The Chlamydia trachomatis IncA protein is required for homotypic vesicle fusion
The Chlamydia trachomatis IncA protein is required for homotypic vesicle fusion
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DOI：
10.1046/j.1462-5822.1999.00012.x
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发表时间：
1999-09-01
影响因子：
3.4
通讯作者：
Fischer, ER
中科院分区：
文献类型：
--
作者：
Hackstadt, T;Scidmore-Carlson, MA;Fischer, ER
衣原体在细胞内的空泡内复制，称为包涵体，它是非融合性的，带有内体或溶酶体隔间的小泡。相反，包涵体似乎与衣原体从高尔基体到质膜的途中截取鞘磷脂的胞外途径相交。衣原体蛋白的合成是建立这种相互作用所必需的。为了鉴定控制囊泡融合的衣原体蛋白，我们制备了几种沙眼衣原体包涵膜蛋白的多克隆抗体。将抗沙眼衣原体包涵膜蛋白Inca、F和G的多克隆抗体微量注射到沙眼衣原体感染细胞的胞浆中，发现与包涵膜表面的抗原有反应，但对衣原体的增殖没有明显的抑制作用。然而，显微注射抗沙眼衣原体Inca蛋白的抗体会导致异常的多叶包涵体结构的形成，与鹦鹉热衣原体GPIC的结构非常相似。这些结果表明沙眼衣原体Inca蛋白参与了同型囊泡融合和/或包涵膜的分离，该包涵膜被认为伴随着鹦鹉热衣原体的细菌细胞分裂。沙眼衣原体和鹦鹉热支原体在酵母双杂交系统中的表达证实了这一建议，证明了沙眼衣原体，而不是鹦鹉热支原体与印加的相互作用。尽管沙眼衣原体包涵体的同型融合受到抑制，但含有鞘磷脂的囊泡与包涵体的融合并未受到抑制。
Chlamydiae replicate within an intracellular vacuole, termed an inclusion, that is non-fusogenic with vesicles of the endosomal or lysosomal compartments. Instead, the inclusion appears to intersect an exocytic pathway from which chlamydiae intercept sphingomyelin en route from the Golgi apparatus to the plasma membrane. Chlamydial protein synthesis is required to establish this interaction. In an effort to identify those chlamydial proteins controlling vesicle fusion, we have prepared polyclonal antibodies against several Chlamydia trachomatis inclusion membrane proteins. Microinjection of polyclonal antibodies against three C. trachomatis inclusion membrane proteins, IncA, F and G, into the cytosol of cells infected with C. trachomatis demonstrates reactivity with antigens on the cytoplasmic face of the inclusion membrane, without apparent inhibition of chlamydial multiplication. Microinjection of antibodies against the C. trachomatis IncA protein, however, results in the development of an aberrant multilobed inclusion structure remarkably similar to that of C. psittaci GPIC. These results suggest that the C. trachomatis IncA protein is involved in homotypic vesicle fusion and/or septation of the inclusion membrane that is believed to accompany bacterial cell division in C. psittaci. This proposal is corroborated by the expression of C. trachomatis and C. psittaci IncA in a yeast two-hybrid system to demonstrate C. trachomatis, but not C. psittaci, IncA interactions. Despite the inhibition of homotypic fusion of C. trachomatis inclusions, fusion of sphingomyelin-containing vesicles with the inclusion was not suppressed.