| Structural highlights
Function
PHR1_ARATH Transcription factor involved in phosphate starvation signaling (PubMed:11511543, PubMed:17927693, PubMed:26586833). Binds as a dimer to P1BS, an imperfect palindromic sequence 5'-GNATATNC-3', to promote the expression of inorganic phosphate (Pi) starvation-responsive genes (PubMed:11511543, PubMed:20838596, PubMed:26586833). SPX1 is a competitive inhibitor of this DNA-binding (PubMed:25271326). PHR1 binding to its targets is low Pi-dependent (PubMed:25271326). Regulates the expression of miR399 (PubMed:20838596). Regulates the expression of IPS1 (At3g09922), a non-coding RNA that mimics the target of miR399 to block the cleavage of PHO2 under Pi-deficient conditions (PubMed:17643101). Regulates lipid remodeling and triacylglycerol accumulation during phosphorus starvation (PubMed:25680792). Required for the shoot-specific hypoxic response (PubMed:24753539). Regulates FER1 expression upon phosphate starvation, linking iron and phosphate homeostasis (PubMed:23788639). Contributes to the homeostasis of both sulfate and phosphate in plants under phosphate deficiency (PubMed:21261953). Required for adaptation to high light and retaining functional photosynthesis during phosphate starvation (PubMed:21910737). Involved in the coregulation of Zn and Pi homeostasis (PubMed:24420568).[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12]
Publication Abstract from PubMed
Phosphorus is an essential nutrient taken up by organisms in the form of inorganic phosphate (Pi). Eukaryotes have evolved sophisticated Pi sensing and signaling cascades, enabling them to stably maintain cellular Pi concentrations. Pi homeostasis is regulated by inositol pyrophosphate signaling molecules (PP-InsPs), which are sensed by SPX domain-containing proteins. In plants, PP-InsP-bound SPX receptors inactivate Myb coiled-coil (MYB-CC) Pi starvation response transcription factors (PHRs) by an unknown mechanism. Here we report that a InsP(8)-SPX complex targets the plant-unique CC domain of PHRs. Crystal structures of the CC domain reveal an unusual four-stranded anti-parallel arrangement. Interface mutations in the CC domain yield monomeric PHR1, which is no longer able to bind DNA with high affinity. Mutation of conserved basic residues located at the surface of the CC domain disrupt interaction with the SPX receptor in vitro and in planta, resulting in constitutive Pi starvation responses. Together, our findings suggest that InsP(8) regulates plant Pi homeostasis by controlling the oligomeric state and hence the promoter binding capability of PHRs via their SPX receptors.
Inositol pyrophosphates promote the interaction of SPX domains with the coiled-coil motif of PHR transcription factors to regulate plant phosphate homeostasis.,Ried MK, Wild R, Zhu J, Pipercevic J, Sturm K, Broger L, Harmel RK, Abriata LA, Hothorn LA, Fiedler D, Hiller S, Hothorn M Nat Commun. 2021 Jan 15;12(1):384. doi: 10.1038/s41467-020-20681-4. PMID:33452263[13]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Rubio V, Linhares F, Solano R, Martin AC, Iglesias J, Leyva A, Paz-Ares J. A conserved MYB transcription factor involved in phosphate starvation signaling both in vascular plants and in unicellular algae. Genes Dev. 2001 Aug 15;15(16):2122-33. PMID:11511543 doi:http://dx.doi.org/10.1101/gad.204401
- ↑ Franco-Zorrilla JM, Valli A, Todesco M, Mateos I, Puga MI, Rubio-Somoza I, Leyva A, Weigel D, Garcia JA, Paz-Ares J. Target mimicry provides a new mechanism for regulation of microRNA activity. Nat Genet. 2007 Aug;39(8):1033-7. doi: 10.1038/ng2079. Epub 2007 Jul 22. PMID:17643101 doi:http://dx.doi.org/10.1038/ng2079
- ↑ Nilsson L, Muller R, Nielsen TH. Increased expression of the MYB-related transcription factor, PHR1, leads to enhanced phosphate uptake in Arabidopsis thaliana. Plant Cell Environ. 2007 Dec;30(12):1499-512. doi:, 10.1111/j.1365-3040.2007.01734.x. Epub 2007 Oct 9. PMID:17927693 doi:http://dx.doi.org/10.1111/j.1365-3040.2007.01734.x
