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PMID: 12032094 Published · ppublish English Journal Article Research Support, U.S. Gov't, Non-P.H.S.

Telomere length deregulation and enhanced sensitivity to genotoxic stress in Arabidopsis mutants deficient in Ku70.

The EMBO journal ·Vol. 21 ·No. 11 ·2002-06-03 ·Pages 2819-26

Riha K, Watson JM, Parkey J, Shippen DE

Abstract

The Ku70/80 heterodimer is a critical component of the non-homologous end-joining (NHEJ) pathway and of the telomere cap in yeast and mammals. We report the molecular characterization of the KU70 and KU80 genes in Arabidopsis and describe the consequences of a Ku70 deficiency. Arabidopsis KU70/80 genes are ubiquitously expressed and their products form stable heterodimers in vitro. Plants harboring a T-DNA insertion in KU70 exhibit no growth or developmental defects under standard growth conditions. However, mutant seedlings are hypersensitive to gamma-irradiation-induced double-strand breaks. Unexpectedly, we found that mutants are hypersensitive to methyl methanosulfonate during seed germination, but lose this sensitivity in seedlings, implying that the requirement for NHEJ varies during plant development. Lack of Ku70 results in a dramatic deregulation of telomere length control, with mutant telomeres expanding to more than twice the size of wild type by the second generation. Furthermore, in contrast to the situation in mammals, chromosome fusions are not associated with a Ku deficiency in Arabidopsis. These findings imply that Ku may play a different role in capping plant and animal telomeres.

MeSH Terms
Alleles Amino Acid Sequence Antigens, Nuclear Arabidopsis/genetics DNA Helicases DNA, Complementary/metabolism DNA-Binding Proteins/genetics,metabolism,physiology Dimerization Genetic Complementation Test Ku Autoantigen Methyl Methanesulfonate/pharmacology Models, Genetic Molecular Sequence Data Mutagens/pharmacology Mutation Nuclear Proteins/genetics,metabolism,physiology RNA, Complementary/metabolism Saccharomyces cerevisiae Proteins Telomere/ultrastructure
Chemicals
Antigens, Nuclear DNA, Complementary DNA-Binding Proteins Mutagens Nuclear Proteins RNA, Complementary Saccharomyces cerevisiae Proteins high affinity DNA-binding factor, S cerevisiae Methyl Methanesulfonate DNA Helicases XRCC5 protein, human Xrcc6 protein, human Ku Autoantigen
Authors & Affiliations
4 authors, click to expand affiliations / ORCID
Riha Karel
Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, TX 77843-2128, USA.
Watson J Matthew
Parkey Jeffrey
Shippen Dorothy E
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Article Info
Journal
The EMBO journal
Abbr.
EMBO J
ISSN
0261-4189
DOI
10.1093/emboj/21.11.2819
Published
2002-06-03
Pages
2819-26
Language
English
Region
England
NLM ID
8208664
PMCID
PMC126030
Subset
IM
External Links
PubMed source DOI: 10.1093/emboj/21.11.2819 PMC Full Text View journal details
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