The properties of the RNA-binding protein NF90 are considerably modulated by complex formation with NF45

2017 ◽  
Vol 474 (2) ◽  
pp. 259-280 ◽  
Author(s):  
Tobias Schmidt ◽  
Paul Knick ◽  
Hauke Lilie ◽  
Susann Friedrich ◽  
Ralph Peter Golbik ◽  
...  

Nuclear factor 90 (NF90) is an RNA-binding protein (RBP) that regulates post-transcriptionally the expression of various mRNAs. NF90 was recently shown to be capable of discriminating between different RNA substrates. This is mediated by an adaptive and co-operative interplay between three RNA-binding motifs (RBMs) in the protein's C-terminus. In many cell types, NF90 exists predominantly in a complex with NF45. Here, we compared the RNA-binding properties of the purified NF90 monomer and the NF90–NF45 heterodimer by biophysical and biochemical means, and demonstrate that the interaction with NF45 considerably affects the characteristics of NF90. Along with a thermodynamic stabilization, complex formation substantially improves the RNA-binding capacity of NF90 by modulating its binding mode and by enhancing its affinity for single- and double-stranded RNA substrates. Our data suggest that features of both the N- and C-termini of NF90 participate in the heterodimerization with NF45 and that the formation of NF90–NF45 changes the conformation of NF90's RBMs to a status in which the co-operative interplay of the RBMs is optimal. NF45 is considered to act as a conformational scaffold for NF90's RBMs, which alters the RNA-binding specificity of NF90. Accordingly, the monomeric NF90 and the NF90–NF45 heterodimer may exert different functions in the cell.

1994 ◽  
Vol 14 (12) ◽  
pp. 8399-8407 ◽  
Author(s):  
J Flach ◽  
M Bossie ◽  
J Vogel ◽  
A Corbett ◽  
T Jinks ◽  
...  

RNA-binding proteins have been suggested to move in association with RNA as it leaves the nucleus. The NPL3 gene of the yeast Saccharomyces cerevisiae encodes in nuclear protein with consensus RNA-binding motifs and similarity to heterogeneous nuclear ribonucleoproteins and members of the S/R protein family. We show that although Npl3 is located in the nucleus, it can shuttle between nuclei in yeast heterokaryons. In contrast, other nucleus-targeted proteins do not leave the nucleus under similar conditions. Mutants missing the RNA-binding motifs or the N terminus are still capable of shuttling in and out of the nucleus. Npl3 mutants missing the C terminus fail to localize to the nucleus. Overproduction of Npl3 in wild-type cells shows cell growth. This toxicity depends on the presence of series of unique repeats in the N terminus and localization to the nucleus. We suggest that the properties of Npl3 are consistent with it being involved in export of RNAs from the nucleus.


2001 ◽  
Vol 183 (20) ◽  
pp. 6017-6027 ◽  
Author(s):  
Seshagirirao Gudapaty ◽  
Kazushi Suzuki ◽  
Xin Wang ◽  
Paul Babitzke ◽  
Tony Romeo

ABSTRACT The global regulator CsrA (carbon storage regulator) ofEscherichia coli is a small RNA binding protein that represses various metabolic pathways and processes that are induced in the stationary phase of growth, while it activates certain exponential phase functions. Both repression and activation by CsrA involve posttranscriptional mechanisms, in which CsrA binding to mRNA leads to decreased or increased transcript stability, respectively. CsrA also binds to a small untranslated RNA, CsrB, forming a ribonucleoprotein complex, which antagonizes CsrA activity. We have further examined the regulatory interactions of CsrA and CsrB RNA. The 5′ end of the CsrB transcript was mapped, and acsrB::cam null mutant was constructed. CsrA protein and CsrB RNA levels were estimated throughout the growth curves of wild-type and isogenic csrA,csrB, rpoS, or csrA rpoSmutant strains. CsrA levels exhibited modest or negligible effects of these mutations. The intracellular concentration of CsrA exceeded the total CsrA-binding capacity of intracellular CsrB RNA. In contrast, CsrB levels were drastically decreased (∼10-fold) in thecsrA mutants. CsrB transcript stability was unaffected by csrA. The expression of a csrB-lacZtranscriptional fusion containing the region from −242 to +4 bp of thecsrB gene was decreased ∼20-fold by acsrA::kanR mutation in vivo but was unaffected by CsrA protein in vitro. These results reveal a significant, though most likely indirect, role for CsrA in regulatingcsrB transcription. Furthermore, our findings suggest that CsrA mediates an intriguing form of autoregulation, whereby its activity, but not its levels, is modulated through effects on an RNA antagonist, CsrB.


