Expression of homing endonuclease gene and insertion-like element in sea anemone mitochondrial genomes: Lesson learned from Anemonia viridis

Ighem, Sylvia; Urbárová, Ilona; Johansen, Steinar

doi:10.1016/j.gene.2018.01.067

Cited by 13 publications

(30 citation statements)

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“…Mitochondrial RNA sequencing reveals perfectly ligated ND5 mRNA exons in sea anemones [12,15], colonial anemones [14], and mushroom corals [16], which support a biological splicing activity of ND5-717 introns. In the mushroom corals Ricordea and Amplexodiscus, the splicing efficiency of the ND5-717 intron was reported to be about 10% of that of the COI-884 intron located in the same mitochondrial genome [16].…”

Section: Unconventional Splicing Of Nd5-717 Intronsmentioning

confidence: 74%

“…Mitochondrial RNAs have been investigated in a few hexacoral species representing sea anemones, colonial anemones, and mushroom corals [6,12,[14][15][16]. RNAseq data were obtained from 454 pyrosequencing and Ion Torrent PGM sequencing.…”

Section: Mitochondrial Rna In Hexacoralsmentioning

confidence: 99%

“…A common feature, however, is the large insertion within helical segment P8 harboring a HEG that codes for a homing endonuclease of the LAGLIDADG family. These HEGs extend beyond P8 and into the ribozyme domains [12,14,15,43]. Thus, COI-720, COI-867, and COI-884 intron sequences possess dual coding potentials of catalytic RNAs and homing endonucleases.…”

Section: Three Different Insertion Sites In the Coi Genementioning

confidence: 99%

“…The circular and economically organized mtDNA encodes the same set of 2 ribosomal RNAs and 13 hydrophobic proteins involved in the oxidative phosphorylation (OxPhos) system [11]. However, noncanonical and optional mitochondrial genes may occur in some hexacoral species [11][12][13][14][15][16]. More unusual features, however, are the highly reduced tRNA gene repertoire (only 1-2 tRNA genes) and the presence of complex group I introns [11,[17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

“…Intron homing is initiated by a DNA double-strand break catalyzed by the intron-encoded homing endonuclease. Expression of HEGs has been studied in COI introns of sea anemones, colonial anemones, and mushroom corals [12,[14][15][16]. Two main versions were noted, leading to either highly expressed or repressed HEGs (Figure 5C).…”

Section: Expression Of Intron-encoded Homing Endonucleasesmentioning

confidence: 99%

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Mitochondrial Group I Introns in Hexacorals Are Regulatory Genetic Elements

Johansen¹,

Emblem²

2020

Advances in the Studies of the Benthic Zone

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Hexacoral mitochondrial genomes are highly economically organized and vertebrate-like in size, structure, and gene content. A hallmark, however, is the presence of group I introns interrupting essential oxidative phosphorylation (OxPhos) genes. Two genes, encoding NADH dehydrogenase subunit 5 (ND5) and cytochrome c oxidase subunit I (COI), are interrupted with introns. The ND5 intron, located at position 717, is obligatory in all hexacoral specimens investigated. The ND5-717 intron is a giant-sized intron that carries several canonical OxPhos genes. Different modes of splicing appear to apply for the ND5-717 intron, including conventional cis-splicing, backsplicing, and trans-splicing. Three distinct versions of hexacoral COI introns are noted at genic positions 884, 867, and 720. The COI introns are of the mobile-type, carrying homing endonuclease genes (HEGs). Some COI-884 intron HEGs are highly expressed as in-frame COI exon fusions, while the expression of COI-867 intron HEGs appear repressed. We discuss biological roles of hexacoral mitochondrial ND5 and COI introns and suggest that the ND5-717 intron has gained new regulatory functions beyond self-splicing.

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