Structural basis for catalytic activation of a serine recombinase.
Keenholtz, R.A., Rowland, S.J., Boocock, M.R., Stark, W.M., Rice, P.A.(2011) Structure 19: 799-809
- PubMed: 21645851 
- DOI: https://doi.org/10.1016/j.str.2011.03.017
- Primary Citation of Related Structures:  
3PKZ - PubMed Abstract: 
Sin resolvase is a site-specific serine recombinase that is normally controlled by a complex regulatory mechanism. A single mutation, Q115R, allows the enzyme to bypass the entire regulatory apparatus, such that no accessory proteins or DNA sites are required. Here, we present a 1.86 Å crystal structure of the Sin Q115R catalytic domain, in a tetrameric arrangement stabilized by an interaction between Arg115 residues on neighboring subunits. The subunits have undergone significant conformational changes from the inactive dimeric state previously reported. The structure provides a new high-resolution view of a serine recombinase active site that is apparently fully assembled, suggesting roles for the conserved active site residues. The structure also suggests how the dimer-tetramer transition is coupled to assembly of the active site. The tetramer is captured in a different rotational substate than that seen in previous hyperactive serine recombinase structures, and unbroken crossover site DNA can be readily modeled into its active sites.
Organizational Affiliation: 
Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA.