title: A Dual Laser Scanning Confocal and Transmission Electron Microscopy Analysis of the Intracellular Localization, Aggregation and Particle Formation of African Horse Sickness Virus Major Core Protein VP7.
abstract: The bulk of the major core protein VP7 in African horse sickness virus (AHSV) self-assembles into flat, hexagonal crystalline particles in a process appearing unrelated to viral replication. Why this unique characteristic of AHSV VP7 is genetically conserved, and whether VP7 aggregation and particle formation have an effect on cellular biology or the viral life cycle, is unknown. Here we investigated how different small peptide and enhanced green fluorescent protein (eGFP) insertions into the VP7 top domain affected VP7 localization, aggregation, and particle formation. This was done using a dual laser scanning confocal and transmission electron microscopy approach in conjunction with analyses of the solubility, aggregation, and fluorescence profiles of the proteins. VP7 top domain modifications did not prevent trimerization, or intracellular trafficking, to one or two discrete sites in the cell. However, modifications that resulted in a misfolded and insoluble VP7-eGFP component blocked trafficking, and precluded protein accumulation at a single cellular site, perhaps by interfering with normal trimer-trimer interactions. Furthermore, the modifications disrupted the stable layering of the trimers into characteristic AHSV VP7 crystalline particles. It was concluded that VP7 trafficking is driven by a balance between VP7 solubility, trimer forming ability, and trimer-trimer interactions.
authors.affiliation: Department of Genetics,University of Pretoria,Pretoria,0002,South Africa.
authors.forename: Gayle V
authors.identifier: 0000-0002-2517-2381
authors.initials: GV
authors.lastname: Wall
authors.affiliation: Department of Genetics,University of Pretoria,Pretoria,0002,South Africa.
authors.forename: Daria A
authors.initials: DA
authors.lastname: Rutkowska
authors.affiliation: Department of Genetics,University of Pretoria,Pretoria,0002,South Africa.
authors.forename: Eshchar
authors.initials: E
authors.lastname: Mizrachi
authors.affiliation: Department of Genetics,University of Pretoria,Pretoria,0002,South Africa.
authors.forename: Henk
authors.initials: H
authors.lastname: Huismans
authors.affiliation: Department of Genetics,University of Pretoria,Pretoria,0002,South Africa.
authors.forename: Vida
authors.initials: V
authors.lastname: van Staden
mesh_terms: D000356:African Horse Sickness Virus / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D016367:Baculoviridae / Q000235:genetics; D015967:Gene Expression Regulation, Viral; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins; D008018:Life Cycle Stages; D018613:Microscopy, Confocal / Q000379:methods*; D046529:Microscopy, Electron, Transmission / Q000379:methods*; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000648:ultrastructure; D061987:Sf9 Cells; D014758:Viral Core Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure*; D014760:Viral Fusion Proteins / Q000502:physiology / Q000648:ultrastructure; D014779:Virus Replication
chemical_list: D011993:Recombinant Fusion Proteins; D014758:Viral Core Proteins; D014760:Viral Fusion Proteins; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins
keywords: AHSV VP7; VP7 localization; particle formation; protein aggregation; protein solubility