Project description:RpfB is one of five resuscitation promoting factors in Mycobacterium tuberculosis. We previously published data indicating the 5' UTR of the gene contains a regulatory riboswitch with an unknown (at the time) ligand. We overexpressed the switch in Mycobacterium smegmatis (which does not contain the rpfB gene), reasoning that overexpression of the switch would s sequester the unknown ligand, giving rise to a phenotype that would help us identify it.
Project description:Riboswitches are ligand-binding elements contained within the 5’ untranslated regions of bacterial transcripts, which generally regulate expression of downstream open reading frames. Here we show that in Listeria monocytogenes, a Vitamin B12-binding (B12) riboswitch controls expression of a non-coding regulatory RNA, Rli55. Rli55 in turn controls expression of the eut genes, which enable ethanolamine utilization and require B12 as a cofactor. Defects in ethanolamine utilization, or in its regulation by Rli55, significantly attenuate Listeria virulence in mice. Rli55 functions by sequestering the two-component response regulator, EutV via a EutV binding-site contained within the RNA. Thus Rli55 is a riboswitch-regulated member of the small group of regulatory RNAs that function by sequestering a protein and reveals a unique mechanism of signal integration in bacterial gene regulation.
Project description:Riboswitches are ligand-binding elements contained within the 5M-bM-^@M-^Y untranslated regions of bacterial transcripts, which generally regulate expression of downstream open reading frames. Here we show that in Listeria monocytogenes, a Vitamin B12-binding (B12) riboswitch controls expression of a non-coding regulatory RNA, Rli55. Rli55 in turn controls expression of the eut genes, which enable ethanolamine utilization and require B12 as a cofactor. Defects in ethanolamine utilization, or in its regulation by Rli55, significantly attenuate Listeria virulence in mice. Rli55 functions by sequestering the two-component response regulator, EutV via a EutV binding-site contained within the RNA. Thus Rli55 is a riboswitch-regulated member of the small group of regulatory RNAs that function by sequestering a protein and reveals a unique mechanism of signal integration in bacterial gene regulation. RNA-Seq and CLIP-Seq to investigate the sequestration of EutV by rli55
Project description:Single-molecule correlated chemical probing (smCCP) is an experimentally concise strategy for characterizing higher-order structural interactions in RNA. smCCP data yield rich, but complex, structural information on base pairing, conformational ensembles, and tertiary interactions. To date, through-space communication specifically measuring RNA tertiary structure has been difficult to isolate from structural communication reflective of other interactions. Here we introduce mutual information as a filtering metric to isolate tertiary structure communication contained within smCCP data and use this strategy to characterize the structural ensemble of the SAM-III riboswitch. We identified a smCCP fingerprint that is selective for states containing tertiary structure that forms concurrently with cognate ligand binding. We then successfully applied mutual information filters to independent RNAs and isolated through-space tertiary interactions in riboswitches and large RNAs with complex structures. smCCP, coupled with mutual information criteria, can now be used as a tertiary structure discovery tool, including to identify specific states in an ensemble that have higher-order structure. These studies pave the way for use of the straightforward smCCP experiment for discovery and characterization of tertiary structure motifs in complex RNAs.
Project description:Synthetic riboswitches mediating ligand-dependent RNA cleavage or splicing-modulation represent elegant tools to control gene expression in various applications, including next-generation gene therapy. However, due to the limited understanding of context-dependent structure-function relationships, the identification of functional riboswitches requires large-scale-screening of aptamer-effector-domain designs, which is hampered by the lack of suitable cellular high-throughput methods. Here we describe a fast and broadly applicable method to functionally screen complex riboswitch libraries (~1.8x104 constructs) by cDNA-amplicon-sequencing in transiently transfected and stimulated human cells. The self-barcoding nature of each construct enables quantification of differential mRNA levels without additional pre-selection or cDNA-manipulation steps. We apply this method to engineer tetracycline- and guanine-responsive ON- and OFF-switches based on hammerhead, hepatitis-delta-virus and Twister ribozymes as well as U1-snRNP polyadenylation-dependent RNA devices. In summary, our method enables fast and efficient high-throughput riboswitch identification, thereby overcoming a major hurdle in the development cascade for therapeutically applicable gene switches. DOI:10.1038/s41467-020-14491-x
Project description:A375 and HT1080 cells are treated with G-quadruplex ligands PDS or PhenDC3 following genome-wide shRNA knockdown. This enables the identification of genes that when silenced, specifically compromises cell growth in the presence of the ligand. First, a pilot screen was performed to determine a ligand concentration and experimental duration that caused ligand-specific, significant changes in shRNA levels. Second, a genome-wide screen was performed to globally evaluate G4-ligand synthetic lethal interactions. Third, to corroborate the G4-sensitisers uncovered in the genome-wide screen, a focussed screen was performed with a custom shRNA pool.
