Mechanistic basis of plasmid-specific DNA binding of the F plasmid regulatory protein, TraM

Experimental Data Snapshot

  • Resolution: 2.00 Å
  • R-Value Free: 0.230 
  • R-Value Work: 0.192 
  • R-Value Observed: 0.194 

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Mechanistic Basis of Plasmid-Specific DNA Binding of the F Plasmid Regulatory Protein, TraM.

Peng, Y.Lu, J.Wong, J.J.Edwards, R.A.Frost, L.S.Mark Glover, J.N.

(2014) J Mol Biol 426: 3783-3795

  • DOI: https://doi.org/10.1016/j.jmb.2014.09.018
  • Primary Citation of Related Structures:  
    4QPO, 4QPQ

  • PubMed Abstract: 

    The conjugative transfer of bacterial F plasmids relies on TraM, a plasmid-encoded protein that recognizes multiple DNA sites to recruit the plasmid to the conjugative pore. In spite of the high degree of amino acid sequence conservation between TraM proteins, many of these proteins have markedly different DNA binding specificities that ensure the selective recruitment of a plasmid to its cognate pore. Here we present the structure of F TraM RHH (ribbon-helix-helix) domain bound to its sbmA site. The structure indicates that a pair of TraM tetramers cooperatively binds an underwound sbmA site containing 12 base pairs per turn. The sbmA is composed of 4 copies of a 5-base-pair motif, each of which is recognized by an RHH domain. The structure reveals that a single conservative amino acid difference in the RHH β-ribbon between F and pED208 TraM changes its specificity for its cognate 5-base-pair sequence motif. Specificity is also dictated by the positioning of 2-base-pair spacer elements within sbmA; in F sbmA, the spacers are positioned between motifs 1 and 2 and between motifs 3 and 4, whereas in pED208 sbmA, there is a single spacer between motifs 2 and 3. We also demonstrate that a pair of F TraM tetramers can cooperatively bind its sbmC site with an affinity similar to that of sbmA in spite of a lack of sequence similarity between these DNA elements. These results provide a basis for the prediction of the DNA binding properties of the family of TraM proteins.

  • Organizational Affiliation

    Department of Biochemistry, University of Alberta, Edmonton, AB, T6G 2H7, Canada.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Relaxosome protein TraM
A, B, C, D
53Escherichia coli K-12Mutation(s): 0 
Gene Names: traMECOK12F071
Find proteins for P10026 (Escherichia coli (strain K12))
Explore P10026 
Go to UniProtKB:  P10026
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP10026
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.00 Å
  • R-Value Free: 0.230 
  • R-Value Work: 0.192 
  • R-Value Observed: 0.194 
  • Space Group: H 3
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 115.682α = 90
b = 115.682β = 90
c = 54.713γ = 120
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
PDB_EXTRACTdata extraction
HKL-2000data reduction
HKL-2000data scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2014-09-03
    Type: Initial release
  • Version 1.1: 2014-10-22
    Changes: Database references
  • Version 1.2: 2014-12-17
    Changes: Database references