Complex protein targeting to dinoflagellate plastids
Complex protein targeting to dinoflagellate plastids
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DOI：
10.1016/j.jmb.2005.03.030
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发表时间：
2005-05-13
影响因子：
5.6
通讯作者：
Keeling, PJ
中科院分区：
文献类型：
--
作者：
Patron, NJ;Waller, RF;Keeling, PJ
蛋白质向质体的运输途径由N-末端靶向肽指导。在植物中，它由一个相对简单的转运肽组成，而在具有次生质体（位于内膜系统内）的生物体中，一个信号肽附加到转运肽上。尽管生物体之间的氨基酸组成差异，通常是由于核苷酸的偏见，质体靶向序列的功能通常是一致的物种。甲藻则偏离了这一趋势。我们已经进行了表达序列标签（EST）调查的甲藻异囊藻的peridin-plastid含有识别和表征许多靶向前序列的质体蛋白编码的核。与存在于其他二级含质体生物体中的靶向系统一致，这些都在其N末端具有典型的信号肽，然而存在两种主要类型的转运肽。这两类转运肽具有共同的N-末端部分，但一类转运肽含有疏水结构域，据报道其可作为停止转移膜锚，暂时阻止蛋白质插入内质网。第二类转运肽缺乏这种特征。这两类代表大致相等，并为任何给定的蛋白质类是保守的所有甲藻类群调查的日期。这种二分法表明，两种机制，甚至贩运路线，可能直接蛋白质的甲藻质体。四个残基的苯丙氨酸基序也是H的一致特征。triquetra运输肽，这是一个古老的功能，早于红藻和海藻，失去了绿色质体。(c)2005爱思唯尔有限公司保留所有权利。
Protein trafficking pathways to plastids are directed by N-terminal targeting peptides. In plants this consists of a relatively simple transit peptide, while in organisms with secondary plastids (which reside within the endomembrane system) a signal peptide is appended to the transit peptide. Despite amino acid compositional differences between organisms, often due to nucleotide biases, the features of plastid targeting sequences are generally consistent within species. Dinoflagellate algae deviate from this trend. We have conducted an expressed sequence tag (EST) survey of the peridinin-plastid containing dinoflagellate Heterocapsa triquetra to identify and characterize numerous targeting presequences of plastid proteins encoded in the nucleus. Consistent with targeting systems present in other secondary plastid-containing organisms, these all possess a canonical signal peptide at their N termini, however two major classes of transit peptides occur. Both classes possess a common N-terminal portion of the transit peptide, but one class of transit peptides contains a hydrophobic domain that has been reported to act as a stop-transfer membrane anchor, temporarily arresting protein insertion into the endoplasmic reticulum. A second class of transit peptide lacks this feature. These two classes are represented approximately equally, and for any given protein the class is conserved across all dinoflagellate taxa surveyed to date. This dichotomy suggests that two mechanisms, perhaps even trafficking routes, may direct proteins to dinoflagellate plastids. A four-residue phenylalanine-based motif is also a consistent feature of H. triquetra transit peptides, which is an ancient feature predating red algae and galucophytes that was lost in green plastids. (c) 2005 Elsevier Ltd. All rights reserved.