7d3t
Crystal structure of OSPHR2 in complex with DNA
Structural highlights
FunctionPHR2_ORYSI Transcription factor involved in phosphate starvation signaling (By similarity). Binds to P1BS, an imperfect palindromic sequence 5'-GNATATNC-3', to promote the expression of inorganic phosphate (Pi) starvation-responsive genes (By similarity). Functionally redundant with PHR1 and PHR3 in regulating Pi starvation response and Pi homeostasis (By similarity). Involved in both systematic and local Pi-signaling pathways (By similarity). Regulates several Pi transporters (By similarity). PHR2 binding to DNA is repressed redundantly by SPX1, SPX2 and SPX4 in a PI-dependent manner (By similarity). The DNA-binding activity is also repressed by SPX4 (By similarity). Involved in root growth under Pi deprivation (By similarity). Involved in the modulation of Pi response and homeostasis together with RLI1; promotes RLI1 expression in response to nitrate availability, thus triggering the nitrate-induced phosphate response (NIPR) (By similarity).[UniProtKB:Q6Z156] Publication Abstract from PubMedPhosphate (Pi) starvation response (PHR) transcription factors play key roles in plant Pi homeostasis maintenance. They are negatively regulated by stand-alone SPX proteins, cellular receptors for inositol pyrophosphate (PP-InsP) nutrient messengers. How PP-InsP-bound SPX interacts with PHRs is poorly understood. Here, we report crystal structures of the rice SPX2/InsP(6)/PHR2 complex and of the PHR2 DNA binding (MYB) domain in complex with target DNA at resolutions of 3.1 A and 2.7 A, respectively. In the SPX2/InsP(6)/PHR2 complex, the signalling-active SPX2 assembles into a domain-swapped dimer conformation and binds two copies of PHR2, targeting both its coiled-coil (CC) oligomerisation domain and MYB domain. Our results reveal that the SPX2 senses PP-InsPs to inactivate PHR2 by establishing severe steric clashes with the PHR2 MYB domain, preventing DNA binding, and by disrupting oligomerisation of the PHR2 CC domain, attenuating promoter binding. Our findings rationalize how PP-InsPs activate SPX receptor proteins to target PHR family transcription factors. Mechanistic insights into the regulation of plant phosphate homeostasis by the rice SPX2 - PHR2 complex.,Guan Z, Zhang Q, Zhang Z, Zuo J, Chen J, Liu R, Savarin J, Broger L, Cheng P, Wang Q, Pei K, Zhang D, Zou T, Yan J, Yin P, Hothorn M, Liu Z Nat Commun. 2022 Mar 24;13(1):1581. doi: 10.1038/s41467-022-29275-8. PMID:35332155[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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