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A Phylogenetic Approach to Structural Variation in Organization of Nuclear Group I Introns and Their Ribozymes
Betty M N Furulund1, Bård O Karlsen2, Igor Babiak1
1Genomic Division, Faculty of Biosciences and Aquaculture, Nord University, 8049 Bodø, Norway.
Non-Coding RNA
|August 27, 2021
Summary
Nuclear group I introns in myxomycete protists exhibit conserved structures but surprising sequence variations. These ribosomal DNA introns show evidence of both vertical and horizontal genetic transfer during evolution.
Area of Science:
- Molecular Biology
- Evolutionary Biology
- Genetics
Background:
- Nuclear group I introns are genetic elements found in ribosomal DNA of some eukaryotic microorganisms.
- Myxomycete protists are a rich source of these introns due to their evolutionary history.
Purpose of the Study:
- To investigate the group I introns within the ribosomal DNA of the myxomycete *Mucilago crustacea*.
- To analyze and compare S1389 group IC1 introns across diverse myxomycete taxa.
Main Methods:
- Collected and analyzed 72 S1389 group IC1 introns from myxomycete taxa.
- Determined consensus secondary structures.
- Performed phylogenetic analyses of introns and host genes.
Main Results:
- Identified seven group I introns in *Mucilago crustacea*, including a direct repeat-containing intron at insertion site S1389.
- Observed a conserved ribozyme core with sequence variations in the guanosine binding site (P7).
- Found extension sequences with repeat arrays in P9 and homing endonuclease genes in P1, some interrupted by spliceosomal introns.
Conclusions:
- S1389 introns display conserved structural elements alongside sequence variability.
- Phylogenetic analyses suggest both vertical and horizontal intron transfer in myxomycetes.
- The study reveals sporadic occurrences of direct repeats, homing endonuclease genes, and P7 variants.
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