Team:Chiba/Experiments:LuxR mutant

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LuxR mutant (Under Planning)

Design

Receiver switch mLuxR chiba.jpg
Table.1 Seisitivity of LuxR mutants. Data modified from Collins et.al. Mol. Microbiol. 55, 712–723 (2005)
Table. Ahl activation of mutagenized LuxR molecules. Data modfied from B.Kock et al. Microbiology (2005), 151, 3589-3602

Collins et.al. described the hyper-sensitive variants of luxR to AHL.(1) CollonsらとKockらによって、LuxRに変異を入れることでLuxRのAHLに対する感受性を変えることができると報告されている。(1),(2)

  1. Ile45PheとするとAHLに対する感受性が約10倍上昇する(1)
  2. Leu42AlaとするとAHLに対する感受性が1/15に減少する(2)
  3. Leu42SerとするとAHLに対する感受性が1/1000に減少する(2)


Experiment

変異のはいっていないLuxRと比較すると、AHLに対する感受性を上げたLuxRはより早く、感受性を下げたLuxRはより遅く遺伝子発現が起こるはずである。 変異を入れたLuxRを発現する下の表のような遺伝子回路と、変異の入っていないT9002をAHLで遺伝子発現の仕方を比較する。

  • Sender
  • Receivers
**[http://partsregistry.org/Part:BBa_S03623 BBa_S03623 (AHL autoinucer)]

LuxI-sender Chiba.gif

  • mutant LuxR Receiver |

Mutant-LuxR-genetic-circuit Chiba.giff]]

  • WT LuxR Receiver ([http://partsregistry.org/Part:BBa_S03623 BBa_T9002 ])

T9002 Chiba.gif

Method

  1. Transformed sender (Ptet-luxI), mutant LuxR Receiver (Ptet-mLuxR-Plux-GFP) and WT LuxR Receiver ()into E coli strains (BW⊿FliC)
  2. Inoculated Sender, WT Receiver (wild type luxR/BW⊿FliC) and mutated Receiver (1point mutation/BW⊿FliC) in liquid media for 12 h at 37℃.
  3. Inoculated again in liquid media upto about OD600=2 at 37℃
  4. Washed Senders and receiver.
  5. Mixed them. (Sender:Receiver=1000μL:1000μL)
  6. Incubated at 30°C.
  7. Measured intensity of green fluorescence at regular time intervals.

Reference

  1. Collins et.al. Directed evolution of Vibrio fischeri LuxR for increased sensitivity to a broad spectrum of acyl-homoserine lactones. Mol. Microbiol. 55, 712–723 (2005)
  2. B.Koch et.al.:The LuxR receptor: the sites of interaction with quorum-sensing signals and inhibitors. Microbiol. 2005 Nov;151(Pt 11):3589-602.

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