title: Synergism of the two Myb domains of Tay1 protein results in high affinity binding to telomeres.
abstract: Double-stranded regions of the telomeres are recognized by proteins containing Myb-like domains conferring specificity toward telomeric repeats. Although biochemical and structural studies revealed basic molecular principles involved in DNA binding, relatively little is known about evolutionary pathways leading to various types of Myb domain-containing proteins in divergent species of eukaryotes. Recently we identified a novel type of telomere-binding protein YlTay1p from the yeast Yarrowia lipolytica containing two Myb domains (Myb1, Myb2) very similar to the Myb domain of mammalian TRF1 and TRF2. In this study we prepared mutant versions of YlTay1p lacking Myb1, Myb2, or both Myb domains and found that YlTay1p carrying either Myb domain exhibits preferential affinity to both Y. lipolytica (GGGTTAGTCA)(n) and human (TTAGGG)(n) telomeric sequences. Quantitative measurements of the protein binding to telomeric DNA revealed that the presence of both Myb domains is required for a high affinity of YlTay1p to either telomeric repeat. Additionally, we performed detailed thermodynamic analysis of the YlTay1p interaction with its cognate telomeric DNA, which is to our knowledge the first energetic description of a full-length telomeric-protein binding to DNA. Interestingly, when compared with human TRF1 and TRF2 proteins, YlTay1p exhibited higher affinity not only for Y. lipolytica telomeres but also for human telomeric sequences. The duplication of the Myb domain region in YlTay1p thus produces a synergistic effect on its affinity toward the cognate telomeric sequence, alleviating the need for homodimerization observed in TRF-like proteins possessing a single Myb domain.
authors: Department of Genetics and Biochemistry, Comenius University, Faculty of Natural Sciences, Mlynska dolina, 842 15 Bratislava, Slovakia.
authors: Katarina
authors: K
authors: Visacka
authors: Ctirad
authors: C
authors: Hofr
authors: Smaranda
authors: S
authors: Willcox
authors: Ivona
authors: I
authors: Necasova
authors: Jana
authors: J
authors: Pavlouskova
authors: Regina
authors: R
authors: Sepsiova
authors: Michaela
authors: M
authors: Wimmerova
authors: Lucia
authors: L
authors: Simonicova
authors: Jozef
authors: J
authors: Nosek
authors: Jiri
authors: J
authors: Fajkus
authors: Jack D
authors: JD
authors: Griffith
authors: Lubomir
authors: L
authors: Tomaska
mesh_terms: D000595:Amino Acid Sequence; D016880:Anisotropy; D001703:Biophysics / Q000379:methods; D002151:Calorimetry / Q000379:methods; D002874:Chromosome Mapping; D019143:Evolution, Molecular; D005656:Fungal Proteins / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008856:Microscopy, Fluorescence / Q000379:methods; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D020598:Proto-Oncogene Proteins c-myb / Q000737:chemistry*; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D016615:Telomere / Q000648:ultrastructure; D035321:Telomeric Repeat Binding Protein 1 / Q000737:chemistry*; D013816:Thermodynamics; D025062:Yarrowia / Q000378:metabolism*
chemical_list: D005656:Fungal Proteins; D020598:Proto-Oncogene Proteins c-myb; D035321:Telomeric Repeat Binding Protein 1