title: Interactions among SARS-CoV accessory proteins revealed by bimolecular fluorescence complementation assay.
abstract: The accessory proteins (3a, 3b, 6, 7a, 7b, 8a, 8b, 9b and ORF14), predicted unknown proteins (PUPs) encoded by the genes, are considered to be unique to the severe acute respiratory syndrome coronavirus (SARS-CoV) genome. These proteins play important roles in various biological processes mediated by interactions with their partners. However, very little is known about the interactions among these accessory proteins. Here, a EYFP (enhanced yellow fluorescent protein) bimolecular fluorescence complementation (BiFC) assay was used to detect the interactions among accessory proteins. 33 out of 81 interactions were identified by BiFC, much more than that identified by the yeast two-hybrid (Y2H) system. This is the first report describing direct visualization of interactions among accessory proteins of SARS-CoV. These findings attest to the general applicability of the BiFC system for the verification of protein-protein interactions.
authors.affiliation: State Key Laboratory of Bioactive Substance and Function of Natural Medicines & Ministry of Health Key Laboratory of Biosynthesis of Natural Products, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China.
authors.forename: Jianqiang
authors.initials: J
authors.lastname: Kong
authors.affiliation: State Key Laboratory of Bioactive Substance and Function of Natural Medicines & Ministry of Health Key Laboratory of Biosynthesis of Natural Products, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China.
authors.forename: Yanwei
authors.initials: Y
authors.lastname: Shi
authors.affiliation: State Key Laboratory of Bioactive Substance and Function of Natural Medicines & Ministry of Health Key Laboratory of Biosynthesis of Natural Products, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China.
authors.forename: Zhifang
authors.initials: Z
authors.lastname: Wang
authors.affiliation: School of Chemical Engineering, Beijing Institute of Petrochemical Technology, Beijing 102617, China.
authors.forename: Yiting
authors.initials: Y
authors.lastname: Pan
keywords: AD, activation domain; Accessory proteins; BD, binding domain; BiFC, bimolecular fluorescence complementation; Bimolecular fluorescence complementation assay; Co-IP, co-immunoprecipitation; E, envelope; EYFP, enhanced yellow fluorescent protein; M, membrane; N, nucleocapsid; NLS, nuclear localization signal; ORFs, open reading frames; PCR, polymerase chain reaction; PPIs, protein-protein interactions; PUPs, predicted unknown proteins; S, spike; SARS-CoV; SARS-CoV, severe acute respiratory syndrome coronavirus; Y2H; Y2H, yeast two-hybrid; aa, amino acids