Lrp acts as both a positive and negative regulator for type 1 fimbriae production in Salmonella enterica serovar Typhimurium.
Lrp acts as both a positive and negative regulator for type 1 fimbriae production in Salmonella enterica serovar Typhimurium.
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DOI：
10.1371/journal.pone.0026896
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发表时间：
2011
期刊：
影响因子：
3.7
通讯作者：
Curtiss R 3rd
中科院分区：
文献类型：
--
作者：
Baek CH;Kang HY;Roland KL;Curtiss R 3rd
亮氨酸响应调节蛋白（Lrp）已知是鼠伤寒沙门氏菌1型菌毛合成的间接激活因子，它通过直接调控FimZ（1型菌毛产生的直接正调控因子）来发挥作用。我们之前利用逆转录聚合酶链反应（RT - PCR）表明，在lrp缺失（Δlrp）和组成型lrp表达（lrpC）突变株中，fimA转录显著受损。在这项工作中，我们使用染色体PfimA - lacZ融合基因以及酵母凝集试验来证实并扩展我们之前的结果。通过电泳迁移率变动分析（EMSA）和DNA足迹分析表明Lrp与PfimA直接结合。定点诱变显示PfimA中的Lrp结合基序在1型菌毛产生的激活和抑制中都起作用。Lrp的过量产生也会抑制fimZ的表达。EMSA数据显示Lrp和FimZ蛋白独立地与PfimA结合，不存在竞争排斥。此外，与单独存在每种蛋白时的迁移相比，Lrp和FimZ与PfimA的结合都会导致DNA - 蛋白质复合物的高度阻滞（超迁移）。依赖营养的细胞内Lrp水平与1型菌毛的产生量密切相关。这些观察结果表明，Lrp通过作为正调控因子和负调控因子在1型菌毛形成中发挥重要作用，并且其作用至少在一定程度上取决于细胞对营养环境作出反应时Lrp的细胞浓度。
Leucine-responsive regulatory protein (Lrp) is known to be an indirect activator of type 1 fimbriae synthesis in Salmonella enterica serovar Typhimurium via direct regulation of FimZ, a direct positive regulator for type 1 fimbriae production. Using RT-PCR, we have shown previously that fimA transcription is dramatically impaired in both lrp-deletion (Δlrp) and constitutive-lrp expression (lrpC) mutant strains. In this work, we used chromosomal PfimA-lacZ fusions and yeast agglutination assays to confirm and extend our previous results. Direct binding of Lrp to PfimA was shown by an electrophoretic mobility shift assay (EMSA) and DNA footprinting assay. Site-directed mutagenesis revealed that the Lrp-binding motifs in PfimA play a role in both activation and repression of type 1 fimbriae production. Overproduction of Lrp also abrogates fimZ expression. EMSA data showed that Lrp and FimZ proteins independently bind to PfimA without competitive exclusion. In addition, both Lrp and FimZ binding to PfimA caused a hyper retardation (supershift) of the DNA-protein complex compared to the shift when each protein was present alone. Nutrition-dependent cellular Lrp levels closely correlated with the amount of type 1 fimbriae production. These observations suggest that Lrp plays important roles in type 1 fimbriation by acting as both a positive and negative regulator and its effect depends, at least in part, on the cellular concentration of Lrp in response to the nutritional environment.
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影响因子：
3.6
作者：
Blomfield, IC;Kulasekara, DH;Eisenstein, BI
通讯作者：
Eisenstein, BI
影响因子：
3.2
作者：
BUCHANAN, K;FALKOW, S;HULL, SI
通讯作者：
HULL, SI
DOI：
10.1111/j.1432-1033.1984.tb08386.x
发表时间：
1984-01-01
期刊：
EUROPEAN JOURNAL OF BIOCHEMISTRY
影响因子：
--
作者：
KLEMM, P
通讯作者：
KLEMM, P
影响因子：
3.2
作者：
Baek, Chang-Ho;Wang, Shifeng;Curtiss, Roy, III
通讯作者：
Curtiss, Roy, III
影响因子：
3.2
作者：
GALLY, DL;RUCKER, TJ;BLOMFIELD, IC
通讯作者：
BLOMFIELD, IC