Identification of a telomeric DNA-binding protein in Eimeria tenella

Coccidiosis is considered to be a major problem for the poultry industry, and coccidiosis control is yet urgent. Due to the roles in telomere length regulation and end protection, telomere-binding proteins have been considered as a good target for drug design. In this work, a putative Gbp1p that is similar to telomeric DNA-binding protein Gbp (G-strand binding protein) of Cryptosporidium parvum, was searched in the database of Eimeria tenella. Sequence analysis indicated E.tenella Gbp1p (EtGbp1p) has significant sequence similarity to other eukaryotic Gbps in their RNA recognition motif (RRM) domains. Electrophoretic mobility shift assays (EMSAs) demonstrated recombinant EtGbp1p bound G-rich telomeric DNA, but not C-rich or double-stranded telomeric DNA sequences. Competition and antibody supershift assays confirmed the interaction of DNA-protein complex. Chromatin immunoprecipitation assays confirmed that EtGbp1p interacted with telomeric DNA in vivo. Collectively, these evidences suggest that EtGbp1p represents a G-rich single-stranded telomeric DNA-binding protein in E.tenella.