Intron-encoded ribosomal proteins and N-acetyltransferases within the mitochondrial genomes of fungi: here today, gone tomorrow?

Abstract

In the mitochondrial genomes of the filamentous Ascomycota, aside from the usual ‘core’ set of genes, one can encounter genes encoding for ribosomal protein S3 (rps3), N-acetyltransferase, and in a few instances aminotransferases. Based on a survey using sequence data from various databases, it was observed that these genes can be located within introns or exist as freestanding genes in intergenic regions. Furthermore, they can also be absent from fungal mitochondrial genomes. The rps3 gene is highly conserved among fungal mitochondrial genomes although examples were noted where the mtDNA version of this gene has been translocated into the nuclear genome. The N-acetyltransferase gene was less frequently encountered and may be a more recent import from the nuclear genome. Both genes serve as examples of genetic elements that appear to be capable of ‘cycling’ or mobilizing between introns and intergenic regions and possible between the nuclear and mitochondrial genomes. This ‘cycling’ mechanism is currently not understood but may involve recombination events and/or movement via RNA intermediates.

Keywords:

• Ascomycotina
• rps3
• group I introns
• mobile elements

Acknowledgements

The authors would like to acknowledge all the Scientists who provided permission to utilize their data from the MycCosm JGI database: Nadya Cardona, Patrik Inderbitzin, Pedro W. Crous, Adrian Tsangk, Alexey Grum-Grzhimaylo, Amy Jo Powell, Colleen Hansel, Daniel Raudabaugh, Dave Greenshields, David Ezra, Donald L. Nuss, Francis Michel Martin, Gerald Bills, Gregory Bonito, Kabir Peay, Kerry O'Donnell.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this paper.

Additional information

Funding

GH would like to acknowledge funding from a Natural Sciences and Engineering Research Council of Canada Discovery grant [Discovery Grant RGPIN-2015-06658]. PWC would like to acknowledge the funding support from the Dutch Ministry of Education, Culture and Science through an endowment of the FES program ‘Making the tree of life work’. In addition AW and CS would like to acknowledge funding from the University of Manitoba GETS program.