Pseudomonas aeruginosa is a ubiquitous and metabolically versatile microorganism naturally found in soil and water.It is also an opportunistic pathogen in plants,insects,animals,and humans.In response to increasing ce...Pseudomonas aeruginosa is a ubiquitous and metabolically versatile microorganism naturally found in soil and water.It is also an opportunistic pathogen in plants,insects,animals,and humans.In response to increasing cell density,P.aeruginosa uses two acylhomoserine lactone(AHL)quorum-sensing(QS)signals(i.e.,N-3-oxo-dodecanoyl homoserine lactone[3-oxo-C12-HSL]and Nbutanoyl-homoserine lactone[C4-HsL]),which regulate the expression of hundreds of genes.However,how the biosynthesis of these two QS signals is coordinated remains unknown.We studied the regulation of these two QS signals in the rhizosphere strain PA1201.PA1201 sequentially produced 3-oxo-C12-HSL and C4-HSL at the early and late growth stages,respectively.The highest 3-oxo-C12-HSL-dependent elastase activity was observed at the early stage,while the highest C4-HSL-dependent rhamnolipid production was observed at the late stage.The atypical regulator RsaL played a pivotal role in coordinating 3-oxo-C12-HSL and C4-HSL biosynthesis and QS-associated virulence.RsaL repressed las/transcription by binding the-10 and-35 boxes of the lasl promoter.In contrast,RsaL activated rhll transcription by binding the region encoding the 5'-untranslated region of the rhll mRNA.Further,RsaL repressed its own expression by binding a nucleotide motif located in the-35 box of the rsaL promoter.Thus,RsaL acts as a molecular switch that coordinates the sequential biosynthesis of AHL QS signals and differential virulence in PA1201.Finally,C4-HSL activation by RsaL was independent of the Las and Pseudomonas quinolone signal(PQS)QS signaling systems.Therefore,we propose a new model of the QS regulatory network in PA1201,in which RsaL represents a superior player acting at the top of the hierarchy.展开更多
基金financially supported by grants from the National Key R&D Program of China(2018YFA0901900 to H.Y.W.)the National Natural Science Foundation of China(No.31972231 to H.Y.W)。
文摘Pseudomonas aeruginosa is a ubiquitous and metabolically versatile microorganism naturally found in soil and water.It is also an opportunistic pathogen in plants,insects,animals,and humans.In response to increasing cell density,P.aeruginosa uses two acylhomoserine lactone(AHL)quorum-sensing(QS)signals(i.e.,N-3-oxo-dodecanoyl homoserine lactone[3-oxo-C12-HSL]and Nbutanoyl-homoserine lactone[C4-HsL]),which regulate the expression of hundreds of genes.However,how the biosynthesis of these two QS signals is coordinated remains unknown.We studied the regulation of these two QS signals in the rhizosphere strain PA1201.PA1201 sequentially produced 3-oxo-C12-HSL and C4-HSL at the early and late growth stages,respectively.The highest 3-oxo-C12-HSL-dependent elastase activity was observed at the early stage,while the highest C4-HSL-dependent rhamnolipid production was observed at the late stage.The atypical regulator RsaL played a pivotal role in coordinating 3-oxo-C12-HSL and C4-HSL biosynthesis and QS-associated virulence.RsaL repressed las/transcription by binding the-10 and-35 boxes of the lasl promoter.In contrast,RsaL activated rhll transcription by binding the region encoding the 5'-untranslated region of the rhll mRNA.Further,RsaL repressed its own expression by binding a nucleotide motif located in the-35 box of the rsaL promoter.Thus,RsaL acts as a molecular switch that coordinates the sequential biosynthesis of AHL QS signals and differential virulence in PA1201.Finally,C4-HSL activation by RsaL was independent of the Las and Pseudomonas quinolone signal(PQS)QS signaling systems.Therefore,we propose a new model of the QS regulatory network in PA1201,in which RsaL represents a superior player acting at the top of the hierarchy.
