Expression of Multiple Outer Membrane Protein Sequence Variants from a Single Genomic Locus of Anaplasma phagocytophilum

ABSTRACT Anaplasma phagocytophilum is the causative agent of an emerging tick-borne zoonosis in the United States and Europe. The organism causes a febrile illness accompanied by other nonspecific symptoms and can be fatal, especially if treatment is delayed. Persistence of A. phagocytophilum within mammalian reservoir hosts is important for ensuring continued disease transmission. In the related organism Anaplasma marginale, persistence is associated with antigenic variation of the immunoprotective outer membrane protein MSP2. Extensive diversity of MSP2 is achieved by combinatorial gene conversion of a genomic expression site by truncated pseudogenes. The major outer membrane protein of A. phagocytophilum, MSP2(P44), is homologous to MSP2 of A. marginale, has a similar organization of conserved and variable regions, and is also encoded by a multigene family containing some truncated gene copies. This suggests that the two organisms could use similar mechanisms to generate diversity in outer membrane proteins from their small genomes. We define here a genomic expression site for MSP2(P44) in A. phagocytophilum. As in A. marginale, the msp2(p44) gene in this expression site is polymorphic in all populations of organisms we have examined, whether organisms are obtained from in vitro culture in human HL-60 cells, from culture in the tick cell line ISE6, or from infected human blood. Changes in culture conditions were found to favor the growth and predominance of certain msp2(p44) variants. Insertions, deletions, and substitutions in the region of the genomic expression site encoding the central hypervariable region matched sequence polymorphisms in msp2(p44) mRNA. These data suggest that, similarly to A. marginale, A. phagocytophilum uses combinatorial mechanisms to generate a large array of outer membrane protein variants. Such gene polymorphism has profound implications for the design of vaccines, diagnostic tests, and therapy.

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Structure of the Expression Site Reveals Global Diversity in MSP2 (P44) Variants in Anaplasma phagocytophilum

Infection and Immunity ◽

10.1128/iai.00809-06 ◽

2006 ◽

Vol 74 (11) ◽

pp. 6429-6437 ◽

Cited By ~ 39

Author(s):

Anthony F. Barbet ◽

Anna M. Lundgren ◽

A. Rick Alleman ◽

Snorre Stuen ◽

Anneli Bjöersdorff ◽

...

Keyword(s):

United States ◽

Membrane Protein ◽

Outer Membrane ◽

Outer Membrane Protein ◽

Anaplasma Phagocytophilum ◽

Animal Species ◽

The United States ◽

Genomic Locus ◽

Global Diversity ◽

Expression Site

ABSTRACT Anaplasma phagocytophilum, a recently reclassified bacteria in the order Rickettsiales, infects many different animal species and causes an emerging tick-borne disease of humans. The genome contains a large number of related genes and gene fragments encoding partial or apparently full-length outer membrane protein MSP2 (P44). Previous data using strains isolated from humans in the United States suggest that antigenic diversity results from RecF-mediated conversion of a single MSP2 (P44) expression site by partially homologous donor sequences. However, whether similar mechanisms operate in naturally infected animal species and the extent of global diversity in MSP2 (P44) are unknown. We analyzed the structure and diversity of the MSP2 (P44) expression site in strains derived from the United States and Europe and from infections of different animal species, including wildlife reservoirs. The results show that a syntenic expression site is present in all strains of A. phagocytophilum investigated. This genomic locus contained diverse MSP2 (P44) variants in all infected animals sampled, and variants also differed at different time points during infection. Although similar variants were found among different populations of U.S. origin, there was little sequence identity between U.S. strain variants (including genomic copies from a completely sequenced U.S. strain) and expression site variants infecting sheep and dogs in Norway and Sweden. Finally, the possibility that combinatorial mechanisms can generate additional diversity beyond the basic donor sequence repertoire is supported by the observation of shared sequence blocks throughout the MSP2 (P44) hypervariable region in reservoir hosts. These data suggest similar genetic mechanisms for A. phagocytophilum variation in all hosts but worldwide diversity of the MSP2 (P44) outer membrane protein.

