Cyanobacterial ribosomal RNA genes with multiple, endonuclease-encoding group I introns
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https://hdl.handle.net/10037/1250DOI
doi:10.1186/1471-2148-7-159Date
2007-09-08Type
Journal articleTidsskriftartikkel
Peer reviewed
Author
Haugen, Peik; Bhattacharya, Debashish; Palmer, Jeffrey D.; Turner, Seán; Lewis, Louise A.; Pryer, Kathleen M.Abstract
Background: Group I introns are one of the four major classes of introns as defined by their
distinct splicing mechanisms. Because they catalyze their own removal from precursor transcripts,
group I introns are referred to as autocatalytic introns. Group I introns are common in fungal and
protist nuclear ribosomal RNA genes and in organellar genomes. In contrast, they are rare in all
other organisms and genomes, including bacteria.
Results: Here we report five group I introns, each containing a LAGLIDADG homing
endonuclease gene (HEG), in large subunit (LSU) rRNA genes of cyanobacteria. Three of the
introns are located in the LSU gene of Synechococcus sp. C9, and the other two are in the LSU gene
of Synechococcus lividus strain C1. Phylogenetic analyses show that these introns and their HEGs are
closely related to introns and HEGs located at homologous insertion sites in organellar and
bacterial rDNA genes. We also present a compilation of group I introns with homing endonuclease
genes in bacteria.
Conclusion: We have discovered multiple HEG-containing group I introns in a single bacterial
gene. To our knowledge, these are the first cases of multiple group I introns in the same bacterial
gene (multiple group I introns have been reported in at least one phage gene and one prophage
gene). The HEGs each contain one copy of the LAGLIDADG motif and presumably function as
homodimers. Phylogenetic analysis, in conjunction with their patchy taxonomic distribution,
suggests that these intron-HEG elements have been transferred horizontally among organelles and
bacteria. However, the mode of transfer and the nature of the biological connections among the
intron-containing organisms are unknown.
Publisher
BioMed CentralCitation
BMC Evolutionary Biology 7(2007) article no 159Metadata
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