Chimeric human mitochondrial PheRS exhibits editing activity to discriminate nonprotein amino acids

• Published in: Protein science 2016-03, Vol.25 (3), p.618-626
• Main Authors: Kartvelishvili, Ekaterine, Peretz, Moshe, Tworowski, Dmitry, Moor, Nina, Safro, Mark
• Format: Article
• Language: English
• Subjects: Acylation; Amino acids; Amino Acids - metabolism; Aminoacylation; aminoacyl‐tRNA synthetases; chimera; Cloning, Molecular; Dihydroxyphenylalanine; Editing; Fusion protein; Humans; Hydrolysis; Isomers; Levodopa; Mitochondria; Mitochondria - chemistry; Mitochondria - enzymology; Mitochondria - genetics; Mitochondria - metabolism; Models, Molecular; Neurotoxicity; Phenylalanine; Phenylalanine - metabolism; Phenylalanine-tRNA Ligase - chemistry; Phenylalanine-tRNA Ligase - genetics; Phenylalanine-tRNA Ligase - metabolism; Proteins; Reactive oxygen species; Reactive Oxygen Species - metabolism; Recombinant Fusion Proteins - chemistry; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; RNA, Transfer, Amino Acyl - metabolism; ROS‐damaged amino acid; tRNA; Tyrosine
• ISSN: 0961-8368; 1469-896X
• DOI: 10.1002/pro.2855

Mitochondria are considered as the primary source of reactive oxygen species (ROS) in nearly all eukaryotic cells during respiration. The harmful effects of these compounds range from direct neurotoxicity to incorporation into proteins producing aberrant molecules with multiple physiological problems. Phenylalanine exposure to ROS produces multiple oxidized isomers: tyrosine, Levodopa, ortho‐Tyr, meta‐Tyr (m‐Tyr), and so on. Cytosolic phenylalanyl‐tRNA synthetase (PheRS) exerts control over the translation accuracy, hydrolyzing misacylated products, while monomeric mitochondrial PheRS lacks the editing activity. Recently we showed that “teamwork” of cytosolic and mitochondrial PheRSs cannot prevent incorporation of m‐Tyr and l‐Dopa into proteins. Here, we present human mitochondrial chimeric PheRS with implanted editing module taken from EcPheRS. The monomeric mitochondrial chimera possesses editing activity, while in bacterial and cytosolic PheRSs this type of activity was detected for the (αβ)2 architecture only. The fusion protein catalyzes aminoacylation of tRNAPhe with cognate phenylalanine and effectively hydrolyzes the noncognate aminoacyl‐tRNAs: Tyr‐tRNAPhe and m‐Tyr‐tRNAPhe.