Structure-function relationships in a self-splicing group II intron: a large part of domain II of the mitochondrial intron aI5 is not essential for self-splicing.
Structure-function relationships in a self-splicing group II intron: a large part of domain II of the mitochondrial intron aI5 is not essential for self-splicing.
复制标题
自剪接 II 族内含子中的结构-功能关系：线粒体内含子 aI5 的结构域 II 的大部分对于自剪接不是必需的。
作者：
J. Kwakman;Danielle Konings;H. Pel;L. Grivell
An oligonucleotide-directed deletion of 156 nucleotides has been introduced into the yeast mitochondrial group II intron al5 (887 nt). The deletion comprises almost all of domain II, which is one of the six phylogenetically conserved structural elements of group II introns. This mutant displays reduced self-splicing activity, but results of chemical probing with dimethylsulphate suggest that sequences at the site of the deletion interfere with the normal folding of the intron. This is supported by computer analyses, which predict a number of alternative structures involving conserved intron sequences. Splicing activity could be restored by insertion of a 10-nucleotide palindromic sequence into the unique Smal site of the deletion mutant, resulting in the formation of a small stable stem-loop element at the position of domain II. These results provide a direct correlation between folding of the RNA and its activity. We conclude that at least a large part of domain II of the group II intron al5 is not required for self-splicing activity. This deletion mutant with a length of 731 nucleotides represents the smallest self-splicing group II intron so far known.
