Mechanism of maturase-promoted group II intron splicing.
Mobile group II introns encode reverse transcriptases that also function as intron-specific splicing factors (maturases). We showed previously that the reverse transcriptase/maturase encoded by the Lactococcus lactis Ll.LtrB intron has a high affinity binding site at the beginning of its own coding region in an idiosyncratic structure, DIVa. Here, we identify potential secondary binding sites in conserved regions of the catalytic core and show via chemical modification experiments that binding of the maturase induces the formation of key tertiary interactions required for RNA splicing. The interaction with conserved as well as idiosyncratic regions explains how maturases in some organisms could evolve into general group II intron splicing factors, potentially mirroring a key step in the evolution of spliceosomal introns.
Matsuura
M
M
Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA.
Noah
J W
JW
Lambowitz
A M
AM
D000447:Aldehydes / Q000737:chemistry; D001483:Base Sequence; D002074:Butanones; D007438:Introns; D007455:Iodine / Q000737:chemistry; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D012313:RNA / Q000737:chemistry / Q000378:metabolism*; D012326:RNA Splicing; D012194:RNA-Directed DNA Polymerase / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins
D000447:Aldehydes; D002074:Butanones; D029701:Saccharomyces cerevisiae Proteins; D012313:RNA; D007455:Iodine; C005135:kethoxal; C066564:aI2 protein, S cerevisiae; D012194:RNA-Directed DNA Polymerase