Synthesis of multiple exoproducts in Pseudomonas aeruginosa is under the control of RhlR-RhlI, another set of regulators in strain PAO1 with homology to the autoinducer-responsive LuxR-LuxI family

Author:

Brint J M1,Ohman D E1

Affiliation:

1. Department of Medicine, University of Tennessee, Memphis, USA.

Abstract

Mutants of Pseudomonas aeruginosa PAO1 that were deficient in the ability to produce proteases that degrade casein were detected among the survivors of chemical mutagenesis. One such mutant (PDO31) showed reduced production of elastolytic activity, beta-hemolytic activity, and pyocyanin. A 4.3-kb EcoRI fragment from a gene bank of PAO1 that complemented defects in PDO31 was found. Transposon mutagenesis and deletion derivatives of the clone were used in conjunction with complementation tests to determine the physical location of the gene of interest. Nucleotide sequence analysis revealed an open reading frame (rhlR) encoding a putative 27.6-kDa protein (RhlR) with homology to autoinducer-responsive regulators of quorum sensing systems such as LuxR of Vibrio fischeri and LasR of P. aeruginosa. Further sequence analysis downstream of rhlR revealed an independently transcribed gene (rhlI) that encodes a putative 22.2-kDa protein with homology to members of the family of autoinducer synthetases, such as LuxI of V. fischeri and LasI of P. aeruginosa. The rhlRI sequences were also recently reported by others (U.A. Ochsner and J. Reiser, Proc. Natl. Acad. Sci. USA 92: 6424-6428, 1995) as an autoinducer-mediated regulation mechanism for rhamnolipid biosurfactant synthesis in P. aeruginosa PG201. Mutants with defects in rhlR or rhlI were constructed in PAO1 by gene replacement, using clones modified by Tn501 insertion. Compared with the wild type, the rhlR and rhlI mutants both showed defects in the production of elastase, LasA protease, rhamnolipid, and pyocyanin. Transcription from the gene for elastase, as measured with a lasB-cat fusion, demonstrated that production of elastase was subject to cell density-dependent gene activation in PAO1. However, transcription of lasB-cat in the rhlI mutant, which had lost the presumptive autoinducer synthetase (predicted to activate RhlR), showed low basal activity and had lost all cell density-dependent transcription of lasB. Thus, RhlR-RhlI represent the second autoinducer-responsive regulatory mechanism found in P. aeruginosa that controls expression of multiple virulence factor exoproducts, including elastase.

Publisher

American Society for Microbiology

Subject

Molecular Biology,Microbiology

Reference65 articles.

1. A general role for the lux autoinducer in bacterial cell signaling: control of antibiotic synthesis in Erwinia;Bainton N. J.;Gene,1992

2. Multiple signalling systems controlling expression of Iuminescence in Vibrio harveyi: sequence and function of genes encoding a second sensory pathway;Bassler B. L.;Mol. Microbiol.,1994

3. Evaluation of Pseudomonas aeruginosa exotoxin A and elastase as virulence factors in acute Iung infection;Blackwood L. L.;Infect. Immun.,1983

4. Brint J. M. 1992. Pseudomonas aeruginosa lasM encodes a regulator of lasB transcription exoproduct synthesis and growth phase transition abstr. D49. In Abstracts of the 92nd Annual Meeting of the American Society for Microbiology 1992. American Society for Microbiology Washington D.C.

5. Interaction of the Pseudomonas aeruginosa secretory products pyocyanin and pyochelin generates hydroxyl radicals and causes synergistic damage to endothelial cells;Britigan B. E.;J. Clin. Invest.,1992

同舟云学术

1.学者识别学者识别

2.学术分析学术分析

3.人才评估人才评估

"同舟云学术"是以全球学者为主线,采集、加工和组织学术论文而形成的新型学术文献查询和分析系统,可以对全球学者进行文献检索和人才价值评估。用户可以通过关注某些学科领域的顶尖人物而持续追踪该领域的学科进展和研究前沿。经过近期的数据扩容,当前同舟云学术共收录了国内外主流学术期刊6万余种,收集的期刊论文及会议论文总量共计约1.5亿篇,并以每天添加12000余篇中外论文的速度递增。我们也可以为用户提供个性化、定制化的学者数据。欢迎来电咨询!咨询电话:010-8811{复制后删除}0370

www.globalauthorid.com

TOP

Copyright © 2019-2024 北京同舟云网络信息技术有限公司
京公网安备11010802033243号  京ICP备18003416号-3