Author(s):  
Jasmine Cubuk ◽  
Jhullian J. Alston ◽  
J. Jeremías Incicco ◽  
Sukrit Singh ◽  
Melissa D. Stuchell-Brereton ◽  
...  

AbstractThe SARS-CoV-2 nucleocapsid (N) protein is an abundant RNA binding protein critical for viral genome packaging, yet the molecular details that underlie this process are poorly understood. Here we combine single-molecule spectroscopy with all-atom simulations to uncover the molecular details that contribute to N protein function. N protein contains three dynamic disordered regions that house putative transiently-helical binding motifs. The two folded domains interact minimally such that full-length N protein is a flexible and multivalent RNA binding protein. N protein also undergoes liquid-liquid phase separation when mixed with RNA, and polymer theory predicts that the same multivalent interactions that drive phase separation also engender RNA compaction. We offer a simple symmetry-breaking model that provides a plausible route through which single-genome condensation preferentially occurs over phase separation, suggesting that phase separation offers a convenient macroscopic readout of a key nanoscopic interaction.


2018 ◽  
Author(s):  
Yanping Han ◽  
Dong Chen ◽  
Yanfeng Yan ◽  
Hongduo Wang ◽  
Zizhong Liu ◽  
...  

ABSTRACTHfq is a ubiquitous Sm-like RNA binding protein in bacteria involved in physiological fitness and pathogenesis, while its in vivo binding natures still remain elusive. Here we reported the first study of the Hfq-bound RNAs map in Yersinia pestis, the causative agent of a kind of plague, by using Cross-Linking Immunoprecipitation coupled with deep sequencing (CLIP-Seq) approach. We show that Hfq binds over 80% mRNAs of Y. pestis, and also globally binds non-coding sRNAs encoded by the intergenic, antisense, and the 3’ regions of mRNAs. Hfq U-rich stretch is highly enriched in sRNAs, while motifs partially complementary to AGAAUAA and GGGGAUUA are enriched in both mRNAs and sRNAs. Hfq binding motifs are enriched at both terminal sites and in the gene body of mRNAs. Surprisingly, a large fraction of the sRNA and mRNA regions bound by Hfq and those downstream are destabilized, likely via a 5’P-activated RNase E degradation pathway and consistent with Hfq-facilitated sRNA-mRNA base-pairing and the coupled degradation in Y. pestis. These results together have presented a high-quality Hfq-RNA interaction map in Y. pestis, which should be important for further deciphering the regulatory role of Hfq-sRNAs in Y. pestis.AUTHOR SUMMARYDiscovered in 1968 as an Escherichia coli host factor that was essential for replication of the bacteriophage Qβ, the Hfq protein is a ubiquitous and highly abundant RNA binding protein in many bacteria. Under the assistance of Hfq, small RNAs in bacteria play important role in regulating the stability and translation of mRNAs by base-pairing. In this study, we want to elucidate the Hfq assisted sRNA-mRNA regulation in Yersinia pestis. A global map of Hfq interaction sites in Y. pestis was obtained by sequencing of cDNAs converted from the Hfq-bound RNA fragments using UV cross-linking coupled immunoprecipitation technology. We demonstrate that Hfq could hundreds of sRNAs and the majority of mRNAs in living Y. pestis. The enriched binding motifs in sRNAs and mRNA are significantly complementary to each other, suggesting a general base-pairing mechanism for sRNA-mRNA interaction. The Hfq-bound sRNA and mRNA regions were both destabilized. The results suggest that Hfq binding facilitates sRNA-mRNA base-pairing and coordinates their degradation, which might enable Hfq to surveil the hemostasis of most mRNAs in bacteria.


2020 ◽  
Author(s):  
Kristina Sakers ◽  
Yating Liu ◽  
Lorida Llaci ◽  
Michael J. Vasek ◽  
Michael A. Rieger ◽  
...  

