細菌多細胞行為傳訊 - SERRATIA MARCESCENS調控族群表面移行之QUORUM-SENSING系統及細胞分化調控網之研究
Date Issued
2000
Date
2000
Author(s)
賴信志
DOI
892320B002088
Abstract
We have identified and characterized a pair of luxI/R homologues termed smaI/R
from Serratia marcescens SS-1. From cell-free culture supernatants, two N-acyl
homoserine lactone (AHL) molecules, N-(3-oxohexanoyl) homoserine lactone (C6-
HSL) and N-(3-oxooctanoyl) homoserine lactone (C8-HSL), were chemically
characterized. Unlike the swrI/R system of S. liquefaciens, the presence of multicopy,
plasmid-encoded smaR inhibits the spreading of S. marcescens SS-1. Further study
showed that production of biosurfactants and expression of one of the virulence
factors, nuclease gene nucA, were also repressed. These repressed phenotypes were
specifically de-repressed by AHL signals produced by smaI. Different modifications
of the AHL signals had either without or inhibitory effect on S. marcescens SS-1
spreading. Long chain AHLs show a trend of competition with the native AHL signals
synthesized by SmaI. Mutation of S. marcescens chromosomal smaR shortens the time
before spreading motility is initiated for 1 hour. On the contrary, mutation of smaI
significantly delays initiation of spreading. Plasmid-encoded PsmaI::luxAB and
PsmaR::luxAB reporter of smaI and smaR transcription, respectively, are constructed.
Using this reporter system, the expression patterns of smaI and smaR following the
growth in liquid broth culture were monitored. Further studies showed the evidence of
smaR positive autoregulation, and that AHL signals were constitutively produced in
the log phase and its production was turned off as the cells entered into stationary
phase. Our findings indicate that smaI/R quorum-sensing system is a component of the
complex regulatory network that controls multicellular behaviour of of S. marcescens.
Publisher
臺北市：國立臺灣大學醫學院醫學檢驗暨生物技術學系
Type
journal article
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