LMB 365 – Day 123

The image for day 123 of #LMB365 shows the Ty3 retrotransposon capsid. Like retroviruses, Ty3 builds a capsid, replicates its nucleic acid, and inserts itself into new positions in the genome, but unlike a virus it never leaves the yeast cells in which it is found. Ty3 and the human virus HIV-1 diverged from a common ancestor that existed before the divergence of plants and animals 1.5 billion years ago. Surprisingly, Ty3 is also similar to a neuronal protein called Arc1. John Briggs’ group in the Structural Studies Division collaborated with the Sandmeyer lab who discovered Ty3 in the 1980’s, to determine the structure of the Ty3 capsid using cryo-electron microscopy and found that it has many similarities to the capsid of HIV-1. https://www.pnas.org/content/early/2019/04/26/1900931116