Domain necessary for Drosophila ELAV nuclear localization: function requires nuclear ELAV

1999 ◽  
Vol 112 (24) ◽  
pp. 4501-4512 ◽  
Author(s):  
Y.M. Yannoni ◽  
K. White

The neuron specific Drosophila ELAV protein belongs to the ELAV family of RNA binding proteins which are characterized by three highly conserved RNA recognition motifs, an N-terminal domain, and a hinge region between the second and third RNA recognition motifs. Despite their highly conserved RNA recognition motifs the ELAV family members are a group of proteins with diverse posttranscriptional functions including splicing regulation, mRNA stability and translatability and have a variety of subcellular localizations. The role of the ELAV hinge in localization and function was examined using transgenes encoding ELAV hinge deletions, in vivo. Subcellular localization of the hinge mutant proteins revealed that residues between amino acids 333–374 are necessary for nuclear localization. This delineated sequence has no significant homology to classical nuclear localization sequences, but it is similar to the recently characterized nucleocytoplasmic shuttling sequence, the HNS, from a human ELAV family member, HuR. This defined sequence, however, was insufficient for nuclear localization as tested using hinge-GFP fusion proteins. Functional assays revealed that mutant proteins that fail to localize to the nucleus are unable to provide ELAV vital function, but their function is significantly restored when translocated into the nucleus by a heterologous nuclear localization sequence tag.

1991 ◽  
Vol 113 (1) ◽  
pp. 1-12 ◽  
Author(s):  
W C Lee ◽  
Z X Xue ◽  
T Mélèse

We previously identified a protein (p67) in the yeast, Saccharomyces cerevisiae, that specifically recognizes nuclear localization sequences. We report here the partial purification of p67, and the isolation, sequencing, and disruption of the gene (NSR1) encoding this protein. p67 was purified using an affinity column conjugated with a peptide containing the histone H2B nuclear localization sequence from yeast. Using antibodies against p67 we have cloned the gene for this protein. The protein encoded by the NSR1 gene recognizes the wild-type H2B nuclear localization sequence, but does not recognize a mutant H2B sequence that is incompetent for nuclear localization in vivo. Interestingly, the NSR1 protein has two RNA recognition motifs, as well as an acidic NH2 terminus containing a series of serine clusters, and a basic COOH terminus containing arg-gly repeats. We have confirmed the nuclear localization of p67 by immunofluorescence and found that a restricted portion of the nucleus is highlighted. We have also shown that NSR1 (p67) is required for normal cell growth.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Sashank Agrawal ◽  
Pan-Hsien Kuo ◽  
Lee-Ya Chu ◽  
Bagher Golzarroshan ◽  
Monika Jain ◽  
...  

RNA Biology ◽  
2010 ◽  
Vol 7 (3) ◽  
pp. 339-344 ◽  
Author(s):  
Alejandro Cassola ◽  
Griselda Noé ◽  
Alberto C. Frasch

Author(s):  
Mitsuru Okuwaki ◽  
Ai Saotome-Nakamura ◽  
Masashi Yoshimura ◽  
Shoko Saito ◽  
Hiroko Hirawake-Mogi ◽  
...  

Abstract Nucleolin (NCL) is a nucleolar protein that is involved in the regulation of the nucleolar structure and functions, and consists of three distinct regions: the N-terminal region; the middle region, which contains four RNA-recognition motifs (RRMs); and the C-terminal glycine and arginine-rich (GAR) region. The primary function of the RRMs and GAR is thought to be specific RNA binding. However, it is not well understood how these RNA-binding regions of NCL separately or cooperatively regulate its nucleolar localization and functions. To address this issue, we constructed mutant proteins carrying point mutations at the four RRMs individually or deletion of the C-terminal GAR region. We found that the GAR deletion and the mutations in the fourth RRM (RRM4) decreased the nucleolar localization of NCL. Biochemical analyses showed that NCL interacted directly with ribosomal RNAs (rRNAs) and G-rich oligonucleotides, and that this interaction was decreased by mutations at RRM1 and RRM4 and GAR deletion. Although GAR deletion decreased the rRNA-binding activity of NCL, the mutant was efficiently co-precipitated with rRNAs and nucleolar proteins from cell extracts. These contradictory results suggest that NCL stably localizes to the nucleoli via the interactions with rRNAs and nucleolar proteins via GAR, RRM1, and RRM4.


