Evasion of antiviral bacterial immunity by phage tRNAs
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ABSTRACT:
ORGANISM(S): Escherichia coli
PROVIDER: GSE229290 | GEO | 2024/09/12
REPOSITORIES: GEO
Similar Datasets
Project description:Retrons are bacterial genetic retroelements that encode reverse transcriptase capable of producing multicopy single-stranded DNA (msDNA) and function as antiphage defense systems. Phages employ several strategies to counter the host defense systems, but no mechanisms for evading retrons are known. Here, we show that tRNATyr and Rad (retron anti defense) of T5 phage family inhibit the defense activity of retron 78 and a broad range of retrons, respectively. The effector protein of retron 78, ptuAB, specifically degraded tRNATyr leading abortive infection, but phage countervailed this defense by supplying tRNATyr. Rad inhibited retron function by degrading noncoding RNA, the precursor of msDNA. In summary, we demonstrated that viruses encode at least two independent strategies for overcoming bacterial defense systems: anti-defense, such as Rad, and defense canceler, like tRNA.
2024-10-10 | GSE256078 | GEO
Project description:Retrons are bacterial genetic retroelements that encode reverse transcriptase capable of producing multicopy single-stranded DNA (msDNA) and function as antiphage defense systems. Phages employ several strategies to counter the host defense systems, but no mechanisms for evading retrons are known. Here, we show that tRNATyr and Rad (retron anti defense) of T5 phage family inhibit the defense activity of retron 78 and a broad range of retrons, respectively. The effector protein of retron 78, ptuAB, specifically degraded tRNATyr leading abortive infection, but phage countervailed this defense by supplying tRNATyr. Rad inhibited retron function by degrading noncoding RNA, the precursor of msDNA. In summary, we demonstrated that viruses encode at least two independent strategies for overcoming bacterial defense systems: anti-defense, such as Rad, and defense canceler, like tRNA.
2024-10-10 | GSE256077 | GEO
Project description:Viruses compete with other viruses for limited cellular recourses, and some viruses deliver defense mechanisms that protect the host from competing genetic parasites. PARIS is a defense system, often encoded in viral genomes, that is composed of a 53 kDa ABC ATPase (AriA) and a 35 kDa TOPRIM nuclease (AriB). Here we show that AriA and AriB assemble into a 425 kDa supramolecular immune complex. We use cryo-EM to determine the structure of this complex which explains how six molecules of AriA assemble into a propeller-shaped scaffold that coordinates three subunits of AriB. ATP-dependent detection of foreign proteins triggers the release of AriB, which assembles into a homodimeric nuclease that blocks infection by cleaving the host Lysine tRNA. Phage T5 can subvert PARIS immunity through expression of a non-cleavable tRNA variant. Collectively, these data explain how AriA functions as an ATP-dependent sensor that detects viral proteins and activates the AriB toxin. PARIS is one of an emerging set of immune systems that form macromolecular complexes for the recognition of foreign proteins, rather than foreign nucleic acids.
2024-06-24 | GSE270519 | GEO
Project description:Retrons are toxin-antitoxin systems protecting bacteria against bacteriophages via abortive infection. The Retron-Eco1 antitoxin is formed by a reverse transcriptase (RT) and a non-coding RNA (ncRNA)/multi-copy single-stranded DNA (msDNA) hybrid that neutralizes an uncharacterized toxic effector. Yet, the molecular mechanisms underlying phage defense remain unknown. Here, we show that the N-glycosidase effector, which belongs to the STIR superfamily, hydrolyzes NAD+ during infection. Cryoelectron microscopy (cryo-EM) analysis shows that the msDNA stabilizes a filament that cages the effector in a low-activity state in which ADPr, a NAD+ hydrolysis product, is covalently linked to the catalytic E106 residue. Mutations shortening the msDNA induce filament disassembly and the effector’s toxicity, underscoring the msDNA role in immunity. Furthermore, we discovered a phage-encoded Retron-Eco1 inhibitor (U56) that binds ADPr, highlighting the intricate interplay between retron systems and phage evolution. Our work outlines the structural basis of Retron-Eco1 defense, uncovering ADPr’s pivotal role in immunity.
