Skip to main content
Article thumbnail
Location of Repository

Clusters of Basic Amino Acids Contribute to RNA Binding and Nucleolar Localization of Ribosomal Protein L22

By Jennifer L. Houmani and Ingrid K. Ruf

Abstract

The ribosomal protein L22 is a component of the 60S eukaryotic ribosomal subunit. As an RNA-binding protein, it has been shown to interact with both cellular and viral RNAs including 28S rRNA and the Epstein-Barr virus encoded RNA, EBER-1. L22 is localized to the cell nucleus where it accumulates in nucleoli. Although previous studies demonstrated that a specific amino acid sequence is required for nucleolar localization, the RNA-binding domain has not been identified. Here, we investigated the hypothesis that the nucleolar accumulation of L22 is linked to its ability to bind RNA. To address this hypothesis, mutated L22 proteins were generated to assess the contribution of specific amino acids to RNA binding and protein localization. Using RNA-protein binding assays, we demonstrate that basic amino acids 80–93 are required for high affinity binding of 28S rRNA and EBER-1 by L22. Fluorescence localization studies using GFP-tagged mutated L22 proteins further reveal that basic amino acids 80–93 are critical for nucleolar accumulation and for incorporation into ribosomes. Our data support the growing consensus that the nucleolar accumulation of ribosomal proteins may not be mediated by a defined localization signal, but rather by specific interaction with established nucleolar components such as rRNA

Topics: Research Article
Publisher: Public Library of Science
OAI identifier: oai:pubmedcentral.nih.gov:2668802
Provided by: PubMed Central
Download PDF:
Sorry, we are unable to provide the full text but you may find it at the following location(s):
  • http://www.pubmedcentral.nih.g... (external link)
  • Suggested articles

    Citations

    1. (2000). A
    2. (1999). A Box H/ACA Small Nucleolar RNALike Domain at the Human Telomerase RNA 39 End.
    3. (2007). Ablation of ribosomal protein L22 selectively impairs alphabeta T cell development by activation of a p53-dependent checkpoint.
    4. (1997). Association of herpes simplex virus regulatory protein ICP22 with transcriptional complexes containing EAP, ICP4, RNA polymerase II, and viral DNA requires posttranslational modification by the U(L)13 proteinkinase.
    5. (1991). Binding of Epstein-Barr virus small RNA EBER-1 to the double-stranded RNA-activated protein kinase DAI.
    6. (1990). Discovery of the nucleolar targeting signal.
    7. (1996). Distinct domains in ribosomal protein L5 mediate 5 S rRNA binding and nucleolar localization.
    8. (1991). EAP, a highly conserved cellular protein associated with Epstein-Barr virus small RNAs (EBERs).
    9. (2006). Epstein-Barr virus noncoding RNAs are confined to the nucleus, whereas their partner, the human La protein, undergoes nucleocytoplasmic shuttling.
    10. (2005). Evolutionary conservation of nuclear and nucleolar targeting sequences in yeast ribosomal protein S6A.
    11. (1996). Extraribosomal functions of ribosomal proteins.
    12. (1996). Functional interaction and colocalization of the herpes simplex virus 1 major regulatory protein ICP4 with EAP, a nucleolarribosomal protein.
    13. (2001). Hepatitis C virus 39X region interacts with human ribosomal proteins.
    14. (2000). Human ribosomal protein L5 contains defined nuclear localization and export signals.
    15. (2000). Identification of two RNA-binding proteins associated with human telomerase RNA.
    16. (1995). In vitro selection of RNA ligands for the ribosomal L22 protein associated with Epstein-Barr virus-expressed RNA by using randomized and cDNA-derived RNA libraries.
    17. (2003). Isolation of polysomal RNA for microarray analysis. Methods Mol Biol 224: 79–87. L22
    18. (2006). Mapping a nucleolar targeting sequence of an RNA binding nucleolar protein,
    19. (2006). Multiple domains of EBER 1, an Epstein-Barr virus noncoding RNA, recruit human ribosomal protein L22.
    20. (1999). Nuclear and nucleolar localization of Saccharomyces cerevisiae ribosomal proteins S22 and S25.
    21. (1999). Nuclear and nucleolar targeting of human ribosomal protein S25: common features shared with HIV-1 regulatory proteins.
    22. (1998). Nuclear import and nucleolar accumulation of the human ribosomal protein S7 depends on both a minimal nuclear localization sequence and an adjacent basic region.
    23. (2000). Nuclear Import of Ribosomal Proteins: Evidence for a Novel Type of Nuclear Localization Signal. In:
    24. (1991). Nuclear targeting sequences–a consensus?
    25. (2008). Nucleolar binding sequences of the ribosomal protein S6e family reside in evolutionary highly conserved peptide clusters.
    26. (2003). Nucleolar localization of RPS19 protein in normal cells and mislocalization due to mutations in the nucleolar localization signals in 2 Diamond-Blackfan anemia patients: potential insights into pathophysiology.
    27. (1999). Nucleolar localization signals of box H/ACA small nucleolar RNAs.
    28. (1998). Nucleolar protein p120 contains an arginine-rich domain that binds to ribosomal RNA.
    29. (1993). Protein localization to the nucleolus: a search for targeting domains in nucleolin.
    30. (2005). Ribosomal protein L7a binds RNA through two distinct RNA-binding domains.
    31. (1987). Role of acidic phosphoproteins in the partial reconstitution of the active 60 S ribosomal subunit.
    32. (1984). Secondary structure of mouse 28S rRNA and general model for the folding of the large rRNA in eukaryotes.
    33. (1996). Sequence requirement for nucleolar localization of rat ribosomal protein L31.
    34. (1989). Sequence requirements for synthetic peptide-mediated translocation to the nucleus.
    35. (2003). Specific inhibition of gene expression using a stably integrated, inducible small-interfering-RNA vector.
    36. (2004). Targeted disruption of the ribosomal protein S19 gene is lethal prior to implantation.
    37. (1993). The cellular RNA-binding protein EAP recognizes a conserved stem-loop in the Epstein-Barr virus small RNA
    38. (1994). The Epstein-Barr virus (EBV) small RNA EBER1 binds and relocalizes ribosomal protein L22 in EBVinfected human B lymphocytes.
    39. (2005). The moving parts of the nucleolus.
    40. (1995). The nucleolus: an organelle formed by the act of building a ribosome.
    41. (1995). The nucleolus.
    42. (2000). To be or not to be in the nucleolus.
    43. (1981). Two small RNAs encoded by Epstein-Barr virus and complexed with protein are precipitated by antibodies from patients with systemic lupus erythematosus.

    To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.