Altered Quorum Sensing and Physiology of Staphylococcus aureus During Spaceflight Detected by Multi-omics Data Analysis (BRIC-23: Secretomics)

Staphylococcus aureus colonizes the nares of approximately 30% of humans, a risk factor for opportunistic infections. Because of the potential threat of S. aureus to astronaut health, the effect of spaceflight conditions on this pathogen is of great interest. To gain insight into the virulence potential of S. aureus in the spaceflight environment, we performed differential expression (DE) analysis of RNA-Seq and cellular proteomics data from the “Biological Research in Canisters-23” (BRIC-23) GeneLab spaceflight experiment, a mission designed to measure the response of S. aureus to growth in low earth orbit (LEO) on the international space station (ISS). This experiment used Biological Research in Canisters-Petri Dish Fixation Units (BRIC-PDFUs) to grow asynchronous ground controls (GCs) and spaceflight cultures of S. aureus for 48 hours. Analysis of the RNA-Seq data revealed that RNAIII, the effector of the Accessory Gene Regulator (Agr) quorum sensing system, was the most highly upregulated gene in spaceflight cultures (~88-fold) relative to GCs. Genes of the agr operon (~14 fold) were also highly upregulated during spaceflight, followed by genes encoding secreted phenol-soluble modulins (PSMs) and secreted proteases, all of which are positively regulated by Agr. Upregulated spaceflight genes/proteins also had functions related to urease activity, Ess secretion, and copper transport. We also performed a secretome analysis of culture supernatant samples from BRIC-23. In line with the other BRIC-23 omics data, spaceflight supernatants displayed significantly increased abundance of several known secreted virulence factors, including Agr-regulated proteases (SspA, SspB), staphylococcal nuclease (Nuc), and EsxA, a small protein secreted by the type VII-like Ess secretion system. These data also suggested that S. aureus metabolism is altered in space flight conditions relative to the ground controls (increased amino acid metabolism, TCA cycle and PTS systems, and decreased glycolysis/fermentation and translation machinery). Collectively, these data suggest that S. aureus experiences increased quorum sensing and altered expression of virulence factors in response to the spaceflight environment that may impact its pathogenic potential.

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  "026:00"
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  "026:000"
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[
  "Biological and Physical Sciences"
]