7yx4

Publication Abstract from PubMed

Mimivirus is the prototype of the Mimiviridae 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 microm 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.

The giant mimivirus 1.2 Mb genome is elegantly organized into a 30-nm diameter helical protein shield.,Villalta A, Schmitt A, Estrozi LF, Quemin ERJ, Alempic JM, Lartigue A, Prazak V, Belmudes L, Vasishtan D, Colmant AMG, Honore FA, Coute Y, Grunewald K, Abergel C Elife. 2022 Jul 28;11:e77607. doi: 10.7554/eLife.77607. PMID:35900198^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.