to a distinct gene expression profile and DNA repair response which dictates how antigenic variation proceeds in African trypanosomes.

scholarly journals Immunodominant surface epitopes power immune evasion in the African trypanosome

2021 ◽  
Author(s):  
Anastasia Gkeka ◽  
Francisco Aresta-Branco ◽  
Gianna Triller ◽  
Evi P Vlachou ◽  
Mirjana Lilic ◽  
...  
Keyword(s):  
Immune Evasion ◽  
Antigenic Variation ◽  
Cross Reactivity ◽  
Surface Glycoprotein ◽  
Mammalian Host ◽  
African Trypanosome ◽  
Repetitive Nature ◽  
Variable Surface ◽  
Major Surface ◽  
Immunodominant Epitopes

The African trypanosome survives the immune response of its mammalian host by antigenic variation of its major surface antigen (the Variable Surface Glycoprotein, or VSG). Here we describe the antibody repertoires elicited by different VSGs. We show that the repertoires are highly restricted, directed predominantly to epitopes on the surface of the VSGs. They are also highly discriminatory: minor alterations within these exposed epitopes confer antigenically-distinct properties to these VSGs and elicit different repertoires. We propose that the patterned and repetitive nature of the VSG coat focuses host immunity to a restricted set of immunodominant epitopes per VSG, eliciting a highly stereotyped response, minimizing cross reactivity between different VSGs and facilitating prolonged immune evasion through epitope variation.

scholarly journals The genomic basis of host and vector specificity in non-pathogenic trypanosomatids

2022 ◽  
Author(s):  
Guy Oldrieve ◽  
Beatrice Malacart ◽  
Javier López-Vidal ◽  
Keith Matthews
Keyword(s):  
Draft Genome ◽  
Surface Protein ◽  
Surface Proteins ◽  
Surface Glycoprotein ◽  
Mammalian Host ◽  
African Trypanosomes ◽  
Protein Architecture ◽  
Vector Specificity ◽  
Pathogenic Parasite ◽  
Genomic Basis

The ability of trypanosome parasites to survive and sustain infections is dependent on diverse and intricate immune evasion mechanisms. Pathogenic trypanosomes often have broad host niches that preclude identification of host specific adaptations. In contrast, some non-pathogenic species of the genus Trypanosoma have highly specific hosts and vectors. Trypanosoma theileri, a non-pathogenic parasite of bovines, has a predicted surface protein architecture that likely aids survival in its mammalian host, distinct from the dominant variant surface glycoprotein coat of pathogenic African trypanosomes. In both species, their surface proteins are encoded by genes which account for ~10% of their genome. A non-pathogenic parasite of sheep, Trypanosoma melophagium, is transmitted by the sheep ked and is closely related to T. theileri. To explore host and vector specificity between these closely related species, we sequenced the T. melophagium genome and transcriptome and an annotated draft genome was assembled. T. melophagium was compared to 43 kinetoplastid genomes, including T. theileri. T. melophagium and T. theileri have an AT biased genome, the greatest bias of publicly available trypanosomatids. This trend may result from selection acting to decrease the genome nucleotide cost. The T. melophagium genome is 6.3Mb smaller than T. theileri and large families of proteins, characteristic of the predicted surface of T. theileri, were found to be absent or greatly reduced in T. melophagium. Instead, T. melophagium has modestly expanded protein families associated with the avoidance of complement-mediated lysis. The genome of T. melophagium contains core genes required for development, glycolysis, RNA interference, and meiotic exchange, each being shared with T. theileri. Comparisons between T. melophagium and T. theileri provide insight into the specific adaptations of these related trypanosomatids to their distinct mammalian hosts and arthropod vectors.

scholarly journals Surface Protein Variation by Expression Site Switching in the Relapsing Fever Agent Borrelia hermsii

