THE LEUCINE-RESPONSIVE REGULATORY PROTEIN BINDS TO THE FIM SWITCH TO CONTROL PHASE VARIATION OF TYPE-1 FIMBRIAL EXPRESSION IN ESCHERICHIA-COLI K-12
THE LEUCINE-RESPONSIVE REGULATORY PROTEIN BINDS TO THE FIM SWITCH TO CONTROL PHASE VARIATION OF TYPE-1 FIMBRIAL EXPRESSION IN ESCHERICHIA-COLI K-12
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DOI：
10.1128/jb.176.18.5665-5672.1994
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发表时间：
1994-09-01
影响因子：
3.2
通讯作者：
BLOMFIELD, IC
中科院分区：
文献类型：
--
作者：
GALLY, DL;RUCKER, TJ;BLOMFIELD, IC
大肠杆菌中1型菌毛的相位变化与314 bp DNA可逆元件的位点特异性重组有关。fim开关指导fimA（主要菌毛亚基基因）的转录，在一个方向上（打开），而不是另一个方向（关闭）。转换需要funB（on-to-off或off-to-on倒位）或fimE（仅on-to-off倒位），并且在含有lrp：：Tn 10突变的菌株中急剧减少。fimE促进的开关和fimB促进的开关都受到丙氨酸、异亮氨酸、亮氨酸和缬氨酸的刺激，并且这种调节需要lrp。这里显示亮氨酸响应性调节蛋白（Lrp）结合在fim开关中和附近。在体外降低Lrp结合的fim突变对体内fimB促进的转换和fimE促进的转换都有相应的影响。Lrp在fim交换机内的两个站点之一启动绑定。额外的协同结合导致广泛的保护区域免受DNA酶I和1，10-菲咯啉-铜络合物激活的DNA切割;保护区域可以延伸到右反向重复序列（关闭）的12 bp内，并占据开关的三分之一以上。有人提出，需要将fim DNA包裹在Lrp复合物周围以形成重组熟练的结构。
Phase variation of type 1 fimbriation in Escherichia coli is associated with the site-specific recombination of a 314-bp DNA invertible element. The fim switch directs transcription of fimA, the major fimbrial subunit gene, in one orientation (on) but not the other (off). Switching requires either funB (on-to-off or off-to-on inversion) or fimE (on-to off inversion only) and is reduced sharply in strains containing lrp::Tn10 mutations. Both fimE-promoted switching and fimB-promoted switching are stimulated by the amino acids alanine, isoleucine, leucine, and valine, and this regulation requires lrp, Here it is shown that the leucine-responsive regulatory protein (Lrp) binds in and adjacent to the fim switch. Mutations in fim that lower Lrp binding in vitro have corresponding effects on both fimB-promoted switching and fimE-promoted switching in vivo. Lrp initiates binding at one of two sites within the fim switch. Additional cooperative binding results in an extensive region of protection from both DNase I and 1,10-phenanthroline-copper complex-activated DNA cleavage; The region of protection can extend to within 12 bp of the right inverted repeat (switch off) and occupies over one-third of the switch. It is proposed that wrapping of fim DNA around an Lrp complex is required to form a recombination-proficient structure.