Modification Defect at Anticodon Wobble Nucleotide of Mitochondrial tRNAsLeu(UUR) with Pathogenic Mutations of Mitochondrial Myopathy, Encephalopathy, Lactic Acidosis, and Stroke-like Episodes
Year: 2000
Type: article
Abstract: The mitochondrial tRNA(Leu)(UUR) (R = A or G) gene possesses several hot spots for pathogenic mutations. A point mutation at nucleotide position 3243 or 3271 is associated with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes and maternally inherited diabetes with deafness. Detailed studies on two tRNAs(Leu)(UUR) with the 3243 or 3271 mutation revealed some common characteristics in cybrid cells: (i) a decreased life span, resulting in a 70% decrease in the amounts of the tRNAs in the steady state, (ii) a slight decrease in the ratios of aminoacyl-tRNAs(Leu)(UUR) versus uncharged tRNAs(Leu)(UUR), and (iii) accurate aminoacylation with leucine without any misacylation. As a marked result, both of the mutant tRNA molecules were deficient in a modification of uridine that occurs in the normal tRNA(Leu)(UUR) at the first position of the anticodon. The lack of this modification may lead to the mistranslation of leucine into non-cognate phenylalanine codons by mutant tRNAs(Leu)(UUR), according to the mitochondrial wobble rule, and/or a decrease in the rate of mitochondrial protein synthesis. This finding could explain why two different mutations (3243 and 3271) manifest indistinguishable clinical features.
Source: Journal of Biological Chemistry
Authors: Takehiro Yasukawa, Tsutomu Suzuki, Takeo Suzuki, Takuya Ueda, Shigeo Ohta, Kimitsuna Watanabe
Institutions: The University of Tokyo, Nippon Medical School
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $3,430
OpenAlex ID: W2075835114