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Project description:Both prokaryotic and eukaryotic RNAs can be 5'-capped by the metabolite nicotinamide adenine dinucleotide (NAD). Nudix hydrolases, such as bacterial NudC, specifically remove NAD-caps; however, the molecular and cellular functions of these epitranscriptomic modulators remain elusive. Here, we discuss the roles of NudC under stress conditions and the effects of extracellular cues on the NAD epitranscriptome. Our proteome-wide analysis detected the proteins associated with the RNA degradosome as well as ribosomes and stress-responsive proteins in a NudC interactome. Moreover, we confirmed the physical association of NudC with the cold shock DEAD-box RNA helicase CsdA and the RNA chaperone Hfq. Interestingly, knocking out csdA similar to ∆nudC leads to an increased number of identified 5'-NAD-RNA species compared to wild type, exposing CsdA as a new player in a potentially unexplored layer of NAD-epitranscriptomic landscape. Mass spectrometry analysis also revealed the drastic up-regulation of 5'-NAD-RNA in response to cold. Furthermore, the inactivation of NudC in bacteria changes the levels of sRNA and protein-coding transcripts associated with bacterial chemotaxis and flagellar assembly pathways. We experimentally demonstrate that the decapping hydrolase NudC suppresses the flagellar movement, while CsdA stimulates it. Thus, the interplay between NudC and CsdA regulates bacterial mobility and coordinates stress-avoidance behavior. IMPORTANCE Non-canonical 5'-caps removing RNA hydrolase NudC, along with stress-responsive RNA helicase CsdA, is crucial for 5'-NAD-RNA decapping and bacterial movement.
| S-EPMC10654059 | biostudies-literature
Project description:Nicotinamide adenine dinucleotide (NAD) "cap" recently discovered in bacteria could have similar functions as eukaryotic 7-methylguanine (m7G) "cap", which protects RNA 5'-terminus from degradation and mediates RNA interactions with proteins involved in its transportation, editing and translation. The only known 5'-NAD-RNA-interacting E. coli protein is Nudix superfamily hydrolase NudC which is responsible for this "cap" hydrolysis. We conducted the search for NudC-interacting proteins and discovered that in vivo and in vitro NudC interacts with RNA helicase DeaD. We also discovered using bacterial two hybrid system that N-terminal parts of both proteins are involved in this interaction, particularly the N-terminal domain and zinc finger motif of NudC and RecA1, RecA2 and dimerization domains of DeaD. Detailed investigation on the hydrolase interactome revealed NudC contacts with at least three proteins involved in formation of RNA degradosome complex, DeaD, Hfq and PNPase, under stress conditions raising the idea that NudC could also function within the RNA degradosome. On the other hand, NudC together with DeaD interacts with 70S ribosome proteins. Thus, NudC is closely related to protein synthesis in ribosomes. Finally, since at least six NudC-interacting partners are involved in cell stress response we think that the helicase could play important role by moduling the cell conditions in response to environment changes.
2022-07-10 | MSV000089861 | MassIVE
Project description:Interplay between bacterial RNA 5'-termini deNADding protein NudC and DEAD-box RNA helicase CsdA in stress-responses
| PRJNA931943 | ENA
Project description:DEAD-box proteins comprise a large protein family with members from all kingdoms and play important roles in all types of processes in RNA metabolism. In this study, a rice gene OsBIRH1, which encodes a DEAD-box RNA helicase protein, was cloned and characterized. The predicted OsBIRH1 protein contains a DEAD domain and all conserved motifs that are common characteristics of DEAD-box RNA helicases. Recombinant OsBIRH1 protein purified from Escherichia coli was shown to have both RNA-dependent ATPase and ATP-dependent RNA helicase activities in vitro. Expression of OsBIRH1 was activated in rice seedling leaves after treatment with defence-related signal chemicals, for example benzothiadiazole, salicylic acid, l-aminocyclopropane-1-carboxylic acid, and jasmonic acid, and was also up-regulated in an incompatible interaction between a resistant rice genotype and the blast fungus, Magnaporthe grisea. Transgenic Arabidopsis plants that overexpress the OsBIRH1 gene were generated. Disease resistance phenotype assays revealed that the OsBIRH1-overexpressing transgenic plants showed an enhanced disease resistance against Alternaria brassicicola and Pseudomonas syringae pv. tomato DC3000. Meanwhile, defence-related genes, for example PR-1, PR-2, PR-5, and PDF1.2, showed an up-regulated expression in the transgenic plants. Moreover, the OsBIRH1 transgenic Arabidopsis plants also showed increased tolerance to oxidative stress and elevated expression levels of oxidative defence genes, AtApx1, AtApx2, and AtFSD1. The results suggest that OsBIRH1 encodes a functional DEAD-box RNA helicase and plays important roles in defence responses against biotic and abiotic stresses.
