Limits...
Echinococcus granulosus antigen B structure: subunit composition and oligomeric states.

Monteiro KM, Cardoso MB, Follmer C, da Silveira NP, Vargas DM, Kitajima EW, Zaha A, Ferreira HB - PLoS Negl Trop Dis (2012)

Bottom Line: AgB8/1, AgB8/2, AgB8/3 and AgB8/4 subunits were identified in all samples analyzed, and an AgB8/2 variant (AgB8/2v8) was found in one bovine sample.We showed that AgB oligomers are formed by different subunits, which have distinct abundances and oligomerization properties.Overall, our findings have significantly contributed to increase the current knowledge on AgB expression and structure, highlighting issues that may help to understand the parasite adaptive response during chronic infection.

View Article: PubMed Central - PubMed

Affiliation: Laboratório de Biologia Molecular de Cestódeos and Laboratório de Genômica Estrutural e Funcional, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.

ABSTRACT

Background: Antigen B (AgB) is the major protein secreted by the Echinococcus granulosus metacestode and is involved in key host-parasite interactions during infection. The full comprehension of AgB functions depends on the elucidation of several structural aspects that remain unknown, such as its subunit composition and oligomeric states.

Methodology/principal findings: The subunit composition of E. granulosus AgB oligomers from individual bovine and human cysts was assessed by mass spectrometry associated with electrophoretic analysis. AgB8/1, AgB8/2, AgB8/3 and AgB8/4 subunits were identified in all samples analyzed, and an AgB8/2 variant (AgB8/2v8) was found in one bovine sample. The exponentially modified protein abundance index (emPAI) was used to estimate the relative abundance of the AgB subunits, revealing that AgB8/1 subunit was relatively overrepresented in all samples. The abundance of AgB8/3 subunit varied between bovine and human cysts. The oligomeric states formed by E. granulosus AgB and recombinant subunits available, rAgB8/1, rAgB8/2 and rAgB8/3, were characterized by native PAGE, light scattering and microscopy. Recombinant subunits showed markedly distinct oligomerization behaviors, forming oligomers with a maximum size relation of rAgB8/3>rAgB8/2>rAgB8/1. Moreover, the oligomeric states formed by rAgB8/3 subunit were more similar to those observed for AgB purified from hydatid fluid. Pressure-induced dissociation experiments demonstrated that the molecular assemblies formed by the more aggregative subunits, rAgB8/2 and rAgB8/3, also display higher structural stability.

Conclusions/significance: For the first time, AgB subunit composition was analyzed in samples from single hydatid cysts, revealing qualitative and quantitative differences between samples. We showed that AgB oligomers are formed by different subunits, which have distinct abundances and oligomerization properties. Overall, our findings have significantly contributed to increase the current knowledge on AgB expression and structure, highlighting issues that may help to understand the parasite adaptive response during chronic infection.

Show MeSH

Related in: MedlinePlus

Ultrastructure of the AgB oligomers analyzed by TEM.TEM images from rAgB8/1 (A), rAgB8/2 (B), rAgB8/3 (C), and AgB (D) oligomers. Recombinant AgB subunits were incubated at 37°C before sample preparation for TEM analysis. (Scale bar in nm).
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3295803&req=5

pntd-0001551-g004: Ultrastructure of the AgB oligomers analyzed by TEM.TEM images from rAgB8/1 (A), rAgB8/2 (B), rAgB8/3 (C), and AgB (D) oligomers. Recombinant AgB subunits were incubated at 37°C before sample preparation for TEM analysis. (Scale bar in nm).

Mentions: Image techniques (TEM and AFM) were used in order to characterize the ultrastructure of AgB oligomers and its recombinant counterparts formed at 37°C. The differential oligomerization behavior of AgB recombinant subunits were also detected by microscopy experiments (Figures 4 and 5), with a rAgB8/3>rAgB8/2>rAgB8/1 oligomer size relation. In the three-dimensional AFM images, the AgB oligomers display a near-globular shape and showed heterogeneity in size and morphology both between and within samples (Figure 5A–D). Among recombinant subunits, the oligomeric states formed by rAgB8/3 subunit were more similar, both in size and morphology, to those observed for E. granulosus AgB (Figure 5C–F).


