Zoantharian mitochondrial genomes contain unique complex group I introns and highly conserved intergenic regions

Ighem, Sylvia; Johansen, Steinar

doi:10.1016/j.gene.2017.07.023

Cited by 17 publications

(38 citation statements)

References 30 publications

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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%

“…(2) All canonical mitochondrial genes (OxPhos genes, rRNA, and tRNA genes) are encoded by the same DNA strand. 3The tRNA gene repertoire is highly reduced, corresponding to tRNA fMet and tRNA Trp in sea anemones, stony corals, mushroom corals, and black corals, and only tRNA fMet in colonial anemones [14,28,29]. This indicates extensive tRNA import into mitochondria [20].…”

Section: Mitochondrial Gene Organization and Expression In Hexacoralsmentioning

confidence: 99%

“…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%

“…The COI gene is interrupted by group I introns at three genic positions, where each intron site represents a unique evolutionary history [14,41]. The intron insertion sites correspond to positions 720, 867, and 884 (human COI gene numbering [19]).…”

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%

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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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