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Journal of Molecular Evolution

, Volume 48, Issue 5, pp 493–500 | Cite as

A Group I Intron in the Nuclear Small Subunit rRNA Gene of Cryptendoxyla hypophloia, an Ascomycetous Fungus: Evidence for a New Major Class of Group I Introns

  • Sung-Oui  Suh
  • Kevin G.  Jones
  • Meredith  Blackwell

Abstract.

The ascomycetous fungus Cryptendoxyla hypophloia contains an insertion of 433 base pairs in the genes encoding nuclear small subunit ribosomal RNA. Secondary structure analyses of the insert reveal characteristics indicative of a Group I intron, including elements P, Q, R, and S; however, the sequences of these conserved regions deviate significantly from recognized consensus sequences for Group I introns. Principal-components analysis, based on 79 nucleotide positions from the conserved core sequences of 93 Group I introns, identified 17 introns similar to that of C. hypophloia. This grouping, which includes inserts from phylogenetically diverse organisms, cannot readily be classified in any previously recognized major group of Group I introns. We propose the creation of a new group, IE, to accommodate these sequences, and discuss the evolutionary relationships between group IE and other major groups of Group I introns.

Key words: Group I intron-ribosomal RNA gene —Cryptendoxyla hypophloia— Comparative sequence analysis 

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Copyright information

© Springer-Verlag New York Inc. 1999

Authors and Affiliations

  • Sung-Oui  Suh
    • 1
  • Kevin G.  Jones
    • 1
  • Meredith  Blackwell
    • 1
  1. 1.Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USAUS

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