Recruitment of intron-encoded and co-opted proteins in splicing of the bI3 group I intron RNA
AUTOR(ES)
Bassi, Gurminder S.
FONTE
The National Academy of Sciences
RESUMO
Detectable splicing by the Saccharomyces cerevisiae mitochondrial bI3 group I intron RNA in vitro is shown to require both an intron-encoded protein, the bI3 maturase, and the nuclear-encoded protein, Mrs1. Both proteins bind independently to the bI3 RNA. The bI3 maturase binds as a monomer, whereas Mrs1 is a dimer in solution that assembles as two dimers, cooperatively, on the RNA. The active six-subunit complex has a molecular mass of 420 kDa, splices with a kcat of 0.3 min−1, and binds the guanosine nucleophile with an affinity comparable to other group I introns. The functional bI3 maturase domain is translated from within the RNA that encodes the intron, has evolved a high-affinity RNA-binding activity, and is a member of the LAGLIDADG family of DNA endonucleases, but appears to have lost DNA cleavage activity. Mrs1 is a divergent member of the RNase H fold superfamily of dimeric DNA junction-resolving enzymes that also appears to have lost its nuclease activity and now functions as a tetramer in RNA binding. Thus, the bI3 ribonucleoprotein is the product of a process in which a once-catalytically active RNA now obligatorily requires two facilitating protein cofactors, both of which are compromised in their original functions.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=117526Documentos Relacionados
- Complex recognition site for the group I intron-encoded endonuclease I-SceII.
- Complex recognition site for the group I intron-encoded endonuclease I-SceII.
- Kluyveromyces lactis maintains Saccharomyces cerevisiae intron-encoded splicing signals.
- I-Sce III: a novel group I intron-encoded endonuclease from the yeast mitochondria.
- Evolution of mobile group I introns: recognition of intron sequences by an intron-encoded endonuclease.
