(p)ppGpp regulates type 1 fimbriation of Escherichia coli by modulating the expression of the site-specific recombinase FimB
(p)ppGpp regulates type 1 fimbriation of Escherichia coli by modulating the expression of the site-specific recombinase FimB
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DOI：
10.1111/j.1365-2958.2006.05191.x
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发表时间：
2006-06-01
影响因子：
3.6
通讯作者：
Balsalobre, Carlos
中科院分区：
文献类型：
--
作者：
Aberg, Anna;Shingler, Victoria;Balsalobre, Carlos
在这份报告中，我们研究了调节alarmone（p）ppGpp对尿路致病性大肠杆菌菌株毒力决定簇表达的作用。在（p）ppGpp缺陷型菌株中，形成生物膜的能力显着降低。我们提供的证据表明：（i）（p）ppGpp紧密调节大肠杆菌和致病性大肠杆菌中1型菌毛的表达。通过增加表达1型菌毛的细胞亚群来抑制大肠杆菌分离株;和（ii）（p）ppGpp对菌毛表达细胞数量的影响最终可以追溯到其在fimB重组酶基因转录中的作用，其产物介导fim启动子向生产性（ON）方向的反转。引物延伸分析表明，（p）ppGpp对fimB转录的影响是通过改变两个fimB启动子中仅一个的活性而发生的。此外，具有ppGpp（0）抑制子特性的自发突变体在不存在（p）ppGpp的情况下恢复fimB转录和随后的下游效应。一致地，rpoB 3770等位基因也完全恢复ppGpp（0）菌株中fimB的转录，并且人为升高的FimB水平绕过了1型菌毛形成对（p）ppGpp的需要。我们的研究结果表明，（p）ppGpp刺激的1型菌毛表达可能与致病性E.大肠杆菌与宿主
In this report we have examined the role of the regulatory alarmone (p)ppGpp on expression of virulence determinants of uropathogenic Escherichia coli strains. The ability to form biofilms is shown to be markedly diminished in (p)ppGpp-deficient strains. We present evidence (i) that (p)ppGpp tightly regulates expression of the type 1 fimbriae in both commensal and pathogenic E. coli isolates by increasing the subpopulation of cells that express the type 1 fimbriae; and (ii) that the effect of (p)ppGpp on the number of fimbrial expressing cells can ultimately be traced to its role in transcription of the fimB recombinase gene, whose product mediates inversion of the fim promoter to the productive (ON) orientation. Primer extension analysis suggests that the effect of (p)ppGpp on transcription of fimB occurs by altering the activity of only one of the two fimB promoters. Furthermore, spontaneous mutants with properties characteristic of ppGpp(0) suppressors restore fimB transcription and consequent downstream effects in the absence of (p)ppGpp. Consistently, the rpoB3770 allele also fully restores transcription of fimB in a ppGpp(0) strain and artificially elevated levels of FimB bypass the need for (p)ppGpp for type 1 fimbriation. Our findings suggest that the (p)ppGpp-stimulated expression of type 1 fimbriae may be relevant during the interaction of pathogenic E. coli with the host.