O'Farrell Heather C, Pulicherla Nagesh, Desai Pooja M, Rife Jason P
Department of Biochemistry, Virginia Commonwealth University, Richmond 23298-0133, USA.
RNA. 2006 May;12(5):725-33. doi: 10.1261/rna.2310406. Epub 2006 Mar 15.
Ribosome biogenesis is a complicated process, involving numerous cleavage, base modification and assembly steps. All ribosomes share the same general architecture, with small and large subunits made up of roughly similar rRNA species and a variety of ribosomal proteins. However, the fundamental assembly process differs significantly between eukaryotes and eubacteria, not only in distribution and mechanism of modifications but also in organization of assembly steps. Despite these differences, members of the KsgA/Dim1 methyltransferase family and their resultant modification of small-subunit rRNA are found throughout evolution and therefore were present in the last common ancestor. In this paper we report that KsgA orthologs from archaeabacteria and eukaryotes are able to complement for KsgA function in bacteria, both in vivo and in vitro. This indicates that all of these enzymes can recognize a common ribosomal substrate, and that the recognition elements must be largely unchanged since the evolutionary split between the three domains of life.
核糖体生物合成是一个复杂的过程，涉及众多切割、碱基修饰和组装步骤。所有核糖体都具有相同的总体结构，其小亚基和大亚基由大致相似的rRNA种类和多种核糖体蛋白组成。然而，真核生物和真细菌之间的基本组装过程存在显著差异，不仅在修饰的分布和机制方面，而且在组装步骤的组织方面。尽管存在这些差异，但KsgA/Dim1甲基转移酶家族成员及其对小亚基rRNA的修饰在整个进化过程中都存在，因此在最后的共同祖先中就已存在。在本文中，我们报道古细菌和真核生物中的KsgA直系同源物在体内和体外都能够补充细菌中KsgA的功能。这表明所有这些酶都能识别共同的核糖体底物，并且自生命的三个域在进化上分离以来，识别元件必定基本未变。
