Shigella flexneri 2a strain 2457T expresses three members of the H-NS-like protein family:: characterization of the Sfh protein
Shigella flexneri 2a strain 2457T expresses three members of the H-NS-like protein family:: characterization of the Sfh protein
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DOI：
10.1007/s00438-003-0897-0
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发表时间：
2003-09-01
影响因子：
3.1
通讯作者：
Dorman, CJ
中科院分区：
文献类型：
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作者：
Beloin, C;Deighan, P;Dorman, CJ
已知福氏志贺菌2a表达H-NS核结构蛋白和旁系同源蛋白StpA。利用生物信息学分析，我们现在已经在菌株2457 T中发现了H-NS蛋白家族的第三个成员，Sfh（福氏志贺菌H-NS样蛋白）。这种蛋白质由sfh基因编码，该基因位于与自传递质粒R27密切相关的高分子量质粒上。当在大肠杆菌中表达时，Sfh蛋白可以补充hns无效突变，恢复野生型Bgl、孔蛋白和粘液性表型，以及fliC和proU基因的野生型表达。而sfh基因敲除突变对S.当sfh损伤与hns中的突变相结合时，可见毒力基因去阻遏的累加效应。sfh基因的过表达抑制了VirB毒力调节蛋白的表达和VirB依赖性结构基因启动子的转录。纯化的Sfh蛋白特异性结合到含有virF和virB毒力调节基因启动子的DNA序列上。这些发现表明，Sfh有能力影响编码它的遗传元件以外的遗传事件，包括S。弗氏菌毒力基因他们提出了三种密切相关的蛋白质之间存在三角关系的可能性，这种关系对携带它们的细菌中的遗传事件产生了广泛的影响。
Shigella flexneri 2a is known to express the H-NS nucleoid-structuring protein and the paralogous protein StpA. Using bioinformatic analysis we have now discovered a third member of the H-NS protein family, Sfh (Shigella flexneri H-NS-like protein), in strain 2457T. This protein is encoded by the sfh gene, which is located on a high-molecular-mass plasmid that is closely related to the self-transmissible plasmid R27. When expressed in Escherichia coli, the Sfh protein can complement an hns null mutation, restoring wild-type Bgl, porin protein, and mucoidy phenotypes, and wild-type expression of the fliC and proU genes. While a knockout mutation in the sfh gene alone had no effect on the expression of virulence genes in S. flexneri, an additive effect on virulence gene derepression was seen when the sfh lesion was combined with a mutation in hns. Over-expression of the sfh gene repressed expression of the VirB virulence regulatory protein and transcription of a VirB-dependent structural gene promoter. The purified Sfh protein bound specifically to DNA sequences containing the promoters of the virF and virB virulence regulatory genes. These findings show that Sfh has the ability to influence genetic events beyond the genetic element that encodes it, including the expression of the S. flexneri virulence genes. They raise the possibility of a triangular relationship among three closely related proteins with broad consequences for genetic events in the bacterium that harbours them.