The Structure of the Excisionase (Xis) Protein from Conjugative Transposon Tn916 Provides Insights into the Regulation of Heterobivalent Tyrosine Recombinases

Experimental Data Snapshot

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

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The structure of the excisionase (xis) protein from conjugative transposon tn916 provides insights into the regulation of heterobivalent tyrosine recombinases

Abbani, M.Iwahara, M.Clubb, R.T.

(2005) J Mol Biol 347: 11-25

  • DOI: https://doi.org/10.1016/j.jmb.2005.01.019
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Heterobivalent tyrosine recombinases play a prominent role in numerous bacteriophage and transposon recombination systems. Their enzymatic activities are frequently regulated at a structural level by excisionase factors, which alter the ability of the recombinase to assemble into higher-order recombinogenic nucleoprotein structures. The Tn916 conjugative transposon spreads antibiotic resistance in pathogenic bacteria and is mobilized by a heterobivalent recombinase (Tn916Int), whose activity is regulated by an excisionase factor (Tn916Xis). Unlike the well-characterized (lambda)Xis excisionase from bacteriophage lambda, Tn916Xis stimulates excision in vitro and in Escherichia coli only modestly. To gain insights into this functional difference, we have performed in vitro DNA-binding studies of Tn916Xis and Tn916Int, and we have solved the solution structure of Tn916Xis. We show that the heterobivalent Tn916Int protein is capable of bridging the DR2-type and core-type sites on the left arm of the tranpsoson. Consistent with the notion that Tn916Int is regulated only loosely, we find that Tn916Xis binding does not alter the stability of DR2-Tn916Int-core bridges or the ability of Tn916Int to recognize the arms of the transposon in vitro. Despite a high degree of divergence at the primary sequence level, we show that Tn916Xis and (lambda)Xis adopt related prokaryotic winged-helix structures. However, they differ at their C termini, with Tn916Xis replacing the flexible integrase contacting tail found in (lambda)Xis with a positively charged alpha-helix. This difference provides a structural explanation for why Tn916Xis does not interact cooperatively with its cognate integrase in vitro, and reveals how subtle changes in the winged-helix fold can modulate the functional properties of excisionase factors.

  • Organizational Affiliation

    Department of Chemistry and Biochemistry, UCLA-DOE Institute of Genomics and Proteomics, and the Molecular Biology Institute, University of California, Los Angeles, 405 Hilgard Avenue, Los Angeles, CA 90095-1570, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Excisionase from transposon Tn91670Enterococcus faecalisMutation(s): 0 
Gene Names: xis
Find proteins for Q79DA1 (Enterococcus faecalis)
Explore Q79DA1 
Go to UniProtKB:  Q79DA1
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ79DA1
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

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

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2005-03-15
    Type: Initial release
  • Version 1.1: 2008-04-30
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2022-03-02
    Changes: Data collection, Database references, Derived calculations