Archaeal tRNA-Splicing Endonuclease as an Effector for RNA Recombination and Novel Trans-Splicing Pathways in Eukaryotes

We have examined the substrate requirements for efficient and accurate splicing of tRNA precursors in Saccharomyces cerevisiae. The effects of Schizosaccharomyces pombe tRNASer gene mutations on the two steps in splicing, intron excision and joining of tRNA halves, were determined independently by using partially purified splicing endonuclease and tRNA ligase from S. cerevisiae. Two mutations (G14 and A46) reduced the efficiency of excision and joining in parallel, whereas two others (U47:7 and C33) produced differential effects on these two steps; U47:7 affected primarily the excision reaction, and C33 had a greater impact on ligation. These data indicate that endonuclease and ligase recognize both common and unique features of their substrates. Another two mutations (Ai26 and A37:13) induced miscutting, although with converse effects on the two splice sites. Thus, the two cutting events appear to be independent. Finally, we suggest that splice sites may be determined largely through their position relative to sites within the tRNA-like domain of the precursors. Several of these important sites were identified, and others are proposed based on the data described here.

Download Full-text

Substrate recognition and identification of splice sites by the tRNA-splicing endonuclease and ligase from Saccharomyces cerevisiae

Molecular and Cellular Biology ◽

10.1128/mcb.7.1.76-84.1987 ◽

1987 ◽

Vol 7 (1) ◽

pp. 76-84

Author(s):

C L Greer ◽

D Söll ◽

I Willis

Keyword(s):

Saccharomyces Cerevisiae ◽

Schizosaccharomyces Pombe ◽

Substrate Recognition ◽

Gene Mutations ◽

Splice Sites ◽

Differential Effects ◽

Trna Splicing ◽

Trna Halves

We have examined the substrate requirements for efficient and accurate splicing of tRNA precursors in Saccharomyces cerevisiae. The effects of Schizosaccharomyces pombe tRNASer gene mutations on the two steps in splicing, intron excision and joining of tRNA halves, were determined independently by using partially purified splicing endonuclease and tRNA ligase from S. cerevisiae. Two mutations (G14 and A46) reduced the efficiency of excision and joining in parallel, whereas two others (U47:7 and C33) produced differential effects on these two steps; U47:7 affected primarily the excision reaction, and C33 had a greater impact on ligation. These data indicate that endonuclease and ligase recognize both common and unique features of their substrates. Another two mutations (Ai26 and A37:13) induced miscutting, although with converse effects on the two splice sites. Thus, the two cutting events appear to be independent. Finally, we suggest that splice sites may be determined largely through their position relative to sites within the tRNA-like domain of the precursors. Several of these important sites were identified, and others are proposed based on the data described here.

Download Full-text