Plant GRAS and metazoan STATs: one family?

Abstract

GRAS is a recently discovered family of plant‐specific proteins that play important regulatory roles in diverse aspects of plant development. Several of the motifs present in the GRAS proteins suggest that they function as transcription factors, although homology‐searching programs have revealed no significant similarity to any non‐plant proteins. Here we propose that the GRAS proteins are related to the Signal Transducers and Activators of Transcription (STAT) family of proteins. STATs are known in many non‐plant species, and act as intracellular intermediaries between extracellular ligands and the transcription and activation of genes. Our hypothesis is that the GRAS proteins perform this function in plants, with mechanisms similar to those of the animal STATs. If true, this hypothesis has important implications for the evolution of phosphotyrosine based signal transduction systems in eukaryotic organisms. BioEssays 22:573–577, 2000. © 2000 John Wiley & Sons, Inc.

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

“…However, many GRAS proteins remain functionally uncharacterized. Through intense sequence profile searches, Structure of Os-SCL7 GRAS Domainphylogenetic analyses, and structural comparisons, it was reported that the GRAS domain and metazoan STAT shared a similar domain organization, with a SH2-like motif and tyrosine phosphorylation site in GRAS proteins suggested but not yet demonstrated (Peng et al, 1999;Richards et al, 2000). However, there is also an opposing opinion that the structure of GRAS domain shares similarity with the Rossmann fold methyltransferase superfamily involved with binding or modifying GA derivatives in GA signaling, though the plant GRAS proteins appear to lack methyltransferase activity and the residues critical for specific substrate interaction (Zhang et al, 2012).…”

TheArabidopsis lue1mutant defines a katanin p60 ortholog involved in hormonal control of microtubule orientation during cell growth

“…Numerous reports have shown that GA signaling regulates the transcription of target genes and the post-translational control of certain proteins. For example, levels of the Arabidopsis GA signaling repressor RGA, a member of the GRAS protein family thought to act as transcription factors (Richards et al, 2000), are rapidly reduced upon GA application (Silverstone Journal of Cell Science 116 (6) al., 2001). In addition, SPY encodes an O-linked Nacetylglucosamine transferase (OGT) whose loss-of-function produces a constitutive GA-response mutant phenotype (Thornton et al, 1999).…”

“…Dominant mutations of GAI/RGA, which encode GRAS proteins proposed to function as the metazoan STAT transcription factors (Richards et al, 2000), result in semi-dwarfism, an important agronomic trait. Recessive mutations in SPY, which encodes an O-linked N-acetylglucosamine transferase [OGT (Thornton et al, 1999)], result in elongated plants with a constitutive GAresponse phenotype.…”

Evolution of Cytokine Receptor Signaling

“…STAT proteins consist of conserved central coiled-coil, DNA binding, and SH2 domains, as well as the more variable N-terminal and C-terminal domains (23). This protein family has ancient roots, with the most divergent being the plant GRAS proteins, which possess an SH2-like domain and a putative DNA-binding domain (27), whereas present-day slime mold possess a STAT-like protein that includes a coiled-coil domain involved in transcriptional regulation added via domain accretion (28,29). The N-terminal and C-terminal transactivation domains formed later (30)(31)(32)(33), with a definitive archetypal STAT clearly identifiable in bilateria (11,34), as exemplified in the present-day fruit fly Marelle protein (34), which is most homologous to higher vertebrate STAT5 and STAT6.…”