2000 ◽  
Vol 68 (12) ◽  
pp. 7114-7121 ◽  
Author(s):  
Alan G. Barbour ◽  
Carol J. Carter ◽  
Charles D. Sohaskey
Keyword(s):  
Membrane Protein ◽  
Antigenic Variation ◽  
Surface Protein ◽  
Relapsing Fever ◽  
Borrelia Hermsii ◽  
Immunodeficient Mice ◽  
Major Surface Protein ◽  
Protein Variation ◽  
Expression Site ◽  
Major Surface

ABSTRACT Borrelia hermsii, an agent of relapsing fever, undergoes antigenic variation of serotype-specifying membrane proteins during mammalian infections. When B. hermsii is cultivated in broth medium, one serotype, 33, eventually predominates in the population. Serotype 33 has also been found to be dominant in ticks but not in mammalian hosts. We investigated the biology and genetics of two independently derived clonal populations of serotype 33 of B. hermsii. Both isolates infected immunodeficient mice, but serotype 33 cells were limited in number and were only transiently present in the blood. Probes for vsp33, which encodes the serotype-specifying Vsp33 outer membrane protein, revealed that the gene was located on a 53-kb linear plasmid and that there was only one locus for the gene in serotype 33. The vsp33 probe and probes for other variable membrane protein genes showed that expression of Vsp33 was determined at the level of transcription and that when thevsp33 expression site was active, an expression site for other variable proteins was silent. The study confirmed that serotype 33 is distinct from other serotypes of B. hermsii in its biology and demonstrated that B. hermsii can change its major surface protein through switching between two expression sites.

scholarly journals Proteomic Analysis of Neorickettsia sennetsu Surface-Exposed Proteins and Porin Activity of the Major Surface Protein P51

2010 ◽  
Vol 192 (22) ◽  
pp. 5898-5905 ◽  
Author(s):  
Kathryn Gibson ◽  
Yumi Kumagai ◽  
Yasuko Rikihisa
Keyword(s):  
Surface Protein ◽  
Etiologic Agent ◽  
Surface Proteins ◽  
Open Reading Frames ◽  
Host Cells ◽  
Mammalian Host ◽  
Liquid Chromatography Tandem Mass ◽  
Proteomic Study ◽  
Major Surface ◽  
Immunofluorescence Labeling

ABSTRACT Neorickettsia sennetsu is an obligate intracellular bacterium of monocytes and macrophages and is the etiologic agent of human Sennetsu neorickettsiosis. Neorickettsia proteins expressed in mammalian host cells, including the surface proteins of Neorickettsia spp., have not been defined. In this paper, we isolated surface-exposed proteins from N. sennetsu by biotin surface labeling followed by streptavidin-affinity chromatography. Forty-two of the total of 936 (4.5%) N. sennetsu open reading frames (ORFs) were detected by liquid chromatography-tandem mass spectrometry (LC/MS/MS), including six hypothetical proteins. Among the major proteins identified were the two major β-barrel proteins: the 51-kDa antigen (P51) and Neorickettsia surface protein 3 (Nsp3). Immunofluorescence labeling not only confirmed surface exposure of these proteins but also showed rosary-like circumferential labeling with anti-P51 for the majority of bacteria and polar to diffuse punctate labeling with anti-Nsp3 for a minority of bacteria. We found that the isolated outer membrane of N. sennetsu had porin activity, as measured by a proteoliposome swelling assay. This activity allowed the diffusion of l-glutamine, the monosaccharides arabinose and glucose, and the tetrasaccharide stachyose, which could be inhibited with anti-P51 antibody. We purified native P51 and Nsp3 under nondenaturing conditions. When reconstituted into proteoliposomes, purified P51, but not Nsp3, exhibited prominent porin activity. This the first proteomic study of a Neorickettsia sp. showing new sets of proteins evolved as major surface proteins for Neorickettsia and the first identification of a porin for the genus Neorickettsia.

