Mrm2, also known as RRMJ2 and encoded by FTSJ2, is a mitochondrial methyltransferase. It is responsible for the 2'-O-methyl modification of nucleotides in the 16S rRNA A-loop, an essential component of the peptidyl transferase center in mitochondrial ribosomes. This modification is crucial for the biogenesis and function of the large subunit of the mitochondrial ribosome, and thus for mitochondrial translation and respiration [2,3]. Yeast Saccharomyces cerevisiae serves as a valuable research model for studying Mrm2 [6].

In human cells, inactivation of Mrm2 by RNA interference leads to respiratory incompetence due to diminished mitochondrial translation and aberrant assembly of the large subunit of the mitochondrial ribosome [2]. In yeast, deletion of the MRM2 gene causes thermosensitive respiration and rapid loss of mitochondrial DNA [5]. A knockout yeast model for the orthologous gene showed a defect in respiration and reduction of the 2'-O-methyl modification at the equivalent position in yeast mitochondrial 21S rRNA [4].

In conclusion, Mrm2 is essential for the modification of 16S rRNA, which is crucial for mitochondrial ribosome biogenesis, translation, and respiration. Studies using gene knockout models, especially in yeast, have been instrumental in revealing Mrm2's role in mitochondrial function. Mutations in Mrm2 are associated with various human diseases, including complex dystonic syndromes and MELAS-like clinical syndromes, highlighting its significance in understanding disease mechanisms [1,4].

References:

1. Shafique, Anum, Arif, Beenish, Chu, Mary Lynn, Lohmann, Katja, Naz, Sadaf. 2022. MRM2 variants in families with complex dystonic syndromes: evidence for phenotypic heterogeneity. In Journal of medical genetics, 60, 352-358. doi:10.1136/jmg-2022-108521. https://pubmed.ncbi.nlm.nih.gov/36002240/

2. Rorbach, Joanna, Boesch, Pierre, Gammage, Payam A, Perocchi, Fabiana, Minczuk, Michal. 2014. MRM2 and MRM3 are involved in biogenesis of the large subunit of the mitochondrial ribosome. In Molecular biology of the cell, 25, 2542-55. doi:10.1091/mbc.E14-01-0014. https://pubmed.ncbi.nlm.nih.gov/25009282/

3. Rebelo-Guiomar, Pedro, Pellegrino, Simone, Dent, Kyle C, Warren, Alan J, Minczuk, Michal. 2022. A late-stage assembly checkpoint of the human mitochondrial ribosome large subunit. In Nature communications, 13, 929. doi:10.1038/s41467-022-28503-5. https://pubmed.ncbi.nlm.nih.gov/35177605/

4. Garone, Caterina, D'Souza, Aaron R, Dallabona, Cristina, Ferrero, Ileana, Minczuk, Michal. . Defective mitochondrial rRNA methyltransferase MRM2 causes MELAS-like clinical syndrome. In Human molecular genetics, 26, 4257-4266. doi:10.1093/hmg/ddx314. https://pubmed.ncbi.nlm.nih.gov/28973171/

5. Pintard, Lionel, Bujnicki, Janusz M, Lapeyre, Bruno, Bonnerot, Claire. . MRM2 encodes a novel yeast mitochondrial 21S rRNA methyltransferase. In The EMBO journal, 21, 1139-47. doi:. https://pubmed.ncbi.nlm.nih.gov/11867542/

6. Gilea, Alexandru Ionut, Ceccatelli Berti, Camilla, Magistrati, Martina, Baruffini, Enrico, Dallabona, Cristina. 2021. Saccharomyces cerevisiae as a Tool for Studying Mutations in Nuclear Genes Involved in Diseases Caused by Mitochondrial DNA Instability. In Genes, 12, . doi:10.3390/genes12121866. https://pubmed.ncbi.nlm.nih.gov/34946817/