TRMT1L-catalyzed m22G27 on tyrosine tRNA is required for efficient mRNA translation and cell survival under oxidative stress. [Nano-tRNAseq]
Ontology highlight
ABSTRACT: Mapping of the epitranscriptome has revealed the chemical diversity of RNA modifications and their functional importance in regulating gene expression. Transfer RNAs (tRNAs) are one of the most modified cellular RNAs, containing on average 10-13 modifications per molecule. These modifications have been shown to be critical for several aspects of tRNA functions, such as decoding, folding, and stability. Here we report that the human RNA methyltransferase TRMT1L associates with components of the Rix1 ribosome biogenesis complex and co-sediments with pre-60S ribosomes. Using eCLIP-Seq, we show that TRMT1L binds to a subset of tRNAs and to the 28S rRNA. Additionally, we demonstrate that TRMT1L is responsible for catalyzing N2, N2-dimethylguanosine (m22G) solely at position 27 of tRNA-Tyr-GUA by Nano-tRNAseq and RNA LC-MS. Surprisingly, TRMT1L depletion also impaired the deposition of acp3U and dihydrouridine on tRNA-Tyr-GUA, Cys-GCA, and Ala-CGC. TRMT1L knockout cells have a marked decrease in tRNA-Tyr-GUA levels, coinciding with a reduction in global translation rates and hypersensitivity of oxidative stress. Our results establish TRMT1L as the elusive methyltransferase catalyzing the m22G27 modification on tRNA Tyr, resolving a long-standing gap of knowledge and highlighting its potential role in a tRNA modification circuit crucial for translation regulation and stress response.
Project description:Mapping of the epitranscriptome has revealed the chemical diversity of RNA modifications and their functional importance in regulating gene expression. Transfer RNAs (tRNAs) are one of the most modified cellular RNAs, containing on average 10-13 modifications per molecule. These modifications have been shown to be critical for several aspects of tRNA functions, such as decoding, folding, and stability. Here we report that the human RNA methyltransferase TRMT1L associates with components of the Rix1 ribosome biogenesis complex and co-sediments with pre-60S ribosomes. Using eCLIP-Seq, we show that TRMT1L binds to a subset of tRNAs and to the 28S rRNA. Additionally, we demonstrate that TRMT1L is responsible for catalyzing N2, N2-dimethylguanosine (m22G) solely at position 27 of tRNA-Tyr-GUA by Nano-tRNAseq and RNA LC-MS. Surprisingly, TRMT1L depletion also impaired the deposition of acp3U and dihydrouridine on tRNA-Tyr-GUA, Cys-GCA, and Ala-CGC. TRMT1L knockout cells have a marked decrease in tRNA-Tyr-GUA levels, coinciding with a reduction in global translation rates and hypersensitivity of oxidative stress. Our results establish TRMT1L as the elusive methyltransferase catalyzing the m22G27 modification on tRNA Tyr, resolving a long-standing gap of knowledge and highlighting its potential role in a tRNA modification circuit crucial for translation regulation and stress response.
Project description:The tRNA methyltransferase 1 (TRMT1) enzyme catalyzes the formation of dimethylguanosine (m2,2G) in tRNAs. Loss-of-function mutations in TRMT1 lead to intellectual disability disorders in humans. In addition to TRMT1, vertebrates encode a tRNA methyltransferase 1-like (TRMT1L) paralog. Here, we use a comprehensive tRNA sequencing approach to decipher the landscape of tRNAs that are modified by human TRMT1 and TRMT1L. We find that TRMT1 modifies a single position in more than half of all cytoplasmic tRNAs and a subset of mitochondrial tRNAs. Notably, TRMT1 and TRMT1L catalyze m2,2G formation at distinct positions in tyrosine tRNAs that are each required for the efficient installation of additional modifications. Moreover, we identify a role for m2,2G modification in the stability of tyrosine and serine tRNAs that is abrogated in human patient cells homozygous for pathogenic TRMT1 variants. Human cells deficient in TRMT1 and/or TRMT1L exhibit reduced translation of specific codons, indicating that m2,2G modifications are necessary for maintaining functional levels of certain tRNAs. These findings uncover key roles for the m2,2G modification, and pinpoint tRNAs that are dysregulated in neurodevelopmental disorders caused by tRNA modification deficiency.
Project description:TRMT1L is a paralog of the tRNA m22G-methyltransferase TRMT1 and, similarly to TRMT1, it is involved in cognitive functioning. To functionally dissect the biological role of TRMT1L, here we have employed a combined strategy of LC-MS/MS and next-generation sequencing of both long and short RNAs, to compare the levels and locations of m2,2G in brain tissues from TRMT1L knock-out mice, relative to wild-type.
Project description:TRMT1L is a paralog of the tRNA m22G-methyltransferase TRMT1 and, similarly to TRMT1, it is involved in cognitive functioning. To functionally dissect the biological role of TRMT1L, here we have employed a combined strategy of LC-MS/MS and next-generation sequencing of both long and short RNAs, to compare the levels and locations of m2,2G in brain tissues from TRMT1L knock-out mice, relative to wild-type.