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Sequence Polymorphism, Predicted Secondary Structures, and Surface-Exposed Conformational Epitopes of Campylobacter Major Outer Membrane Protein

Infection and Immunity ◽

10.1128/iai.68.10.5679-5689.2000 ◽

2000 ◽

Vol 68 (10) ◽

pp. 5679-5689 ◽

Cited By ~ 64

Author(s):

Qijing Zhang ◽

Jerrel C. Meitzler ◽

Shouxiong Huang ◽

Teresa Morishita

Keyword(s):

Amino Acid ◽

Membrane Protein ◽

Outer Membrane ◽

Outer Membrane Protein ◽

Outer Membrane Proteins ◽

Major Outer Membrane Protein ◽

Amino Acid Sequences ◽

Variable Regions ◽

Conserved Sequences ◽

Conformational Epitopes

ABSTRACT The major outer membrane protein (MOMP), a putative porin and a multifunction surface protein of Campylobacter jejuni, may play an important role in the adaptation of the organism to various host environments. To begin to dissect the biological functions and antigenic features of this protein, the gene (designatedcmp) encoding MOMP was identified and characterized from 22 strains of C. jejuni and one strain of C. coli. It was shown that the single-copy cmp locus encoded a protein with characteristics of bacterial outer membrane proteins. Prediction from deduced amino acid sequences suggested that each MOMP subunit consisted of 18 β-strands connected by short periplasmic turns and long irregular external loops. Alignment of the amino acid sequences of MOMP from different strains indicated that there were seven localized variable regions dispersed among highly conserved sequences. The variable regions were located in the putative external loop structures, while the predicted β-strands were formed by conserved sequences. The sequence homology of cmp appeared to reflect the phylogenetic proximity of C. jejuni strains, since strains with identical cmp sequences had indistinguishable or closely related macrorestriction fragment patterns. Using recombinant MOMP and antibodies recognizing linear or conformational epitopes of the protein, it was demonstrated that the surface-exposed epitopes of MOMP were predominantly conformational in nature. These findings are instrumental in the design of MOMP-based diagnostic tools and vaccines.

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Estimation of Full-Length TprK Diversity in Treponema pallidum subsp. pallidum

mBio ◽

10.1128/mbio.02726-20 ◽

2020 ◽

Vol 11 (5) ◽

Author(s):

Amin Addetia ◽

Michelle J. Lin ◽

Quynh Phung ◽

Hong Xie ◽

Meei-Li Huang ◽

...

Keyword(s):

Immune System ◽

Membrane Protein ◽

Outer Membrane ◽

Deep Sequencing ◽

Outer Membrane Protein ◽

Treponema Pallidum ◽

The United States ◽

Full Length ◽

Variable Regions ◽

Content Type

ABSTRACT Immune evasion and disease progression of Treponema pallidum subsp. pallidum are associated with sequence diversity in the hypervariable outer membrane protein TprK. Previous attempts to study variation within TprK have sequenced at depths insufficient to fully appreciate the hypervariable nature of the protein, failed to establish linkage between the protein’s seven variable regions, or were conducted on isolates passed through rabbits. As a consequence, a complete profile of tprK during infection in the human host is still lacking. Furthermore, prior studies examining how T. pallidum subsp. pallidum uses its repertoire of genomic donor sites to generate diversity within the variable regions of the tprK have yielded a partial understanding of this process due to the limited number of tprK alleles examined. In this study, we used short- and long-read deep sequencing to directly characterize full-length tprK alleles from T. pallidum subsp. pallidum collected from early lesions of patients attending two sexually transmitted infection clinics in Italy. We demonstrate that strains collected from cases of secondary syphilis contain significantly more unique variable region sequences and full-length TprK sequences than those from cases of primary syphilis. Our data, combined with recent data available on Chinese T. pallidum subsp. pallidum specimens, show the near-complete absence of overlap in TprK sequences among the 41 specimens profiled to date. We further estimate that the potential antigenic variability carried by TprK rivals that of current estimates of the human adaptive immune system. These data underscore the immunoevasive ability of TprK that allows T. pallidum subsp. pallidum to establish lifelong infection. IMPORTANCE Syphilis continues to be a significant public health issue in both low- and high-income countries, including the United States where the rate of syphilis infection has increased over the past 5 years. Treponema pallidum subsp. pallidum, the causative agent of syphilis, carries the outer membrane protein TprK that undergoes segmental gene conversion to constantly create new sequences. We performed full-length deep sequencing of TprK to examine TprK diversity in clinical T. pallidum subsp. pallidum strains. We then combined our results with data from all samples for which TprK deep sequencing results were available. We found almost no overlap in TprK sequences between different patients. Moreover, our data allowed us to estimate the total number of TprK variants that T. pallidum subsp. pallidum can potentially generate. Our results support how the T. pallidum subsp. pallidum TprK antigenic variation system is an equal adversary of the human immune system leading to pathogen persistence in the host.

