The in vitro DNA-binding and heterologous transcriptional activation studies presented here indicate that the LBD protein family represents a new class of DNA-binding transcription factors that recognize the cis-element GCGGCG. The DNA-binding activity is present within the LOB domain, which is conserved throughout the 43 Arabidopsis family members as well as LBD proteins in other plant species.
The LBD genes encode a novel class of DNA-binding transcription factors. Post-translational regulation of transcription factors is often crucial for control of gene expression. In our study, we demonstrate that members of the basic helix-loop-helix (bHLH) family of transcription factors are capable of interacting with LOB. The expression patterns of bHLH048 and LOB overlap at lateral organ boundaries. Interestingly, the interaction of bHLH048 with LOB results in reduced affinity of LOB for the consensus DNA motif. Thus, our studies suggest that bHLH048 post-translationally regulates the function of LOB at lateral organ boundaries.
