Structural ensemble and dynamics of toroidal-like DNA shapes in bacteriophage ϕ29 exit cavity.

ABSTRACT: In the bacteriophage ϕ29, DNA is packed into a preassembled capsid from which it ejects under high pressure. A recent cryo-EM reconstruction of ϕ29 revealed a compact toroidal DNA structure (30-40 basepairs) lodged within the exit cavity formed by the connector-lower collar protein complex. Using multiscale models, we compute a detailed structural ensemble of intriguing DNA toroids of various lengths, all highly compatible with experimental observations. In particular, coarse-grained (elastic rod) and atomistic (molecular dynamics) models predict the formation of DNA toroids under significant compression, a largely unexplored state of DNA. Model predictions confirm that a biologically attainable compressive force of 25 pN sustains the toroid and yields DNA electron density maps highly cons

SUBMITTER: Hirsh AD 

PROVIDER: S-EPMC3647152 | biostudies-literature | 2013 May

REPOSITORIES: biostudies-literature