細(xì)菌能自發(fā)產(chǎn)生,、釋放一些特定的信號(hào)分子,，并能感知其濃度變化，調(diào)節(jié)微生物的群體行為,，這一調(diào)控系統(tǒng)稱為群體感應(yīng)(quorum sensing,，QS),。細(xì)菌群體感應(yīng)在細(xì)菌和宿主之間的相互作用中起著重要的調(diào)控作用。
在鏈霉菌中,，γ-丁酸內(nèi)酯(gamma-butyrolactone) 類群體感應(yīng)信號(hào)系統(tǒng)在次級(jí)代謝合成調(diào)控中扮演著重要的角色,。其中，γ-丁酸內(nèi)酯識(shí)別受體作為該信號(hào)途徑的基礎(chǔ)執(zhí)行者被廣為研究,。然而,，鏈霉菌的基因組中存在大量的“疑似”γ-丁酸內(nèi)酯受體的編碼基因，其中一些成員被證明并不能結(jié)合γ-丁酸內(nèi)酯,，因此它們被稱為假γ-丁酸內(nèi)酯受體蛋白,。
前期，中科院微生物研究所譚華榮研究員實(shí)驗(yàn)室和楊克遷研究員實(shí)驗(yàn)室的研究工作證實(shí),，委內(nèi)瑞拉鏈霉菌中的JadR2和天藍(lán)色鏈霉菌中的ScbR2均為假γ-丁酸內(nèi)酯受體,，它們能特異性地與內(nèi)源性抗生素分子相結(jié)合，在不同抗生素合成途徑間起交互調(diào)控作用,。
近期,，楊克遷研究員實(shí)驗(yàn)室對(duì)ScbR2和JadR2功能進(jìn)一步研究發(fā)現(xiàn)，假γ-丁酸內(nèi)酯受體還具有全新的功能,，即它們能調(diào)控鏈霉菌中群體感應(yīng)信號(hào)分子γ-丁酸內(nèi)酯的生物合成,。ScbR2和JadR2通過(guò)特異性地終止γ-丁酸內(nèi)酯的合成，與真正的γ-丁酸內(nèi)酯受體蛋白相協(xié)作,，在鏈霉菌中控制群體感應(yīng)信號(hào)的開(kāi)啟和關(guān)閉,。這種調(diào)控模式在鏈霉菌中普遍存在。
鏈霉菌中重要調(diào)控蛋白新功能的揭示,，加深了人們對(duì)微生物群體感應(yīng)信號(hào)系統(tǒng)的認(rèn)識(shí),，對(duì)人們理性改造鏈霉菌，科學(xué)提高抗生素合成水平具有重要指導(dǎo)意義,。
上述結(jié)果所形成的研究論文近日在Molecular Microbiology發(fā)表,。（生物谷 Bioon.com）
doi:10.1111/j.1365-2958.2011.07811.x
PMC:
PMID:
A novel role of ‘pseudo’γ‐utyrolactone receptors in controlling γ‐utyrolactone biosynthesis in Streptomyces
Wang, Juan; Wang, Weishan; Wang, Linqi; Zhang, Guifeng; Fan, Keqiang; Tan, Huarong; Yang, Keqian
In streptomycetes, a quorum-sensing mechanism mediated by -butyrolactones (GBLs) and their cognate receptors was known to trigger secondary metabolism and morphological differentiation. However, many aspects on the control of GBL signal production are not understood. In this work, we report that ScbR2, the pseudo GBL receptor in Streptomyces coelicolor, negatively controls the biosynthesis of -butyrolactone (SCB1) by directly repressing the transcription of scbA, which encodes the key enzyme for SCB1 biosynthesis. Similarly, the pseudo GBL receptor JadR2 in Streptomyces venezuelae was shown to repress the expression of jadW1, which also encodes the putative GBL synthase. These regulatory relationships were verified in Escherichia coli using lux-based reporter constructs. Additionally, the temporal expression profiles of scbA, scbR2 and scbR (receptor gene for SCB1) were examined in Streptomyces coelicolor, which showed the sequential expression of ScbR/R2 regulators in the control of SCB1 production. Overall, our results clearly demonstrated that pseudo GBL receptors play a novel role in controlling GBL biosynthesis in streptomycetes. As ScbR/R2 homologues and their binding sites upstream of GBL synthase genes are commonly found in Streptomyces species, and ScbR2 homologues cross-recognize each other's target promoters, the ScbA/R/R2 quorum-sensing regulatory system appears to represent an evolutionarily conserved signal control mechanism.
