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Molecular evolution of the three short PGRPs of the malaria vectors Anopheles gambiae and Anopheles arabiensis in East Africa.

Mendes C, Felix R, Sousa AM, Lamego J, Charlwood D, do Rosário VE, Pinto J, Silveira H - BMC Evol. Biol. (2010)

Bottom Line: All the comparisons made for PGRP-S1 showed significant P-values for Fst estimates and AMOVA confirming a clear separation between species.Phylogenetic networks reinforced the results obtained by the AMOVA and Fst values.Different types of selection acting on PGRP-S1 and PGRP-S2 and S3 might be related to their different function and catalytic activity.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centro de Malária e outras Doenças Tropicais, UEI Malária, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Rua da Junqueira, 96, 1349-008 Lisbon, Portugal.

ABSTRACT

Background: Immune responses to parasites, which start with pathogen recognition, play a decisive role in the control of the infection in mosquitoes. Peptidoglycan recognition proteins (PGRPs) are an important family of pattern recognition receptors that are involved in the activation of these immune reactions. Pathogen pressure can exert adaptive changes in host genes that are crucial components of the vector's defence. The aim of this study was to determine the molecular evolution of the three short PGRPs (PGRP-S1, PGRP-S2 and PGRP-S3) in the two main African malaria vectors - Anopheles gambiae and Anopheles arabiensis.

Results: Genetic diversity of An. gambiae and An. arabiensis PGRP-S1, PGRP-S2 and PGRP-S3 was investigated in samples collected from Mozambique and Tanzania. PGRP-S1 diversity was lower than for PGRP-S2 and PGRP-S3. PGRP-S1 was the only gene differentiated between the two species. All the comparisons made for PGRP-S1 showed significant P-values for Fst estimates and AMOVA confirming a clear separation between species. For PGRP-S2 and PGRP-S3 genes it was not possible to group populations either by species or by geographic region. Phylogenetic networks reinforced the results obtained by the AMOVA and Fst values. The ratio of nonsynonymous substitutions (Ka)/synonymous substitutions (Ks) for the duplicate pair PGRP-S2 and PGRP-S3 was very similar and lower than 1. The 3D model of the different proteins coded by these genes showed that amino acid substitutions were concentrated at the periphery of the protein rather than at the peptidoglycan recognition site.

Conclusions: PGRP-S1 is less diverse and showed higher divergence between An. gambiae and An. arabiensis regardless of geographic location. This probably relates to its location in the chromosome-X, while PGRP-S2 and PGRP-S3, located in chromosome-2L, showed signs of autosomal introgression. The two short PGRP genes located in the chromosome-2L were under purifying selection, which suggests functional constraints. Different types of selection acting on PGRP-S1 and PGRP-S2 and S3 might be related to their different function and catalytic activity.

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Structural model of PGRP-S2 and PGRP-S3 proteins. Three-dimensional (3D) structural localization of mutated amino acids represented as yellow and blue (Van de Walls spheres). The PGRP domain has three α helices (red), five β strands (green) and coils (grey); Arrow indicates the specificity-determining residues responsible for the muramyl pentapeptide - MPP-Dap recognition.
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Figure 4: Structural model of PGRP-S2 and PGRP-S3 proteins. Three-dimensional (3D) structural localization of mutated amino acids represented as yellow and blue (Van de Walls spheres). The PGRP domain has three α helices (red), five β strands (green) and coils (grey); Arrow indicates the specificity-determining residues responsible for the muramyl pentapeptide - MPP-Dap recognition.

Mentions: In order to understand if different protein sequences for PGRP-S2 and PGRP-S3 display different 3D configurations, proteins were modelled and visualized with the Swiss-PdB viewer v. 4.0.1. [12-14]. The best fitting 3D model for PGRP-S2 and PGRP-S3 was based on the crystal structure of the human PGRP-Iα (2aphB). The homology model shows the presence of three α helices, five β strands and coils (Figure 4).


