Vesicles bearing Toxoplasma apicoplast membrane proteins persist following loss of the relict plastid or Golgi body disruption.
Vesicles bearing Toxoplasma apicoplast membrane proteins persist following loss of the relict plastid or Golgi body disruption.
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DOI：
10.1371/journal.pone.0112096
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发表时间：
2014
期刊：
影响因子：
3.7
通讯作者：
Parsons M
中科院分区：
文献类型：
--
作者：
Bouchut A;Geiger JA;DeRocher AE;Parsons M
弓形虫和疟疾寄生虫含有一种独特且必需的残余质体，称为顶端质体。大多数顶质体蛋白在细胞核中编码，并通过内质网 (ER) 转运至细胞器。顶质体膜蛋白被提出了三种运输途径：（i）从内质网到高尔基体然后到顶质体的囊泡运输，（ii）内质网膜和顶质体之间的连续性允许蛋白质直接流动，以及（iii）直接从内质网到顶质体的囊泡运输。此前，我们鉴定了弓形虫顶端质体的一组膜蛋白，这些蛋白也在细胞器附近的大囊泡中检测到。这里提供的数据表明，携带顶质体膜蛋白的大囊泡不是管腔蛋白的主要载体。囊泡继续出现在由于错误分离而失去质体的寄生虫中，表明囊泡并非源自顶质体。为了测试高尔基体在囊泡形成中的作用，用布雷菲德菌素 A 处理寄生虫或用 Sar1 的显性失活突变体（一种 ER 到高尔基体运输所需的 GTP 酶）瞬时转染。免疫荧光图案几乎没有变化。这些发现得到了稳定转染子的证实，稳定转染子在 Cre-loxP 介导的启动子并置后表达有毒的显性失活 sar1。我们的数据支持这样的假设：大囊泡不介导管腔蛋白向顶质体的运输。结果进一步表明，在缺乏高尔基体和质体功能的情况下，仍然可以观察到带有顶质体膜蛋白的大囊泡。这些数据提出了这样的可能性：顶端质体蛋白质组是由两种新的内质网到质体运输途径以及由顶端质体基因组编码的一小组蛋白质产生的。
Toxoplasma gondii and malaria parasites contain a unique and essential relict plastid called the apicoplast. Most apicoplast proteins are encoded in the nucleus and are transported to the organelle via the endoplasmic reticulum (ER). Three trafficking routes have been proposed for apicoplast membrane proteins: (i) vesicular trafficking from the ER to the Golgi and then to the apicoplast, (ii) contiguity between the ER membrane and the apicoplast allowing direct flow of proteins, and (iii) vesicular transport directly from the ER to the apicoplast. Previously, we identified a set of membrane proteins of the T. gondii apicoplast which were also detected in large vesicles near the organelle. Data presented here show that the large vesicles bearing apicoplast membrane proteins are not the major carriers of luminal proteins. The vesicles continue to appear in parasites which have lost their plastid due to mis-segregation, indicating that the vesicles are not derived from the apicoplast. To test for a role of the Golgi body in vesicle formation, parasites were treated with brefeldin A or transiently transfected with a dominant-negative mutant of Sar1, a GTPase required for ER to Golgi trafficking. The immunofluorescence patterns showed little change. These findings were confirmed using stable transfectants, which expressed the toxic dominant-negative sar1 following Cre-loxP mediated promoter juxtaposition. Our data support the hypothesis that the large vesicles do not mediate the trafficking of luminal proteins to the apicoplast. The results further show that the large vesicles bearing apicoplast membrane proteins continue to be observed in the absence of Golgi and plastid function. These data raise the possibility that the apicoplast proteome is generated by two novel ER to plastid trafficking pathways, plus the small set of proteins encoded by the apicoplast genome.
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影响因子：
15.1
作者：
Daher JP;Ying M;Banerjee R;McDonald RS;Hahn MD;Yang L;Flint Beal M;Thomas B;Dawson VL;Dawson TM;Moore DJ
通讯作者：
Moore DJ
影响因子：
3.7
作者：
Behnke MS;Wootton JC;Lehmann MM;Radke JB;Lucas O;Nawas J;Sibley LD;White MW
通讯作者：
White MW
影响因子：
48
作者：
Andenmatten, Nicole;Egarter, Saskia;Jackson, Allison J;Jullien, Nicolas;Herman, Jean-Paul;Meissner, Markus
通讯作者：
Meissner, Markus
影响因子：
4.8
作者：
Bradley, PJ;Ward, C;Boothroyd, JC
通讯作者：
Boothroyd, JC
DOI：
10.1083/jcb.109.1.61
发表时间：
1989-07
期刊：
The Journal of cell biology
影响因子：
--
作者：
Doms RW;Russ G;Yewdell JW
通讯作者：
Yewdell JW