Implications of structures of synaptic tetramers of gamma delta resolvase for the mechanism of recombination

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 103; no. 28; pp. 10642 - 10647
• Main Authors: Kamtekar, Satwik, Ho, Roger S, Cocco, Melanie J, Li, Weikai, Wenwieser, Sandra V C T, Boocock, Martin R, Grindley, Nigel D F, Steitz, Thomas A
• Format: Journal Article
• Language: English
• Published: United States 11-07-2006
• Subjects: Crystallography, X-Ray; DNA - metabolism; DNA Nucleotidyltransferases - chemistry; DNA Nucleotidyltransferases - genetics; DNA Nucleotidyltransferases - physiology; Humans; Mutant Chimeric Proteins - chemistry; Mutant Chimeric Proteins - physiology; MUTANTS; national synchrotron light source; NSLS; PARTICLE ACCELERATORS; RECOMBINATION; Recombination, Genetic - physiology; RESOLUTION; Transposon Resolvases - chemistry; Transposon Resolvases - genetics; Transposon Resolvases - physiology
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0604062103

The structures of two mutants of the site-specific recombinase, gammadelta resolvase, that form activated tetramers have been determined. One, at 3.5-A resolution, forms a synaptic intermediate of resolvase that is covalently linked to two cleaved DNAs, whereas the other is of an unliganded structure determined at 2.1-A resolution. Comparisons of the four known tetrameric resolvase structures show that the subunits interact through the formation of a common core of four helices. The N-terminal halves of these helices superimpose well on each other, whereas the orientations of their C termini are more variable. The catalytic domains of resolvase in the unliganded structure are arranged asymmetrically, demonstrating that their positions can move substantially while preserving the four-helix core that forms the tetramer. These results suggest that the precleavage synaptic tetramer of gammadelta resolvase, whose structure is not known, may be formed by a similar four-helix core, but differ in the relative orientations of its catalytic and DNA-binding domains.