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Telomere protein and telomere protein homolog in Euplotes crassus
Abstract
Telomeres, the nucleoprotein complexes at the end of the chromosomes, consist of repeated DNA sequence and the associated proteins. While the telomeric DNA has been well characterized in many species, the studies of the telomere-associated proteins lag far behind. Hypotrichous ciliates such as Euplotes and Oxytricha are particularly well suited for studying telomeres and telomere-binding proteins because they have enormous amounts of telomeres. Both Euplotes and Oxytricha telomere-binding proteins have been isolated and characterized. It appears that the two proteins comprise a very unusual category of DNA-binding proteins because they specifically bind to the 3$\sp\prime$ terminus of the telomeric DNA. In order to learn more about the DNA-binding motif(s) of the Euplotes telomere-binding proteins, we isolated the gene encoding the Euplotes telomere-binding protein. We have shown that the gene encoding the Euplotes telomere-binding protein is highly homologous to the gene encoding the Oxytricha telomere-binding protein $\alpha$ subunit in various regions. As these regions lie within the DNA-binding domain, they might make up the DNA-binding site(s). While we were cloning the gene encoding the Euplotes telomere-binding protein, we also cloned a gene encoding a related protein--the telomere protein homolog. We have shown that the telomere protein homology shares extensive amino acid sequence identity with the Euplotes and Oxytricha telomere-binding protein in their N-terminal DNA-binding domain. In the C-terminal region, however, the telomere protein homolog exhibits little sequence homology with Euplotes telomere-binding protein. To identify the native telomere protein homology, we expressed the N-terminal and the C-terminal domains of the homolog protein and made antibodies against the expressed proteins. Using these antibodies we detected the homolog protein in the regions of the macronucleus where DNA replication is taking place. This subcellular location of the homolog protein indicates that the homolog protein might be involved in telomere replication.
Subject Area
Biochemistry|Molecular biology
Recommended Citation
Wang, Wenlan, "Telomere protein and telomere protein homolog in Euplotes crassus" (1993). ETD collection for University of Nebraska-Lincoln. AAI9416002.
https://digitalcommons.unl.edu/dissertations/AAI9416002