A Role for the Mitochondrial Protein Mrpl44 in Maintaining OXPHOS Capacity

• DOI: 10.1371/journal.pone.0134326
• Publication Date: 2015-07-29T18:16:36Z
• Authors: Janet H. C. Yeo; Jarrod P. J. Skinner; Matthew J. Bird; Luke E. Formosa; Jian-Guo Zhang; Ruth M. Kluck; Gabrielle T. Belz; Mark M. W. Chong
• Keywords: Ribonuclease III; Ribosomal Proteins; 570; 1300 Biochemistry; DISORDERS; Science; RIBONUCLEASE-III; LARGE SUBUNIT; 610; Genetics and Molecular Biology; Mitochondria, Liver; MOLECULAR DIAGNOSIS; DNA, Mitochondrial; Oxidative Phosphorylation; Cell Line; Mitochondrial Proteins; Mitochondrial Ribosomes; 1100 Agricultural and Biological Sciences; Mice; 03 medical and health sciences; RNA-POLYMERASE; Adenosine Triphosphate; Oxygen Consumption; OXIDATIVE-PHOSPHORYLATION; Animals; Humans; RIBOSOME; MUTATION; 0303 health sciences; Science & Technology; Q; R; Multidisciplinary Sciences; GENOME; HEK293 Cells; Gene Expression Regulation; 1000 General; Gene Knockdown Techniques; NIH 3T3 Cells; Science & Technology - Other Topics; Medicine; Cattle; TRANSLATION; Protein Multimerization; Research Article

We identified Mrpl44 in a search for mammalian proteins that contain RNase III domains. This protein was previously found in association with the mitochondrial ribosome of bovine liver extracts. However, the precise Mrpl44 localization had been unclear. Here, we show by immunofluorescence microscopy and subcellular fractionation that Mrpl44 is localized to the matrix of the mitochondria. We found that it can form multimers, and confirm that it is part of the large subunit of the mitochondrial ribosome. By manipulating its expression, we show that Mrpl44 may be important for regulating the expression of mtDNA-encoded genes. This was at the level of RNA expression and protein translation. This ultimately impacted ATP synthesis capability and respiratory capacity of cells. These findings indicate that Mrpl44 plays an important role in the regulation of the mitochondrial OXPHOS capacity.