1993 ◽  
Vol 123 (5) ◽  
pp. 1081-1091 ◽  
Author(s):  
C Yan ◽  
T Mélèse

NSR1, a 67-kD nucleolar protein, was originally identified in our laboratory as a nuclear localization signal binding protein, and has subsequently been found to be involved in ribosome biogenesis. NSR1 has three regions: an acidic/serine-rich NH2 terminus, two RNA recognition motifs, and a glycine/arginine-rich COOH terminus. In this study we show that NSR1 itself has a bipartite nuclear localization sequence. Deletion of either basic amino acid stretch results in the mislocation of NSR1 to the cytoplasm. We further demonstrate that either of two regions, the NH2 terminus or both RNA recognition motifs, are sufficient to localize a bacterial protein, beta-galactosidase, to the nucleolus. Intensive deletion analysis has further defined a specific acidic/serine-rich region within the NH2 terminus as necessary for nucleolar accumulation rather than nucleolar targeting. In addition, deletion of either RNA recognition motif or point mutations in one of the RNP consensus octamers results in the mislocalization of a fusion protein within the nucleus. Although the glycine/arginine-rich region in the COOH terminus is not sufficient to bring beta-galactosidase to the nucleolus, our studies show that this domain is necessary for nucleolar accumulation when an RNP consensus octamer in one of the RNA recognition motifs is mutated. Our findings are consistent with the notion that nucleolar localization is a result of the binding interactions of various domains of NSR1 within the nucleolus rather than the presence of a specific nucleolar targeting signal.


2016 ◽  
Vol 214 (1) ◽  
pp. 45-59 ◽  
Author(s):  
Taro Mannen ◽  
Seisuke Yamashita ◽  
Kozo Tomita ◽  
Naoki Goshima ◽  
Tetsuro Hirose

The mammalian cell nucleus contains membraneless suborganelles referred to as nuclear bodies (NBs). Some NBs are formed with an architectural RNA (arcRNA) as the structural core. Here, we searched for new NBs that are built on unidentified arcRNAs by screening for ribonuclease (RNase)-sensitive NBs using 32,651 fluorescently tagged human cDNA clones. We identified 32 tagged proteins that required RNA for their localization in distinct nuclear foci. Among them, seven RNA-binding proteins commonly localized in the Sam68 nuclear body (SNB), which was disrupted by RNase treatment. Knockdown of each SNB protein revealed that SNBs are composed of two distinct RNase-sensitive substructures. One substructure is present as a distinct NB, termed the DBC1 body, in certain conditions, and the more dynamic substructure including Sam68 joins to form the intact SNB. HNRNPL acts as the adaptor to combine the two substructures and form the intact SNB through the interaction of two sets of RNA recognition motifs with the putative arcRNAs in the respective substructures.


Genome ◽  
2006 ◽  
Vol 49 (3) ◽  
pp. 254-262 ◽  
Author(s):  
Walther Traut ◽  
Teruyuki Niimi ◽  
Kazuho Ikeo ◽  
Ken Sahara

The Sex-lethal (SXL) protein belongs to the family of RNA-binding proteins and is involved in the regulation of pre-mRNA splicing. SXL has undergone an obvious change of function during the evolution of the insect clade. The gene has acquired a pivotal role in the sex-determining pathway of Drosophila, although it does not act as a sex determiner in non-drosophilids. We collected SXL sequences of insect species ranging from the pea aphid (Acyrtho siphom pisum) to Drosophila melanogaster by searching published articles, sequencing cDNAs, and exploiting homology searches in public EST and whole-genome databases. The SXL protein has moderately conserved N- and C-terminal regions and a well-conserved central region including 2 RNA recognition motifs. Our phylogenetic analysis shows that a single orthologue of the Drosophila Sex-lethal (Sxl) gene is present in the genomes of the malaria mosquito Anopheles gambiae, the honeybee Apis mellifera, the silkworm Bombyx mori, and the red flour beetle Tribolium castaneum. The D. melanogaster, D. erecta, and D. pseudoobscura genomes, however, contain 2 paralogous genes, Sxl and CG3056, which are orthologous to the Anopheles, Apis, Bombyx, and Tribolium Sxl. Hence, a duplication in the fly clade generated Sxl and CG3056. Our hypothesis maintains that one of the genes, Sxl, adopted the new function of sex determiner in Drosophila, whereas the other, CG3056, continued to serve some or all of the yet-unknown ancestral functions.Key words: sex determination, Sxl, CG3056, Bombyx, Apis, Anopheles, Aedes, Acyrtosiphon, Megaselia, Lucilia, Musca, Drosophila, Tribolium, Sciarids, Drosophila melanogaster, Drosophila erecta, Drosophila pseudoobscura, gene duplication.


2008 ◽  
Vol 36 (3) ◽  
pp. 520-521 ◽  
Author(s):  
Christine Clayton ◽  
Angela Schwede ◽  
Mhairi Stewart ◽  
Ana Robles ◽  
Corinna Benz ◽  
...  

Control of gene expression in trypanosomes relies almost exclusively on post-transcriptional mechanisms. Trypanosomes have the normal enzymes for mRNA decay: both the exosome and a 5′–3′-exoribonuclease are important in the degradation of very unstable transcripts, whereas the CAF1/NOT complex plays a major role in the degradation of all mRNAs tested. Targeted RNA interference screening was used to identify RNA-binding proteins that regulate mRNA degradation, and it revealed roles for proteins with RNA recognition motifs or pumilio domains.


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