DNA replication requires processivity factors that allow replicative DNA polymerases to extend long stretches of DNA. Some DNA viruses encode their own replicative DNA polymerase, such as the white spot syndrome virus (WSSV) that infects decapod crustaceans but still require host replication accessory factors. We have determined by X-ray diffraction the threedimensional structure of the Pacific white leg shrimp Litopenaeus vannamei Proliferating Cell Nuclear Antigen (LvPCNA). This protein is a member of the sliding clamp family of proteins, that binds DNA replication and DNA repair proteins through a motif called PIP-box (PCNA-Interacting Protein). The crystal structure of LvPCNA was refined to a resolution of 3 AA , and allowed us to determine the trimeric protein assembly and details of the interactions between PCNA and the DNA. To address the possible interaction between LvPCNA and the viral DNA polymerase, we docked a theoretical model of a PIPbox peptide from the WSSV DNA polymerase within LvPCNA crystal structure. The theoretical model depicts a feasible model of interaction between both proteins. The crystal structure of shrimp PCNA allows us to further understand the mechanisms of DNA replication processivity factors in non-model systems.
Bibliographical noteFunding Information:
J.S. Carrasco-Miranda and A.A. Lopez-Zavala were supported by Ph.D. fellowships from CONACyT (Mexicós National Science and Research Council). R. Sotelo-Mundo acknowledges financial support from CONACyT grant CB-2009-131859. L.G. Brieba acknowledges financial support of CONACyT grant CB-2009-128647. We thank the staff at BNL-NSLS beamlines X4C and X6A (Dr. John Schwanoff) for data-collection facilities. Beamline X6A is funded by NIGMS (GM-0080) and the US Department of Energy (No. DE-AC02-98CH10886). We also thank technical bibliographical support from Gerardo Reyna and computational technical support from Felipe Isac-Martinez, Luis Leyva-Durán, Adalberto Murrieta-Valenciana, José L. Aguilar-Valenzuela and Martin Peralta-Contreras, all of them from CIAD.