A chemical phylogeny of group I introns based upon interference mapping of a bacterial ribozyme

Juliane K. Strauss-Soukup, Scott A. Strobel

Research output: Contribution to journalArticle

40 Citations (Scopus)

Abstract

Despite its small size, the 205 nt group I intron from Azoarcus tRNA(lle) is an exceptionally stable self-splicing RNA. This IC3 class intron retains the conserved secondary structural elements common to group I ribozymes, but lacks several peripheral helices. These features make it an ideal system to establish the conserved chemical basis of group I intron activity. We collected nucleotide analog interference mapping (NAIM) data of the Azoarcus intron using 14 analogs that modified the phosphate backbone, the ribose sugar, or the purine base functional groups. In conjunction with a complete interference set collected on the Tetrahymena group I intron (IC1 class), these data define a 'chemical phylogeny' of functional groups that are important for the activity of both introns and that may be common chemical features of group I intron catalysts. The data identify the functional moieties most likely to play a conserved role as ligands for catalytic metal ions, the substrate helix, and the guanosine cofactor. These include backbone functional groups whose nucleotide identity is not conserved, and hence are difficult to identify by standard phylogenetic sequence comparisons. The data suggest that both introns utilize an equivalent set of long range tertiary interactions for 5'-splice site selection between the P1 substrate helix and its receptor in the J4/5 asymmetric bulge, as well as an equivalent set of 2'-OH groups for P1 helix docking into most of the single stranded segment J8/7. However, the Azoarcus intron appears to make an alternative set of interactions at the base of the P1 helix and at the 5'-end of the J8/7. Extensive differences were observed within the intron peripheral domains, particularly in P2 and P8 where the Azoarcus data strongly support the proposed formation of a tetraloop-tetraloop receptor interaction. This chemical phylogeny for group I intron catalysis helps to refine structural models of the RNA active site and identifies functional groups that should be carefully investigated for their role in transition state stabilization. (C) 2000 Academic Press.

Original languageEnglish
Pages (from-to)339-358
Number of pages20
JournalJournal of Molecular Biology
Volume302
Issue number2
DOIs
StatePublished - Sep 15 2000
Externally publishedYes

Fingerprint

Catalytic RNA
Phylogeny
Introns
Azoarcus
Nucleotides
RNA Splicing
Tetrahymena
RNA Splice Sites
Ribose
Guanosine
Structural Models
Transfer RNA
Catalysis
Catalytic Domain
Metals
Phosphates
RNA
Ions

All Science Journal Classification (ASJC) codes

  • Virology

Cite this

A chemical phylogeny of group I introns based upon interference mapping of a bacterial ribozyme. / Strauss-Soukup, Juliane K.; Strobel, Scott A.

In: Journal of Molecular Biology, Vol. 302, No. 2, 15.09.2000, p. 339-358.

Research output: Contribution to journalArticle

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