- ↑ Bustos R, Castrillo G, Linhares F, Puga MI, Rubio V, Perez-Perez J, Solano R, Leyva A, Paz-Ares J. A central regulatory system largely controls transcriptional activation and repression responses to phosphate starvation in Arabidopsis. PLoS Genet. 2010 Sep 9;6(9):e1001102. doi: 10.1371/journal.pgen.1001102. PMID:20838596 doi:http://dx.doi.org/10.1371/journal.pgen.1001102
- ↑ Rouached H, Secco D, Arpat B, Poirier Y. The transcription factor PHR1 plays a key role in the regulation of sulfate shoot-to-root flux upon phosphate starvation in Arabidopsis. BMC Plant Biol. 2011 Jan 24;11:19. doi: 10.1186/1471-2229-11-19. PMID:21261953 doi:http://dx.doi.org/10.1186/1471-2229-11-19
- ↑ Nilsson L, Lundmark M, Jensen PE, Nielsen TH. The Arabidopsis transcription factor PHR1 is essential for adaptation to high light and retaining functional photosynthesis during phosphate starvation. Physiol Plant. 2012 Jan;144(1):35-47. doi: 10.1111/j.1399-3054.2011.01520.x. Epub, 2011 Oct 19. PMID:21910737 doi:http://dx.doi.org/10.1111/j.1399-3054.2011.01520.x
- ↑ Bournier M, Tissot N, Mari S, Boucherez J, Lacombe E, Briat JF, Gaymard F. Arabidopsis ferritin 1 (AtFer1) gene regulation by the phosphate starvation response 1 (AtPHR1) transcription factor reveals a direct molecular link between iron and phosphate homeostasis. J Biol Chem. 2013 Aug 2;288(31):22670-80. doi: 10.1074/jbc.M113.482281. Epub 2013, Jun 20. PMID:23788639 doi:http://dx.doi.org/10.1074/jbc.M113.482281
- ↑ Khan GA, Bouraine S, Wege S, Li Y, de Carbonnel M, Berthomieu P, Poirier Y, Rouached H. Coordination between zinc and phosphate homeostasis involves the transcription factor PHR1, the phosphate exporter PHO1, and its homologue PHO1;H3 in Arabidopsis. J Exp Bot. 2014 Mar;65(3):871-84. doi: 10.1093/jxb/ert444. Epub 2014 Jan 13. PMID:24420568 doi:http://dx.doi.org/10.1093/jxb/ert444
- ↑ Klecker M, Gasch P, Peisker H, Dormann P, Schlicke H, Grimm B, Mustroph A. A Shoot-Specific Hypoxic Response of Arabidopsis Sheds Light on the Role of the Phosphate-Responsive Transcription Factor PHOSPHATE STARVATION RESPONSE1. Plant Physiol. 2014 Jun;165(2):774-790. doi: 10.1104/pp.114.237990. Epub 2014 Apr, 21. PMID:24753539 doi:http://dx.doi.org/10.1104/pp.114.237990
- ↑ Puga MI, Mateos I, Charukesi R, Wang Z, Franco-Zorrilla JM, de Lorenzo L, Irigoyen ML, Masiero S, Bustos R, Rodriguez J, Leyva A, Rubio V, Sommer H, Paz-Ares J. SPX1 is a phosphate-dependent inhibitor of Phosphate Starvation Response 1 in Arabidopsis. Proc Natl Acad Sci U S A. 2014 Oct 14;111(41):14947-52. doi:, 10.1073/pnas.1404654111. Epub 2014 Sep 30. PMID:25271326 doi:http://dx.doi.org/10.1073/pnas.1404654111
- ↑ Pant BD, Burgos A, Pant P, Cuadros-Inostroza A, Willmitzer L, Scheible WR. The transcription factor PHR1 regulates lipid remodeling and triacylglycerol accumulation in Arabidopsis thaliana during phosphorus starvation. J Exp Bot. 2015 Apr;66(7):1907-18. doi: 10.1093/jxb/eru535. Epub 2015 Feb 13. PMID:25680792 doi:http://dx.doi.org/10.1093/jxb/eru535
- ↑ Sun L, Song L, Zhang Y, Zheng Z, Liu D. Arabidopsis PHL2 and PHR1 Act Redundantly as the Key Components of the Central Regulatory System Controlling Transcriptional Responses to Phosphate Starvation. Plant Physiol. 2016 Jan;170(1):499-514. doi: 10.1104/pp.15.01336. Epub 2015 Nov, 19. PMID:26586833 doi:http://dx.doi.org/10.1104/pp.15.01336
- ↑ Ried MK, Wild R, Zhu J, Pipercevic J, Sturm K, Broger L, Harmel RK, Abriata LA, Hothorn LA, Fiedler D, Hiller S, Hothorn M. Inositol pyrophosphates promote the interaction of SPX domains with the coiled-coil motif of PHR transcription factors to regulate plant phosphate homeostasis. Nat Commun. 2021 Jan 15;12(1):384. PMID:33452263 doi:10.1038/s41467-020-20681-4
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