Contribution of Spheroplast Protein Y (SPY) in the ceftriaxone resistance of Salmonella enterica serovar Typhimurium
| Autor: | Chi-Fan Shen, 沈啟帆 |
|---|---|
| Rok vydání: | 2011 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 99 Two-component systems are a unique family of proteins that allow bacteria to modulate the expression of downstream genes in response to various environmental cues. We previously identified the CpxAR and BaeSR two component systems participating in ceftriaxone resistance of Salmonella enterica serovar Typhimurium. The mRNA levels of stm1530, stm3031, stm3030, ompD, acrD, cpxP, and spy were altered in S. enterica serovar Typhimurim strains R200(ΔcpxAR) and R200(ΔbaeSR) compared to R200. Of these mRNAs, spy mRNA level is significantly decreased in both strains R200(ΔcpxAR) and R200(ΔbaeSR) compared to the ceftriaxone-resistant strain R200. Spy was identified when E. coli forming spheroplast; and recently, this protein was suggested to be an ATP independent chaperone. To investigate whether spy, which known to be regulated by CpxAR and BaeSR, may also associated with the ceftriaxone resistance of S. enterica serovar Typhimurim. A spy gene deletion mutant, R200(Δspy), was generated from strain R200 using one-step inactivation of chromosomal genes method. Strain R200(Δspy) showed a 85-fold reduction in resistance to ceftriaxone compared to the R200 strain. In contrast, there were a 4 to 16-fold reduction in the resistance to cefamandole、meropenem and aztreonam in R200(Δspy) strain. These results suggest that Spy protein plays an important role in the ceftriaxone resistance of S. enterica serovar Typhimurium. The outer membrane proteins from S. enterica serovar Typhimurium 01-4, R200 and R200(Δspy) were compared by SDS-PAGE analysis. The level of STM1530 and STM3031 proteins were significantly decreased in R200(Δspy) compared to R200. The level of porin OmpD in strain R200(Δspy) was returned the level in the ceftriaxone-susceptible strain 01-4. The STM3031, STM1530 and OmpD have been shown to play the important roles in ceftriaxone resistance. The stm3031, stm1530 and ompD mRNA levels correlated with their proteins levels when the three strains were compared. Furthermore, the decreased mRNA level of efflux pump acrF gene in R200(Δspy) suggested that AcrF is influenced by spy gene and may also participate in ceftriaxone resistance. Taken together, these results suggest that Spy plays an important role in the ceftriaxone resistance, probably mediating by STM3031, STM1530 and OmpD proteins of S. enterica serovar Typhimurium. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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