Crystal Structure of the GRAS Domain of SCARECROW-LIKE7 inOryza sativa

Abstract

GRAS proteins belong to a plant-specific protein family with many members and play essential roles in plant growth and development, functioning primarily in transcriptional regulation. Proteins in the family are minimally defined as containing the conserved GRAS domain. Here, we determined the structure of the GRAS domain of Os-SCL7 from rice (Oryza sativa) to 1.82 Å. The structure includes cap and core subdomains and elucidates the features of the conserved GRAS LRI, VHIID, LRII, PFYRE, and SAW motifs. The structure is a dimer, with a clear groove to accommodate double-stranded DNA. Docking a DNA segment into the groove to generate an Os-SCL7/DNA complex provides insight into the DNA binding mechanism of GRAS proteins. Furthermore, the in vitro DNA binding property of Os-SCL7 and model-defined recognition residues are assessed by electrophoretic mobility shift analysis and mutagenesis assays. These studies reveal the structure and preliminary DNA interaction mechanisms of GRAS proteins and open the door to in-depth investigation and understanding of the individual pathways in which they play important roles.

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

“…Our study revealed that the GRAS domains of SHR and SCR each comprise an α-helical cap and α/β core subdomains, which is similar to the recently reported structure of SCARECROWLIKE7 in rice (OsSCL7) (Supplementary Fig. 11) 30 . In general, the GRAS domain shows structural similarity with SAM-MT α/β enzymes.…”

“…12). In addition, OsSCL7 forms a homodimer 30 . These findings suggest that there are subtypes of GRAS proteins with different physical properties as determined by the α-helical caps, which mediate hetero- and/or homo-dimerization, or the absence of dimerization altogether.…”

“…Our study shows that SHR-SCR forms a heterodimer via their α-helical caps in a head-to-head configuration, which is mediated by both polar and non-polar specific interactions. However, OsSCL7 was shown to form a homodimer in a side-by-side configuration mainly via hydrophobic interactions, with creation of a putative DNA binding groove at the dimer interface 30 . Although GRAS proteins function in transcriptional regulation, only two GRAS proteins, OsSCL7 and Nodulation Signaling Pathway1 (NSP1) in Medicago truncatula , have been reported to bind DNA directly by EMSA analysis 29,30 .…”

A Structure for Plant-Specific Transcription Factors: The GRAS Domain Revealed

“…Whereas their N-terminal regions vary, members of this family are characterized by a C-terminal region harboring the GRAS domain. In a landmark article, Li et al (2016) report the crystal structure of the GRAS domain, thereby providing long-awaited insight into potential mechanisms underlying the widespread importance of GRAS domain proteins.…”

“…The five subdomains of the Os-SCL7 GRAS domain are colored according to the schematic below the structure (adapted from Figure 1 of Li et al [2016] …”