| Summary: | 碩士 === 國立陽明大學 === 醫學生物技術暨檢驗學系暨研究所 === 98 === Abstract
We previously showed that the expression levels of the outer membrane protein C (OmpC) and the putative outer membrane protein D (OmpD) were significantly decreased in ceftriaxone-resistant strain R200 compared to that of ceftriaxone-susceptible strain 01-4. To investigate whether OmpC and OmpD are indeed associated with ceftriaxone resistance, 01-4 (ΔompC) and 01-4 (ΔompD) deletion mutants, were generated and used to determine the MICs of a number of antibiotics. For beta-lactam drug, strain 01-4(ΔompD) resulted in a 2-4 fold elevation in resistance to cephalothin, cefamandole and ceftriaxone compared to strain 01-4; however, strain 01-4(ΔompC) resulted in a 2-fold elevation in resistance to cephalothin. It been show that two small non-coding RNAs (sRNAs), InvR and RybB, play a major role in post-transcriptional regulation of the expression level of OmpD in Salmonella.
Our results showed that deletion of baeS/R and cpxA/R, R200 ( ΔbaeS/R ) and R200 ( ΔcpxA/R ), respectively, can retore the OmpD protein level which similar to that of the 01-4 strain. The regulation of OmpD protein level seems more likely influenced by InvR rather than RybB. The deletion mutants 01-4 (ΔompC) and 01-4 (ΔompD), particular 01-4 (ΔompD),showed the decreased RybB, but not InvR, sRNA level. Further studies are necessary to elucidate how two component system to influence sRNA expression then regulate OmpD expression.
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