Evolution from the Prokaryotic to the Higher Plant Chloroplast Signal Recognition Particle: The Signal Recognition Particle RNA Is Conserved in Plastids of a Wide Range of Photosynthetic Organisms[W]-猫眼课题宝

DOI：

10.1105/tpc.112.102996

发表时间：

2012-12

期刊：

Plant Cell

影响因子：

11.6

通讯作者：

中科院分区：

生物学1区

文献类型：

--

作者：

Chantal Träger;M. A. Rosenblad;Dominik Ziehe;Christel Garcia-Petit;L. Schrader;Klaus Kock;Christine Vera Richter;B. Klinkert;F. Narberhaus;C. Herrmann;E. Hofmann;H. Aronsson;D. Schünemann

本文对绿藻系和红藻系内叶绿体信号识别颗粒（cpSRP）的进化进行了分析。重点在于质体编码的SRP RNA组分的分布和特性描述。此外，对小立碗藓（Physcomitrella patens）含SRP RNA和cpSRP43组分的cpSRP系统进行了研究，并解析了cpFtsY受体的结构。高等植物叶绿体中的蛋白质靶向信号识别颗粒（SRP）途径经历了巨大的进化变化。它舍弃了其RNA（RNA在细菌中是一种必不可少的SRP组分），并使用一种独特的叶绿体特异性蛋白质cpSRP43。然而，保守的SRP54和SRP受体FtsY的同源物存在于高等植物叶绿体中。在本研究中，我们分析了光合生物中SRP组分的系统发育分布，以阐明SRP系统的进化。我们在所有非种子植物陆地植物谱系以及所有绿藻分支中鉴定出保守的质体SRP RNA。此外，我们表明这些生物中同时存在cpSRP43。这种新型SRP系统的功能在苔藓小立碗藓中从生物化学和结构方面进行了表征。我们表明小立碗藓叶绿体SRP（cpSRP）RNA结合cpSRP54，但已失去显著刺激SRP54和FtsY的GTP酶循环的能力。此外，测定了小立碗藓cpFtsY的1.8 Å分辨率的晶体结构和核苷酸特异性，并与细菌FtsY和高等植物叶绿体FtsY进行了比较。我们的数据表明，小立碗藓cpSRP系统在从细菌型SRP到高等植物型cpSRP系统的进化过程中处于中间位置。

This article provides an analysis of chloroplast signal recognition particle (cpSRP) evolution within the green and red lineages. A focus lies on the distribution and characterization of the plastid-encoded SRP RNA component. Furthermore, the cpSRP system of Physcomitrella patens containing an SRP RNA and a cpSRP43 component was investigated, and the structure of the cpFtsY receptor was solved. The protein targeting signal recognition particle (SRP) pathway in chloroplasts of higher plants has undergone dramatic evolutionary changes. It disposed of its RNA, which is an essential SRP component in bacteria, and uses a unique chloroplast-specific protein cpSRP43. Nevertheless, homologs of the conserved SRP54 and the SRP receptor, FtsY, are present in higher plant chloroplasts. In this study, we analyzed the phylogenetic distribution of SRP components in photosynthetic organisms to elucidate the evolution of the SRP system. We identified conserved plastid SRP RNAs within all nonspermatophyte land plant lineages and in all chlorophyte branches. Furthermore, we show the simultaneous presence of cpSRP43 in these organisms. The function of this novel SRP system was biochemically and structurally characterized in the moss Physcomitrella patens. We show that P. patens chloroplast SRP (cpSRP) RNA binds cpSRP54 but has lost the ability to significantly stimulate the GTPase cycle of SRP54 and FtsY. Furthermore, the crystal structure at 1.8-Å resolution and the nucleotide specificity of P. patens cpFtsY was determined and compared with bacterial FtsY and higher plant chloroplast FtsY. Our data lead to the view that the P. patens cpSRP system occupies an intermediate position in the evolution from bacterial-type SRP to higher plant-type cpSRP system.