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Elghondakly A, Jermain MD, Winkler WC, Ferré-D'Amaré AR. Major-groove sequence-specific RNA recognition by LoaP, a paralog of transcription elongation factor NusG. Structure 2024:S0969-2126(24)00219-3. [PMID: 38959899 DOI: 10.1016/j.str.2024.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 05/07/2024] [Accepted: 06/06/2024] [Indexed: 07/05/2024]
Abstract
LoaP is a member of the universal NusG protein family. Previously, we reported that unlike other characterized homologs, LoaP binds RNA sequence-specifically, recognizing a stem-loop in the 5'-untranslated region of operons it regulates. To elucidate how this NusG homolog acquired this ability, we now determined the co-crystal structure of Thermoanaerobacter pseudethanolicus LoaP bound to its cognate 26-nucleotide dfn RNA element. Our structure reveals that the LoaP C-terminal KOW domain recognizes the helical portion of the RNA by docking into a broadened major groove, while a protruding β-hairpin of the N-terminal NusG-like domain binds the UNCG tetraloop capping the stem-loop. Major-groove RNA recognition is unusual and is made possible by conserved features of the dfn hairpin. Superposition with structures of other NusG proteins implies that LoaP can bind concurrently to the dfn RNA and the transcription elongation complex, suggesting a new level of co-transcriptional regulation by proteins of this conserved family.
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Affiliation(s)
- Amr Elghondakly
- Laboratory of Nucleic Acids, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Madison D Jermain
- Department of Cell Biology and Molecular Genetics, The University of Maryland, College Park, MD 20742, USA
| | - Wade C Winkler
- Department of Cell Biology and Molecular Genetics, The University of Maryland, College Park, MD 20742, USA; Department of Chemistry and Biochemistry, The University of Maryland, College Park, MD, USA.
| | - Adrian R Ferré-D'Amaré
- Laboratory of Nucleic Acids, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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Luo X, Zhang A, Tai CH, Chen J, Majdalani N, Storz G, Gottesman S. An acetyltranferase moonlights as a regulator of the RNA binding repertoire of the RNA chaperone Hfq in Escherichia coli. Proc Natl Acad Sci U S A 2023; 120:e2311509120. [PMID: 38011569 PMCID: PMC10710024 DOI: 10.1073/pnas.2311509120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 10/23/2023] [Indexed: 11/29/2023] Open
Abstract
Bacterial small RNAs (sRNAs) regulate gene expression by base-pairing with their target mRNAs. In Escherichia coli and many other bacteria, this process is dependent on the RNA chaperone Hfq, a mediator for sRNA-mRNA annealing. YhbS (renamed here as HqbA), a putative Gcn5-related N-acetyltransferase (GNAT), was previously identified as a silencer of sRNA signaling in a genomic library screen. Here, we studied how HqbA regulates sRNA signaling and investigated its physiological roles in modulating Hfq activity. Using fluorescent reporter assays, we found that HqbA overproduction suppressed all tested Hfq-dependent sRNA signaling. Direct interaction between HqbA and Hfq was demonstrated both in vivo and in vitro, and mutants that blocked the interaction interfered with HqbA suppression of Hfq. However, an acetylation-deficient HqbA mutant still disrupted sRNA signaling, and HqbA interacted with Hfq at a site far from the active site. This suggests that HqbA may be bifunctional, with separate roles for regulating via Hfq interaction and for acetylation of undefined substrates. Gel shift assays revealed that HqbA strongly reduced the interaction between the Hfq distal face and low-affinity RNAs but not high-affinity RNAs. Comparative RNA immunoprecipitation of Hfq and sequencing showed enrichment of two tRNA precursors, metZWV and proM, by Hfq in mutants that lost the HqbA-Hfq interaction. Our results suggest that HqbA provides a level of quality control for Hfq by competing with low-affinity RNA binders.
