Open AccessStructure-function relationships of two closely related group IC3 intron ribozymes from Azoarcus and Synechococcus pre-tRNA
Author(s) -
Yoshiya Ikawa,
Daisuke Naito,
Hiroaki Shiraishi,
Tan Inoue
Publication year - 2000
Publication title -
nucleic acids research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 9.008
H-Index - 537
eISSN - 1362-4954
pISSN - 0305-1048
DOI - 10.1093/nar/28.17.3269
Subject(s) - ribozyme , biology , group ii intron , group i catalytic intron , genetics , intron , transfer rna , base pair , biochemistry , rna , gene , rna splicing
The two group IC3 pre-tRNA introns from Azoarcus and Synechococcus share very analogous secondary structures. They are small group I ribozymes that possess only two peripheral domains, P2 and P9. However, the 3'-splice site hydrolysis activity of the Synechococcus ribozyme critically depends on P2 whereas that of Azoarcus does not, indicating that the structure-function relationships of the two ribozymes are strikingly different despite their structural resemblance. To identify the element(s) that determines the catalytic properties of these ribozymes, we undertook analyses of chimeric ribozymes prepared by swapping their structural elements. We found that the difference can be attributed to a small number of nucleotides within the conserved core region. Further analysis by employing in vitro selection revealed that a base triple interaction (P4bp3 x J6/7-2) is a critical element for determining activity and suggests the existence of a novel base quintuple involving the base triple P4bp5 x J8/7-5.