https://ogma.newcastle.edu.au/vital/access/ /manager/Index ${session.getAttribute("locale")} 5 https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:36671 Tue 23 Jun 2020 12:57:42 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:38500 Tue 12 Oct 2021 11:48:00 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:27778 Staphylococcus aureus is thought to be due to its extraordinary capacity to rapidly adapt to changes in environmental conditions. This study was carried out to investigate whether the cytoplasmic profiles of metabolites and proteins of S. aureus were altered in response to prolonged exposure to cold stress. Metabolic profiling and proteomics were used to characterise alterations in cytoplasmic proteins and metabolites in cells from the mid-exponential phase of growth under ideal conditions at 37 °C and compared with equivalent cells exposed to prolonged cold stress for 2 weeks at 4 °C. Principle component analysis (PCA) of the metabolomic and proteomic data indicated that, at the mid-exponential phase of growth, prolonged cold stress conditions generated cells with different metabolite and protein profiles compared with those grown at 37 °C. Nine ribosomal proteins and citric acid were substantially elevated in the cytoplasmic fractions from the cells adapted to cold-stress but most amino acids showed a reduction in their concentration in cold-stressed samples. The data provided strong evidence supporting the hypothesis that specific changes in metabolic homeostasis and protein composition were critical to the adaptive processes required for survival under cold stress. Biological significance: Work in our laboratory has shown that prolonged exposure of S. aureus to cold stress can result in the formation of small colony variants (SCVs) associated with significant alterations in the cell wall composition [8]. Further studies revealed that S. aureus altered cell size and cell wall thickness in response to exposure to cold temperatures, alterations in pH and exposure to antibiotics [10]. The current study has utilised the prolonged exposure to cold stress as a model system to explore changes in the proteome and associated metabolic homeostasis following environmental challenges. The study provides an improved understanding of how S. aureus adapts to the changing environment whilst in transition between human hosts. The results indicated an unexpected production of 9 ribosomal proteins and citric acid in response to cold stress suggesting specific survival roles for these proteins and citric acid as an adaptation mechanism for empowering survival under these conditions.]]> Sat 24 Mar 2018 07:37:06 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:40916 Mon 25 Jul 2022 12:44:17 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:27773 Staphylococcus aureus is an opportunistic pathogen responsible for a high proportion of nosocomial infections. This study was conducted to assess the bacterial responses in the cytoplasmic composition of amino acids and ribosomal proteins under various environmental conditions designed to mimic those on the human skin or within a wound site: pH6-8, temperature 35-37°C, and additional 0-5% NaCl. It was found that each set of environmental conditions elicited substantial adjustments in cytoplasmic levels of glutamic acid, aspartic acid, proline, alanine and glycine (P< 0.05). These alterations generated characteristic amino acid profiles assessed by principle component analysis (PCA). Substantial alterations in cytoplasmic amino acid and protein composition occurred during growth under conditions of higher salinity stress implemented via additional levels of NaCl in the growth medium. The cells responded to additional NaCl at pH 6 by reducing levels of ribosomal proteins, whereas at pH 8 there was an upregulation of ribosomal proteins compared with the reference control. The levels of two ribosomal proteins, L32 and S19, remained constant across all experimental conditions. The data supported the hypothesis that the bacterium was continually responding to the dynamic environment by modifying the proteome and optimising metabolic homeostasis.]]> Fri 05 Aug 2022 15:55:12 AEST ]]>