Overexpression of the response regulator BaeR of the two-component system confer ceftriaxone resistance in Salmonella typhimurium

• Main Authors: Pei-chuan Li, 李佩娟
• Other Authors: Wensi S. Hu
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/99770622385284621851

碩士 === 國立陽明大學 === 醫學生物技術研究所 === 91 === Salmonella enterica serovar Typhimurium is an important etiological agent causing human food-borne illness, and known with the property of multidrug resistantce. The third-generation cephalosporin is the popular drug which applied for treatment of infection. However, it has a tendency towards cephalosporin resistance, recently. In this study, we investigated genes are involved in Salmonella serova typhimurium to ceftriaxone(CRO) resistance. Tn5 tansposome was transformed into highly resistance strain of salmonella typhimuium by electroporation to construct Tn5 mutant library. Screening of this library, 46 CRO-sensitive mutant strains were obtained. Every mutant strain has confirmed to have a single Tn5 insertion by Southern hybridization assay, and then the inserted position in chromosomal gene was identified. Based on the function of protein, these genes were classified into four groups that include: transporter and membrane proteins; proteins related to LPS; enzyme and others. We selected baeR gene of CRO-sensitive mutants for further investigation.In addition, BaeR is a response regulator of baeSR two component signal transduction system and control regulon gene experession. In the complementation experiment, CRO-resistance was conferred by the introduction of expression plasmid carrying baeR gene. To understand which outer membrane protein can be regulated by BaeR, the outer membrane protein profile between highly resistant strain and baeR mutant strain was compared using two-dimensional gel electrophoresis. The result showed STM3031 were up-regulated and OmpW were down-regulated in baeR mutant strain. These proteins how to regulate by baeR either direct or indirect will be needed to further investigation in the future.