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Sequencing ofporAfrom clinical isolates ofNeisseria meningitidisdefines a subtyping scheme and its genetic regulation

Canadian Journal of Microbiology ◽

10.1139/w97-121 ◽

1998 ◽

Vol 44 (1) ◽

pp. 56-63 ◽

Cited By ~ 20

Author(s):

Francis F Arhin ◽

France Moreau ◽

James W Coulton ◽

Elaine L Mills

Keyword(s):

Membrane Protein ◽

Dna Sequencing ◽

Neisseria Meningitidis ◽

Outer Membrane ◽

Outer Membrane Protein ◽

Promoter Region ◽

Outer Membrane Proteins ◽

Coding Region ◽

Variable Regions ◽

Class 1

Subtyping Neisseria meningitidis by methods that rely on monoclonal antibody (mAb) reactivity results in an unusually high number of strains that are not subtypeable. To subtype 48 strains isolated (1993-1994) in the province of Quebec that were not subtypeable by mAb-based techniques, we used DNA sequencing of the variable regions of porA, a gene that encodes the class 1 outer membrane protein. We assigned subtypes to all the previously nonserosubtypeable isolates and identified some novel subtypes. Because our sequencing strategy included the promoter region of porA, different isolates were compared in their sequences of the porA promoter region. A poly(G) stretch lies between the -10 and -35 regions of the promoter; replacement of a G residue by an A residue in this region resulted in loss of expression of porA. No correlation was found between the number of G residues in the poly(G) stretch and the level of expression; a minimum of 10 G residues is required in this stretch for expression of porA. One isolate expressed no class 1 outer membrane protein because of the insertion sequence IS1301 in the coding region of porA. Another isolate did not express the protein owing to a frame-shift mutation within the coding region of porA. Sequencing of porA allowed assignments of subtypes to previously uncharacterized isolates and provided insights about the regulation of expression of this gene in N. meningitidis.Key words: Neisseria meningitidis, outer membrane proteins, subtyping, PorA, DNA sequencing.

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Estimation of Full-Length TprK Diversity in Treponema pallidum subspecies pallidum

10.1101/2020.01.23.917484 ◽

2020 ◽

Author(s):

Amin Addetia ◽

Michelle Lin ◽

Quynh Phung ◽

Hong Xie ◽

Meei-Li Huang ◽

...

Keyword(s):

