2MM2

Solution Structures of Active Ptr ToxB and its inactive Homolog highlight Protein Dynamics as a Modulator of Toxin activity.


Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Calculated: 200 
  • Conformers Submitted: 20 
  • Selection Criteria: structures with the lowest energy 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Solution NMR Structures of Pyrenophora tritici-repentis ToxB and Its Inactive Homolog Reveal Potential Determinants of Toxin Activity.

Nyarko, A.Singarapu, K.K.Figueroa, M.Manning, V.A.Pandelova, I.Wolpert, T.J.Ciuffetti, L.M.Barbar, E.

(2014) J.Biol.Chem. 289: 25946-25956

  • DOI: 10.1074/jbc.M114.569103
  • Primary Citation of Related Structures:  2MM0

  • PubMed Abstract: 
  • Pyrenophora tritici-repentis Ptr ToxB (ToxB) is a proteinaceous host-selective toxin produced by Pyrenophora tritici-repentis (P. tritici-repentis), a plant pathogenic fungus that causes the disease tan spot of wheat. One feature that distinguishes T ...

    Pyrenophora tritici-repentis Ptr ToxB (ToxB) is a proteinaceous host-selective toxin produced by Pyrenophora tritici-repentis (P. tritici-repentis), a plant pathogenic fungus that causes the disease tan spot of wheat. One feature that distinguishes ToxB from other host-selective toxins is that it has naturally occurring homologs in non-pathogenic P. tritici-repentis isolates that lack toxic activity. There are no high-resolution structures for any of the ToxB homologs, or for any protein with >30% sequence identity, and therefore what underlies activity remains an open question. Here, we present the NMR structures of ToxB and its inactive homolog Ptr toxb. Both proteins adopt a β-sandwich fold comprising three strands in each half that are bridged together by two disulfide bonds. The inactive toxb, however, shows higher flexibility localized to the sequence-divergent β-sandwich half. The absence of toxic activity is attributed to a more open structure in the vicinity of one disulfide bond, higher flexibility, and residue differences in an exposed loop that likely impacts interaction with putative targets. We propose that activity is regulated by perturbations in a putative active site loop and changes in dynamics distant from the site of activity. Interestingly, the new structures identify AvrPiz-t, a secreted avirulence protein produced by the rice blast fungus, as a structural homolog to ToxB. This homology suggests that fungal proteins involved in either disease susceptibility such as ToxB or resistance such as AvrPiz-t may have a common evolutionary origin.


    Organizational Affiliation

    From the Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon 97331.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Toxb
A
65Pyrenophora tritici-repentisGene Names: toxb
Find proteins for Q8J0U6 (Pyrenophora tritici-repentis)
Go to UniProtKB:  Q8J0U6
Experimental Data & Validation

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Calculated: 200 
  • Conformers Submitted: 20 
  • Selection Criteria: structures with the lowest energy 

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

  • Deposited Date: 2014-03-06 
  • Released Date: 2014-08-06 
  • Deposition Author(s): Barbar, E., Nyarko, A.

Revision History 

  • Version 1.0: 2014-08-06
    Type: Initial release
  • Version 1.1: 2014-08-20
    Type: Database references
  • Version 1.2: 2014-10-01
    Type: Database references