Detailed studies of the binding mechanism of the Sinorhizobium meliloti transcriptional activator ExpG to DNA

被引:32
作者
Baumgarth, B
Bartels, FW
Anselmetti, D
Becker, A [1 ]
Ros, R
机构
[1] Univ Bielefeld, Fak Biol, Lehrstuhl Genet, D-33615 Bielefeld, Germany
[2] Univ Bielefeld, Fak Phys, D-33615 Bielefeld, Germany
来源
MICROBIOLOGY-SGM | 2005年 / 151卷
关键词
D O I
10.1099/mic.0.27442-0
中图分类号
Q93 [微生物学];
学科分类号
071005 ; 100705 ;
摘要
The exopolysaccharide galactoglucan promotes the establishment of symbiosis between the nitrogen-fixing Gram-negative soil bacterium Sinorhizobium meliloti 2011 and its host plant alfalfa. The transcriptional regulator ExpG activates expression of galactoglucan biosynthesis genes by direct binding to the expA1, expGlexpD1 and expE1 promoter regions. ExpG is a member of the MarR family of regulatory proteins. Analysis of target sequences of an ExpG(His)(6) fusion protein in the exp promoter regions resulted in the identification of a binding site composed of a conserved palindromic region and two associated sequence motifs. Association and dissociation kinetics of the specific binding of ExpG(His)(6) to this binding site were characterized by standard biochemical methods and by single-molecule spectroscopy based on the atomic force microscope (AFM). Dynamic force spectroscopy indicated a distinct difference in the kinetics between the wild-type binding sequence and two mutated binding sites, leading to a closer understanding of the ExpG-DNA interaction.
引用
收藏
页码:259 / 268
页数:10
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