Characterization of the nuclear localization signal in the DNA helicase responsible for Bloom syndrome.

  • Authors:
    • S Hayakawa
    • H Kaneko
    • T Fukao
    • K Kasahara
    • T Matsumoto
    • Y Furuichi
    • N Kondo
  • View Affiliations

  • Published online on: May 1, 2000     https://doi.org/10.3892/ijmm.5.5.477
  • Pages: 477-561
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Abstract

Bloom syndrome (BS) is a rare genetic disorder characterized by small body size, photosensitivity, immunodeficiency and a high predisposition to various types of cancer. BLM was identified as the causative gene for BS. The BLM protein is homologous to DNA helicase and has two basic amino acid clusters in its C-terminal region. Previously, we reported that the distal arm of these basic amino acids clusters in the BLM protein functioned as the nuclear localization signal (NLS) of the protein. In this study, we generated plasmid constructs for expression of enhanced green fluorescent protein (EGFP) fused with various BLM protein variants having a mutation with deletions or substitutions in the basic amino acid and analyzed the subcellular localization of the expressed proteins. The EGFP-fused protein containing the basic amino acid cluster region proximal to the C-terminus of BLM helicase was localized exclusively in the nucleus. However, the EGFP-BLM proteins that lacked either Arg1344 or Lys1346 distributed in both the cytoplasm and the nucleus equally. Deletion of Arg1347 also resulted in localization in both the nucleus and cytoplasm, and substitution of Arg1344, Lys1346, Arg1347 or Arg1348 with non-basic amino acids reduced the nuclear localization of BLM protein. Mouse BLM protein which also migrate to the nucleus has two basic amino acid clusters in the C-terminus and the basic amino acids (Lys1346-Pro1347-Lys1348-Arg1349-Arg1350) proximal to the C-terminus are conserved between mouse and human. These findings suggest that the Arg1344-Ser1345-Lys1346-Arg1347 sequence at the C-terminus of the human BLM protein is essential for nuclear localization of this protein.

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May 2000
Volume 5 Issue 5

Print ISSN: 1107-3756
Online ISSN:1791-244X

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Spandidos Publications style
Hayakawa S, Kaneko H, Fukao T, Kasahara K, Matsumoto T, Furuichi Y and Kondo N: Characterization of the nuclear localization signal in the DNA helicase responsible for Bloom syndrome.. Int J Mol Med 5: 477-561, 2000.
APA
Hayakawa, S., Kaneko, H., Fukao, T., Kasahara, K., Matsumoto, T., Furuichi, Y., & Kondo, N. (2000). Characterization of the nuclear localization signal in the DNA helicase responsible for Bloom syndrome.. International Journal of Molecular Medicine, 5, 477-561. https://doi.org/10.3892/ijmm.5.5.477
MLA
Hayakawa, S., Kaneko, H., Fukao, T., Kasahara, K., Matsumoto, T., Furuichi, Y., Kondo, N."Characterization of the nuclear localization signal in the DNA helicase responsible for Bloom syndrome.". International Journal of Molecular Medicine 5.5 (2000): 477-561.
Chicago
Hayakawa, S., Kaneko, H., Fukao, T., Kasahara, K., Matsumoto, T., Furuichi, Y., Kondo, N."Characterization of the nuclear localization signal in the DNA helicase responsible for Bloom syndrome.". International Journal of Molecular Medicine 5, no. 5 (2000): 477-561. https://doi.org/10.3892/ijmm.5.5.477