scholarly journals Characterization of the nucleic acid-binding activity of the avian reovirus non-structural protein σNS

2005 ◽  
Vol 86 (4) ◽  
pp. 1159-1169 ◽  
Author(s):  
Fernando Tourís-Otero ◽  
José Martínez-Costas ◽  
Vikram N. Vakharia ◽  
Javier Benavente

The avian reovirus non-structural protein σNS has previously been shown to bind single-stranded (ss) RNA in vitro in a sequence-independent manner. The results of the present study further reveal that σNS binds poly(A), poly(U) and ssDNA, but not poly(C), poly(G) or duplex nucleic acids, suggesting that σNS has some nucleotide-sequence specificity for ssRNA binding. The current findings also show that σNS is present in large ribonucleoprotein complexes in the cytoplasm of avian reovirus-infected cells, indicating that it exists in intimate association with ssRNAs in vivo. Removal of RNA from the complexes generates a σNS protein form that sediments between 4·5 and 7 S, suggesting that RNA-free σNS associates into small oligomers. Expression and purification of recombinant σNS in insect cells allowed us to generate specific antibodies and to perform a variety of assays. The results of these assays revealed that: (i) RNA-free σNS exists as homodimers and homotrimers; (ii) the minimum RNA size for σNS binding is between 10 and 20 nt; (iii) σNS does not have a preference for viral mRNA sequences; and (iv) its RNA-binding activity is conformation-dependent. Baculovirus expression of point and deletion σNS mutants in insect cells showed that the five conserved basic amino acids that are important for RNA binding and ribonucleoprotein-complex formation are dispersed throughout the entire σNS sequence, suggesting that this protein binds ssRNA through conformational domains. Finally, the properties of the avian reovirus protein σNS are compared with those of its mammalian reovirus counterpart.

1997 ◽  
Vol 17 (7) ◽  
pp. 3915-3923 ◽  
Author(s):  
F Bringaud ◽  
R Stripecke ◽  
G C Frech ◽  
S Freedland ◽  
C Turck ◽  
...  

To identify specific proteins interacting with guide RNAs (gRNAs) in mitochondrial ribonucleoprotein complexes from Leishmania tarentolae, fractionated and unfractionated mitochondrial extracts were subjected to UV cross-linking with added labeled gRNA and also with [alpha-32P]UTP-labeled endogenous RNA. An abundant 110-kDa protein (p110) localized in the T-V complex, which sediments in glycerol gradients at the leading edge of the 10S terminal uridylyltransferase peak, was found to interact with both types of labeled RNAs. The p110 protein was gel isolated and subjected to microsequence analysis, and the gene was cloned. The sequence revealed significant similarity with mitochondrial glutamate dehydrogenases. A polyclonal antiserum was raised against a recombinant fragment of the p110 gene and was used to demonstrate a stable and specific gRNA-binding activity by coimmunoprecipitation and competitive gel shift analyses. Complex formation was strongly inhibited by competition with poly(U) or by deletion or substitution of the gRNA 3' oligo(U) tail. Also, addition of a 3' oligo(U) tail to an unrelated transcript was sufficient for p110 binding. Both the gRNA-binding activity of the p110 protein and in vitro gRNA-independent and gRNA-dependent uridine insertion activities in the mitochondrial extract were inhibited by high concentrations of dinucleotides.


2005 ◽  
Vol 86 (1) ◽  
pp. 225-229 ◽  
Author(s):  
Masamichi Isogai ◽  
Nobuyuki Yoshikawa

The RNA-binding properties of the cell-to-cell movement protein (MP) of Apple chlorotic leaf spot virus were analysed. MP was expressed in Escherichia coli and was used in UV-crosslinking analysis, using a digoxigenin–UTP-labelled RNA probe and gel-retardation analysis. The analyses demonstrated that MP bound cooperatively to single-stranded RNA (ssRNA). When analysed for NaCl dependence of the RNA-binding activity, the majority of the MP could bind ssRNA even in binding buffer with 1 M NaCl. Furthermore, competition binding experiments showed that the MP bound preferentially to ssRNA and single-stranded DNA without sequence specificity. MP deletion mutants were used to identify the RNA-binding domain by UV-crosslinking analysis. Amino acid residues 82–126 and 127–287 potentially contain two independently active, single-stranded nucleic acid-binding domains.


