A tyrosyl-tRNA synthetase can function similarly to an RNA structure in the Tetrahymena ribozyme.
Group I introns are highly structured RNAs which catalyse their own splicing by guanosine-initiated transesterification reactions. Their catalytic core is generally stabilized by RNA-RNA interactions within the core and with peripheral RNA structures. Additionally, some group I introns require proteins for efficient splicing in vivo. The Neurospora CYT-18 protein, the mitochondrial tyrosyl-transfer RNA synthetase (mt TyrRS), promotes splicing of the Neurospora mitochondrial large ribosomal RNA (LSU) and other group I introns by stabilizing the catalytically active structure of the intron core. We report here that CYT-18 functions similarly to a peripheral RNA structure, P5abc, that stabilizes the catalytic core of the Tetrahymena LSU intron. The CYT-18 protein and P5abc RNA bind to overlapping sites in the intron core, inducing similar conformational changes correlated with splicing activity. Our results show that a protein can play the role of an RNA structure in a catalytic RNA, a substitution postulated for the evolution of nuclear pre-messenger RNA introns from self-splicing introns.
Department of Molecular Genetics, Ohio State University, Columbus 43210-1292.
G
G
Mohr
M G
MG
Caprara
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Guo
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Lambowitz
D000818:Animals; D001483:Base Sequence; D005656:Fungal Proteins / Q000378:metabolism; D007438:Introns; D008969:Molecular Sequence Data; D009491:Neurospora / Q000235:genetics; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D016337:RNA, Catalytic / Q000378:metabolism*; D016053:RNA, Protozoan / Q000378:metabolism; D013768:Tetrahymena / Q000235:genetics; D014448:Tyrosine-tRNA Ligase / Q000378:metabolism*
D005656:Fungal Proteins; D016337:RNA, Catalytic; D016053:RNA, Protozoan; D014448:Tyrosine-tRNA Ligase