Immune System ◽

Membrane Protein ◽

Outer Membrane ◽

Deep Sequencing ◽

Outer Membrane Protein ◽

Treponema Pallidum ◽

The United States ◽

Full Length ◽

Public Health Issue ◽

Variable Regions

AbstractImmune evasion and disease progression of Treponema pallidum subspecies pallidum are associated with sequence diversity in the hypervariable, putative outer membrane protein TprK. Previous attempts to study variation within TprK have sequenced at depths insufficient to fully appreciate the hypervariable nature of the protein, failed to establish linkage between the protein’s 7 variable regions, or were conducted on strains passed through rabbits. As a consequence, a complete profiling of tprK during infection in the human host is still lacking. Furthermore, prior studies examining how T. pallidum uses its repertoire of genomic donor sites to generate diversity within the V regions of the tprK also yielded a partial understanding of this process, due to the limited number of tprK alleles examined. In this study, we used short- and long-read deep sequencing to directly characterize full-length tprK alleles from T. pallidum collected from early lesions of patients attending two STD clinics in Italy. Our data, combined with recent data available on Chinese T. pallidum strains, show the near complete absence of overlap in TprK sequences among the 41 strains profiled to date. Moreover, our data allowed us to redefine the boundaries of tprK V regions, identify 55 donor sites, and estimate the total number of TprK variants that T. pallidum can potentially generate. Altogether, our results support how T. pallidum TprK antigenic variation system is an unsurmountable obstacle for the human immune system to naturally achieve infection eradication, and reiterate the importance of this mechanism for pathogen persistence in the host.ImportanceSyphilis continues to be a significant public health issue in both low- and high-income nations, including the United States, where the number of infectious syphilis cases has increased dramatically over the past five years. T. pallidum, the causative agent of syphilis, encodes an outer membrane protein TprK that undergoes segmental gene conversion to constantly create new sequences. We performed deep TprK profiling to understand full-length TprK diversity in T. pallidum-positive clinical specimens and compared these to all samples for which TprK deep sequencing is available. We found almost no overlap in TprK sequences between different patients. We further estimate that the total baseline junctional diversity of full-length TprK rivals that of current estimates of the human adaptive immune system. These data underscore the immunoevasive ability of TprK that allows T. pallidum to establish lifelong infection.

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Anaplasma phagocytophilum Outer Membrane Protein A Interacts with Sialylated Glycoproteins To Promote Infection of Mammalian Host Cells

Infection and Immunity ◽

10.1128/iai.00654-12 ◽

2012 ◽

Vol 80 (11) ◽

pp. 3748-3760 ◽

Cited By ~ 36

Author(s):

Nore Ojogun ◽

Amandeep Kahlon ◽

Stephanie A. Ragland ◽

Matthew J. Troese ◽

Juliana E. Mastronunzio ◽

...

Keyword(s):

Membrane Protein ◽

Outer Membrane ◽

Outer Membrane Protein ◽

Anaplasma Phagocytophilum ◽

Protein A ◽

Host Cells ◽

Mammalian Host ◽

Content Type ◽

Outer Membrane Protein A ◽

Sialylated Glycoproteins

ABSTRACTAnaplasma phagocytophilumis the tick-transmitted obligate intracellular bacterium that causes human granulocytic anaplasmosis (HGA).A. phagocytophilumbinding to sialyl Lewis x (sLex) and other sialylated glycans that decorate P selectin glycoprotein 1 (PSGL-1) and other glycoproteins is critical for infection of mammalian host cells. Here, we demonstrate the importance ofA. phagocytophilumouter membrane protein A (OmpA) APH_0338 in infection of mammalian host cells. OmpA is transcriptionally induced during transmission feeding ofA. phagocytophilum-infected ticks on mice and is upregulated during invasion of HL-60 cells. OmpA is presented on the pathogen's surface. Sera from HGA patients and experimentally infected mice recognize recombinant OmpA. Pretreatment ofA. phagocytophilumorganisms with OmpA antiserum reduces their abilities to infect HL-60 cells. The OmpA N-terminal region is predicted to contain the protein's extracellular domain. GlutathioneS-transferase (GST)-tagged versions of OmpA and OmpA amino acids 19 to 74 (OmpA19-74) but not OmpA75-205bind to, and competitively inhibitA. phagocytophiluminfection of, host cells. Pretreatment of host cells with sialidase or trypsin reduces or nearly eliminates, respectively, GST-OmpA adhesion. Therefore, OmpA interacts with sialylated glycoproteins. This study identifies the firstA. phagocytophilumadhesin-receptor pair and delineates the region of OmpA that is critical for infection.

