Distinct DNA exit and packaging portals in the virus Acanthamoeba polyphaga mimivirus

Nathan Zauberman, Yael Mutsafi, Daniel Ben Halevy, Eyal Shimoni, Eugenia Klein, Chuan Xiao, Siyang Sun, Abraham Minsky*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Icosahedral double-stranded DNA viruses use a single portal for genome delivery and packaging. The extensive structural similarity revealed by such portals in diverse viruses, as well as their invariable positioning at a unique icosahedral vertex, led to the consensus that a particular, highly conserved vertex-portal architecture is essential for viral DNA translocations. Here we present an exception to this paradigm by demonstrating that genome delivery and packaging in the virus Acanthamoeba polyphaga mimivirus occur through two distinct portals. By using high-resolution techniques, including electron tomography and cryo-scanning electron microscopy, we show that Mimivirus genome delivery entails a large-scale conformational change of the capsid, whereby five icosahedral faces open up. This opening, which occurs at a unique vertex of the capsid that we coined the "stargate", allows for the formation of a massive membrane conduit through which the viral DNA is released. A transient aperture centered at an icosahedral face distal to the DNA delivery site acts as a non-vertex DNA packaging portal. In conjunction with comparative genomic studies, our observations imply a viral packaging pathway akin to bacterial DNA segregation, which might be shared by diverse internal membrane-containing viruses.

Original languageEnglish
Article numbere114
Pages (from-to)1104-1114
Number of pages11
JournalPLoS Biology
Issue number5
StatePublished - May 2008
Externally publishedYes


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