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Project description:The CCA-adding enzyme adds CCA to the 3' ends of transfer RNAs (tRNAs), a critical step in tRNA biogenesis that generates the amino acid attachment site. We found that the CCA-adding enzyme plays a key role in tRNA quality control by selectively marking unstable tRNAs and tRNA-like small RNAs for degradation. Instead of adding CCA to the 3' ends of these transcripts, CCA-adding enzymes from all three kingdoms of life add CCACCA. Here, we report deep sequencing analysis of the 3' ends of tRNA-Ser-CGA and tRNA-Ser-UGA from S. cerevisiae strains and show that hypomodified mature tRNAs are subjected to CCACCA (or poly(A) addition) as part of a rapid tRNA decay pathway in vivo. We conjecture that CCACCA addtion is a universal mechanism for controlling tRNA levels and preventing errors in translation. 121 samples analyzed in total, representing time courses of 10 different yeast strains; Biological replicates for each time point are included
2011-11-17 | E-GEOD-33756 | biostudies-arrayexpress
Project description:Eukaryotic transfer RNAs (tRNA) contain on average 13 modifications that perform a wide range of roles in translation and in the generation of tRNA fragments that regulate gene expression. Queuosine (Q) modification occurs in the wobble anticodon position of tRNAs for amino acids His, Asn, Tyr, and Asp. In eukaryotes, Q modification is fully dependent on diet or on gut microbiome in multi-cellular organisms. Despite decades of study, cellular roles of Q modification remain to be fully elucidated. Here we show that in human cells, Q modification specifically protects its cognate tRNAHis and tRNAAsn against cleavage by ribonucleases. We generated cell lines that contain completely depleted or fully Q-modified tRNAs. Using these resources, we found that Q modification significantly reduces angiogenin cleavage of its cognate tRNAs in vitro. Q modification does not change the cellular abundance of the cognate full-length tRNAs, but alters the cellular content of their fragments in vivo in the absence and presence of stress. Our results provide a new biological aspect of Q modification and a mechanism of how Q modification alters small RNA pool in human cells.
2018-08-10 | GSE102570 | GEO
Project description:Bacteriophages (hereafter “phages”) are ubiquitous predators of bacteria in the natural world, but interest is growing in their development into antibacterial therapy as complement or replacement for antibiotics. However, bacteria have evolved a huge variety of anti-phage defense systems allowing them to resist phage lysis to a greater or lesser extent, and in pathogenic bacteria these inevitably impact phage therapy outcomes. In addition to dedicated phage defense systems, some aspects of the general stress response also impact phage susceptibility, but the details of this are not well known. In order to elucidate these factors in the opportunistic pathogen Pseudomonas aeruginosa, we used the laboratory-conditioned strain PAO1 as host for phage infection experiments as it is naturally poor in dedicated phage defense systems. Screening by transposon insertion sequencing indicated that the uncharacterized operon PA3040-PA3042 was potentially associated with resistance to lytic phages. However, we found that its primary role appeared to be in regulating biofilm formation. Its expression was highly growth-phase dependent and responsive to phage infection and cell envelope stress.
2023-10-30 | GSE246284 | GEO
Project description:To ensure faithful translation of the genetic code, some aminoacyl-tRNA synthetases have a quality control (QC) mechanism that allows them to remove similarly shaped, non-protein amino acids (NPAs) from a mischarged tRNA. In E. coli, the QC function of phenyalanyl-tRNA synthetase (PheRS) is required for resistantce to the toxic NPA, meta-Tyrosine (m-Tyr). Here, we sought to understand the mechanism of m-Tyr toxicity. Using RNA-seq, we observed >500 genes were differential expressed after the addition of m-Tyr. The most strongly up-regulated genes are involved in unfolded-protein stress response, and cells exposed to m-Tyr contained large, electron-dense protein aggregates, indicating that m-Tyr destabilized a large fraction of the proteome. Additionally, we observed that amino acid biosynthesis and transport regulons, controlled by ArgR, TrpR, and TyrR, and the stringent-response regulon, controlled by DksA/ppGpp, were differentially expressed. m-Tyr resistant mutants were isolated and found to have altered a promoter to increase expression of the enzymes for Phe production or to have altered transporters, which likely result in less uptake or increased efflux of m-Tyr. These findings indicate that QC by PheRS is the critical point for resisting the toxic effects of m-Tyr, when m-Tyr has passed the QC checkpoint and enters the proteome, it is sequestered in protein aggregates that are eventually lost through cell division.
2020-11-30 | GSE140211 | GEO
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.
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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.
2024-05-08 | GSE266587 | GEO