Project description:Members of the mammalian AlkB family are known to mediate nucleic acid demethylation. ALKBH7, a mammalian AlkB homologue, localizes in mitochondria (mt) and affects metabolism, but its function and mechanism of action are unknown. Here, we report an approach to site-specifically detect m1A, m3C, m1G, and m22G modifications simultaneously within all cellular RNAs, and discovered that human ALKBH7 demethylates N2, N2-dimethylguanosine (m22G) and N1-methyladenosine (m1A) within mt-Ile and mt-Leu1 pre-tRNA regions, respectively, in nascent polycistronic mt-RNA. We further show that ALKBH7 regulates the processing and structural dynamics of polycistronic mt-RNAs. Depletion of ALKBH7 leads to increased polycistronic mt-RNA processing, reduced steady-state mitochondria-encoded tRNA levels and protein translation, as well as notably decreased mitochondrial activity. Thus, we identify ALKBH7 as an RNA demethylase that controls nascent mt-RNA processing and mitochondrial activity.
Project description:Some codons of the genetic code can be read not only by cognate, but also by near-cognate tRNAs. This flexibility is thought to be conferred mainly by a mismatch between the third base of the codon and the first of the anticodon (the so-called wobble position). However, this simplistic explanation underestimates the importance of nucleotide modifications in the decoding process. Using a system in which only near-cognate tRNAs can decode a specific codon, we investigated the role of six modifications of the anticodon, or adjacent nucleotides, of the tRNAs specific for Tyr, Gln, Lys, Trp, Cys and Arg in Saccharomyces cerevisiae. Modifications almost systematically rendered these tRNAs able to act as near-cognate tRNAs at stop codons, even though they involve non-canonical base-pairs, without markedly affecting their ability to decode cognate or near-cognate sense codons. These findings reveal an important effect of modifications to tRNA decoding with implications for understanding the flexibility of the genetic code.
Project description:Queuosine (Q) is a conserved tRNA modification at the wobble anticodon position of tRNAs that read the codons of amino acids Tyr, His, Asn, and Asp. Q-modification in tRNA plays important roles in the regulation of translation efficiency and fidelity. Queuosine tRNA modification is synthesized de novo in bacteria, whereas the substrate for Q-modification in tRNA in mammals is queuine, the catabolic product of the Q-base of gut bacteria. This gut microbiome dependent tRNA modification may play pivotal roles in translational regulation in different cellular contexts, but extensive studies of Q-modification biology are hindered by the lack of high throughput sequencing methods for its detection and quantitation. Here, we describe a periodate-treatment method of biological RNA samples that enables single base resolution profiling of Q-modification in tRNAs by Nextgen sequencing. Periodate oxidizes the Q-base, which results in specific deletion signatures in the RNA-seq data. Unexpectedly, we found that periodate-treatment also enables the detection of several 2-thio-modifications including τm5s2U, mcm5s2U, cmnm5s2U, and s2C by sequencing in human and E. coli tRNA. We term this method Periodate-dependent analysis of queuosine and thio modification sequencing (PAQS-seq). We assess Q- and 2-thio-modifications at the tRNA isodecoder level, and 2-thio modification changes in stress response. PAQS-seq should be widely applicable in the biological studies of Q- and 2-thio-modifications in mammalian and microbial tRNAs.
Project description:Transfer RNAs (tRNAs) are fundamental for both cellular and viral gene expression during viral infection. Moreover, mounting evidence supports a noncanonical role for tRNA cleavage products in the control of gene expression during diverse conditions of stress and infection. We previously reported that infection with the model murine gammaherpesvirus, MHV68, leads to altered tRNA transcription, suggesting that tRNA regulation may play an important role in mediating viral replication or the host response. To better understand how viral infection alters tRNA expression, we combined Ordered Two Template Relay (OTTR) with tRNA-specific bioinformatic software called tRAX to profile full-length tRNAs and fragmented tRNA-derived RNAs (tDRs) during infection with the model gammaherpesvirus, MHV68. We find that OTTR-tRAX is a powerful sequencing strategy for combined tRNA/tDR profiling, and reveal that MHV68 infection triggers pre-tRNA and mature tRNA cleavage, resulting in the accumulation of specific tDRs. Fragments of virally-encoded tRNAs (virtRNAs), as well as virtRNA base modification signatures are also detectable during infection. We further dissected the biogenesis pathway of an MHV68-induced cleavage product from a pre-tRNA. Our data shows that pre-tDR-Tyr expression is dependent on the tRNA splicing factor, TSEN2, and that pre-tDR-Tyr expression is inhibited by the kinase, CLP1, which regulates tRNA splicing. Significantly, our findings suggest that CLP1 kinase is required for infectious gammaherpesvirus production, offering new insight into the importance of tRNA processing during viral infection.
Project description:In the ribosome complex, tRNA is a critical element of mRNA translation. We reported a new technology for profiling ribosome-embedded tRNAs and their modifications. With the method, we generated a comprehensive survey of the quanity and quality of intra-ribosomal tRNAs (Ribo-tRNA-seq). Ribo-tRNA-seq can provide new insights on translation control mechanism in diverse biological contexts.
Project description:Retrons are bacterial genetic elements that encode a reverse transcriptase and, in combination with toxic effector proteins, can serve as antiphage defense systems. However, the mechanisms of action of most retron effectors, and how phages evade retrons, are not well understood. Here, we show that some phages can evade retrons and other defense systems by producing specific tRNAs. We find that expression of retron-Eco7 effector proteins (PtuA and PtuB) leads to degradation of tRNA-Tyr and abortive infection. The genomes of T5 phages that evade retron-Eco7 include a tRNA-rich region, including a highly expressed tRNA-Tyr gene, which confers protection against retron-Eco7. Furthermore, we show that other phages (T1, T7) can use a similar strategy, expressing a tRNA-Lys, to counteract a tRNA anticodon defense system (PrrC170).