Loss of aTrans-Splicingnad1Intron from Geraniaceae and Transfer of the Maturase GenematRto the Nucleus inPelargonium

Abstract

The mitochondrial nad1 gene of seed plants has a complex structure, including four introns in cis or trans configurations and a maturase gene (matR) hosted within the final intron. In the geranium family (Geraniaceae), however, sequencing of representative species revealed that three of the four introns, including one in a trans configuration and another that hosts matR, were lost from the nad1 gene in their common ancestor. Despite the loss of the host intron, matR has been retained as a freestanding gene in most genera of the family, indicating that this maturase has additional functions beyond the splicing of its host intron. In the common ancestor of Pelargonium, matR was transferred to the nuclear genome, where it was split into two unlinked genes that encode either its reverse transcriptase or maturase domain. Both nuclear genes are transcribed and contain predicted mitochondrial targeting signals, suggesting that they express functional proteins that are imported into mitochondria. The nuclear localization and split domain structure of matR in the Pelargonium nuclear genome offers a unique opportunity to assess the function of these two domains using transgenic approaches.

Non-coding RNA may be associated with cytoplasmic male sterility in Silene vulgaris

“…The internal drop in coverage may reflect the existence of two distinct mRNAs and the production of the two MatR domains as separate protein molecules. This scenario would be consistent with the recent finding in Pelargonium that matR has been transferred to the nucleus and split into two distinct genes ( Grewe et al , 2016 ). In addition, the transcription of the matR domain X from an internal promoter, which also directed the co-transcription with the trans -spliced nad1 exon 5 and nad5 exon 3, was described in wheat mitochondria ( Farré and Araya, 1999 ).…”

Order, please! Uncertainty in the ordinal-level classification of Chlorophyceae

“…While most SV taxa have three trans-spliced psaA exons, the first two exons appear re-joined in Tetradesmus obliquus and Golenkinia longispicula . A retroprocessing mechanism behind genomic reconnection was recently proposed by Grewe, Zhu & Mower (2016), who discussed an analogous example in a mitochondrial gene of a vascular plant ( Pelargonium , Geraniaceae). In general, trans-spliced arrangement is considered prohibitive of intron loss, but green algae might provide further exceptions to this rule.…”

Plastome-Wide Rearrangements and Gene Losses in Carnivorous Droseraceae

“…Three of the introns thought to require MatK are missing from the Droseraceae plastid genomes ( trnK , rpl2 , and rps12 intron 2) but several putative MatK targets remain. There is an interesting parallel in Geraniaceae mitochondria, where loss of several nad1 introns has left the matR gene (usually encoded within nad1 intron 4) as a free-standing and presumably functional gene (Grewe et al. 2016), because it is required for splicing of introns in other genes (Sultan et al.…”