AbstractQuaking RNA binding protein(QKI) is essential for oligodendrocyte development as myelination requires MBP mRNA regulation and localization by the cytoplasmic isoforms(e.g. QKI-6). QKI-6 is also highly expressed in astrocytes, which were recently demonstrated to have regulated mRNA localization. Here, we show via CLIPseq that QKI-6 binds 3’ UTRs of a subset of astrocytic mRNAs, including many enriched in peripheral processes. Binding is enriched near stop codons, which is mediated partially by QKI binding motifs(QBMs) yet spreads to adjacent sequences. We developed CRISPR TRAPseq: a viral approach for mosaic, cell-type specific gene mutation with simultaneous translational profiling. This enabled study of QKI-deleted astrocytes in an otherwise normal brain. Astrocyte-targeted QKI deletion altered translation and maturation, while also increasing synaptic density within the astrocyte’s territory. Overall, our data indicate QKI is required for astrocyte maturation and demonstrate an approach for a highly targeted translational assessment of gene knockout in specific cell-types in vivo.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kristina Sakers ◽  
Yating Liu ◽  
Lorida Llaci ◽  
Scott M. Lee ◽  
Michael J. Vasek ◽  
...  

AbstractQuaking RNA binding protein (QKI) is essential for oligodendrocyte development as myelination requires myelin basic protein mRNA regulation and localization by the cytoplasmic isoforms (e.g., QKI-6). QKI-6 is also highly expressed in astrocytes, which were recently demonstrated to have regulated mRNA localization. Here, we define the targets of QKI in the mouse brain via CLIPseq and we show that QKI-6 binds 3′UTRs of a subset of astrocytic mRNAs. Binding is also enriched near stop codons, mediated partially by QKI-binding motifs (QBMs), yet spreads to adjacent sequences. Using a viral approach for mosaic, astrocyte-specific gene mutation with simultaneous translating RNA sequencing (CRISPR-TRAPseq), we profile ribosome associated mRNA from QKI-null astrocytes in the mouse brain. This demonstrates a role for QKI in stabilizing CLIP-defined direct targets in astrocytes in vivo and further shows that QKI mutation disrupts the transcriptional changes for a discrete subset of genes associated with astrocyte maturation.


1994 ◽  
Vol 14 (12) ◽  
pp. 8399-8407
Author(s):  
J Flach ◽  
M Bossie ◽  
J Vogel ◽  
A Corbett ◽  
T Jinks ◽  
...  

RNA-binding proteins have been suggested to move in association with RNA as it leaves the nucleus. The NPL3 gene of the yeast Saccharomyces cerevisiae encodes in nuclear protein with consensus RNA-binding motifs and similarity to heterogeneous nuclear ribonucleoproteins and members of the S/R protein family. We show that although Npl3 is located in the nucleus, it can shuttle between nuclei in yeast heterokaryons. In contrast, other nucleus-targeted proteins do not leave the nucleus under similar conditions. Mutants missing the RNA-binding motifs or the N terminus are still capable of shuttling in and out of the nucleus. Npl3 mutants missing the C terminus fail to localize to the nucleus. Overproduction of Npl3 in wild-type cells shows cell growth. This toxicity depends on the presence of series of unique repeats in the N terminus and localization to the nucleus. We suggest that the properties of Npl3 are consistent with it being involved in export of RNAs from the nucleus.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jasmine Cubuk ◽  
Jhullian J. Alston ◽  
J. Jeremías Incicco ◽  
Sukrit Singh ◽  
Melissa D. Stuchell-Brereton ◽  
...  

AbstractThe SARS-CoV-2 nucleocapsid (N) protein is an abundant RNA-binding protein critical for viral genome packaging, yet the molecular details that underlie this process are poorly understood. Here we combine single-molecule spectroscopy with all-atom simulations to uncover the molecular details that contribute to N protein function. N protein contains three dynamic disordered regions that house putative transiently-helical binding motifs. The two folded domains interact minimally such that full-length N protein is a flexible and multivalent RNA-binding protein. N protein also undergoes liquid-liquid phase separation when mixed with RNA, and polymer theory predicts that the same multivalent interactions that drive phase separation also engender RNA compaction. We offer a simple symmetry-breaking model that provides a plausible route through which single-genome condensation preferentially occurs over phase separation, suggesting that phase separation offers a convenient macroscopic readout of a key nanoscopic interaction.


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