Yeast Ku as a Regulator of Chromosomal DNA End Structure

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Science  01 May 1998:
Vol. 280, Issue 5364, pp. 741-744
DOI: 10.1126/science.280.5364.741

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During telomere replication in yeast, chromosome ends acquire an S-phase–specific overhang of the guanosine-rich strand. Here it is shown that in cells lacking Ku, a heterodimeric protein involved in nonhomologous DNA end joining, these overhangs are present throughout the cell cycle. In vivo cross-linking experiments demonstrated that Ku is bound to telomeric DNA. These results show that Ku plays a direct role in establishing a normal DNA end structure on yeast chromosomes, conceivably by functioning as a terminus-binding factor. Because Ku-mediated DNA end joining involving telomeres would result in chromosome instability, our data also suggest that Ku has a distinct function when bound to telomeres.

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