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The recombination dynamics of Staphylococcus aureus inferred from spA gene.

Santos-Júnior CD, Veríssimo A, Costa J - BMC Microbiol. (2016)

Bottom Line: The alignment of SpA sequences enabled the clustering of several isoforms as a result of non-randomly distributed amino acid variations, located in two clusters of polymorphic sites in domains D to B and Xr (a).The detection of positive selection operating on spA combined with frequent non-synonymous mutations, domain duplication and frequent intragenic recombination events represent important mechanisms acting in the evolutionary adaptive mechanism promoting spA genetic plasticity.These findings argue that crucial allelic forms correlated with pathogenicity can be identified by sequences analysis enabling the design of more robust schemes.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biology and Evolutionary Genetics, Federal University of São Carlos (UFSCar), São Paulo, Brazil.

ABSTRACT

Background: Given the role of spA as a pivotal virulence factor decisive for Staphylococcus aureus ability to escape from innate and adaptive immune responses, one can consider it as an object subject to adaptive evolution and that variations in spA may uncover pathogenicity variations.

Results: The population genetic structure was deduced from the extracellular domains of SpA gene sequence (domains A-E and the X-region) and compared to the MLST-analysis of 41 genetically diverse methicillin-resistant (MRSA) and methicillin-susceptible (MSSA) S. aureus strains. Incongruence between tree topologies was noticeable and in the inferred spA tree most MSSA isolates were clustered in a distinct group. Conversely, the distribution of strains according to their spA-type was not always congruent with the tree inferred from the complete spA gene foreseeing that spA is a mosaic gene composed of different segments exhibiting different evolutionary histories. Evidences of a network-like organization were identified through several conflicting phylogenetic signals and indeed several intragenic recombination events (within subdomains of the gene) were detected within and between CC's of MRSA strains. The alignment of SpA sequences enabled the clustering of several isoforms as a result of non-randomly distributed amino acid variations, located in two clusters of polymorphic sites in domains D to B and Xr (a). Nevertheless, evidences of cluster specific structural arrangements were detected reflecting alterations on specific residues with potential impact on S. aureus pathogenicity.

Conclusions: The detection of positive selection operating on spA combined with frequent non-synonymous mutations, domain duplication and frequent intragenic recombination events represent important mechanisms acting in the evolutionary adaptive mechanism promoting spA genetic plasticity. These findings argue that crucial allelic forms correlated with pathogenicity can be identified by sequences analysis enabling the design of more robust schemes.

No MeSH data available.


Related in: MedlinePlus

Population snapshot of S. aureus strains after a MLST BURTS clustering and bspA BURP grouping. The MLST minimum-spanning tree was obtained with BURST clustering.. spA types were clustered into spA-CCs with the algorithm BURP. Strains are represented by circles highlighted according to their MLST-based clonal complexes, CC8 (yellow circles), CC15 (green circles), CC1 (purple circles) and CC5 (blue circles). Black circles represent singletons
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Fig1: Population snapshot of S. aureus strains after a MLST BURTS clustering and bspA BURP grouping. The MLST minimum-spanning tree was obtained with BURST clustering.. spA types were clustered into spA-CCs with the algorithm BURP. Strains are represented by circles highlighted according to their MLST-based clonal complexes, CC8 (yellow circles), CC15 (green circles), CC1 (purple circles) and CC5 (blue circles). Black circles represent singletons

Mentions: Sixteen different Sequence Type (STs) were identified from the 38 S. aureus strains by comparison with the MLST database, and a new MLST profile was identified for the TCH60 strain (90-2-2-2-6-3-2) (Table 1). Most strains belonged to ST228, comprising 21 % of all strains (8 out of 38 strains); ST8 (15.8 %) and ST5 (10.5 %), all well-known epidemic types [69–71]. The 16 STs were split by eBURST into 2 main clonal complex (CC) (CC5 and −8), 2 minor CC’s (CC1 and −15), and 8 singletons (S30, −59, −75, −80, −93, −97, −425 and the new ST from strain MSHR1132) (Fig. 1a and Table 1). The major CC’s, CC5 and −8, comprised 4 and 3 different STs that included 15 and 10 S. aureus strains, respectively.Fig. 1


The recombination dynamics of Staphylococcus aureus inferred from spA gene.

