Abstract
It has been generally thought that tRNA modifications are stable and static, and their frequencies are rarely regulated. N6-threonylcarbamoyladenosine (t6A) occurs at position 37 of five mitochondrial (mt-)tRNA species. We show that YRDC and OSGEPL1 are responsible for t6A37 formation, utilizing L-threonine, ATP, and CO2/bicarbonate as substrates. OSGEPL1-knockout cells exhibit respiratory defects and reduced mitochondrial translation. We find low level of t6A37 in mutant mt-tRNA isolated from the MERRF-like patient's cells, indicating that lack of t6A37 results in pathological consequences. Kinetic measurements of t6A37 formation reveal that the Km value of CO2/bicarbonate is extremely high (31 mM), suggesting that CO2/bicarbonate is a rate-limiting factor for t6A37 formation. Consistent with this, we observe a low frequency of t6A37 in mt-tRNAs isolated from human cells cultured without bicarbonate. These findings indicate that t6A37 is regulated by sensing intracellular CO2/bicarbonate concentration, implying that mitochondrial translation is modulated in a codon-specific manner under physiological conditions.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adenosine / analogs & derivatives
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Adenosine / chemistry
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Adenosine / metabolism
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Apoptosis Regulatory Proteins
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Base Pairing
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Bicarbonates / metabolism
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Bicarbonates / pharmacology*
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CRISPR-Cas Systems
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Carbon Dioxide / metabolism
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Carbon Dioxide / pharmacology*
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Cell Line
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Cell Respiration
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Fibroblasts / drug effects
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Fibroblasts / metabolism
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Fibroblasts / pathology
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GTP-Binding Proteins / genetics
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GTP-Binding Proteins / metabolism
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Gene Deletion
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HEK293 Cells
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HT29 Cells
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HeLa Cells
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Humans
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MERRF Syndrome / genetics
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MERRF Syndrome / metabolism*
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MERRF Syndrome / pathology
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Mitochondria / metabolism*
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Mitochondria / pathology
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Models, Biological
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Myoblasts / drug effects
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Myoblasts / metabolism
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Myoblasts / pathology
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Nucleic Acid Conformation
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Proteins / genetics
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Proteins / metabolism*
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RNA Processing, Post-Transcriptional / drug effects*
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RNA, Transfer / chemistry*
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RNA, Transfer / genetics
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RNA, Transfer / metabolism
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RNA-Binding Proteins / genetics
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RNA-Binding Proteins / metabolism
Substances
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Apoptosis Regulatory Proteins
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Bicarbonates
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OSGIN1 protein, human
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Proteins
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RNA-Binding Proteins
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Carbon Dioxide
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N(6)-(N-threonylcarbonyl)adenosine
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RNA, Transfer
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GTP-Binding Proteins
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YRDC protein, human
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Adenosine