|Title:||廢水生物處理系統生化指標與分析技術之建立||Authors:||何憲武||Keywords:||Serratia marcescens, two-component system, thermosensor, swarming motility, fatty acids.||Issue Date:||2003||Publisher:||臺北市：國立臺灣大學醫學院醫學檢驗暨生物技術學系||Abstract:||
Serratia marcescens swarming behavior is thermoregulated, which is characterized by
continuous populational surface migration on rich swarming agar surface at 30°C, but
not at 37°C. Here we report that environmental temperature shift and fatty acids
(especially the saturated fatty acids, SFAs) act as the signal cues regulating S.
marcescens swarming through an RssA-RssB two component signal transduction
system. SFAs or temperature upshift specifically and negatively regulate S.
marcescens swarming, but not swimming motility or the identified factors known to
be involved in Serratia swarming, possibly through influencing pattern of cellular
fatty acid profile. Fatty acid profile analysis strongly indicates that addition of SFAs
at a constant temperature and temperature upshift may either directly or indirectly
affect the signaling state of the RssA sensor protein by increasing the incorporation of
the high-melting point fatty acids into membrane phospholipid, which subsequently
inhibits S. marcescens swarming. The RssA-RssB two-component system mediates
this response, as both partners are required to sense and transduce the signals.
Expression of a fatty acid synthesis gene fabG and a hemolysin gene shlA is
coordinately regulated with swarming by RssA-RssB. Biofilm formation, cell surface
structure and extracellular polysaccharide are also affected in the rssA or rssB mutant.
Similar phenomena of SFA inhibition are also observed in swarming regulation of
Proteus mirabilis and Salmonella typhimurium. Thus, evidence suggests it may be
common that membrane fluidity optimization through modulation of cellular fatty
acid profile under different physiological culture conditions may subsequently affect
two-component signaling pathway, which regulates the composition of cellular fatty
acids, expression of virulence factor and multicellular swarming behaviours. This may
provide an unidentified and common regulatory circuit for controlling swarming
behaviour of not only S. marcescens, but also other swarming bacteria.
|Appears in Collections:||醫學檢驗暨生物技術學系|
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