| S-EPMC2413282 | biostudies-literature
Project description:RNA helicases represent a large family of proteins implicated in many biological processes including ribosome biogenesis, splicing, translation and mRNA degradation. However, these proteins have little substrate specificity, making inhibition of selected helicases a challenging problem. The prototypical DEAD box RNA helicase, eIF4A, works in conjunction with other translation factors to prepare mRNA templates for ribosome recruitment during translation initiation. Herein, we provide insight into the selectivity of a small molecule inhibitor of eIF4A, hippuristanol. This coral-derived natural product binds to amino acids adjacent to, and overlapping with, two conserved motifs present in the carboxy-terminal domain of eIF4A. Mutagenesis of amino acids within this region allowed us to alter the hippuristanol-sensitivity of eIF4A and undertake structure/function studies. Our results provide an understanding into how selective targeting of RNA helicases for pharmacological intervention can be achieved.
| S-EPMC2216682 | biostudies-literature
Project description:We have shown previously that CrhC is a unique member of the DEAD-box family of RNA helicases whose expression occurs specifically under conditions of cold stress. Here we show that recombinant His-tagged CrhC, purified from Escherichia coli, is an ATP-independent RNA binding protein possessing RNA-dependent ATPase activity which is stimulated most efficiently by rRNA and polysome preparations. RNA strand displacement assays indicate that CrhC possesses RNA unwinding activity that is adenosine nucleotide specific. Unwinding of partially duplexed RNA proceeds in the 5'-->3' but not the 3'-->5' direction using standard assay conditions. Immunoprecipitation and far-western analysis indicate that CrhC is a component of a multisubunit complex, interacting specifically with a 37 kDa polypeptide. We propose that CrhC unwinds cold-stabilized secondary structure in the 5'-UTR of RNA during cold stress.
| S-EPMC110790 | biostudies-literature
Project description:DDX3 is a member of the family of DEAD-box RNA helicases. DDX3 is a multifaceted helicase and plays essential roles in key biological processes such as cell cycle, stress response, apoptosis, and RNA metabolism. In this study, we found that DDX3 interacted with ALKBH5, an m6A RNA demethylase. The ATP domain of DDX3 and DSBH domain of ALKBH5 were indispensable to their interaction with each other. Furthermore, DDX3 could modulate the demethylation of mRNAs. We also showed that DDX3 regulated the methylation status of microRNAs and there was an interaction between DDX3 and AGO2. The dynamics of m6A RNA modification is still a field demanding further investigation, and here, we add a link by showing that RNA demethylation can be regulated by proteins such as DDX3.
| S-EPMC5733242 | biostudies-literature
Project description:MDM2 mediates the ubiquitylation and thereby triggers the proteasomal degradation of the tumor suppressor protein p53. However, genetic evidence suggests that MDM2 contributes to multiple regulatory networks independently of p53 degradation. We have now identified the DEAD-box RNA helicase DDX24 as a nucleolar protein that interacts with MDM2. DDX24 was found to bind to the central region of MDM2, resulting in the polyubiquitylation of DDX24 both in vitro and in vivo. Unexpectedly, however, the polyubiquitylation of DDX24 did not elicit its proteasomal degradation but rather promoted its association with preribosomal ribonucleoprotein (pre-rRNP) processing complexes that are required for the early steps of pre-rRNA processing. Consistently with these findings, depletion of DDX24 in cells impaired pre-rRNA processing and resulted both in abrogation of MDM2 function and in consequent p53 stabilization. Our results thus suggest an unexpected role of MDM2 in the nonproteolytic ubiquitylation of DDX24, which may contribute to the regulation of pre-rRNA processing.
| S-EPMC4135551 | biostudies-literature
Project description:Tissue homeostasis is critical for maintaining organ shape, size, and function. The condition is regulated by the balance between the generation of new cells and the loss of senescent cells, and it involves many factors and mechanisms. The midgut, an important part of the intestinal tract, is responsible for digestion and nutrient absorption in insects. LmDDX47, the ortholog of DEAD-box helicase 47 from Locusta migratoria, is indispensable for sustaining a normal midgut in the nymphs. However, the underlying cellular and molecular mechanisms remain to be elucidated. In this study, LmDDX47 knockdown resulted in atrophy of the midgut and gastric cecum in both nymph and adult locusts. After LmDDX47 knockdown, the number of regenerative and columnar cells in the midgut was significantly reduced, and cell death was induced in columnar tissue. LmDDX47 was localized to the nucleolus; this was consistent with the reduction in 18S rRNA synthesis in the LmDDX47 knockdown group. In addition, the acetylation and crotonylation levels of midgut proteins were significantly increased. Therefore, LmDDX47 could be a key regulator of midgut homeostasis, regulating 18S rRNA synthesis as well as protein acetylation and crotonylation in the migratory locust.
| S-EPMC8775783 | biostudies-literature
Project description:During eukaryotic translation initiation, the small ribosomal subunit, assisted by initiation factors, locates the messenger RNA start codon by scanning from the 5' cap. This process is powered by the eukaryotic initiation factor 4A (eIF4A), a DEAD-box helicase. eIF4A has been thought to unwind structures formed in the untranslated 5' region via a nonprocessive mechanism. Using a single-molecule assay, we found that eIF4A functions instead as an adenosine triphosphate-dependent processive helicase when complexed with two accessory proteins, eIF4G and eIF4B. Translocation occurred in discrete steps of 11 ± 2 base pairs, irrespective of the accessory factor combination. Our findings support a memory-less stepwise mechanism for translation initiation and suggest that similar factor-dependent processivity may be shared by other members of the DEAD-box helicase family.
| S-EPMC4605566 | biostudies-literature