Riedel L, Pütz A, Hauser M T, Luckinger R, Wassenegger M, Sänger H L
Max-Planck-Institut für Biochemie, Abteilung Viroidforschung, Martinsried, Germany.
Plant Mol Biol. 1995 Feb;27(4):669-80. doi: 10.1007/BF00020221.
Molecular cloning of 30 cDNAs and subsequent characterization of the corresponding SRP RNA from four cultivars of tomato (Lycopersicon esculentum) revealed altogether 14 sequence variants, which could be ordered into six groups. The expression of five representatives from these groups was examined by reverse transcriptase-polymerase chain reaction (RT-PCR) in different cultivars and different tissues. Although one cultivar-specific SRP RNA variant could be detected in the leaf SRP RNA population, identical SRP RNA populations seem to be present in the four different cultivars as well as in different tissues, such as leaves, flowers, fruits, stems and roots. Sequence comparison revealed that several variants might have evolved by recombination of two different SRP RNA sequences. On the basis of five SRP RNA variants, the current secondary structure model was refined and a new conserved structural element was detected. Comparative sequence analysis of domain II from all known SRP RNA homologues reveals a remarkable conservation of this element. As demonstrated previously, the corresponding area overlaps with a region that interact with the SRPp68/p72 heterodimer and/or with ribosomes. Based on structural and functional considerations, we propose that the domain IV structure together with the highly conserved area of domain II constitutes the essential core of the SRP RNA.
对来自四个番茄（Lycopersicon esculentum）品种的30个cDNA进行分子克隆，并对相应的信号识别颗粒（SRP）RNA进行后续表征，共发现了14个序列变体，可分为六组。通过逆转录聚合酶链反应（RT-PCR）检测了这些组中的五个代表在不同品种和不同组织中的表达。尽管在叶片SRP RNA群体中可检测到一个品种特异性的SRP RNA变体，但相同的SRP RNA群体似乎存在于四个不同品种以及不同组织中，如叶片、花朵、果实、茎和根。序列比较表明，几个变体可能是由两种不同的SRP RNA序列重组进化而来。基于五个SRP RNA变体，对当前的二级结构模型进行了优化，并检测到一个新的保守结构元件。对所有已知SRP RNA同源物的结构域II进行比较序列分析，发现该元件具有显著的保守性。如先前所示，相应区域与与SRPp68/p72异二聚体和/或核糖体相互作用的区域重叠。基于结构和功能方面的考虑，我们提出结构域IV结构与结构域II的高度保守区域共同构成了SRP RNA的核心。
