Single Particle Observation of SV40 VP1 Polyanion-Induced Assembly Shows That Substrate Size and Structure Modulate Capsid Geometry.
Simian virus 40 capsid protein (VP1) is a unique system for studying substrate-dependent assembly of a nanoparticle. Here, we investigate a simplest case of this system where 12 VP1 pentamers and a single polyanion, e.g., RNA, form a T = 1 particle. To test the roles of polyanion substrate length and structure during assembly, we characterized the assembly products with size exclusion chromatography, transmission electron microscopy, and single-particle resistive-pulse sensing. We found that 500 and 600 nt RNAs had the optimal length and structure for assembly of uniform T = 1 particles. Longer 800 nt RNA, shorter 300 nt RNA, and a linear 600 unit poly(styrene sulfonate) (PSS) polyelectrolyte produced heterogeneous populations of products. This result was surprising as the 600mer PSS and 500-600 nt RNA have similar mass and charge. Like ssRNA, PSS also has a short 4 nm persistence length, but unlike RNA, PSS lacks a compact tertiary structure. These data indicate that even for flexible substrates, shape as well as size affect assembly and are consistent with the hypothesis that work, derived from protein-protein and protein-substrate interactions, is used to compact the substrate.
Department of Molecular and Cellular Biochemistry and ‡Department of Chemistry, Indiana University , Bloomington, Indiana 47405, United States.
Chenglei
C
Li
Department of Molecular and Cellular Biochemistry and ‡Department of Chemistry, Indiana University , Bloomington, Indiana 47405, United States.
Andrew R
AR
Kneller
Department of Molecular and Cellular Biochemistry and ‡Department of Chemistry, Indiana University , Bloomington, Indiana 47405, United States.
Stephen C
0000-0003-2415-041X
SC
Jacobson
Department of Molecular and Cellular Biochemistry and ‡Department of Chemistry, Indiana University , Bloomington, Indiana 47405, United States.
Adam
0000-0001-9945-6267
A
Zlotnick
D002213:Capsid / Q000737:chemistry*; D036022:Capsid Proteins / Q000502:physiology*; D000071228:Polyelectrolytes; D058105:Polymerization; D011108:Polymers; D011137:Polystyrenes; D012313:RNA; D013539:Simian virus 40 / Q000648:ultrastructure*; D019065:Virus Assembly
D036022:Capsid Proteins; D000071228:Polyelectrolytes; D011108:Polymers; D011137:Polystyrenes; D012313:RNA; C062481:VP1 protein, polyomavirus; C003321:polystyrene sulfonic acid