Structure of SHR–SCR heterodimer bound to BIRD/IDD transcriptional factor JKD

Structural biology provides a key link between genotype and phenotype. Hirano et al. probe the structure of a heterodimer of plant-specific GRAS family transcriptional regulators [SHORT-ROOT (SHR) and SCARECROW (SCR)] as bound to the transcription factor JACKDAW (JKD). The GRAS family proteins (encoded by 33 genes in Arabidopsis and 66 in rice) are involved in several signaling pathways, including root development and gibberellin and phytochrome signaling. Their analysis suggests that in GRAS proteins, the alpha-helical cap domain affects whether the proteins homo- or hetero-dimerize. The authors also found no evidence for direct DNA binding of the SHR-SCR complex, and propose that it acts as a transcription cofactors that requires complex formation with JKD for DNA binding. Nature Plants 10.1038/nplants.2017.10