Paper

Receptor-Like Kinase Phosphorylation of Arabidopsis Heterotrimeric G-Protein Gα - Subunit AtGPA1

Walley, Justin W, Hicks, Leslie M, Jones, Alan M, Song, Gaoyuan, Werth, Emily G, Jia, Haiyan

2019

Overview

As molecular on-off switches, heterotrimeric G protein complexes, comprised of a G alpha subunit and an obligate G beta gamma dimer, transmit extracellular signals received by G protein coupled receptors (GPCRs) to cytoplasmic targets that respond to biotic and abiotic stimuli. Signal transduction is modulated by phosphorylation of GPCRs and G protein complexes. In Arabidopsis thaliana, the G alpha subunit AtGPA1 is phosphorylated by the receptor like kinase (RLK) BRI1-ASSOCIATED Kinase 1 (BAK1), but the extent that other RLKs phosphorylates AtGPA1 is unknown. We mapped 22 trans-phosphorylation sites on AtGPA1 by 12 RLKs hypothesized to act in the Arabidopsis G protein signaling pathway. Cis-phosphorylation sites on these RLKs were also identified. BRI1, BAK1, and SERK1 have been reported as Ser/Thr and Tyr dual specificity kinases. We identified 4 more dual specificity kinases: IOS1, PSY1R, PEPR1, and AT2G37050. Multiple sites are present in the core AtGPA1 functional units, including pSer52 and/or pThr53 of the conserved P-loop that directly binds nucleotide/phosphate, pThr164 and pSer175 from αE helix in the intramolecular domain interface for nucleotide exchange and GTP hydrolysis, and pThr193 and/or pThr194 in Switch I (SwI) that coordinates nucleotide exchange and protein partner binding. Several AtGPA1 S/T phosphorylation sites are nucleotide dependent phosphorylation patterns, such as S52 and/or T53 in the P-loop and T193 and/or T194 in SwI.

• Publisher: Cold Spring Harbor Laboratory Press,Cold Spring Harbor Laboratory
• Subject: Arabidopsis / G protein-coupled receptors / Guanosine triphosphate / Kinases / Phosphorylation / Plant Biology / Proteins / Signal transduction