Phosphorylation-induced conformation of beta(2)-adrenoceptor related to arrestin recruitment revealed by NMR

The C-terminal region of G-protein-coupled receptors (GPCRs), stimulated by agonist binding, is phosphorylated by GPCR kinases, and the phosphorylated GPCRs bind to arrestin, leading to the cellular responses. To understand the mechanism underlying the formation of the phosphorylated GPCR-arrestin complex, we performed NMR analyses of the phosphorylated beta(2)-adrenoceptor (beta(2)AR) and the phosphorylated beta(2)AR-beta-arrestin 1 complex, in the lipid bilayers of nanodisc. Here we show that the phosphorylated C-terminal region adheres to either the intracellular side of the transmembrane region or lipids, and that the phosphorylation of the C-terminal region allosterically alters the conformation around M215(5.54) and M279(6.41), located on transemembrane helices 5 and 6, respectively. In addition, we found that the conformation induced by the phosphorylation is similar to that corresponding to the beta-arrestin-bound state. The phosphorylation-induced structures revealed in this study propose a conserved structural motif of GPCRs that enables beta-arrestin to recognize dozens of GPCRs.Peer reviewe

A chloroplast-localized protein LESION AND LAMINA BENDING affects defence and growth responses in rice

Understanding how plants allocate their resources to growth or defence is of long-term importance to the development of new and improved varieties of different crops. Using molecular genetics, plant physiology, hormone analysis and Next-Generation Sequencing (NGS)-based transcript profiling, we have isolated and characterized the rice(Oryza sativa) LESION AND LAMINA BENDING (LLB) gene that encodes a chloroplast-targeted putative leucine carboxyl methyltransferase. Loss of LLB function results in reduced growth and yield, hypersensitive response (HR)-like lesions, accumulation of the antimicrobial compounds momilactones and phytocassanes, and constitutive expression of pathogenesis-related genes. Consistent with these defence-associated responses, llb shows enhanced resistance to rice blast (Magnaporthe oryzae) and bacterial blight (Xanthomonas oryzae pv. oryzae). The lesion and resistance phenotypes are likely to be caused by the over-accumulation of jasmonates (JAs) in the llb mutant including the JA precursor 12-oxo-phytodienoic acid. Additionally, llb shows an increased lamina inclination and enhanced early seedling growth due to elevated brassinosteroid (BR) synthesis and/or signalling. These findings show that LLB functions in the chloroplast to either directly or indirectly repress both JA- and BR-mediated responses, revealing a possible mechanism for controlling how plants allocate resources for defence and growth