Molecular evolution of the three short PGRPs of the malaria vectors Anopheles gambiae and Anopheles arabiensis in East Africa.

Mendes C, Felix R, Sousa AM, Lamego J, Charlwood D, do Rosário VE, Pinto J, Silveira H - BMC Evol. Biol. (2010)

Structural model of PGRP-S2 and PGRP-S3 proteins. Three-dimensional (3D) structural localization of mutated amino acids represented as yellow and blue (Van de Walls spheres). The PGRP domain has three α helices (red), five β strands (green) and coils (grey); Arrow indicates the specificity-determining residues responsible for the muramyl pentapeptide - MPP-Dap recognition.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2820002&req=5

Figure 4: Structural model of PGRP-S2 and PGRP-S3 proteins. Three-dimensional (3D) structural localization of mutated amino acids represented as yellow and blue (Van de Walls spheres). The PGRP domain has three α helices (red), five β strands (green) and coils (grey); Arrow indicates the specificity-determining residues responsible for the muramyl pentapeptide - MPP-Dap recognition.
Mentions: In order to understand if different protein sequences for PGRP-S2 and PGRP-S3 display different 3D configurations, proteins were modelled and visualized with the Swiss-PdB viewer v. 4.0.1. [12-14]. The best fitting 3D model for PGRP-S2 and PGRP-S3 was based on the crystal structure of the human PGRP-Iα (2aphB). The homology model shows the presence of three α helices, five β strands and coils (Figure 4).

Bottom Line: All the comparisons made for PGRP-S1 showed significant P-values for Fst estimates and AMOVA confirming a clear separation between species.Phylogenetic networks reinforced the results obtained by the AMOVA and Fst values.Different types of selection acting on PGRP-S1 and PGRP-S2 and S3 might be related to their different function and catalytic activity.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centro de Malária e outras Doenças Tropicais, UEI Malária, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Rua da Junqueira, 96, 1349-008 Lisbon, Portugal.

ABSTRACT

Background: Immune responses to parasites, which start with pathogen recognition, play a decisive role in the control of the infection in mosquitoes. Peptidoglycan recognition proteins (PGRPs) are an important family of pattern recognition receptors that are involved in the activation of these immune reactions. Pathogen pressure can exert adaptive changes in host genes that are crucial components of the vector's defence. The aim of this study was to determine the molecular evolution of the three short PGRPs (PGRP-S1, PGRP-S2 and PGRP-S3) in the two main African malaria vectors - Anopheles gambiae and Anopheles arabiensis.

Results: Genetic diversity of An. gambiae and An. arabiensis PGRP-S1, PGRP-S2 and PGRP-S3 was investigated in samples collected from Mozambique and Tanzania. PGRP-S1 diversity was lower than for PGRP-S2 and PGRP-S3. PGRP-S1 was the only gene differentiated between the two species. All the comparisons made for PGRP-S1 showed significant P-values for Fst estimates and AMOVA confirming a clear separation between species. For PGRP-S2 and PGRP-S3 genes it was not possible to group populations either by species or by geographic region. Phylogenetic networks reinforced the results obtained by the AMOVA and Fst values. The ratio of nonsynonymous substitutions (Ka)/synonymous substitutions (Ks) for the duplicate pair PGRP-S2 and PGRP-S3 was very similar and lower than 1. The 3D model of the different proteins coded by these genes showed that amino acid substitutions were concentrated at the periphery of the protein rather than at the peptidoglycan recognition site.

Conclusions: PGRP-S1 is less diverse and showed higher divergence between An. gambiae and An. arabiensis regardless of geographic location. This probably relates to its location in the chromosome-X, while PGRP-S2 and PGRP-S3, located in chromosome-2L, showed signs of autosomal introgression. The two short PGRP genes located in the chromosome-2L were under purifying selection, which suggests functional constraints. Different types of selection acting on PGRP-S1 and PGRP-S2 and S3 might be related to their different function and catalytic activity.

Show MeSH
Related in: MedlinePlus