Browsing by Subject "Telomere"

The ends of eukaryotic chromosomes are formed by a special heterochromatic structure, the telomere, which is essential to guarantee chromosome stability. Telomeres protect chromosomic ends from DNA degradation, repair, and recombination events. However, they are difficult to replicate due to their repetitive and heterochromatic nature, which hinder DNA replication fork progression. In yeast, Mph1 helicase promotes replication fork regression, cross-over suppression during homologous recombination (HR), and telomere maintenance. Moreover, Mte1 is a D-loop binding protein involved in response to DNA damage and maintenance of telomere length, which interacts with Mph1, thereby stimulating its regression capacity as a helicase and fork. Thus, the Mte1-Mph1 complex is recruited to stressed telomeres. Mte1 also shares a domain of unknown function, DUF2439, with Rad51 and Rdh54. Additionally, Esc2 protein is involved in the regulation of DNA damage through template switch (TS) recombination, preventing HR events caused by Mph1. This thesis aimed to uncover the potential roles and interactions of proteins involved in telomere maintenance, such as Mph1, Mte1, Esc2 and Rdh54, for which two main assays were conducted: (1) Telomere Stability assay, consisting of Tus/Ter barrier based on the high-affinity binding of the E. coli protein, Tus, to specific DNA sequence called Ter; (2) Template Switching assay, focused on the capability of the proteins in reconstructing a functional LYS2 gene by TS. The obtained results demonstrated that (1) the absence of Rdh54 enhances replication fork regression, (2) Mte1 and Esc2 show opposite roles in telomere maintenance, (3) the interaction between Mte1 and Rad51 plays a crucial role in ensuring telomere stability and nuclear foci formation, (4) Mph1 and Mte1 promote cell survival through the break-induced replication (BIR) pathway. Further studies should assess the plausible interaction between Mph1 and Rdh54 proteins and characterize the function and interplay of the proteins involved in TS.