conservation of complex nuclear localization signals utilizing classical and non-classical nuclear import pathways in lana homologs of kshv and rfhv复杂的核保护定位信号利用经典和非经典的核进口途径拉娜同系物的kshv和rfhv.pdfVIP

Conservation of Complex Nuclear Localization Signals Utilizing Classical and Non-Classical Nuclear Import Pathways in LANA Homologs of KSHV and RFHV Lidia Cherezova1,2., Kellie L. Burnside2,3., Timothy M. Rose2,3* 1 Department of Global Health, University of Washington, Seattle, Washington, United States of America, 2 Center for Childhood Infections and Prematurity Research, Seattle Children’s Research Institute, Seattle, Washington, United States of America, 3 Department of Pediatrics, University of Washington, Seattle, Washington, United States of America Abstract ORF73 latency-associated nuclear antigen (LANA) of the Kaposi’s sarcoma-associated herpesvirus (KSHV) is targeted to the nucleus of infected cells where it binds to chromatin and mediates viral episome persistence, interacts with cellular proteins and plays a role in latency and tumorigenesis. A structurally related LANA homolog has been identified in the retroperitoneal fibromatosis herpesvirus (RFHV), the macaque homolog of KSHV. Here, we report the evolutionary and functional conservation of a novel bi-functional nuclear localization signal (NLS) in KSHV and RFHV LANA. N-terminal peptides from both proteins were fused to EGFP or double EGFP fusions to examine their ability to induce nuclear transport of a heterologous protein. In addition, GST-pull down experiments were used to analyze the ability of LANA peptides to interact with members of the karyopherin family of nuclear transport receptors. Our studies revealed that both LANA proteins contain an N-terminal arginine/glycine (RG)-rich domain spanning a conserved chromatin-binding motif, which binds directly to importin b1 in a RanGTP-sensitive manner and serves as an NLS in the importin b1-mediated non-classical nuclear import pathway. Embedded within this domain is a cons