title: The maize Gα gene COMPACT PLANT2 functions in CLAVATA signalling to control shoot meristem size.
abstract: Shoot growth depends on meristems, pools of stem cells that are maintained by a negative feedback loop between the CLAVATA pathway and the WUSCHEL homeobox gene. CLAVATA signalling involves a secreted peptide, CLAVATA3 (CLV3), and its perception by cell surface leucine-rich repeat (LRR) receptors, including the CLV1 receptor kinase and a LRR receptor-like protein, CLV2 (ref. 4). However, the signalling mechanisms downstream of these receptors are poorly understood, especially for LRR receptor-like proteins, which lack a signalling domain. Here we show that maize COMPACT PLANT2 (CT2) encodes the predicted α-subunit (Gα) of a heterotrimeric GTP binding protein. Maize ct2 phenotypes resemble Arabidopsis thaliana clavata mutants, and genetic, biochemical and functional assays indicate that CT2/Gα transmits a stem-cell-restrictive signal from a CLAVATA LRR receptor, suggesting a new function for Gα signalling in plants. Heterotrimeric GTP-binding proteins are membrane-associated molecular switches that are commonly activated by ligand binding to an associated seven-pass transmembrane (7TM) G-protein-coupled receptor (GPCR). Recent studies have questioned the idea that plant heterotrimeric G proteins interact with canonical GPCRs, and our findings suggest that single pass transmembrane receptors act as GPCRs in plants, challenging the dogma that GPCRs are exclusively 7TM proteins.
authors.affiliation: Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Bommert
authors.forename: Byoung Il
authors.initials: BI
authors.lastname: Je
authors.forename: Alexander
authors.initials: A
authors.lastname: Goldshmidt
authors.forename: David
authors.initials: D
authors.lastname: Jackson
mesh_terms: D003001:Cloning, Molecular; D044385:GTP-Binding Protein alpha Subunits / Q000235:genetics / Q000378:metabolism*; D017343:Genes, Plant / Q000235:genetics*; D018519:Meristem / Q000033:anatomy & histology* / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D020543:Proteome / Q000235:genetics / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000737:chemistry / Q000378:metabolism; D015398:Signal Transduction; D003313:Zea mays / Q000033:anatomy & histology* / Q000235:genetics*
chemical_list: D044385:GTP-Binding Protein alpha Subunits; D010940:Plant Proteins; D020543:Proteome; D043562:Receptors, G-Protein-Coupled
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