Coiled-coil interactions mediate serine integrase directionality. Issue 12 (26th May 2017)

• Record Type: Journal Article
• Authors: Gupta, Kushol; Sharp, Robert; Yuan, Jimmy B.; Li, Huiguang; Van Duyne, Gregory D.
• Is Part Of: Nucleic acids research. Volume 45:Issue 12(2017)
• Page Start: 7339
• Page End: 7353
• Publication Date: 2017-05-26
• Subjects: Nucleic acids -- Periodicals; Molecular biology -- Periodicals; 572.805
• DOI: 10.1093/nar/gkx474
• Languages: English
• ISSNs: 0305-1048

Abstract

Abstract: Serine integrases are bacteriophage enzymes that carry out site-specific integration and excision of their viral genomes. The integration reaction is highly directional; recombination between the phage attachment site att P and the host attachment site att B to form the hybrid sites att L and att R is essentially irreversible. In a recent model, extended coiled-coil (CC) domains in the integrase subunits are proposed to interact in a way that favors the att Px att B reaction but inhibits the att Lx att R reaction. Here, we show for the Listeria innocua integrase (LI Int) system that the CC domain promotes self-interaction in isolated Int and when Int is bound to attachment sites. Three independent crystal structures of the CC domain reveal the molecular nature of the CC dimer interface. Alanine substitutions of key residues in the interface support the functional significance of the structural model and indicate that the same interaction is responsible for promoting integration and for inhibiting excision. An updated model of a LI Int att L complex that incorporates the high resolution CC dimer structure provides insights that help to explain the unusual CC dimer structure and potential sources of stability in Int att L and Int att R complexes. Together, the data provide a molecular basis for understanding serine integrase directionality.