G-quadruplex forming sequences in the genome of all known human viruses: a comprehensive guide

Enrico Lavezzo; Michele Berselli; Ilaria Frasson; Rosalba Perrone; Giorgio Palù; Alessandra R. Brazzale; Sara N. Richter; Stefano Toppo

The copyright holder for this preprint (which was not peer-reviewed) is the . https://doi. org/10.1101/344127 doi: bioRxiv preprint Viruses are intracellular parasites that replicate by exploiting the cell replication and protein synthesis machineries. Viruses that infect humans are very diverse and, according to the Baltimore classification, they can be divided in seven groups based on the type of their genome and mechanism of genome replication: DNA viruses with 1) double-stranded (ds) and 2) single stranded (ss) genome; RNA viruses with 3) ds genome, or ss genome with 4) positive (ssRNA (+)) or 5) negative (ssRNA (-)) polarity; 6) RNA or 7) DNA viruses with reverse transcription (RT) ability, whose genome is converted from RNA to DNA during the virus replication cycle ( Table 1) . Each of these classes possesses a peculiar replication cycle (Flint et al. 2015 The presence of G4s in viruses and their involvement in virus key steps is increasingly evident (Metifiot et al. 2014; Ruggiero and Richter 2018) . In the dsDNA group, the presence of G4s was described in both Herpesviridae and Papillomaviridae families. In particular, the herpes simplex virus 1 (HSV-1) possesses several repeats of important DNA G4-forming sequences (Artusi et al. 2015) that, when visualized with a G4-specific antibody in infected cells, massively form in the cell nucleus, peaking during viral replication and localizing according to the viral genome intracellular movements (Artusi et al. 2016 ). The HSV-1 G4s author/funder. All rights reserved. No reuse allowed without permission.