Author(s):  
Yanisa Laoong-u-thai ◽  
Warapond Wanna ◽  
Autaipohn Kaikaew

Shrimp farming is an important business in Thailand and worldwide. The study of molecular biology and biochemical pathway of the key molecules controlling muscle growth is an essential to improve shrimp livestock. Profilin is a pivotal protein in muscle formation, especially actin protein. Its nuclear function has been reported in many species for gene regulation. Here in this work, we characterized the function of LvProfilin, a marine shrimp profilin from Litopenaeus vannamei, both in silico and in vitro. The phylogenetic tree of LvProfilin among organisms and its 3D protein structure showed that LvProfilin was highly conserved among shrimp and arthropods. The homology modeling of its 3D structure revealed 3 alpha-helices and 6 beta-strands similar to most eukaryotic profilins. To interpret its possible function, the gene expression of LvProfilin in various tissues was performed. We found that this gene was expressed in various tissues. This result may imply that LvProfilin could share a common function in all tissues. Nuclear activity has been a promising function of LvProfilin. We performed a DNA/RNA binding prediction analysis using DRNApred. The result indicated that Lysine-90 and Threonine-91 were the putative DNA-binding sites with the probability of 63.12% and 54.16%, respectively. Its binding activity was confirmed in vitro which bound stronger to single strand DNA than double strand DNA. To our best knowledge, this is the first report of DNA binding activity of profilin in invertebrates.


1991 ◽  
Vol 11 (7) ◽  
pp. 3419-3424 ◽  
Author(s):  
C G Burd ◽  
E L Matunis ◽  
G Dreyfuss

The poly(A)-binding protein (PABP) is the major mRNA-binding protein in eukaryotes, and it is essential for viability of the yeast Saccharomyces cerevisiae. The amino acid sequence of the protein indicates that it consists of four ribonucleoprotein consensus sequence-containing RNA-binding domains (RBDs I, II, III, and IV) and a proline-rich auxiliary domain at the carboxyl terminus. We produced different parts of the S. cerevisiae PABP and studied their binding to poly(A) and other ribohomopolymers in vitro. We found that none of the individual RBDs of the protein bind poly(A) specifically or efficiently. Contiguous two-domain combinations were required for efficient RNA binding, and each pairwise combination (I/II, II/III, and III/IV) had a distinct RNA-binding activity. Specific poly(A)-binding activity was found only in the two amino-terminal RBDs (I/II) which, interestingly, are dispensable for viability of yeast cells, whereas the activity that is sufficient to rescue lethality of a PABP-deleted strain is in the carboxyl-terminal RBDs (III/IV). We conclude that the PABP is a multifunctional RNA-binding protein that has at least two distinct and separable activities: RBDs I/II, which most likely function in binding the PABP to mRNA through the poly(A) tail, and RBDs III/IV, which may function through binding either to a different part of the same mRNA molecule or to other RNA(s).


Methods ◽  
2017 ◽  
Vol 118-119 ◽  
pp. 171-181 ◽  
Author(s):  
Tzu-Fang Lou ◽  
Chase A. Weidmann ◽  
Jordan Killingsworth ◽  
Traci M. Tanaka Hall ◽  
Aaron C. Goldstrohm ◽  
...  

2005 ◽  
Vol 79 (15) ◽  
pp. 10023-10031 ◽  
Author(s):  
Jens Modrof ◽  
Kostas Lymperopoulos ◽  
Polly Roy

ABSTRACT In bluetongue virus (BTV)-infected cells, large cytoplasmic aggregates are formed, termed viral inclusion bodies (VIBs), which are believed to be the sites of viral replication and morphogenesis. The BTV nonstructural protein NS2 is the major component of VIBs. NS2 undergoes intracellular phosphorylation and possesses a strong single-stranded RNA binding activity. By changing phosphorylated amino acids to alanines and aspartates, we have mapped the phosphorylated sites of NS2 to two serine residues at positions 249 and 259. Since both of these serines are within the context of protein kinase CK2 recognition signals, we have further examined if CK2 is involved in NS2 phosphorylation by both intracellular colocalization and an in vitro phosphorylation assay. In addition, we have utilized the NS2 mutants to determine the role of phosphorylation on NS2 activities. The data obtained demonstrate that NS2 phosphorylation is not necessary either for its RNA binding properties or for its ability to interact with the viral polymerase VP1. However, phosphorylated NS2 exhibited VIB formation while unmodified NS2 failed to assemble as VIBs although smaller oligomeric forms of NS2 were readily formed. Our data reveal that NS2 phosphorylation controls VIBs formation consistent with a model in which NS2 provides the matrix for viral assembly.


