A conserved flagella-associated protein in Chlamydomonas, FAP234, is essential for axonemal localization of tubulin polyglutamylase TTLL9.
A conserved flagella-associated protein in Chlamydomonas, FAP234, is essential for axonemal localization of tubulin polyglutamylase TTLL9.
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DOI：
10.1091/mbc.e13-07-0424
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发表时间：
2014-01
影响因子：
3.3
通讯作者：
Kamiya R
中科院分区：
文献类型：
--
作者：
Kubo T;Yanagisawa HA;Liu Z;Shibuya R;Hirono M;Kamiya R
衣原体的一种新的轴丝蛋白FAP 234被发现与微管蛋白-多聚谷氨酰化酶TTLL 9形成复合物，并在TTLL 9的稳定和鞭毛内运输中起作用。这些蛋白质在大多数纤毛生物中是保守的，并且可能专门用于调节纤毛运动。微管蛋白经历各种翻译后修饰，包括多聚谷氨酰化，其由属于微管蛋白酪氨酸连接酶样蛋白（TTLL）家族的酶催化。先前分离的莱茵衣原体突变体tpg 1在编码哺乳动物TTLL 9同源物的基因中携带突变，并且由于轴丝微管蛋白的多聚谷氨酰化降低而显示出降低的运动性。在这里，我们确定了一种新的tpg 1样突变体，tpg 2，它携带的基因编码FAP 234，一个鞭毛相关蛋白的未知功能的突变。免疫沉淀和蔗糖密度梯度离心实验表明FAP 234和TTLL 9形成复合物。突变体tpg 1保留FAP 234在细胞体和鞭毛基质，但缺乏它在轴丝。相比之下，tpg 2在所有级分中都缺乏TTLL 9和FAP 234。fla 10是一种鞭毛内转运（IFT）缺陷的温度敏感突变体，在非允许温度下，TTLL 9和FAP 234都从鞭毛中丢失。这些和其他结果表明，FAP 234在TTLL 9的稳定和IFT依赖性转运中起作用。TTLL 9和FAP 234在大多数纤毛生物中是保守的。我们建议，他们构成了一个专门用于调节纤毛运动的多谷氨酰化复合物。
A novel axonemal protein, FAP234, of Chlamydomonas is found to form a complex with a tubulin-polyglutamylating enzyme, TTLL9, and function in the stabilization and intraflagellar transport of TTLL9. These proteins are conserved in most ciliated organisms and may be specialized for regulation of ciliary motility. Tubulin undergoes various posttranslational modifications, including polyglutamylation, which is catalyzed by enzymes belonging to the tubulin tyrosine ligase–like protein (TTLL) family. A previously isolated Chlamydomonas reinhardtii mutant, tpg1, carries a mutation in a gene encoding a homologue of mammalian TTLL9 and displays lowered motility because of decreased polyglutamylation of axonemal tubulin. Here we identify a novel tpg1-like mutant, tpg2, which carries a mutation in the gene encoding FAP234, a flagella-associated protein of unknown function. Immunoprecipitation and sucrose density gradient centrifugation experiments show that FAP234 and TTLL9 form a complex. The mutant tpg1 retains FAP234 in the cell body and flagellar matrix but lacks it in the axoneme. In contrast, tpg2 lacks both TTLL9 and FAP234 in all fractions. In fla10, a temperature-sensitive mutant deficient in intraflagellar transport (IFT), both TTLL9 and FAP234 are lost from the flagellum at nonpermissive temperatures. These and other results suggest that FAP234 functions in stabilization and IFT-dependent transport of TTLL9. Both TTLL9 and FAP234 are conserved in most ciliated organisms. We propose that they constitute a polyglutamylation complex specialized for regulation of ciliary motility.