Subramanian Selvi, Bonen Linda
Biology Department, University of Ottawa, 30 Marie Curie, Ottawa, Ontario K1N 6N5, Canada.
Genome. 2006 Mar;49(3):275-81. doi: 10.1139/g05-098.
The L2 ribosomal protein is typically one of the most conserved proteins in the ribosome and is universally present in bacterial, archaeal, and eukaryotic cytosolic and organellar ribosomes. It is usually 260-270 amino acids long and its binding to the large-subunit ribosomal RNA near the peptidyl transferase center is mediated by a beta-barrel RNA-binding domain with 10 beta strands. In the diverse land plants Marchantia polymorpha (liverwort) and Oryza sativa (rice), the mitochondrial-encoded L2 ribosomal protein is about 500 amino acids long owing to a centrally located expansion containing the beta3-beta4 strand region. We have determined that, in wheat, the functional rpl2 gene has been transferred to the nucleus and much of the plant-specific internal insert has been deleted. Its mRNA is only 1.2 kb, and two expressed copies in wheat encode proteins of 318 and 319 amino acids, so they are considerably shorter than the maize nuclear-located rpl2 gene of 448 codons. Comparative sequence analysis of cereal mitochondrial L2 ribosomal proteins indicates that the mid region has undergone unexpectedly rapid evolution during the last 60 million years.
L2核糖体蛋白通常是核糖体中最保守的蛋白之一，普遍存在于细菌、古菌以及真核生物的胞质和细胞器核糖体中。它通常由260 - 270个氨基酸组成，其与肽基转移酶中心附近的大亚基核糖体RNA的结合是由一个具有10条β链的β桶状RNA结合结构域介导的。在多种陆生植物地钱（Marchantia polymorpha）和水稻（Oryza sativa）中，线粒体编码的L2核糖体蛋白由于在中央位置有一个包含β3 - β4链区域的扩展片段，长度约为500个氨基酸。我们已经确定，在小麦中，功能性的rpl2基因已转移到细胞核中，并且大部分植物特有的内部插入片段已被删除。其mRNA仅1.2 kb，小麦中的两个表达拷贝编码的蛋白质分别为318和319个氨基酸，因此它们比玉米位于细胞核中的448个密码子的rpl2基因要短得多。对谷物线粒体L2核糖体蛋白的比较序列分析表明，在过去的6000万年中，中间区域经历了意外快速的进化。