Santos-Júnior CD, Veríssimo A, Costa J - BMC Microbiol. (2016)

Population snapshot of S. aureus strains after a MLST BURTS clustering and bspA BURP grouping. The MLST minimum-spanning tree was obtained with BURST clustering.. spA types were clustered into spA-CCs with the algorithm BURP. Strains are represented by circles highlighted according to their MLST-based clonal complexes, CC8 (yellow circles), CC15 (green circles), CC1 (purple circles) and CC5 (blue circles). Black circles represent singletons
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4940709&req=5

Fig1: Population snapshot of S. aureus strains after a MLST BURTS clustering and bspA BURP grouping. The MLST minimum-spanning tree was obtained with BURST clustering.. spA types were clustered into spA-CCs with the algorithm BURP. Strains are represented by circles highlighted according to their MLST-based clonal complexes, CC8 (yellow circles), CC15 (green circles), CC1 (purple circles) and CC5 (blue circles). Black circles represent singletons
Mentions: Sixteen different Sequence Type (STs) were identified from the 38 S. aureus strains by comparison with the MLST database, and a new MLST profile was identified for the TCH60 strain (90-2-2-2-6-3-2) (Table 1). Most strains belonged to ST228, comprising 21 % of all strains (8 out of 38 strains); ST8 (15.8 %) and ST5 (10.5 %), all well-known epidemic types [69–71]. The 16 STs were split by eBURST into 2 main clonal complex (CC) (CC5 and −8), 2 minor CC’s (CC1 and −15), and 8 singletons (S30, −59, −75, −80, −93, −97, −425 and the new ST from strain MSHR1132) (Fig. 1a and Table 1). The major CC’s, CC5 and −8, comprised 4 and 3 different STs that included 15 and 10 S. aureus strains, respectively.Fig. 1

Bottom Line: The alignment of SpA sequences enabled the clustering of several isoforms as a result of non-randomly distributed amino acid variations, located in two clusters of polymorphic sites in domains D to B and Xr (a).The detection of positive selection operating on spA combined with frequent non-synonymous mutations, domain duplication and frequent intragenic recombination events represent important mechanisms acting in the evolutionary adaptive mechanism promoting spA genetic plasticity.These findings argue that crucial allelic forms correlated with pathogenicity can be identified by sequences analysis enabling the design of more robust schemes.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biology and Evolutionary Genetics, Federal University of São Carlos (UFSCar), São Paulo, Brazil.

ABSTRACT

Background: Given the role of spA as a pivotal virulence factor decisive for Staphylococcus aureus ability to escape from innate and adaptive immune responses, one can consider it as an object subject to adaptive evolution and that variations in spA may uncover pathogenicity variations.

Results: The population genetic structure was deduced from the extracellular domains of SpA gene sequence (domains A-E and the X-region) and compared to the MLST-analysis of 41 genetically diverse methicillin-resistant (MRSA) and methicillin-susceptible (MSSA) S. aureus strains. Incongruence between tree topologies was noticeable and in the inferred spA tree most MSSA isolates were clustered in a distinct group. Conversely, the distribution of strains according to their spA-type was not always congruent with the tree inferred from the complete spA gene foreseeing that spA is a mosaic gene composed of different segments exhibiting different evolutionary histories. Evidences of a network-like organization were identified through several conflicting phylogenetic signals and indeed several intragenic recombination events (within subdomains of the gene) were detected within and between CC's of MRSA strains. The alignment of SpA sequences enabled the clustering of several isoforms as a result of non-randomly distributed amino acid variations, located in two clusters of polymorphic sites in domains D to B and Xr (a). Nevertheless, evidences of cluster specific structural arrangements were detected reflecting alterations on specific residues with potential impact on S. aureus pathogenicity.

Conclusions: The detection of positive selection operating on spA combined with frequent non-synonymous mutations, domain duplication and frequent intragenic recombination events represent important mechanisms acting in the evolutionary adaptive mechanism promoting spA genetic plasticity. These findings argue that crucial allelic forms correlated with pathogenicity can be identified by sequences analysis enabling the design of more robust schemes.

No MeSH data available.


Related in: MedlinePlus