Echinococcus granulosus antigen B structure: subunit composition and oligomeric states.

Monteiro KM, Cardoso MB, Follmer C, da Silveira NP, Vargas DM, Kitajima EW, Zaha A, Ferreira HB - PLoS Negl Trop Dis (2012)

Ultrastructure of the AgB oligomers analyzed by TEM.TEM images from rAgB8/1 (A), rAgB8/2 (B), rAgB8/3 (C), and AgB (D) oligomers. Recombinant AgB subunits were incubated at 37°C before sample preparation for TEM analysis. (Scale bar in nm).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3295803&req=5

pntd-0001551-g004: Ultrastructure of the AgB oligomers analyzed by TEM.TEM images from rAgB8/1 (A), rAgB8/2 (B), rAgB8/3 (C), and AgB (D) oligomers. Recombinant AgB subunits were incubated at 37°C before sample preparation for TEM analysis. (Scale bar in nm).
Mentions: Image techniques (TEM and AFM) were used in order to characterize the ultrastructure of AgB oligomers and its recombinant counterparts formed at 37°C. The differential oligomerization behavior of AgB recombinant subunits were also detected by microscopy experiments (Figures 4 and 5), with a rAgB8/3>rAgB8/2>rAgB8/1 oligomer size relation. In the three-dimensional AFM images, the AgB oligomers display a near-globular shape and showed heterogeneity in size and morphology both between and within samples (Figure 5A–D). Among recombinant subunits, the oligomeric states formed by rAgB8/3 subunit were more similar, both in size and morphology, to those observed for E. granulosus AgB (Figure 5C–F).

Bottom Line: AgB8/1, AgB8/2, AgB8/3 and AgB8/4 subunits were identified in all samples analyzed, and an AgB8/2 variant (AgB8/2v8) was found in one bovine sample.We showed that AgB oligomers are formed by different subunits, which have distinct abundances and oligomerization properties.Overall, our findings have significantly contributed to increase the current knowledge on AgB expression and structure, highlighting issues that may help to understand the parasite adaptive response during chronic infection.

View Article: PubMed Central - PubMed

Affiliation: Laboratório de Biologia Molecular de Cestódeos and Laboratório de Genômica Estrutural e Funcional, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.

ABSTRACT

Background: Antigen B (AgB) is the major protein secreted by the Echinococcus granulosus metacestode and is involved in key host-parasite interactions during infection. The full comprehension of AgB functions depends on the elucidation of several structural aspects that remain unknown, such as its subunit composition and oligomeric states.

Methodology/principal findings: The subunit composition of E. granulosus AgB oligomers from individual bovine and human cysts was assessed by mass spectrometry associated with electrophoretic analysis. AgB8/1, AgB8/2, AgB8/3 and AgB8/4 subunits were identified in all samples analyzed, and an AgB8/2 variant (AgB8/2v8) was found in one bovine sample. The exponentially modified protein abundance index (emPAI) was used to estimate the relative abundance of the AgB subunits, revealing that AgB8/1 subunit was relatively overrepresented in all samples. The abundance of AgB8/3 subunit varied between bovine and human cysts. The oligomeric states formed by E. granulosus AgB and recombinant subunits available, rAgB8/1, rAgB8/2 and rAgB8/3, were characterized by native PAGE, light scattering and microscopy. Recombinant subunits showed markedly distinct oligomerization behaviors, forming oligomers with a maximum size relation of rAgB8/3>rAgB8/2>rAgB8/1. Moreover, the oligomeric states formed by rAgB8/3 subunit were more similar to those observed for AgB purified from hydatid fluid. Pressure-induced dissociation experiments demonstrated that the molecular assemblies formed by the more aggregative subunits, rAgB8/2 and rAgB8/3, also display higher structural stability.

Conclusions/significance: For the first time, AgB subunit composition was analyzed in samples from single hydatid cysts, revealing qualitative and quantitative differences between samples. We showed that AgB oligomers are formed by different subunits, which have distinct abundances and oligomerization properties. Overall, our findings have significantly contributed to increase the current knowledge on AgB expression and structure, highlighting issues that may help to understand the parasite adaptive response during chronic infection.

Show MeSH
Related in: MedlinePlus