The guanine nucleotide exchange factor GBF1 participates in rotavirus replication

José L. Martínez; Francesca Arnoldi; Elisabeth M. Schraner; Catherine Eichwald; Daniela Silva-Ayala; Eunjoo Lee; Elizabeth Sztul; Óscar R. Burrone; Susana López; Carlos F. Arias

In line with previous observations, we found that in cells treated with BFA and infected with 375 RRV, the electrophoretic mobility of both VP7 and NSP4 was modified, a modification that 376 was proposed to be related to their oligosaccharide chains (21). Since no infectious virus was 377 produced under those conditions, it was also proposed that the altered oligosaccharide 378 processing of VP7 was responsible for the defective assembly of viral particles. Our results 379 indicate that, at least for VP7, the altered electrophoretic mobility is independent of its The observation that silencing the expression of GBF1 induced changes in the mobility of 388 both VP7 and NSP4 suggests that the activity of this cellular factor is essential for the correct 389 processing of both proteins. Taking into consideration that GBF1 functions at the ER-Golgi 390 interface and that rotaviruses mature in the ER, it seems likely that Golgi-ER transport is the 391 relevant process required for the correct maturation of rotavirus infectious particles. 392 However, considering that LDs have been proposed to play a significant role in the 393 replication cycle of rotaviruses, it remains possible that the protein transport between the ER 394 membrane and LDs is needed for the correct processing of both VP7 (glycosylation 395 independent) and NSP4. However, an unknown function of GBF1 cannot be discarded. The copyright holder for this preprint (which was not peer-reviewed) is the author/funder. . https://doi.org/10.1101/619924 doi: bioRxiv preprint