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Title

Genetic variation in the Staphylococcus aureus 8325 strain lineage revealed by whole-genome sequencing

Authors
Bæk, Kristoffer T
Frees, Dorte
Published in PLOS ONE. 2013, vol. 8, no. 9, p. e77122
Abstract Staphylococcus aureus strains of the 8325 lineage, especially 8325-4 and derivatives lacking prophage, have been used extensively for decades of research. We report herein the results of our deep sequence analysis of strain 8325-4. Assignment of sequence variants compared with the reference strain 8325 (NRS77/PS47) required correction of errors in the 8325 reference genome, and reassessment of variation previously attributed to chemical mutagenesis of the restriction-defective RN4220. Using an extensive strain pedigree analysis, we discovered that 8325-4 contains 16 single nucleotide polymorphisms (SNP) arising prior to the construction of RN4220. We identified 5 indels in 8325-4 compared with 8325. Three indels correspond to expected Φ11, 12, 13 excisions, one indel is explained by a sequence assembly artifact, and the final indel (Δ63bp) in the spa-sarS intergenic region is common to only a sub-lineage of 8325-4 strains including SH1000. This deletion was found to significantly decrease (75%) steady state sarS but not spa transcript levels in post-exponential phase. The sub-lineage 8325-4 was also found to harbor 4 additional SNPs. We also found large sequence variation between 8325, 8325-4 and RN4220 in a cluster of repetitive hypothetical proteins (SA0282 homologs) near the Ess secretion cluster. The overall 8325-4 SNP set results in 17 alterations within coding sequences. Remarkably, we discovered that all tested strains of the 8325-4 lineage lack phenol soluble modulin α3 (PSMα3), a virulence determinant implicated in neutrophil chemotaxis, biofilm architecture and surface spreading. Collectively, our results clarify and define the 8325-4 pedigree and reveal clear evidence that mutations existing throughout all branches of this lineage, including the widely used RN6390 and SH1000 strains, could conceivably impact virulence regulation.
Identifiers
PMID: 24098817
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Article (Published version) (3.1 MB) - public document Free access
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Research group Acquisition et expression de facteurs de virulence chez Staphylococcus aureus (86)
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BÆK, Kristoffer T et al. Genetic variation in the Staphylococcus aureus 8325 strain lineage revealed by whole-genome sequencing. In: PLOS ONE, 2013, vol. 8, n° 9, p. e77122. https://archive-ouverte.unige.ch/unige:38243

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Deposited on : 2014-06-26

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