Kaposi's sarcoma-associated herpesvirus ORF45 interacts with kinesin-2 transporting viral capsid-tegument complexes along microtubules.
Open reading frame (ORF) 45 of Kaposi's sarcoma-associated herpesvirus (KSHV) is a tegument protein. A genetic analysis with a null mutant suggested a possible role for this protein in the events leading to viral egress. In this study, ORF45 was found to interact with KIF3A, a kinesin-2 motor protein that transports cargoes along microtubules to cell periphery in a yeast two-hybrid screen. The association was confirmed by both co-immunoprecipitation and immunoflorescence approaches in primary effusion lymphoma cells following virus reactivation. ORF45 principally mediated the docking of entire viral capsid-tegument complexes onto the cargo-binding domain of KIF3A. Microtubules served as the major highways for transportation of these complexes as evidenced by drastically reduced viral titers upon treatment of cells with a microtubule depolymerizer, nocodazole. Confocal microscopic images further revealed close association of viral particles with microtubules. Inhibition of KIF3A-ORF45 interaction either by the use of a headless dominant negative (DN) mutant of KIF3A or through shRNA-mediated silencing of endogenous KIF3A expression noticeably decreased KSHV egress reflecting as appreciable reductions in the release of extracellular virions. Both these approaches, however, failed to impact HSV-1 egress, demonstrating the specificity of KIF3A in KSHV transportation. This study thus reports on transportation of KSHV viral complexes on microtubules by KIF3A, a kinesin motor thus far not implicated in virus transportation. All these findings shed light on the understudied but significant events in the KSHV life cycle, delineating a crucial role of a KSHV tegument protein in cellular transport of viral particles.
Sathish
Narayanan
N
Department of Microbiology, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
Zhu
Fan Xiu
FX
Yuan
Yan
Y
D000595:Amino Acid Sequence; D015153:Blotting, Western; D002213:Capsid / Q000378:metabolism; D017124:Conserved Sequence; D005455:Fluorescent Antibody Technique; D019288:Herpesvirus 8, Human / Q000502:physiology*; D006790:Host-Parasite Interactions / Q000502:physiology*; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics / Q000378:metabolism*; D047468:Immunoprecipitation; D016547:Kinesins / Q000235:genetics / Q000378:metabolism*; D018613:Microscopy, Confocal; D008870:Microtubules / Q000378:metabolism / Q000821:virology*; D008969:Molecular Sequence Data; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D020798:Two-Hybrid System Techniques; D015678:Viral Structural Proteins / Q000378:metabolism
D017874:Immediate-Early Proteins; C087415:KIF3A protein, human; C456286:ORF45 protein, Kaposi's sarcoma-associated herpesvirus; D015678:Viral Structural Proteins; D016547:Kinesins