Identification of domains of ataxia-telangiectasia mutated required for nuclear localization and chromatin association

Young, David B., Jonnalagadda, Jyoti, Gatei, Magtouf, Jans, David A., Meyn, Stephen and Khanna, Kum Kum (2005) Identification of domains of ataxia-telangiectasia mutated required for nuclear localization and chromatin association. The Journal of Biological Chemistry, 280 30: 27587-27594. doi:10.1074/jbc.M411689200

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Author Young, David B.
Jonnalagadda, Jyoti
Gatei, Magtouf
Jans, David A.
Meyn, Stephen
Khanna, Kum Kum
Title Identification of domains of ataxia-telangiectasia mutated required for nuclear localization and chromatin association
Journal name The Journal of Biological Chemistry   Check publisher's open access policy
ISSN 0021-9258
1083-351X
Publication date 2005-07
Sub-type Article (original research)
DOI 10.1074/jbc.M411689200
Open Access Status File (Publisher version)
Volume 280
Issue 30
Start page 27587
End page 27594
Total pages 8
Place of publication Bethesda, MD, U.S.
Publisher American Society for Biochemistry and Molecular Biology
Language eng
Subject 11 Medical and Health Sciences
1101 Medical Biochemistry and Metabolomics
Abstract Ataxia-telangiectasia mutated (ATM) is essential for rapid induction of cellular responses to DNA double strand breaks (DSBs). In this study, we mapped a nuclear localization signal (NLS), 385KRKK388, within the amino terminus of ATM and demonstrate its recognition by the conventional nuclear import receptor, the importin α1/β1 heterodimer. Although mutation of this NLS resulted in green fluorescent protein (GFP)·ATM(NLSm) localizing predominantly within the cytoplasm, small amounts of nuclear GFP·ATM(NLSm) were still sufficient to elicit a DNA damage response. Insertion of an heterologous nuclear export signal between GFP and ATM(NLSm) resulted in complete cytoplasmic localization of ATM, concomitantly reducing the level of substrate phosphorylation and increasing radiosensitivity, which indicates a functional requirement for ATM nuclear localization. Interestingly, the carboxyl-terminal half of ATM, containing the kinase domain, which localizes to the cytoplasm, could not autophosphorylate itself or phosphorylate substrates, nor could it correct radiosensitivity in response to DSBs even when targeted to the nucleus by insertion of an exogenous NLS, demonstrating that the ATM amino terminus is required for optimal ATM function. Moreover, we have shown that the recruitment/retention of ATM at DSBs requires its kinase activity because a kinase-dead mutant of GFP·ATM failed to form damage-induced foci. Using deletion mutation analysis we mapped a domain in ATM (amino acids 5–224) required for its association with chromatin, which may target ATM to sites of DNA damage. Combined, these data indicate that the amino terminus of ATM is crucial not only for nuclear localization but also for chromatin association, thereby facilitating the kinase activity of ATM in vivo.
Keyword AT
ATM
Mutation
Therapy
Dna
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
School of Medicine Publications
 
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Created: Thu, 14 Jan 2010, 10:01:55 EST by Ms May Balasaize on behalf of Faculty Of Health Sciences