J. Roman et Sa. Woodson, REVERSE SPLICING OF THE TETRAHYMENA IVS - EVIDENCE FOR MULTIPLE REACTION SITES IN THE 23S RIBOSOMAL-RNA, RNA, 1(5), 1995, pp. 478-490
Group I introns in rRNA genes are clustered in highly conserved region
s that include tRNA and mRNA binding sites. This pattern is consistent
with insertion of group I introns by direct interaction with exposed
regions of rRNA. Integration of the Tetrahymena group I intron (or int
ervening sequence, IVS) into targe subunit rRNA via reverse splicing w
as investigated using E. coli 23S rRNA as a model substrate. The resul
ts show that sequences homologous to the splice junction in Tetrahymen
a are the preferred site of integration, but that many other sequences
in the 23S rRNA provide secondary targets. Like the original splice j
unction, many new reaction sites are in regions of stable secondary st
ructure. Reaction at the natural splice junction is observed in 50S su
bunits and to a lesser extent in 70S ribosomes. These results support
the feasibility of intron transposition to new sites in rRNA genes via
reverse splicing.