7YX3

Structure of the Mimivirus genomic fibre in its compact 6-start helix form

Summary for 7YX3

• Entry DOI: 10.2210/pdb7yx3/pdb
• Related: 4z24
• EMDB information: 13641 14353 14354 14355
• Descriptor: Putative GMC-type oxidoreductase, FLAVIN-ADENINE DINUCLEOTIDE (2 entities in total)
• Functional Keywords: mimivirus, genomic fibre, cytoplasmic infectious cycle, 1.2 mb dsdna, virus, viral protein
• Biological source: Acanthamoeba polyphaga mimivirus
• Total number of polymer chains: 2
• Total formula weight: 155607.15

Authors

Villalta, A.,Schmitt, A.,Estrozi, L.F.,Quemin, E.R.J.,Alempic, J.M.,Lartigue, A.,Prazak, V.,Belmudes, L.,Vasishtan, D.,Colmant, A.M.G.,Honore, F.A.,Coute, Y.,Grunewald, K.,Abergel, C. (deposition date: 2022-02-15, release date: 2022-08-10, Last modification date: 2024-07-17)

Primary citation

Villalta, A.,Schmitt, A.,Estrozi, L.F.,Quemin, E.R.J.,Alempic, J.M.,Lartigue, A.,Prazak, V.,Belmudes, L.,Vasishtan, D.,Colmant, A.M.G.,Honore, F.A.,Coute, Y.,Grunewald, K.,Abergel, C.
The giant mimivirus 1.2 Mb genome is elegantly organized into a 30-nm diameter helical protein shield.
Elife, 11:-, 2022

PubMed Abstract: Mimivirus is the prototype of the family of giant dsDNA viruses. Little is known about the organization of the 1.2 Mb genome inside the membrane-limited nucleoid filling the ~0.5 µm icosahedral capsids. Cryo-electron microscopy, cryo-electron tomography, and proteomics revealed that it is encased into a ~30-nm diameter helical protein shell surprisingly composed of two GMC-type oxidoreductases, which also form the glycosylated fibrils decorating the capsid. The genome is arranged in 5- or 6-start left-handed super-helices, with each DNA-strand lining the central channel. This luminal channel of the nucleoprotein fiber is wide enough to accommodate oxidative stress proteins and RNA polymerase subunits identified by proteomics. Such elegant supramolecular organization would represent a remarkable evolutionary strategy for packaging and protecting the genome, in a state ready for immediate transcription upon unwinding in the host cytoplasm. The parsimonious use of the same protein in two unrelated substructures of the virion is unexpected for a giant virus with thousand genes at its disposal.

PubMed: 35900198
DOI: 10.7554/eLife.77607

Experimental method

ELECTRON MICROSCOPY (4 Å)