DNA-Binding Protein Phosphatase AtDBP1 Mediates Susceptibility to Two Potyviruses in Arabidopsis

DBP factors (DNA-binding protein phosphatases) are unique to plants but widely distributed in the plant kingdom. The dual structure of DBP factors suggests that, in addition to directly participating in transcriptional regulation of specific genes by virtue of its DNA-binding capacity, they may also be involved in the regulation of other processes not directly related to gene transcription, particularly in signal transduction pathways. In support of this hypothesis a shuttling mechanism from the nucleus to the cytosol has recently been demonstrated for the dynamic localization of the tobacco (Nicotiana tabacum) NtDBP1 protein (Carrasco et al., 2006). In the model species Arabidopsis (Arabidopsis thaliana) four DBP factors have been identified, with AtDBP1 being the closest structural relative to tobacco NtDBP1, the first member of the family to be isolated (Carrasco et al., 2005). AtDBP1 was found to bind DNA with similar specificity to NtDBP1 and exhibit in vitro Mg2+-dependent protein phosphatase activity as well.