2W8X

Structure of the tick ion-channel modulator Ra-KLP


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.60 Å
  • R-Value Free: 0.173 
  • R-Value Work: 0.139 
  • R-Value Observed: 0.140 

wwPDB Validation   3D Report Full Report


This is version 1.3 of the entry. See complete history


Literature

An Ion-Channel Modulator from the Saliva of the Brown Ear Tick Has a Highly Modified Kunitz/Bpti Structure.

Paesen, G.C.Siebold, C.Dallas, M.L.Peers, C.Harlos, K.Nuttall, P.A.Nunn, M.A.Stuart, D.I.Esnouf, R.M.

(2009) J Mol Biol 389: 734

  • DOI: https://doi.org/10.1016/j.jmb.2009.04.045
  • Primary Citation of Related Structures:  
    2W8X

  • PubMed Abstract: 

    Ra-KLP, a 75 amino acid protein secreted by the salivary gland of the brown ear tick Rhipicephalus appendiculatus has a sequence resembling those of Kunitz/BPTI proteins. We report the detection, purification and characterization of the function of Ra-KLP. In addition, determination of the three-dimensional crystal structure of Ra-KLP at 1.6 A resolution using sulphur single-wavelength anomalous dispersion reveals that much of the loop structure of classical Kunitz domains, including the protruding protease-binding loop, has been replaced by beta-strands. Even more unusually, the N-terminal portion of the polypeptide chain is pinned to the "Kunitz head" by two disulphide bridges not found in classical Kunitz/BPTI proteins. The disulphide bond pattern has been further altered by the loss of the bridge that normally stabilizes the protease-binding loop. Consistent with the conversion of this loop into a beta-strand, Ra-KLP shows no significant anti-protease activity; however, it activates maxiK channels in an in vitro system, suggesting a potential mechanism for regulating host blood supply during feeding.


  • Organizational Affiliation

    CEH Oxford, Mansfield Road, Oxford OX1 3SR, UK. gcp@ceh.ac.uk


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
ION-CHANNEL MODULATOR RAKLP
A, B
72Rhipicephalus appendiculatusMutation(s): 0 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.60 Å
  • R-Value Free: 0.173 
  • R-Value Work: 0.139 
  • R-Value Observed: 0.140 
  • Space Group: P 21 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 57.349α = 90
b = 65.687β = 90
c = 38.472γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
DENZOdata reduction
SCALEPACKdata scaling
SnBphasing
ACORNphasing
ARP/wARPphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2009-05-05
    Type: Initial release
  • Version 1.1: 2011-05-08
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2017-06-28
    Changes: Refinement description