Home  About us  Contact
 

Outer Surface Protein (outer + surface_protein)

Distribution by Scientific Domains
Medical Sciences50%
Chemistry50%

Selected Abstracts

Atomic-resolution crystal structure of Borrelia burgdorferi outer surface protein A via surface engineering

PROTEIN SCIENCE, Issue 8 2006
Koki Makabe
Abstract Outer surface protein A (OspA) from Borrelia burgdorferi has an unusual dumbbell-shaped structure in which two globular domains are connected with a "single-layer" ,-sheet (SLB). The protein is highly soluble, and it has been recalcitrant to crystallization. Only OspA complexes with Fab fragments have been successfully crystallized. OspA contains a large number of Lys and Glu residues, and these "high entropy" residues may disfavor crystal packing because some of them would need to be immobilized in forming a crystal lattice. We rationally designed a total of 13 surface mutations in which Lys and Glu residues were replaced with Ala or Ser. We successfully crystallized the mutant OspA without a bound Fab fragment and extended structure analysis to a 1.15 Å resolution. The new high-resolution structure revealed a unique backbone hydration pattern of the SLB segment in which water molecules fill the "weak spots" on both faces of the antiparallel ,-sheet. These well-defined water molecules provide additional structural links between adjacent ,-strands, and thus they may be important for maintaining the rigidity of the SLB that inherently lacks tight packing afforded by a hydrophobic core. The structure also revealed new information on the side-chain dynamics and on a solvent-accessible cavity in the core of the C-terminal globular domain. This work demonstrates the utility of extensive surface mutation in crystallizing recalcitrant proteins and dramatically improving the resolution of crystal structures, and provides new insights into the stabilization mechanism of OspA. [source]

Pathogenesis of Lyme neuroborreliosis: Borrelia burgdorferi lipoproteins induce both proliferation and apoptosis in rhesus monkey astrocytes

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 9 2003
Geeta Ramesh
Abstract Brain invasion by Borrelia burgdorferi, the agent of Lyme disease, results in an inflammatory and neurodegenerative disorder called neuroborreliosis. In humans, neuroborreliosis has been correlated with enhanced concentration of glial fibrillary acidic protein in the cerebrospinal fluid, a sign of astrogliosis. Rhesus monkeys infected by us with B.,burgdorferi showed evidence of astrogliosis, namely astrocyte proliferation and apoptosis. We formulated the hypothesis that astrogliosis could be caused by spirochetal lipoproteins. We established primary cultures of rhesus monkey astrocytes and stimulated the cells with recombinant lipidated outer surface protein,A (L-OspA), a model B.,burgdorferi lipoprotein, and tripalmitoyl-S-glyceryl-Cys-Ser-Lys4 -OH (Pam3Cys), a synthetic lipopeptide that mimics the structure of the lipoprotein lipid moiety. L-OspA elicited not only astrocyte proliferation but also apoptosis, two features observed during astrogliosis. Astrocytes produced both IL-6 and TNF-, in response to L-OspA and Pam3Cys. Proliferation induced by L-OspA was diminished in the presence of an excess of anti-IL-6 antibody, and apoptosis induced by this lipoprotein was completely suppressed with anti-TNF-, antibody. Hence, IL-6 contributes to, and TNF-, determines, astrocyte proliferation and apoptosis, respectively, as elicited by lipoproteins. Our results provide proof of the principle that spirochetal lipoproteins could be key virulence factors in Lyme neuroborreliosis, and that astrogliosis might contribute to neuroborreliosis pathogenesis. [source]

Expression of the recombinant bacterial outer surface protein A in tobacco chloroplasts leads to thylakoid localization and loss of photosynthesis

FEBS JOURNAL, Issue 21 2007
Anna Hennig
Bacterial lipoproteins play crucial roles in host,pathogen interactions and pathogenesis and are important targets for the immune system. A prominent example is the outer surface protein A (OspA) of Borrelia burgdorferi, which has been efficiently used as a vaccine for the prevention of Lyme disease. In a previous study, OspA could be produced in tobacco chloroplasts in a lipidated and immunogenic form. To further explore the potential of chloroplasts for the production of bacterial lipoproteins, the role of the N-terminal leader sequence was investigated. The amount of recombinant OspA could be increased up to ten-fold by the variation of the insertion site in the chloroplast genome. Analysis of OspA mutants revealed that replacement of the invariant cysteine residue as well as deletion of the leader sequence abolishes palmitolyation of OspA. Also, decoration of OspA with an N-terminal eukaryotic lipidation motif does not lead to palmitoylation in chloroplasts. Strikingly, the bacterial signal peptide of OspA efficiently targets the protein to thylakoids, and causes a mutant phenotype. Plants accumulating OspA at 10% total soluble protein could not grow without exogenously supplied sugars and rapidly died after transfer to soil under greenhouse conditions. The plants were found to be strongly affected in photosystem II, as revealed by the analyses of temporal and spatial dynamics of photosynthetic activity by chlorophyll fluorescence imaging. Thus, overexpression of OspA in chloroplasts is limited by its concentration-dependent interference with essential functions of chloroplastic membranes required for primary metabolism. [source]

Atomic-resolution crystal structure of Borrelia burgdorferi outer surface protein A via surface engineering

