PhoB response regulator receiver domain constitutively-active double mutant D10A and D53E.

Experimental Data Snapshot

  • Resolution: 1.70 Å
  • R-Value Free: 0.256 
  • R-Value Work: 0.223 
  • R-Value Observed: 0.224 

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The X-Ray Crystal Structures of Two Constitutively Active Mutants of the E. Coli Phob Receiver Domain Give Insights Into Activation

Arribas-Bosacoma, R.Kim, S.-K.Ferrer-Orta, C.Blanco, A.G.Pereira, P.J.B.Gomis-Ruth, F.X.Wanner, B.L.Coll, M.Sola, M.

(2007) J Mol Biol 366: 626

  • DOI: https://doi.org/10.1016/j.jmb.2006.11.038
  • Primary Citation of Related Structures:  
    2JB9, 2JBA

  • PubMed Abstract: 

    The PhoR/PhoB two-component system is a key regulatory protein network enabling Escherichia coli to respond to inorganic phosphate (Pi) starvation conditions by turning on Pho regulon genes for more efficient Pi uptake and use of alternative phosphorus sources. Under environmental Pi depletion, the response regulator (RR) component, PhoB, is phosphorylated at the receiver domain (RD), a process that requires Mg(2+) bound at the active site. Phosphorylation of the RD relieves the inhibition of the PhoB effector domain (ED), a DNA-binding region that binds to Pho regulon promoters to activate transcription. The molecular details of the activation are proposed to involve dimerization of the RD and a conformational change in the RD detected by the ED. The structure of the PhoB RD shows a symmetrical interaction involving alpha1, loop beta5alpha5 and N terminus of alpha5 elements, also seen in the complex of PhoB RD with Mg(2+), in which helix alpha4 highly increases its flexibility. PhoB RD in complex with Mg(2+) and BeF(3) (an emulator of the phosphate moiety) undergoes a dramatic conformational change on helix alpha4 and shows another interaction involving alpha4, beta5 and alpha5 segments. We have selected a series of constitutively active PhoB mutants (PhoB(CA)) that are able to turn on the Pho regulon promoters in the absence phosphorylation and, as they cannot be inactivated, should therefore mimic the active RD state of PhoB and its functional oligomerisation. We have analysed the PhoB(CA) RD crystal structures of two such mutants, Asp53Ala/Tyr102Cys and Asp10Ala/Asp53Glu. Interestingly, both mutants reproduce the homodimeric arrangement through the symmetric interface encountered in the unbound and magnesium-bound wild-type PhoB RD structures. Besides, the mutant RD structures show a modified active site organization as well as changes at helix alpha4 that correlate with repositioning of surrounding residues, like the active-site events indicator Trp54, putatively redifining the interaction with the ED in the full-length protein.

  • Organizational Affiliation

    Institut de Biologia Molecular de Barcelona (CSIC), c/Jordi Girona 18-26, 08034 Barcelona, Spain.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B
127Escherichia coliMutation(s): 2 
Find proteins for P0AFJ5 (Escherichia coli (strain K12))
Explore P0AFJ5 
Go to UniProtKB:  P0AFJ5
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP0AFJ5
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.70 Å
  • R-Value Free: 0.256 
  • R-Value Work: 0.223 
  • R-Value Observed: 0.224 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 32.924α = 90
b = 60.157β = 90
c = 116.492γ = 90
Software Package:
Software NamePurpose
MOSFLMdata reduction
SCALAdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2007-01-04
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Advisory, Version format compliance
  • Version 1.2: 2023-12-13
    Changes: Data collection, Database references, Other, Refinement description