The Tyrosyl-DNA Phosphodiesterase 1β (Tdp1β) Gene Discloses an Early Response to Abiotic Stresses.

Tyrosyl-DNA phosphodiesterase 1 (Tdp1) is involved in DNA repair pathways as it mends the topoisomerase I-DNA covalent complexes. In plants, a small gene family, composed by and genes, was identified, but the roles of these genes in abiotic stress responses are not fully understood. To investigate their specific stress response patterns, the present study made use of bioinformatic and molecular tools to look into the gene function, so far described only in the plant kingdom, and compare it with gene coding for the canonical, highly conserved α isoform. The expression profiles of and genes were examined under abiotic stress conditions (cold, heat, high osmolarity, salt, and UV-B) in two model species, and . The two isoforms of topoisomerase I ( and ) were also taken into consideration in view of their known roles in DNA metabolism and cell proliferation. Data relative to gene expression in were retrieved from the AtGenExpress microarray dataset, while quantitative Real-Time PCR was carried out to evaluate the stress response in cell cultures. These analyses revealed that gene expression was enhanced during the first hour of treatment, whereas enhanced expression succeeded at subsequent timepoints. In agreement with the gene-specific responses to abiotic stress conditions, the promoter regions of and genes are well equipped with stress-related -elements. An in-depth bioinformatic characterization of the HIRAN motif, a distinctive feature of the protein, showed its wide distribution in chromatin remodeling and DNA repair proteins. The reported data suggests that functions in the early response to abiotic stresses.