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Outer Membrane Protein Composition in Disease Isolates of Haemophilus influenzae : Pathogenic and Epidemiological Implications

Infection and Immunity ◽

10.1128/iai.30.3.709-717.1980 ◽

1980 ◽

Vol 30 (3) ◽

pp. 709-717

Author(s):

Marilyn R. Loeb ◽

David H. Smith

Keyword(s):

Membrane Proteins ◽

Membrane Protein ◽

Haemophilus Influenzae ◽

Outer Membrane ◽

Outer Membrane Protein ◽

Outer Membrane Proteins ◽

Protein Composition ◽

The Other ◽

Major Protein ◽

Single Strain

The outer membrane protein composition of 50 disease isolates of Haemophilus influenzae has been determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. All strains, including 28 strains of serotype b , one strain each of serotypes a, c, d, e , and f , and 17 untypable strains, had an outer membrane protein composition typical of gram-negative bacteria, i.e., these membranes contained two to three dozen proteins with four to six proteins accounting for most of their protein content. Variation in the mobility of these major outer membrane proteins from strain to strain was common but not universal; the observed patterns provided useful data and new insight into the epidemiology of type b disease. The basic findings can be summarized as follows: (i) All 50 strains possessed three proteins (one minor and two major) each having identical mobilities. The other proteins, both major and minor, varied in mobility. (ii) All type b strains possessed a fourth (major) protein of identical mobility. (iii) The 28 type b strains, on the basis of the mobility of the six major outer membrane proteins, could be divided into eight subtypes. Of all the other strains examined, both typable and untypable, only the serotype a strain belonged to one of these subtypes. (iv) The untypable strains showed considerable variation in the mobilities of their major outer membrane proteins. Of these 17 strains, 13 had an additional major outer membrane protein not present in encapsulated strains. (v) The outer membrane protein composition of a single strain remained unchanged after many passages on solid media, but varied with the growth phase. (vi) The outer membrane protein composition of isolates obtained from nine patients during an epidemic of type b meningitis varied, indicating that a single strain was not responsible for the epidemic. At least five different strains were responsible for these nine cases. (vii) Identical outer membrane protein compositions were observed in the following: in a type b strain and a mutant of this strain deficient in capsule production, indicating that the level of capsule synthesis is not obviously related to outer membrane protein composition; in type b strains isolated from different anatomic sites of patients acutely ill with meningitis, indicating that the strain associated with bacteremia is the same as that isolated from the cerebrospinal fluid; in type b strains isolated from siblings who contracted meningitis at about the same time, indicating infection with the same strain; and in type b strains isolated from the initial and repeat infection of a single patient, suggesting that reinfection was due to the same strain.

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Purification of the Major Outer Membrane Protein of Azospirillum brasilense, Its Affinity to Plant Roots, and Its Involvement in Cell Aggregation

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi.2001.14.4.555 ◽

2001 ◽

Vol 14 (4) ◽

pp. 555-561 ◽

Cited By ~ 44

Author(s):

Saul Burdman ◽

Gabriella Dulguerova ◽

Yaacov Okon ◽

Edouard Jurkevitch

Keyword(s):

Membrane Protein ◽

Outer Membrane ◽

Outer Membrane Protein ◽

Azospirillum Brasilense ◽

Outer Membrane Proteins ◽

Cell Aggregation ◽

Major Outer Membrane Protein ◽

Adhesion Assay ◽

Fab Fragments

The major outer membrane protein (MOMP) of the nitrogen-fixing rhizobacterium Azospirillum brasilense strain Cd was purified and isolated by gel filtration, and antiserum against this protein was obtained. A screening of the binding of outer membrane proteins (OMPs) of A. brasilense to membrane-immobilized root extracts of various plant species revealed different affinities for the MOMP, with a stronger adhesion to extracts of cereals in comparison with legumes and tomatoes. Moreover, this protein was shown to bind to roots of different cereal seedlings in an in vitro adhesion assay. Incubation of A. brasilense cells with MOMP-antiserum led to fast agglutination, indicating that the MOMP is a surface-exposed protein. Cells incubated with Fab fragments obtained from purified MOMP-antiserum immunoglobulin G exhibited significant inhibition of bacterial aggregation as compared with controls. Bacteria preincubated with Fab fragments showed weaker adhesion to corn roots in comparison to controls without Fab fragments. These findings suggest that the A. brasilense MOMP acts as an adhesin involved in root adsorption and cell aggregation of this bacterium.

