Crystal Structure of Histidine-containing Phosphotransfer Protein MtHPt1 from Medicago truncatula

Experimental Data Snapshot

  • Resolution: 1.45 Å
  • R-Value Free: 0.190 
  • R-Value Work: 0.168 
  • R-Value Observed: 0.168 

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Medicago truncatula histidine-containing phosphotransfer protein: Structural and biochemical insights into the cytokinin transduction pathway in plants.

Ruszkowski, M.Brzezinski, K.Jedrzejczak, R.Dauter, M.Dauter, Z.Sikorski, M.Jaskolski, M.

(2013) FEBS J 280: 3709-3720

  • DOI: https://doi.org/10.1111/febs.12363
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Histidine-containing phosphotransfer proteins (HPts) take part in hormone signal transduction in higher plants. The overall pathway of this process is reminiscent of the two-component system initially identified in prokaryotes. HPts function in histidine-aspartate phosphorelays in which they mediate the signal from sensory kinases (usually membrane proteins) to RRs in the nucleus. Here, we report the crystal structure of an HPt protein from Medicago truncatula (MtHPt1) determined at 1.45 Å resolution and refined to an R-factor of 16.7% using low-temperature synchrotron-radiation X-ray diffraction data. There is one MtHPt1 molecule in the asymmetric unit of the crystal lattice with P2(1)2(1)2(1) symmetry. The protein fold consists of six α helices, four of which form a C-terminal helix bundle. The coiled-coil structure of the bundle is stabilized by a network of S-aromatic interactions involving highly conserved sulfur-containing residues. The structure reveals a solvent-exposed side chain of His79, which is the phosphorylation site, as demonstrated by autoradiography combined with site-directed mutation. It is surrounded by highly conserved residues present in all plant HPts. These residues form a putative docking interface for either the receiver domain of the sensory kinase, or for the RR. The biological activity of MtHPt1 was tested by autoradiography. It demonstrated phosphorylation by the intracellular kinase domain of the cytokinin receptor MtCRE1. Complex formation between MtHPt1 and the intracellular fragment of MtCRE1 was confirmed by thermophoresis, with a dissociation constant K(d) of 14 μM.

  • Organizational Affiliation

    Center for Biocrystallographic Research, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan, Poland.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Histidine-containing Phosphotransfer Protein type 1, MtHPt1153Medicago truncatulaMutation(s): 0 
Gene Names: MtHPt
EC: 2.7.3
Find proteins for B7FGU6 (Medicago truncatula)
Explore B7FGU6 
Go to UniProtKB:  B7FGU6
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupB7FGU6
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.45 Å
  • R-Value Free: 0.190 
  • R-Value Work: 0.168 
  • R-Value Observed: 0.168 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 38.554α = 90
b = 44.899β = 90
c = 85.905γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
PDB_EXTRACTdata extraction
MAR345data collection
XDSdata reduction
XSCALEdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2012-01-18
    Type: Initial release
  • Version 1.1: 2013-07-31
    Changes: Database references
  • Version 1.2: 2017-11-08
    Changes: Refinement description
  • Version 1.3: 2023-09-13
    Changes: Data collection, Database references, Refinement description