Project description:The experiments were carried out to map the ligand binding landscape of various DNA and RNA duplexed aptamer families. Duplexed Aptamer (DA) constructs were engineered from (i) natural and synthetic DNA and RNA aptamers and (i) synthetic oligonucleotide aptamer-complementary elements synthesized on custom DNA microarrays. The aptamers tested consist of the ATP DNA aptamer, the ATP RNA aptamer, the cocaine DNA aptamer, the human alpha-thrombin DNA aptamer, and the natural add riboswitch aptamer from the pathogenic bacteria Vibrio vulnificus. Each duplexed aptamer family consists of 1000's of synthetic constructs, each formed by hybridizing the aptamer with an aptamer-complementary element (ACE) - here, ACEs consisted of various DNA oligonucleotides synthesized as a custom DNA microarray.
Project description:The experiments were carried out to map the ligand binding landscape of various DNA and RNA duplexed aptamer families. Duplexed Aptamer (DA) constructs were engineered from (i) natural and synthetic DNA and RNA aptamers and (i) synthetic oligonucleotide aptamer-complementary elements synthesized on custom DNA microarrays. The aptamers tested consist of the ATP DNA aptamer, the ATP RNA aptamer, the cocaine DNA aptamer, the human alpha-thrombin DNA aptamer, and the natural add riboswitch aptamer from the pathogenic bacteria Vibrio vulnificus. Each duplexed aptamer family consists of 1000's of synthetic constructs, each formed by hybridizing the aptamer with an aptamer-complementary element (ACE) - here, ACEs consisted of various DNA oligonucleotides synthesized as a custom DNA microarray.
Project description:The experiments were carried out to map the ligand binding landscape of various DNA and RNA duplexed aptamer families. Duplexed Aptamer (DA) constructs were engineered from (i) natural and synthetic DNA and RNA aptamers and (i) synthetic oligonucleotide aptamer-complementary elements synthesized on custom DNA microarrays. The aptamers tested consist of the ATP DNA aptamer, the ATP RNA aptamer, the cocaine DNA aptamer, the human alpha-thrombin DNA aptamer, and the natural add riboswitch aptamer from the pathogenic bacteria Vibrio vulnificus. Each duplexed aptamer family consists of 1000's of synthetic constructs, each formed by hybridizing the aptamer with an aptamer-complementary element (ACE) - here, ACEs consisted of various DNA oligonucleotides synthesized as a custom DNA microarray.
Project description:The experiments were carried out to map the ligand binding landscape of various DNA and RNA duplexed aptamer families. Duplexed Aptamer (DA) constructs were engineered from (i) natural and synthetic DNA and RNA aptamers and (i) synthetic oligonucleotide aptamer-complementary elements synthesized on custom DNA microarrays. The aptamers tested consist of the ATP DNA aptamer, the ATP RNA aptamer, the cocaine DNA aptamer, the human alpha-thrombin DNA aptamer, and the natural add riboswitch aptamer from the pathogenic bacteria Vibrio vulnificus. Each duplexed aptamer family consists of 1000's of synthetic constructs, each formed by hybridizing the aptamer with an aptamer-complementary element (ACE) - here, ACEs consisted of various DNA oligonucleotides synthesized as a custom DNA microarray.