Figure 10: Pyruvate utilization test of S. epidermidis 1457ΔlytSR. Bacteria were grown in pyruvate fermentation broth at 37 °C, and growth was monitored by measuring the turbidity of the cultures at 600 nm as described in Materials and Methods. Data are means ± SD of 3 independent experiments.

Mentions: Ability of 1457ΔlytSRto utilize pyruvate was found to be impaired by using the Vitek GPI Card system. Meanwhile, expression of genes involved in pyruvate metabolism such as mqo-3, mqo-2 and its neighboring unknown gene SERP2169 were remarkably reduced. For examining the ability to utilize pyruvate, strains 1457 and 1457ΔlytSRwere cultured in pyruvate fermentation broth and bacterial growth was monitored. The 1457ΔlytSR displayed a significantly growth defect in pyruvate fermentation broth, whereas introducing plasmid pNS-lytSR into the mutant restored the phenotype, as shown in Figure 10.

Zhu T, Lou Q, Wu Y, Hu J, Yu F, Qu D - BMC Microbiol. (2010)

Bottom Line: However, the role of LytSR played in S. epidermidis remained unknown.In the present study, we demonstrated that lytSR knock-out in S. epidermidis did not alter susceptibility to Triton X-100 induced autolysis.Compared to the wild-type counterpart, 1457ΔlytSR produced slightly more biofilm, with significantly decreased dead cells inside.Impaired ability to utilize pyruvate and reduced activity of arginine deiminase was observed in 1457ΔlytSR, which is consistent with the microarray data.The preliminary results suggest that in S. epidermidis LytSR two-component system regulates extracellular murein hydrolase activity, bacterial cell death and pyruvate utilization.

Affiliation: Key laboratory of Medical Molecular Virology of Ministries of Education and Health, Shanghai Medical College of Fudan University, Shanghai, PR China.

Abstract: Staphylococcus epidermidis has emerged as one of the most important nosocomial pathogens, mainly because of its ability to colonize implanted biomaterials by forming a biofilm. Extensive studies are focused on the molecular mechanisms involved in biofilm formation. The LytSR two-component regulatory system regulates autolysis and biofilm formation in Staphylococcus aureus. However, the role of LytSR played in S. epidermidis remained unknown.In the present study, we demonstrated that lytSR knock-out in S. epidermidis did not alter susceptibility to Triton X-100 induced autolysis. Quantitative murein hydrolase assay indicated that disruption of lytSR in S. epidermidis resulted in decreased activities of extracellular murein hydrolases, although zymogram showed no apparent differences in murein hydrolase patterns between S. epidermidis strain 1457 and its lytSR mutant. Compared to the wild-type counterpart, 1457ΔlytSR produced slightly more biofilm, with significantly decreased dead cells inside. Microarray analysis showed that lytSR mutation affected the transcription of 164 genes (123 genes were upregulated and 41 genes were downregulated). Specifically, genes encoding proteins responsible for protein synthesis, energy metabolism were downregulated, while genes involved in amino acid and nucleotide biosynthesis, amino acid transporters were upregulated. Impaired ability to utilize pyruvate and reduced activity of arginine deiminase was observed in 1457ΔlytSR, which is consistent with the microarray data.The preliminary results suggest that in S. epidermidis LytSR two-component system regulates extracellular murein hydrolase activity, bacterial cell death and pyruvate utilization. Based on the microarray data, it appears that lytSR inactivation induces a stringent response. In addition, LytSR may indirectly enhance biofilm formation by altering the metabolic status of the bacteria.