Microbiology and Immunology

You are here

The mechanisms of K. lactis Cdc13 in telomere DNA-binding and telomerase regulation.

TitleThe mechanisms of K. lactis Cdc13 in telomere DNA-binding and telomerase regulation.
Publication TypeJournal Article
Year of Publication2018
AuthorsHsu M, Lue NF
JournalDNA Repair (Amst)
Volume61
Pagination37-45
Date Published2018 01
ISSN1568-7856
KeywordsAmino Acid Sequence, Binding Sites, Fungal Proteins, Mutation, Protein Binding, Saccharomycetales, Telomerase, Telomere, Telomere Homeostasis, Telomere-Binding Proteins
Abstract

Eukaryotic chromosome ends, or telomeres, are essential for genome stability and are protected by an intricate nucleoprotein assembly. Cdc13, the major single-strand telomere-binding protein in budding yeasts, mediates critical functions in both telomere protection and telomere elongation by telomerase. In particular, the interaction between S. cerevisiae Cdc13 and telomerase subunit Est1 has long served as a paradigm for telomerase regulation. However, despite extensive investigations, the role of this interaction in regulating telomerase recruitment or activation remains controversial. In addition, budding yeast telomere repeat sequences are extraordinarily variable and how Cdc13 orthologs recognize diverse repeats is not well understood. In this report, we examined these issues using an alternative model, K. lactis. We reconstituted a direct physical interaction between purified K. lactis Cdc13 and Est1, and by analyzing point mutations, we demonstrated a close correspondence between telomere maintenance defects in vivo and Cdc13-Est1 binding defects in vitro, thus supporting a purely recruitment function for this interaction in K. lactis. Because mutations in well aligned residues of Cdc13 and Est1 in S. cerevisiae and K. lactis do not cause identical defects, our results also point to significant evolutionary divergence in the Cdc13-Est1 interface. In addition, we found that K. lactic Cdc13, unlike previously characterized orthologs, recognizes an unusually long and non-G-rich target sequence, underscoring the flexibility of the Cdc13 DNA-binding domain. Analysis of K. lactis Cdc13 and Est1 thus broadens understanding of telomere and telomerase regulation in budding yeast.

DOI10.1016/j.dnarep.2017.11.007
Alternate JournalDNA Repair (Amst.)
PubMed ID29197718
PubMed Central IDPMC5766012
Grant ListR01 GM107287 / GM / NIGMS NIH HHS / United States

Weill Cornell Medicine Microbiology and Immunology 1300 York Avenue, Box 62 New York, NY 10065 Phone: (212) 746-6505 Fax: (212) 746-8587