Characterization of the Francisella tularensis subsp. novicida type IV pilus.
Characterization of the Francisella tularensis subsp. novicida type IV pilus.
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土拉弗朗西斯菌亚种的特征。
DOI：
10.1099/mic.0.2008/018077-0
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
Klose,KarlE
中科院分区：
文献类型：
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作者：
Zogaj,Xhavit;Chakraborty,Subhra;Liu,Jirong;Thanassi,DavidG;Klose,KarlE
土拉菌引起土拉菌血症。IV型菌毛（Tfp）基因存在于所有土拉菌亚种的基因组中。我们发现野生型土拉菌亚种。新生菌在其表面表达菌毛纤维，Tfp基因pilF和pilT的突变破坏了菌毛的生物发生。其他Tfp基因（pilQ和pilG）的突变不会消除菌毛的表达。pilE4的突变消除了毛丝的表达，而其他毛蛋白亚基pilE1-3和pilE5的突变则不会，这表明pilE4是毛丝结构的主要亚基。毒力调节剂MglA是菌毛表达所必需的，它调节一个假定的Tfp糖基化基因（FTN0431）的转录。然而，MglA不调节pilF、pilT或pilE4的转录，缺乏FTN0431的菌株仍然表达毛菌；因此，尚不清楚MglA如何调节毛毛的表达。蛋白分泌也只需要pilF，而pilE4和pilT不需要，说明pil基因的蛋白分泌/Tfp功能重叠很少。蛋白分泌组分pilE1比Tfp组分pilE4对体外巨噬细胞生长和小鼠毒力更重要。我们的研究结果首次提供了土拉菌新型Tfp系统的遗传特征。
Francisella tularensis causes the disease tularaemia. Type IV pili (Tfp) genes are present in the genomes of all F. tularensis subspecies. We show that the wild-type F. tularensis subsp. novicida expresses pilus fibres on its surface, and mutations in the Tfp genes pilF and pilT disrupt pilus biogenesis. Mutations in other Tfp genes (pilQ and pilG) do not eliminate pilus expression. A mutation in pilE4 eliminates pilus expression, whereas mutations in the other pilin subunits pilE1–3 and pilE5 do not, suggesting that pilE4 is the major pilus structural subunit. The virulence regulator MglA is required for pilus expression, and it regulates the transcription of a putative Tfp glycosylation gene (FTN0431). However, MglA does not regulate transcription of pilF, pilT or pilE4, and a strain lacking FTN0431 still expresses pili; thus, it is unclear how MglA regulates pilus expression. Only pilF was also required for protein secretion, while pilE4 and pilT were not, indicating that there is very little overlap of the protein secretion/Tfp functions of the pil genes. The protein secretion component pilE1 was more important for in vitro intramacrophage growth and mouse virulence than the Tfp component pilE4. Our results provide the first genetic characterization of the novel Tfp system of F. tularensis.