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Affiliation(s)
- Xing Luo
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD20892
| | - Aixia Zhang
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD20892-4417
| | - Chin-Hsien Tai
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD20892
| | - Jiandong Chen
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD20892
| | - Nadim Majdalani
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD20892
| | - Gisela Storz
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD20892-4417
| | - Susan Gottesman
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD20892
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Goldberger O, Szoke T, Nussbaum-Shochat A, Amster-Choder O. Heterotypic phase separation of Hfq is linked to its roles as an RNA chaperone. Cell Rep 2022; 41:111881. [PMID: 36577380 DOI: 10.1016/j.celrep.2022.111881] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2021] [Revised: 11/25/2022] [Accepted: 12/03/2022] [Indexed: 12/29/2022] Open
Abstract
Hfq, an Sm-like protein and the major RNA chaperone in E. coli, has been shown to distribute non-uniformly along a helical path under normal growth conditions and to relocate to the cell poles under certain stress conditions. We have previously shown that Hfq relocation to the poles is accompanied by polar accumulation of most small RNAs (sRNAs). Here, we show that Hfq undergoes RNA-dependent phase separation to form cytoplasmic or polar condensates of different density under normal and stress conditions, respectively. Purified Hfq forms droplets in the presence of crowding agents or RNA, indicating that its condensation is via heterotypic interactions. Stress-induced relocation of Hfq condensates and sRNAs to the poles depends on the pole-localizer TmaR. Phase separation of Hfq correlates with its ability to perform its posttranscriptional roles as sRNA-stabilizer and sRNA-mRNA matchmaker. Our study offers a spatiotemporal mechanism for sRNA-mediated regulation in response to environmental changes.
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Affiliation(s)
- Omer Goldberger
- Department of Microbiology and Molecular Genetics, IMRIC, The Hebrew University Faculty of Medicine, P.O. Box 12272, Jerusalem 91120, Israel
| | - Tamar Szoke
- Department of Microbiology and Molecular Genetics, IMRIC, The Hebrew University Faculty of Medicine, P.O. Box 12272, Jerusalem 91120, Israel
| | - Anat Nussbaum-Shochat
- Department of Microbiology and Molecular Genetics, IMRIC, The Hebrew University Faculty of Medicine, P.O. Box 12272, Jerusalem 91120, Israel
| | - Orna Amster-Choder
- Department of Microbiology and Molecular Genetics, IMRIC, The Hebrew University Faculty of Medicine, P.O. Box 12272, Jerusalem 91120, Israel.
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El Mouali Y, Ponath F, Scharrer V, Wenner N, Hinton JCD, Vogel J. Scanning mutagenesis of RNA-binding protein ProQ reveals a quality control role for the Lon protease. RNA (NEW YORK, N.Y.) 2021; 27:1512-1527. [PMID: 34497069 PMCID: PMC8594473 DOI: 10.1261/rna.078954.121] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 08/24/2021] [Indexed: 05/25/2023]
Abstract
The FinO-domain protein ProQ belongs to a widespread family of RNA-binding proteins (RBPs) involved in gene regulation in bacterial chromosomes and mobile elements. While the cellular RNA targets of ProQ have been established in diverse bacteria, the functionally crucial ProQ residues remain to be identified under physiological conditions. Following our discovery that ProQ deficiency alleviates growth suppression of Salmonella with succinate as the sole carbon source, an experimental evolution approach was devised to exploit this phenotype. By coupling mutational scanning with loss-of-function selection, we identified multiple ProQ residues in both the amino-terminal FinO domain and the variable carboxy-terminal region that are required for ProQ activity. Two carboxy-terminal mutations abrogated ProQ function and mildly impaired binding of a model RNA target. In contrast, several mutations in the FinO domain rendered ProQ both functionally inactive and unable to interact with target RNA in vivo. Alteration of the FinO domain stimulated the rapid turnover of ProQ by Lon-mediated proteolysis, suggesting a quality control mechanism that prevents the accumulation of nonfunctional ProQ molecules. We extend this observation to Hfq, the other major sRNA chaperone of enteric bacteria. The Hfq Y55A mutant protein, defective in RNA-binding and oligomerization, proved to be labile and susceptible to degradation by Lon. Taken together, our findings connect the major AAA+ family protease Lon with RNA-dependent quality control of Hfq and ProQ, the two major sRNA chaperones of Gram-negative bacteria.
