An allosteric-feedback mechanism for protein-assisted group I intron splicing.
The I-AniI maturase facilitates self-splicing of a mitochondrial group I intron in Aspergillus nidulans. Binding occurs in at least two steps: first, a specific but labile encounter complex rapidly forms and then this intermediate is slowly resolved into a native, catalytically active RNA/protein complex. Here we probe the structure of the RNA throughout the assembly pathway. Although inherently unstable, the intron core, when bound by I-AniI, undergoes rapid folding to a near-native state in the encounter complex. The next transition includes the slow destabilization and docking into the core of the peripheral stacked helix that contains the 5' splice site. Mutational analyses confirm that both transitions are important for native complex formation. We propose that protein-driven destabilization and docking of the peripheral stacked helix lead to subtle changes in the I-AniI binding site that facilitate native complex formation. These results support an allosteric-feedback mechanism of RNA-protein recognition in which proteins engaged in an intermediate complex can influence RNA structure far from their binding sites. The linkage of these changes to stable binding ensures that the protein and RNA do not get sequestered in nonfunctional complexes.
Caprara
Mark G
MG
Center for RNA Molecular Biology, Case Western Reserve University, School of Medicine, Cleveland, OH 44106-4960, USA. mgc3@po.cwru.edu
Chatterjee
Piyali
P
Solem
Amanda
A
Brady-Passerini
Kristina L
KL
Kaspar
Benjamin J
BJ
D000494:Allosteric Regulation; D001233:Aspergillus nidulans / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D045303:Cytochromes b / Q000235:genetics; D025461:Feedback, Physiological; D005656:Fungal Proteins / Q000378:metabolism*; D007438:Introns; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D012322:RNA Precursors / Q000378:metabolism; D022821:RNA Splice Sites; D012326:RNA Splicing; D016337:RNA, Catalytic / Q000378:metabolism; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism*; D012194:RNA-Directed DNA Polymerase / Q000378:metabolism*
D005656:Fungal Proteins; D012322:RNA Precursors; D022821:RNA Splice Sites; D016337:RNA, Catalytic; D012331:RNA, Fungal; D045303:Cytochromes b; D012194:RNA-Directed DNA Polymerase; C454879:maturase I-AniI