Starch synthase 4 is located in the thylakoid membrane and interacts with plastoglobule-associated proteins in Arabidopsis
Starch synthase 4 is located in the thylakoid membrane and interacts with plastoglobule-associated proteins in Arabidopsis
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DOI：
10.1111/tpj.12633
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发表时间：
2014-10-01
期刊：
影响因子：
7.2
通讯作者：
Merida, Angel
中科院分区：
文献类型：
--
作者：
Gamez-Arjona, Francisco M.;Raynaud, Sandy;Merida, Angel
淀粉合成需要形成引物，随后可以延伸和支化。然而，这种引物是如何产生的仍然未知。每个叶绿体产生的淀粉颗粒数量的控制也是一个有争议的问题。我们之前表明淀粉合酶 4 (SS4) 参与这两个过程，尽管所涉及的机制尚未完全表征。目前的工作表明 SS4 显示出与其他淀粉合酶不同的特定定位。因此，该蛋白位于类囊体膜的特定区域，并与主要位于质体球中的原纤维蛋白 1a (FBN1a) 和 1b (FBN1b) 相互作用。 SS4 似乎与附着在类囊体（或类囊体中质体球起源的部分）上的质体球相关，形成包含 FBN1 和其他尚未鉴定的蛋白质的复合物。目前的结果还表明，SS4 的定位模式及其与 FBN1 蛋白的相互作用是通过其 N 末端区域介导的，该区域包含两个长卷曲螺旋基序。 SS4 在类囊体膜特定区域的定位表明淀粉颗粒起源于叶绿体的特定区域。
Starch synthesis requires the formation of a primer that can be subsequently elongated and branched. How this primer is produced, however, remains unknown. The control of the number of starch granules produced per chloroplast is also a matter of debate. We previously showed starch synthase 4 (SS4) to be involved in both processes, although the mechanisms involved are yet to be fully characterised. The present work shows that SS4 displays a specific localization different from other starch synthases. Thus, this protein is located in specific areas of the thylakoid membrane and interacts with the proteins fibrillin 1a (FBN1a) and 1b (FBN1b), which are mainly located in plastoglobules. SS4 would seem to be associated with plastoglobules attached to the thylakoids (or to that portion of the thylakoids where plastoglobules have originated), forming a complex that includes the FBN1s and other as-yet unidentified proteins. The present results also indicate that the localization pattern of SS4, and its interactions with the FBN1 proteins, are mediated through its N-terminal region, which contains two long coiled-coil motifs. The localization of SS4 in specific areas of the thylakoid membrane suggests that starch granules are originated at specific regions of the chloroplast.