PROTEIN SCIENCE, Issue 8 2006
Koki Makabe
Abstract Outer surface protein A (OspA) from Borrelia burgdorferi has an unusual dumbbell-shaped structure in which two globular domains are connected with a "single-layer" ,-sheet (SLB). The protein is highly soluble, and it has been recalcitrant to crystallization. Only OspA complexes with Fab fragments have been successfully crystallized. OspA contains a large number of Lys and Glu residues, and these "high entropy" residues may disfavor crystal packing because some of them would need to be immobilized in forming a crystal lattice. We rationally designed a total of 13 surface mutations in which Lys and Glu residues were replaced with Ala or Ser. We successfully crystallized the mutant OspA without a bound Fab fragment and extended structure analysis to a 1.15 Å resolution. The new high-resolution structure revealed a unique backbone hydration pattern of the SLB segment in which water molecules fill the "weak spots" on both faces of the antiparallel ,-sheet. These well-defined water molecules provide additional structural links between adjacent ,-strands, and thus they may be important for maintaining the rigidity of the SLB that inherently lacks tight packing afforded by a hydrophobic core. The structure also revealed new information on the side-chain dynamics and on a solvent-accessible cavity in the core of the C-terminal globular domain. This work demonstrates the utility of extensive surface mutation in crystallizing recalcitrant proteins and dramatically improving the resolution of crystal structures, and provides new insights into the stabilization mechanism of OspA. [source]

HLA,DR alleles determine responsiveness to Borrelia burgdorferi antigens in a mouse model of self-perpetuating arthritis

ARTHRITIS & RHEUMATISM, Issue 12 2009
Bettina Panagiota Iliopoulou
Objective Arthritis is a prominent manifestation of Lyme disease, which is caused by infection with Borrelia burgdorferi (Bb). Chronic Lyme arthritis persisting even after antibiotic treatment is linked to HLA,DRB1*0401 (DR4) and related alleles. In contrast, patients whose Lyme arthritis resolves within 3 months postinfection show an increased frequency of HLA,DRB1*1101 (DR11). The aim of this study was to analyze the underlying mechanism by which HLA,DR alleles confer genetic susceptibility or resistance to antibiotic-refractory Lyme arthritis. Methods We generated DR11-transgenic (DR11-Tg) mice on a murine MHCII,/, background and compared their immune response to Bb antigens with the response of DR4-Tg mice after immunization with Bb outer surface protein A (OspA) or infection with live Bb. Results T cells from OspA-immunized and Bb-infected DR11-Tg mice had defective production of interferon-, as compared with those from DR4-Tg mice. In contrast, DR11-Tg mice developed higher titers of anti-OspA and anti-Bb antibodies, respectively, than did DR4-Tg mice. Consistent with this observation, we found that the Bb-infected DR11-Tg mice had a decreased spirochetal burden as compared with the DR4-Tg mice, as measured by quantitative polymerase chain reaction. Conclusion This study provides direct evidence that in the presence of HLA,DR11, the immune response against Bb antigens is directed toward a protective antibody response. In contrast, an inflammatory Th1 response is induced in the presence of DR4. These observations offer an explanation for the differential genetic susceptibility of DR4+ and DR11+ individuals to the development of chronic Lyme arthritis and, eventually, the progression to antibiotic-refractory Lyme arthritis. [source]

HLA type and immune response to Borrelia burgdorferi outer surface protein a in people in whom arthritis developed after Lyme disease vaccination

ARTHRITIS & RHEUMATISM, Issue 4 2009
Robert Ball
Objective To investigate whether persons with treatment-resistant Lyme arthritis,associated HLA alleles might develop arthritis as a result of an autoimmune reaction triggered by Borrelia burgdorferi outer surface protein A (OspA), the Lyme disease vaccine antigen. Methods Persons in whom inflammatory arthritis had developed after Lyme disease vaccine (cases) were compared with 3 control groups: 1) inflammatory arthritis but not Lyme disease vaccine (arthritis controls), 2) Lyme disease vaccine but not inflammatory arthritis (vaccine controls), and 3) neither Lyme disease vaccine nor inflammatory arthritis (normal controls). HLA,DRB1 allele typing, Western blotting for Lyme antigen, and T cell reactivity testing were performed. Results Twenty-seven cases were matched with 162 controls (54 in each control group). Odds ratios (ORs) for the presence of 1 or 2 treatment-resistant Lyme arthritis alleles were 0.8 (95% confidence interval [95% CI] 0.3-2.1), 1.6 (95% CI 0.5,4.4), and 1.75 (95% CI 0.6,5.3) in cases versus arthritis controls, vaccine controls, and normal controls, respectively. There were no significant differences in the frequency of DRB1 alleles. T cell response to OspA was similar between cases and vaccine controls, as measured using the stimulation index (OR 1.6 [95% CI 0.5,5.1]) or change in uptake of tritiated thymidine (counts per minute) (OR 0.7 [95% CI 0.2,2.3]), but cases were less likely to have IgG antibodies to OspA (OR 0.3 [95% CI 0.1,0.8]). Cases were sampled closer to the time of vaccination (median 3.59 years versus 5.48 years), and fewer cases had received 3 doses of vaccine (37% versus 93%). Conclusion Treatment-resistant Lyme arthritis alleles were not found more commonly in persons who developed arthritis after Lyme disease vaccination, and immune responses to OspA were not significantly more common in arthritis cases. These results suggest that Lyme disease vaccine is not a major factor in the development of arthritis in these cases. [source]