2rkj

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spinqualitylabelsall models 2rkj, resolution 4.500Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Cocrystal structure of a tyrosyl-tRNA synthetase splicing factor with a group I intron RNA

Overview

The 'RNA world' hypothesis holds that during evolution the structural and, enzymatic functions initially served by RNA were assumed by proteins, leading to the latter's domination of biological catalysis. This, progression can still be seen in modern biology, where ribozymes, such as, the ribosome and RNase P, have evolved into protein-dependent RNA, catalysts ('RNPzymes'). Similarly, group I introns use RNA-catalysed, splicing reactions, but many function as RNPzymes bound to proteins that, stabilize their catalytically active RNA structure. One such protein, the, Neurospora crassa mitochondrial tyrosyl-tRNA synthetase (TyrRS; CYT-18), is bifunctional and both aminoacylates mitochondrial tRNA(Tyr) and, promotes the splicing of mitochondrial group I introns. Here we determine, a 4.5-A co-crystal structure of the Twort orf142-I2 group I intron, ribozyme bound to splicing-active, carboxy-terminally truncated CYT-18., The structure shows that the group I intron binds across the two subunits, of the homodimeric protein with a newly evolved RNA-binding surface, distinct from that which binds tRNA(Tyr). This RNA binding surface, provides an extended scaffold for the phosphodiester backbone of the, conserved catalytic core of the intron RNA, allowing the protein to, promote the splicing of a wide variety of group I introns. The group I, intron-binding surface includes three small insertions and additional, structural adaptations relative to non-splicing bacterial TyrRSs, indicating a multistep adaptation for splicing function. The co-crystal, structure provides insight into how CYT-18 promotes group I intron, splicing, how it evolved to have this function, and how proteins could, have incrementally replaced RNA structures during the transition from an, RNA world to an RNP world.

About this Structure

2RKJ is a Protein complex structure of sequences from Neurospora crassa and Staphylococcus phage twort. Active as Tyrosine--tRNA ligase, with EC number 6.1.1.1 Full crystallographic information is available from OCA.

Reference

Structure of a tyrosyl-tRNA synthetase splicing factor bound to a group I intron RNA., Paukstelis PJ, Chen JH, Chase E, Lambowitz AM, Golden BL, Nature. 2008 Jan 3;451(7174):94-7. PMID:18172503

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