| Structural highlights
4euk is a 2 chain structure with sequence from Arath. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
| | Ligands: | , |
| Gene: | AHK5, At5g10720, CKI2, MAJ23.80 (ARATH), AHP1, At3g21510, ATHP3, MIL23.8 (ARATH) |
| Activity: | Histidine kinase, with EC number 2.7.13.3 |
| Resources: | FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT |
Function
[AHK5_ARATH] Functions as a histidine kinase and transmits the stress signal to a downstream MAPK cascade. This protein undergoes an ATP-dependent autophosphorylation at a conserved histidine residue in the kinase core, and a phosphoryl group is then transferred to a conserved aspartate residue in the receiver domain. Negative regulator of the ETR1-dependent abscisic acid (ABA) and ethylene signaling pathway that inhibits the root elongation. Promotes stomatal closure. Regulates stomatal opening by integrating multiple signals via hydrogen peroxide H(2)O(2) homeostasis in guard cells in an ABA-independent manner. May contribute to basal defense mechanisms by closing stomata in the presence of bacterial pathogens. Regulates both hormone levels and ROS production in response to stress. Required for full immunity to bacterial pathogen and necrotrophic fungus.[1] [2] [3] [4] [5] [AHP1_ARATH] Functions as two-component phosphorelay mediators between cytokinin sensor histidine kinases and response regulators (B-type ARRs). Plays an important role in propagating cytokinin signal transduction through the multistep His-to-Asp phosphorelay.[6] [7] [8] [9]
Publication Abstract from PubMed
The multi-step phosphorelay (MSP) system defines a key signal transduction pathway in plants and many eukaryotes. In this system, external stimuli first lead to the activation of a histidine kinase, followed by transfer of a phosphoryl group from the receiver domain of the kinase (HK(RD)) to downstream, cytosolic phosphotransfer proteins (HPs). In order to establish the determinants of specificity for this signaling relay system, we have solved the first crystal structure of a plant HK(RD), AHK5(RD), in complex with one of its cognate HPs, AHP1. AHP1 binds AHK5(RD) via a prominent hydrogen bond docking ridge and a hydrophobic patch. These features are conserved among all AHP proteins, but differ significantly from other structurally characterized prokaryotic and eukaryotic HPs. Surface plasmon resonance experiments show that AHK5(RD) binds to AHP1-3 with similar, micromolar affinity, consistent with the transient nature of this signaling complex. Our correlation of structural and functional data provide the first insight, at the atomic level as well as with quantitative affinity data, into the molecular recognition events governing the MSP in plants.
Structure-Function Analysis of Arabidopsis thaliana Histidine Kinase AHK5 Bound to Its Cognate Phosphotransfer Protein AHP1.,Bauer J, Reiss K, Veerabagu M, Heunemann M, Harter K, Stehle T Mol Plant. 2013 Jan 24. PMID:23132142[10]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Iwama A, Yamashino T, Tanaka Y, Sakakibara H, Kakimoto T, Sato S, Kato T, Tabata S, Nagatani A, Mizuno T. AHK5 histidine kinase regulates root elongation through an ETR1-dependent abscisic acid and ethylene signaling pathway in Arabidopsis thaliana. Plant Cell Physiol. 2007 Feb;48(2):375-80. Epub 2007 Jan 3. PMID:17202180 doi:http://dx.doi.org/10.1093/pcp/pcl065
- ↑ Tran LS, Urao T, Qin F, Maruyama K, Kakimoto T, Shinozaki K, Yamaguchi-Shinozaki K. Functional analysis of AHK1/ATHK1 and cytokinin receptor histidine kinases in response to abscisic acid, drought, and salt stress in Arabidopsis. Proc Natl Acad Sci U S A. 2007 Dec 18;104(51):20623-8. Epub 2007 Dec 12. PMID:18077346 doi:http://dx.doi.org/10.1073/pnas.0706547105
- ↑ Desikan R, Horak J, Chaban C, Mira-Rodado V, Witthoft J, Elgass K, Grefen C, Cheung MK, Meixner AJ, Hooley R, Neill SJ, Hancock JT, Harter K. The histidine kinase AHK5 integrates endogenous and environmental signals in Arabidopsis guard cells. PLoS One. 2008 Jun 18;3(6):e2491. doi: 10.1371/journal.pone.0002491. PMID:18560512 doi:http://dx.doi.org/10.1371/journal.pone.0002491
- ↑ Pham J, Liu J, Bennett MH, Mansfield JW, Desikan R. Arabidopsis histidine kinase 5 regulates salt sensitivity and resistance against bacterial and fungal infection. New Phytol. 2012 Apr;194(1):168-80. doi: 10.1111/j.1469-8137.2011.04033.x. Epub, 2012 Jan 18. PMID:22256998 doi:http://dx.doi.org/10.1111/j.1469-8137.2011.04033.x
- ↑ Pham J, Desikan R. Modulation of ROS production and hormone levels by AHK5 during abiotic and biotic stress signaling. Plant Signal Behav. 2012 Aug;7(8):893-7. doi: 10.4161/psb.20692. Epub 2012 Jul, 25. PMID:22827948 doi:http://dx.doi.org/10.4161/psb.20692
- ↑ Suzuki T, Imamura A, Ueguchi C, Mizuno T. Histidine-containing phosphotransfer (HPt) signal transducers implicated in His-to-Asp phosphorelay in Arabidopsis. Plant Cell Physiol. 1998 Dec;39(12):1258-68. PMID:10050311
- ↑ Hwang I, Chen HC, Sheen J. Two-component signal transduction pathways in Arabidopsis. Plant Physiol. 2002 Jun;129(2):500-15. PMID:12068096 doi:http://dx.doi.org/10.1104/pp.005504
- ↑ Tanaka Y, Suzuki T, Yamashino T, Mizuno T. Comparative studies of the AHP histidine-containing phosphotransmitters implicated in His-to-Asp phosphorelay in Arabidopsis thaliana. Biosci Biotechnol Biochem. 2004 Feb;68(2):462-5. PMID:14981318
- ↑ Miyata S, Urao T, Yamaguchi-Shinozaki K, Shinozaki K. Characterization of genes for two-component phosphorelay mediators with a single HPt domain in Arabidopsis thaliana. FEBS Lett. 1998 Oct 16;437(1-2):11-4. PMID:9804162
- ↑ Bauer J, Reiss K, Veerabagu M, Heunemann M, Harter K, Stehle T. Structure-Function Analysis of Arabidopsis thaliana Histidine Kinase AHK5 Bound to Its Cognate Phosphotransfer Protein AHP1. Mol Plant. 2013 Jan 24. PMID:23132142 doi:10.1093/mp/sss126
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