Poster abstracts
Poster number 46 submitted by Seyoung Ree
Amino acid composition in cytosolic and mitochondrial ribosomal proteins
Seyoung Ree (Notre Dame Academy/High School), Craig L. Zirbel (Math and Statistics Department, Bowling Green State University), Neocles Leontis (Chemistry Department, Bowling Green State University)
Abstract:
Animals have two ribosomes, cytosolic and mitochondrial, and they are under different types of evolutionary pressure. Mitochondria are the site of cellular respiration, so mitochondrial ribosomes, like other components of the matrix, are more exposed to reactive oxygen species (ROS), the by-products of cellular respiration. In previous work [1], we have provided evidence that mitochondrial ribosomal RNAs have evolved to protect themselves by reducing the number of guanine nucleotides, which are more easily oxidized than the other nucleotides. Mitochondrial ribosomes also acquired more and longer proteins since their divergence from bacterial origins, so that almost all of the surface of the RNA is protected by solvent from proteins. Another mechanism through which mitochondrial ribosomes may have evolved to protect themselves from ROS is by populating their ribosomal proteins with amino acids that carry electrons from glutathione in the solvent [2] to the RNA. These amino acids include CYS, TRP, TYR, and MET. We analyzed the CYS, TRP, TYR, and MET composition of mitochondrial and cytosolic ribosomal protein sequences of different groups of animals and plants. We find that the mitochondrial ribosomes have a higher percentage of CYS, TRP, TYR, and MET amino acids than the cytosolic ribosomes. Also, animals with high metabolisms, which have a higher rate of cellular respiration in the mitochondria, or larger problems with ROS, may have a higher composition of CYS, TRP, TYR, and MET amino acids in their proteins.
References:
[1] How to fold and protect mitochondrial ribosomal RNA with fewer guanines, by Maryam Hosseini, Poorna Roy, Marie Sissler, Craig L. Zirbel, Eric Westhof and Neocles Leontis. Published September 12, 2018 in Nucleic Acids Research. https://doi.org/10.1093/nar/gky762
[2] Ribas V, García-Ruiz C, Fernández-Checa JC. Glutathione and mitochondria. Front Pharmacol. 2014 Jul 1;5:151. PMID: 25024695; PMCID: PMC4079069. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4079069/
Keywords: mitochondrial ribosomes, reactive oxygen species, amino acids