2019 ◽  
Author(s):  
Linjiang Yang ◽  
Mingshu Wang ◽  
Chunhui Zeng ◽  
Yong Shi ◽  
Anchun Cheng ◽  
...  

Abstract Background pUL21 is a conserved protein of Alphaherpesvirinae that performs multiple important functions. The C-terminus of pUL21 in other members of this subfamily has RNA-binding ability; this domain contributes to pseudorabies virus (PRV) retrograde axonal transport in vitro and in vivo and participates in newly replicated viral DNA packaging and intracellular virus transport. However, knowledge regarding duck enteritis virus (DEV) pUL21 is limited. Methods In our study, recombinant pUL21 was expressed using an pET-32c (+) vector in Escherichia coli BL21 cells induced with 0.4 mM isopropyl β-D-thiogalactoside for 8 h at 30°C. The antibody used for the indirect immunofluorescence (IFA) and western blotting (WB) analysis were prepared. Pharmacological inhibition, WB and quantitative reverse transcription PCR (RT-qPCR) were performed. A coimmunoprecipitation (CO-IP) assay was conducted to test the interaction between pUL21 and pUL16. Results We verified that DEV UL21 is a γ2 gene that encodes a structural protein. Moreover, we observed that pUL21 localized to the nucleus and cytoplasm. DEV pUL21 interacted with pUL16 and formed a complex in transfected human embryonic kidney (HEK) 293T cells and DEV-infected duck embryo fibroblasts (DEFs). These results were further confirmed by CO-IP assays. Conclusions The DEV UL21 gene is a late gene, and pUL21 localizes to the nucleus and cytoplasm. DEV UL21 is a virion component. In addition, pUL21 can interact with pUL16. These findings provide insight into the characteristics of UL21 and the interaction between pUL21 and its binding partner pUL16. Our study enhances the understanding of DEV pUL21. Keywords: Duck enteritis virus, UL21, UL16, late gene, interaction


2017 ◽  
Author(s):  
Kimberly A. Stanek ◽  
Cameron Mura

AbstractHfq is a bacterial RNA-binding protein that plays key roles in the post–transcriptional regulation of gene expression. Like other Sm proteins, Hfq assembles into toroidal discs that bind RNAs with varying affinities and degrees of sequence specificity. By simultaneously binding to a regulatory small RNA (sRNA) and an mRNA target, Hfq hexamers facilitate productive RNA⋯RNA interactions; the generic nature of this chaperone-like functionality makes Hfq a hub in many sRNA-based regulatory networks. That Hfq is crucial in diverse cellular pathways—including stress response, quorum sensing and biofilm formation— has motivated genetic and ‘RNAomic’ studies of its function and physiology (in vivo), as well as biochemical and structural analyses of Hfq⋯RNA interactions (in vitro). Indeed, crystallographic and bio-physical studies first established Hfq as a member of the phylogenetically-conserved Sm superfamily. Crystallography and other biophysical methodologies enable the RNA-binding properties of Hfq to be elucidated in atomic detail, but such approaches have stringent sample requirements, viz.: reconstituting and characterizing an Hfq•RNA complex requires ample quantities of well-behaved (sufficient purity, homogeneity) specimens of Hfq and RNA (sRNA, mRNA fragments, short oligoribonucleotides, or even single nucleotides). The production of such materials is covered in this Chapter, with a particular focus on recombinant Hfq proteins for crystallization experiments.Abbreviations3Dthree-dimensionalAUasymmetric unitCVcolumn volumeDEPCdiethyl pyrocarbonateHDVhepatitis δ virusHDVDhanging-drop vapor diffusionIMACimmobilized metal affinity chromatographyMWmolecular weightMWCOmolecular weight cut-offntnucleotidePDBProtein Data BankRNPribonucleoproteinRTroom temperatureSDVDsitting-drop vapor diffusionJournal formatMethods in Molecular Biology (Springer Protocols series); this volume is entitled “Bacterial Regulatory RNA: Methods and Protocols”; an author guide is linked at http://www.springer.com/series/7651


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