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Team:Chiba/Qurum Sensing Cross-talk
From 2008.igem.org
- The protein sets used in quorum sensing are unique to each spices of bacteria. These are the protein synthesizing signaling molecule AHL (called "I protein"), the protein receiving the signaling molecule (called "R protein") and endogeneous promotors. Interestingly, these sets can cross-talk beyond the species.
- Each speices of bacteria has unique LuxI proteins and they synthesize AHL that has acyl chains with different length and/or different functional group at c-3 position. The names of LuxI proteins and AHL are shown in the table.
・異なる生物はそれぞれに異なるLuxRタイプのタンパク質を持ち、それぞれアシル鎖の長さ、あるいはC-3位の置換基が異なる種類のAHLに応答する。Vibrio fischeriはLuxRにより3OC6HSLに、Pseudomonas aeruginosaはRhlRにより、C4HSL、C6HSLに、LasRにより3OC12HSLに応答する(Fig.).しかし、Pseudomonas aeruginosa由来のRhlR,LasRも3OC6HSLを受け取ることがわかっており、このとき、より高い濃度の3OC6HSLが必要となる(文献).3OC6HSLがゆっくり溜まっていく時、LuxRが最も早く応答し、RhlR、LasRはそれよりも遅く応答する。しかし、他種生物由来のAHLにも応答することが知られており、このとき、より高い濃度のAHLが必要となる(2)。AHLがゆっくり溜まっていく時、LuxRは3OC6HSLに対して最も早く応答し、他のAHLに対してはそれよりも遅く応答する。
梅野先生より In this project, we use acylated homoserine lactones (AHLs), the signaling molecules used in quorum sensing system among gram negative bacteria. Senders express LuxI or its family enzymes, the producer of AHLs. LuxIs are placed under the control of constitutive (Tet) promoter; each cell generates AHL more or less in a constant rate. AHL can freely permeate the cell membranes and get detected by neighboring cells. Receivers constitutively express LuxR proteins (or its homolog), the detector of AHLs. When AHLs bind the LuxR proteins, AHL-LuxR complex activate the Lux promoter on. The switching threshold (in [AHL]) is determined by the affinity between AHL and LuxR.
