Abstract
To date, many genes which are transcriptionally activated upon wound- and defense-responses have been identified, but their biological functions are not necessarily clear yet. In the present study, we focused on a wound- and pathogen-responsive gene encoding a novel bHLH protein, WINB (Wound-Induced bHLH protein), which localizes to plastids in tobacco plants.
In leaves, expression of WINB was induced by wounding and TMV infection. WINB expression was also clearly activated by H2O2. Plastid localization signal of WINB spans about 70 amino acids at the N-terminus, and contains DNA binding domain of a bHLH motif. Using the yeast two hybrid assay, WINB was found not to form a homo-dimer. These results suggest that WINB is up-regulated by ROS, and is localized to plastids by signal sequence containing DNA binding domain. Moreover, WINB might bind to DNA by forming a hetero-dimer with other protein(s), thereby regulating plastid function(s).