scholarly journals Diversity and Complexity of the Large Surface Protein Family in the Compacted Genomes of Multiple Pneumocystis Species

mBio ◽  
2020 ◽  
Vol 11 (2) ◽  
Author(s):  
Liang Ma ◽  
Zehua Chen ◽  
Da Wei Huang ◽  
Ousmane H. Cissé ◽  
Jamie L. Rothenburger ◽  
...  
Keyword(s):  
Immune Evasion ◽  
Disease Transmission ◽  
Antigenic Variation ◽  
The United States ◽  
Surface Proteins ◽  
Surface Glycoprotein ◽  
Mammalian Host ◽  
Content Type ◽  
Multiple Functions ◽  
First Time

ABSTRACT Pneumocystis, a major opportunistic pathogen in patients with a broad range of immunodeficiencies, contains abundant surface proteins encoded by a multicopy gene family, termed the major surface glycoprotein (Msg) gene superfamily. This superfamily has been identified in all Pneumocystis species characterized to date, highlighting its important role in Pneumocystis biology. In this report, through a comprehensive and in-depth characterization of 459 msg genes from 7 Pneumocystis species, we demonstrate, for the first time, the phylogeny and evolution of conserved domains in Msg proteins and provide a detailed description of the classification, unique characteristics, and phylogenetic relatedness of five Msg families. We further describe, for the first time, the relative expression levels of individual msg families in two rodent Pneumocystis species, the substantial variability of the msg repertoires in P. carinii from laboratory and wild rats, and the distinct features of the expression site for the classic msg genes in Pneumocystis from 8 mammalian host species. Our analysis suggests multiple functions for this superfamily rather than just conferring antigenic variation to allow immune evasion as previously believed. This study provides a rich source of information that lays the foundation for the continued experimental exploration of the functions of the Msg superfamily in Pneumocystis biology. IMPORTANCE Pneumocystis continues to be a major cause of disease in humans with immunodeficiency, especially those with HIV/AIDS and organ transplants, and is being seen with increasing frequency worldwide in patients treated with immunodepleting monoclonal antibodies. Annual health care associated with Pneumocystis pneumonia costs ∼$475 million dollars in the United States alone. In addition to causing overt disease in immunodeficient individuals, Pneumocystis can cause subclinical infection or colonization in healthy individuals, which may play an important role in species preservation and disease transmission. Our work sheds new light on the diversity and complexity of the msg superfamily and strongly suggests that the versatility of this superfamily reflects multiple functions, including antigenic variation to allow immune evasion and optimal adaptation to host environmental conditions to promote efficient infection and transmission. These findings are essential to consider in developing new diagnostic and therapeutic strategies.

scholarly journals DNA double strand break position leads to distinct gene expression changes and regulates VSG switching pathway choice

2021 ◽  
Vol 17 (11) ◽  
pp. e1010038
Author(s):  
Alix Thivolle ◽  
Ann-Kathrin Mehnert ◽  
Eliane Tihon ◽  
Emilia McLaughlin ◽  
Annick Dujeancourt-Henry ◽  
...  
Keyword(s):  
Gene Expression ◽  
Antigenic Variation ◽  
Surface Protein ◽  
Strand Break ◽  
Surface Glycoprotein ◽  
Dna Double Strand Breaks ◽  
African Trypanosomes ◽  
Distinct Gene ◽  
Active Expression ◽  
Expression Site

Antigenic variation is an immune evasion strategy used by Trypanosoma brucei that results in the periodic exchange of the surface protein coat. This process is facilitated by the movement of variant surface glycoprotein genes in or out of a specialized locus known as bloodstream form expression site by homologous recombination, facilitated by blocks of repetitive sequence known as the 70-bp repeats, that provide homology for gene conversion events. DNA double strand breaks are potent drivers of antigenic variation, however where these breaks must fall to elicit a switch is not well understood. To understand how the position of a break influences antigenic variation we established a series of cell lines to study the effect of an I-SceI meganuclease break in the active expression site. We found that a DNA break within repetitive regions is not productive for VSG switching, and show that the break position leads to a distinct gene expression profile and DNA repair response which dictates how antigenic variation proceeds in African trypanosomes.

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