title: The Crc protein participates in down-regulation of the Lon gene to promote rhamnolipid production and rhl quorum sensing in Pseudomonas aeruginosa.
abstract: Rhamnolipid acts as a virulence factor during Pseudomonas aeruginosa infection. Here, we show that deletion of the catabolite repression control (crc) gene in P. aeruginosa leads to a rhamnolipid-negative phenotype. This effect is mediated by the down-regulation of rhl quorum sensing (QS). We discover that a disruption of the gene encoding the Lon protease entirely offsets the effect of crc deletion on the production of both rhamnolipid and rhl QS signal C4-HSL. Crc is unable to bind lon mRNA in vitro in the absence of the RNA chaperon Hfq, while Crc contributes to Hfq-mediated repression of the lon gene expression at a posttranscriptional level. Deletion of crc, which results in up-regulation of lon, significantly reduces the in vivo stability and abundance of the RhlI protein that synthesizes C4-HSL, causing the attenuation of rhl QS. Lon is also capable of degrading the RhlI protein in vitro. In addition, constitutive expression of rhlI suppresses the defects of the crc deletion mutant in rhamnolipid, C4-HSL and virulence on lettuce leaves. This study therefore uncovers a novel posttranscriptional regulatory cascade, Crc-Hfq/Lon/RhlI, for the regulation of rhamnolipid production and rhl QS in P. aeruginosa.
authors: Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Pudong Zhangjiang Hi-Tech Park, Shanghai, 201203, China.
authors: Nana
authors: N
authors: Yang
authors: Shuting
authors: S
authors: Ding
authors: Feifei
authors: F
authors: Chen
authors: Xue
authors: X
authors: Zhang
authors: Yongjie
authors: Y
authors: Xia
authors: Hongxia
authors: H
authors: Di
authors: Qiao
authors: Q
authors: Cao
authors: Xin
authors: X
authors: Deng
authors: Min
authors: M
authors: Wu
authors: Catherine C L
authors: CC
authors: Wong
authors: Xiao-Xu
authors: XX
authors: Tian
authors: Cai-Guang
authors: CG
authors: Yang
authors: Jing
authors: J
authors: Zhao
authors: Lefu
authors: L
authors: Lan
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D006017:Glycolipids / Q000378:metabolism*; D035001:Host Factor 1 Protein / Q000378:metabolism; D008025:Ligases / Q000378:metabolism; D049070:Protease La / Q000378:metabolism*; D011485:Protein Binding; D059748:Proteolysis; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D053038:Quorum Sensing; D012333:RNA, Messenger / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D006017:Glycolipids; D035001:Host Factor 1 Protein; D012333:RNA, Messenger; D012097:Repressor Proteins; D014157:Transcription Factors; C101896:crc protein, Pseudomonas; C418382:rhamnolipid; D049070:Protease La; D008025:Ligases; C096955:RHLI protein, Pseudomonas aeruginosa