title: Sumoylation of Rta of Epstein-Barr virus is preferentially enhanced by PIASxbeta.
abstract: Epstein-Barr virus (EBV) expresses an immediate-early protein, Rta, to activate the viral lytic cycle. This study identifies PIASxalpha and PIASxbeta as binding partners of Rta in a yeast two-hybrid screen and demonstrates the binding of Rta to PIASxalpha and PIASxbeta in vitro by GST pull-down analysis. Coimmunoprecipitation experiments and indirect immunofluorescence analysis show that Rta interacts and colocalizes with PIASxalpha and PIASxbeta in the nucleus. These interactions seem to enhance Rta sumoylation as transfecting plasmids expressing PIASxalpha, PIASxbeta, Ubc9, or SUMO-1 increase the capacity of Rta to transactivate a promoter that contains an Rta-response element and the promoters of p21 and BNLF1 in transient transfection assay. This study also finds that Rta sumoylation is preferentially enhanced by PIASxbeta, which could be attributed to the fact that PIASxbeta, compared to PIASxalpha, has a strong affinity to Rta, suggesting that affinity of a SUMO E3 ligase to its target protein influences the function of protein sumoylation.
authors.affiliation: Molecular Genetics Laboratory, Department of Microbiology and Immunology, Chang-Gung University, 259, Wen-Hua 1st Road, Kwei-Shan, Taoyuan 333, Taiwan.
authors.forename: Shih-Tung
authors.initials: ST
authors.lastname: Liu
authors.forename: Wen-Hung
authors.initials: WH
authors.lastname: Wang
authors.forename: Yi-Ren
authors.initials: YR
authors.lastname: Hong
authors.forename: Jian-Ying
authors.initials: JY
authors.lastname: Chuang
authors.forename: Pei-Jung
authors.initials: PJ
authors.lastname: Lu
authors.forename: Li-Kwan
authors.initials: LK
authors.lastname: Chang
mesh_terms: D002467:Cell Nucleus / Q000737:chemistry; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D004854:Herpesvirus 4, Human / Q000378:metabolism*; D017874:Immediate-Early Proteins / Q000378:metabolism*; D047468:Immunoprecipitation; D008156:Luciferases / Q000096:biosynthesis; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D011401:Promoter Regions, Genetic / Q000502:physiology; D011485:Protein Binding; D050828:Protein Inhibitors of Activated STAT / Q000378:metabolism*; D025842:SUMO-1 Protein / Q000378:metabolism*; D015534:Trans-Activators / Q000378:metabolism*; D015533:Transcriptional Activation; D020798:Two-Hybrid System Techniques; D014764:Viral Proteins
chemical_list: C068382:BRLF1 protein, Human herpesvirus 4; D017874:Immediate-Early Proteins; C501001:PIAS2 protein, human; D050828:Protein Inhibitors of Activated STAT; D025842:SUMO-1 Protein; D015534:Trans-Activators; D014764:Viral Proteins; D008156:Luciferases