SPM1 stabilizes subpellicular microtubules in Toxoplasma gondii.
SPM1 stabilizes subpellicular microtubules in Toxoplasma gondii.
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SPM1 稳定弓形虫的表膜下微管。
DOI：
10.1128/ec.05161-11
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
Morrissette,NaomiS
中科院分区：
文献类型：
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作者：
Tran,JohnsonQ;Li,Catherine;Chyan,Alice;Chung,Lawton;Morrissette,NaomiS
我们发现了两个新的蛋白质，共定位与thesubpellicularmicrotubules在原生动物寄生虫弓形虫，并命名为SPM 1和SPM 2。这些蛋白质具有基本的等电点，并且在其他顶复门寄生虫中具有同源物。SPM1含有6个串联拷贝的32个氨基酸重复序列，而SPM2缺乏确定的蛋白质特征。弓形虫SPM2与疟原虫SPM2同源物的比对表明，最大程度的保守性在于蛋白质的羧基末端。疟原虫同源物的SPM 1的分析表明，虽然中央32个氨基酸的重复已扩大到不同程度（7，8，9，12，或13个重复），氨基和羧基末端区域保持保守。相比之下，虽然隐孢子虫SPM1同源物具有保守的羧基尾，但五个重复序列相当分散，并且它具有较小的氨基末端结构域。SPM 1定位于沿着整个长度的膜下微管，但不与圆锥形或纺锤体微管。SPM 2在膜下微管的中间区域沿着具有有限的定位。结构域缺失分析表明，四个或更多个拷贝的SPM 1重复需要定位到微管，和氨基末端63个残基的SPM 2需要定位到膜下微管。基因缺失研究表明，无论是SPM 1或SPM 2是必不可少的速殖子的活力。然而，SPM1的损失降低了整体寄生虫的健身和消除了稳定性的膜下微管洗涤剂提取。
We have identified two novel proteins that colocalize with thesubpellicularmicrotubules in the protozoan parasite Toxoplasma gondii and named these proteins SPM1 and SPM2. These proteins have basic isoelectric points and both have homologs in other apicomplexan parasites. SPM1 contains six tandem copies of a 32-amino-acid repeat, whereas SPM2 lacks defined protein signatures. Alignment of Toxoplasma SPM2 with apparent Plasmodium SPM2 homologs indicates that the greatest degree of conservation lies in the carboxy-terminal half of the protein. Analysis of Plasmodium homologs of SPM1 indicates that while the central 32-amino-acid repeats have expanded to different degrees (7, 8, 9, 12, or 13 repeats), the amino- and carboxy-terminal regions remain conserved. In contrast, although the Cryptosporidium SPM1 homolog has a conserved carboxy tail, the five repeats are considerably diverged, and it has a smaller amino-terminal domain. SPM1 is localized along the full length of the subpellicular microtubules but does not associate with the conoid or spindle microtubules. SPM2 has a restricted localization along the middle region of the subpellicular microtubules. Domain deletion analysis indicates that four or more copies of the SPM1 repeat are required for localization to microtubules, and the amino-terminal 63 residues of SPM2 are required for localization to the subpellicular microtubules. Gene deletion studies indicate that neither SPM1 nor SPM2 is essential for tachyzoite viability. However, loss of SPM1 decreases overall parasite fitness and eliminates the stability of subpellicular microtubules to detergent extraction.