Effector-stimulated single molecule protein-DNA interactions of a quorum-sensing system in Sinorhizobium meliloti

被引:39
作者
Bartels, Frank Wilco
McIntosh, Matthew
Fuhrmann, Alexander
Metzendorf, Christoph
Plattner, Patrik
Sewald, Norbert
Anselmetti, Dario
Ros, Robert [1 ]
Becker, Anke
机构
[1] Univ Bielefeld, Dept Phys, D-33615 Bielefeld, Germany
[2] Univ Bielefeld, Inst Genome Res & Syst Biol, Ctr Biotechnol, D-33615 Bielefeld, Germany
[3] Univ Bielefeld, Dept Chem, D-33615 Bielefeld, Germany
关键词
D O I
10.1529/biophysj.106.082016
中图分类号
Q6 [生物物理学];
学科分类号
071011 ;
摘要
Intercellular communication by means of small signal molecules coordinates gene expression among bacteria. This population density-dependent regulation is known as quorum sensing. The symbiotic nitrogen-fixing bacterium Sinorhizobium meliloti Rm1021 possesses the Sin quorum sensing system based on N-acyl homoserine lactones (AHL) as signal molecules. Here, we demonstrate that the LuxR-type regulator ExpR binds specifically to a target sequence in the sinRI locus in the presence of different AHLs with acyl side chains from 8 to 20 carbons. Dynamic force spectroscopy based on the atomic force microscope provided detailed information about the molecular mechanism of binding upon activation by six different AHLs. These single molecule experiments revealed that the mean lifetime of the bound protein-DNA complex varies depending on the specific effector molecule. The small differences between individual AHLs also had a pronounced influence on the structure of protein-DNA interaction: The reaction length of dissociation varied from 2.6 to 5.8 angstrom. In addition, dynamic force spectroscopy experiments indicate that N-heptanoyl-DL-homoserine lactone binds to ExpR but is not able to stimulate protein-DNA interaction.
引用
收藏
页码:4391 / 4400
页数:10
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