S-Space College of Agriculture and Life Sciences (농업생명과학대학) Dept. of Food and Animal Biotechnology (식품·동물생명공학부) Theses (Master's Degree_식품·동물생명공학부)
Regulation of ssrAB and ssaH in SPI2 encoding salmonella type III secretion system
Salmonella의 Type III secretion system을 발현하는 SPI-2 내에 ssrA와 ssaH의 유전자 조절
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- 서울대학교 대학원
- Salmonella; S. typhimirium; Salmonella pathogenicity island; Type III secretion system; ppGpp (guanosine 3’,5’ - bispyrophosphate)
- Thesis (master`s)--서울대학교 대학원 :농생명공학부,2003.
- The Salmonella enterica serovar Typhimurium contains five pathogenicity
islands (SPIs). Two independent type III secretion systems (TTSS) for
translocation of virulence proteins are encoded by SPI1 and 2. SPI1 is
required for the penetration of the epithelial barrier of the intestine. SPI2 is
important for the subsequent proliferation of bacteria in deeper tissues such as
liver or spleens. Signals sensed by Salmonella in the intracellular
compartment activate SPI2 gene expression through the two-component
regulatory system SsrAB in SPI2. We examined the effects of environmental
signals and regulatory factors on expression of ssrA and ssaH gene.
activation of ssaH expression was detected when cells were grown
at low temperature (30¡É) or in minimal medium (M9). The level of ssrA
transcription from cells grown under anaerobic conditions was higher than
those detected in aerobic growth condition, whereas the induction of ssaH
transcription was reduced in anaerobic growth condition. We have found that
CRP¡¤cAMP and nucleoid-associated proteins such as Fis and IHF were also
involved in the regulation of SPI2 genes. Interestingly, the ssaH gene could be
expressed through SsrAB-independent way in an invF mutant strain. The
differential activation of ssaH expression may suggest that the expression of
SPI2-TTSS can be influenced by SPI1 regulator, InvF, under certain
physiological condition especially in anaerobic growth within an infected host.
In addition, ppGpp and unphosphorylated SsrB action may participate in
SsrAB-independent ssaH expression too.
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