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Affiliation(s)
- Youssef El Mouali
- Institute of Molecular Infection Biology (IMIB), University of Würzburg, D-97080 Würzburg, Germany
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), D-97080 Würzburg, Germany
| | - Falk Ponath
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), D-97080 Würzburg, Germany
| | - Vinzent Scharrer
- Institute of Molecular Infection Biology (IMIB), University of Würzburg, D-97080 Würzburg, Germany
| | - Nicolas Wenner
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, L7 3EA Liverpool, United Kingdom
| | - Jay C D Hinton
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, L7 3EA Liverpool, United Kingdom
| | - Jörg Vogel
- Institute of Molecular Infection Biology (IMIB), University of Würzburg, D-97080 Würzburg, Germany
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), D-97080 Würzburg, Germany
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Basu P, Altuvia S. RelA binding of mRNAs modulates translation or sRNA-mRNA basepairing depending on the position of the GGAG site. Mol Microbiol 2021; 117:143-159. [PMID: 34523176 DOI: 10.1111/mmi.14812] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 09/12/2021] [Accepted: 09/12/2021] [Indexed: 11/26/2022]
Abstract
Previously, we reported that RelA protein facilitates Hfq-mediated mRNA-sRNA regulation by binding sRNAs carrying a Shine-Dalgarno-like GGAG sequence. In turn, sRNA-Hfq monomers are stabilized, enabling the attachment of more Hfq subunits to form a functional hexamer. Here, using CLIP-seq, we present a global analysis of RelA-bound RNAs showing that RelA interacts with sRNAs as well as with mRNAs carrying a GGAG motif. RelA binding of mRNAs carrying GGAG at position -7 relative to the initiation codon (AUG) inhibits translation by interfering with the binding of 30S ribosomes. The extent of inhibition depends on the distance of GGAG relative to the AUG, as shortening the spacing between GGAG and AUG abrogates RelA-mediated inhibition. Interestingly, RelA binding of target mRNAs carrying GGAG in the coding sequence or close to AUG facilitates target gene regulation by sRNA partners that lack GGAG. However, translation inhibition caused by RelA binding of mRNAs carrying GGAG at position -7 relative to the AUG renders sRNA-mRNA basepairing regulation ineffective. Our study indicates that by binding RNAs carrying GGAG the ribosome-associated RelA protein inhibits translation of specific newly synthesized incoming mRNAs or enables basepairing regulation by their respective sRNA partners, thereby introducing a new regulatory concept for the bacterial response.
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Affiliation(s)
- Pallabi Basu
- Department of Microbiology and Molecular Genetics, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Shoshy Altuvia
- Department of Microbiology and Molecular Genetics, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
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The RNA Chaperone Hfq Participates in Persistence to Multiple Antibiotics in the Fish Pathogen Yersinia ruckeri. Microorganisms 2021; 9:microorganisms9071404. [PMID: 34209738 PMCID: PMC8308036 DOI: 10.3390/microorganisms9071404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Revised: 06/11/2021] [Accepted: 06/25/2021] [Indexed: 11/16/2022] Open
Abstract
Yersinia ruckeri causes outbreaks of enteric redmouth disease in salmon aquaculture all over the world. The transient antibiotic tolerance exhibited by bacterial persisters is commonly thought to be responsible for outbreaks; however, the molecular factors underlying this behavior have not been explored in Y. ruckeri. In this study, we investigated the participation of the RNA chaperone Hfq from Y. ruckeri in antibiotic persistence. Cultures of the hfq-knockout mutant (Δhfq) exhibited faster replication, increased ATP levels and a more reductive environment than the wild type. The growth curves of bacteria exposed to sublethal concentrations of ampicillin, oxolinic acid, ciprofloxacin and polymyxin B revealed a greater susceptibility for the Δhfq strain. The time-kill curves of bacteria treated with the antibiotics mentioned above and florfenicol, using inoculums from exponential, stationary and biofilm cultures, demonstrated that the Δhfq strain has significant defects in persister cells production. To shed more light on the role of Hfq in antibiotic persistence, we analyzed its dependence on the (p)ppGpp synthetase RelA by determining the persister cells production in the absence of the relA gene. The ΔrelA and ΔrelAΔhfq strains displayed similar defects in persister cells formation, but higher than Δhfq strain. Similarly, stationary cultures of the ΔrelA and ΔrelAΔhfq strains exhibited comparable levels of ATP but higher than that of the Δhfq strain, indicating that relA is epistatic over hfq. Taken together, our findings provide valuable information on antibiotic persistence in Y. ruckeri, shedding light on the participation of Hfq in the persistence phenomenon.
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