Publications by authors named "Xueling Mao"
ADATs: roles in tRNA editing and relevance to disease.
Acta Biochim Biophys Sin (Shanghai)
July 2024
Transfer RNAs (tRNAs) play central roles in protein biosynthesis. Post-transcriptional RNA modifications affect tRNA function and stability. Among these modifications, RNA editing is a widespread RNA modification in three domains of life.
View Article and Find Full Text PDFMethyltransferase-like 8 (METTL8) encodes a mitochondria-localized METTL8-Iso1 and a nucleolus-distributed METTL8-Iso4 isoform, which differ only in their N-terminal extension (N-extension), by mRNA alternative splicing. METTL8-Iso1 generates 3-methylcytidine at position 32 (mC32) of mitochondrial tRNA and tRNA(UCN). Whether METTL8-Iso4 is an active mC32 methyltransferase and the role of the N-extension in mitochondrial tRNA mC32 formation remain unclear.
View Article and Find Full Text PDFMitochondrial RNA metabolism is suggested to occur in identified compartmentalized foci, i.e. mitochondrial RNA granules (MRGs).
View Article and Find Full Text PDFArticle Synopsis
- - METTL8 is a newly identified enzyme that adds a specific methyl group (3-methylcytidine) to mitochondrial tRNAs, and it may also affect mRNA and R-loop formation, although its exact roles are still being investigated.
- - Different versions (isoforms) of METTL8 are produced through mRNA splicing, with one version (METTL8-Iso1) acting in mitochondria and another (METTL8-Iso4) found mainly in the nucleolus; they have distinct functions in modifying specific tRNAs.
- - The study reveals how METTL8-Iso1 modifies human mitochondrial tRNAThr without needing another modification found in other tRNAs, and it also shows how this enzyme differentiates
Article Synopsis
- N 6-Threonylcarbamoyladenosine (t6A) is an important modification found in tRNAs, and its biosynthesis involves the KEOPS complex, mutations of which are linked to Galloway-Mowat syndrome.
- The research shows that human cytoplasmic tRNAs with an ANN sequence always contain the t6A modification, suggesting a co-evolution of tRNA and modification enzymes.
- t6A plays a crucial role in the aminoacylation of tRNAIle and influences decoding efficiency, revealing both similarities and differences in how KEOPS complexes recognize substrates across different eukaryotes.
In tRNA, the epigenetic mC modification at position 32 in the anticodon loop is highly conserved in eukaryotes, which maintains the folding and basepairing functions of the anticodon. However, the responsible enzymes METTL2 and METTL6 were identified only in recent years. The loss of human METTL6 (hMETTL6) affects the translational process and proteostasis in cells, while in mESCs cells, it leads to defective pluripotency potential.
View Article and Find Full Text PDFArticle Synopsis
- tRNAs exhibit a variety of posttranscriptional modifications, with 3-methylcytidine (m3C) being significant for eukaryotic tRNAThr and tRNASer at position C32, with multiple enzymes involved in its modification process.
- In yeast, one methyltransferase (Trm140) is responsible for m3C32 modification, while mammals use up to three enzymes (METTL2A, METTL2B, and METTL6) for this task, raising questions about their substrate discrimination mechanisms.
- The study established that METTL2A and METTL2B can modify tRNAs in vitro, highlighting specific structural requirements for tRNAThr and tRNASer(G
Carboxyl-terminal repeat domain (CTD) of the largest subunit Rpb1 of RNA polymerace II is essential for transcription regulation. Heptapeptide repeat of CTD of Rpb1 is phosphorylated by carboxyl-terminal repeat domain kinase (CTDK-I), composed of CTK1, CTK2 and CTK3, in order to regulate transcription and transcription associated processes. The yeast specific protein CTK3 binds to cyclin CTK2 to form a heterodimer serving as a regulational factor to control CTK1 activity by binding to CTK1.
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