Enhanced replication of mouse adenovirus type 1 following virus-induced degradation of protein kinase R (PKR)

Danielle E. Goodman; Carla D. Pretto; Tomas A. Krepostman; Kelly E. Carnahan; Katherine R. Spindler

There was no change in the total amount of PKR mRNA bound to ribosomes during infection 369 compared to uninfected cells, nor was there a significant change in the amount of actively 370 translating PKR mRNA during infection (Fig. 4) . We also found that the 5' UTR of mouse PKR 371 This indicates that PKR is not degraded by lysosomal degradation during viral infection, but by 378 proteasomal degradation. Though PKR degradation was due to proteasome activity during 379 MAV-1 infection, we were unable to demonstrate PKR ubiquitination, although we did detect 380 ubiquitination of mouse p53 (Fig. S5 ). This inability to demonstrate PKR ubiquitination could be 381 explained if at any given moment there were only low levels of ubiquitinated PKR present in the 382 cell. Perhaps, increasing the time under MG132 treatment could increase the amounts of 383 ubiquitinated proteins enough so that PKR ubiquitination could be seen. However, our inability 384 to detect ubiquitinated PKR is consistent with a similar inability to identify PKR ubiquitination 385 by RVFV NSs, even though NSs is known to recruit an E3 ligase to PKR (32). Alternatively, it is 386 possible that in MAV-1 infection, PKR is degraded in a ubiquitin-independent manner, possibly 387 because of intrinsic disordered regions of PKR or binding of regulating proteins to PKR that 388 target proteins to the proteasome (74, 75). 389 . CC-BY-NC-ND 4.0 International license is made available under a The copyright holder for this preprint (which was not peer-reviewed) is the author/funder. It . https://doi.org/10.1101/584680 doi: bioRxiv preprint