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Anaplasma phagocytophilum Has a Functional msp2 Gene That Is Distinct from p44

Infection and Immunity ◽

10.1128/iai.72.7.3883-3889.2004 ◽

2004 ◽

Vol 72 (7) ◽

pp. 3883-3889 ◽

Cited By ~ 31

Author(s):

Quan Lin ◽

Yasuko Rikihisa ◽

Suleyman Felek ◽

Xueqi Wang ◽

Robert F. Massung ◽

...

Keyword(s):

Outer Membrane ◽

Anaplasma Phagocytophilum ◽

Ixodes Scapularis ◽

Outer Membrane Proteins ◽

Gene Families ◽

Single Copy ◽

The United States ◽

Granulocytic Anaplasmosis ◽

The United Kingdom ◽

Membrane Protein Gene

ABSTRACT The msp2 and p44 genes encode polymorphic major outer membrane proteins that are considered unique to the intraerythrocytic agent of Anaplasma marginale and the intragranulocytic agent of Anaplasma phagocytophilum, respectively. In the present study, however, we found an msp2 gene in A. phagocytophilum that was remarkably conserved among A. phagocytophilum strains from human granulocytic anaplasmosis (HGA) patients, ticks, and a horse from various regions in the United States, but the gene was different in a sheep isolate from the United Kingdom. The msp2 gene in the A. phagocytophilum strain HZ genome was a single-copy gene and was located downstream of two Ehrlichia chaffeensis omp-1 homologs and a decarboxylase gene (ubiD). The msp2 gene was expressed by A. phagocytophilum in the blood from HGA patients NY36 and NY37 and by A. phagocytophilum isolates from these patients cultured in HL-60 cells at 37°C. The msp2 gene was also expressed in a DBA/2 mouse infected by attaching ticks infected with strain NTN-1 and in a horse experimentally infected by attaching strain HZ-infected ticks. However, the transcript of the msp2 gene was undetectable in A. phagocytophilum strain HZ in SCID mice and Ixodes scapularis ticks infected with strain NTN-1. These results indicate that msp2 is functional in various strains of A. phagocytophilum, and relative expression ratios of msp2 to p44 vary in different infected hosts. These findings may be important in understanding roles that Msp2 proteins play in granulocytic ehrlichia infection and evolution of the polymorphic major outer membrane protein gene families in Anaplasma species.

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Characterization of Outer Membrane Proteins in Chlamydia trachomatis LGV Serovar L2

Journal of Bacteriology ◽

10.1128/jb.183.8.2686-2690.2001 ◽

2001 ◽

Vol 183 (8) ◽

pp. 2686-2690 ◽

Cited By ~ 38

Author(s):

Regina J. Tanzer ◽

Thomas P. Hatch

Keyword(s):

Chlamydia Trachomatis ◽

Membrane Proteins ◽

Membrane Protein ◽

Outer Membrane ◽

Outer Membrane Protein ◽

Outer Membrane Proteins ◽

Major Outer Membrane Protein ◽

Developmental Cycle ◽

Reading Frame

ABSTRACT We used a photoactivatable, lipophilic reagent, 3′-(trifluoromethyl)-3-(m-[125I]iodophenyl)diazirine, to label proteins in the outer membrane of elementary bodies ofChlamydia trachomatis LGV serovar L2 and mass spectrometry to identify the labeled proteins. The identified proteins were polymorphic outer membrane proteins E, G, and H, which were made late in the developmental cycle, the major outer membrane protein, and a mixture of 46-kDa proteins consisting of the open reading frame 623 protein and possibly a modified form of the major outer membrane protein.

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