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The guanine nucleotide exchange factor GBF1 participates in rotavirus replication


Martínez, José L; Arnoldi, Francesca; Schraner, Elisabeth M; Eichwald, Catherine; Silva-Ayala, Daniela; Lee, Eunjoo; Sztul, Elizabeth; Burrone, Óscar R; López, Susana; Arias, Carlos F (2019). The guanine nucleotide exchange factor GBF1 participates in rotavirus replication. Journal of Virology, 93(19):October 2019 Volume 93 Issue 19 e01062-19.

Abstract

Cellular and viral factors participate in the replication cycle of rotavirus. We report that the guanine nucleotide exchange factor GBF1, which activates the small GTPase Arf1 to induce COPI transport processes, is required for rotavirus replication since knocking down GBF1 expression by RNA interference, or inhibiting its activity by treatment with Brefeldin A (BFA) or Golgicide A (GCA) significantly reduce the yield of infectious viral progeny. This reduction in virus yield was related to a block in virus assembly since in the presence of either BFA or GCA the assembly of infectious mature triple-layered virions was significantly prevented and only doubled layered-particles were detected. We report that the catalytic activity of GBF1, but not the activation of Arf1, is essential for the assembly of the outer capsid of rotavirus. We show that both BFA and GCA, as well as interfering with the synthesis of GBF1, alter the electrophoretic mobility of glycoproteins VP7 and NSP4 and block the trimerization of the virus surface VP7, a step required for its incorporation into virus particles. Although a post-translational modification of VP7 (other than glycosylation) could be related to the lack of trimerization, we found that NSP4 might also be involved in this process, since knocking-down its expression reduces VP7 trimerizarion. In support, recombinant VP7 protein overexpressed in transfected cells formed trimers only when co-transfected with NSP4.
<jats:bold>IMPORTANCE</jats:bold>
Rotavirus, a member of the family Reoviridae, is the major cause of severe diarrhea in children and young animals worldwide. Despite the significant advances in the characterization of the biology of this virus, the mechanisms involved in morphogenesis of the virus particle are still poorly understood. In this work, we show that the guanine nucleotide exchange factor GBF1, relevant for the COPI/Arf1-mediated cellular vesicular transport, participates in the replication cycle of the virus, influencing the correct processing of viral glycoproteins VP7 and NSP4, and the assembly of the virus surface proteins VP7 and VP4.

Abstract

Cellular and viral factors participate in the replication cycle of rotavirus. We report that the guanine nucleotide exchange factor GBF1, which activates the small GTPase Arf1 to induce COPI transport processes, is required for rotavirus replication since knocking down GBF1 expression by RNA interference, or inhibiting its activity by treatment with Brefeldin A (BFA) or Golgicide A (GCA) significantly reduce the yield of infectious viral progeny. This reduction in virus yield was related to a block in virus assembly since in the presence of either BFA or GCA the assembly of infectious mature triple-layered virions was significantly prevented and only doubled layered-particles were detected. We report that the catalytic activity of GBF1, but not the activation of Arf1, is essential for the assembly of the outer capsid of rotavirus. We show that both BFA and GCA, as well as interfering with the synthesis of GBF1, alter the electrophoretic mobility of glycoproteins VP7 and NSP4 and block the trimerization of the virus surface VP7, a step required for its incorporation into virus particles. Although a post-translational modification of VP7 (other than glycosylation) could be related to the lack of trimerization, we found that NSP4 might also be involved in this process, since knocking-down its expression reduces VP7 trimerizarion. In support, recombinant VP7 protein overexpressed in transfected cells formed trimers only when co-transfected with NSP4.
<jats:bold>IMPORTANCE</jats:bold>
Rotavirus, a member of the family Reoviridae, is the major cause of severe diarrhea in children and young animals worldwide. Despite the significant advances in the characterization of the biology of this virus, the mechanisms involved in morphogenesis of the virus particle are still poorly understood. In this work, we show that the guanine nucleotide exchange factor GBF1, relevant for the COPI/Arf1-mediated cellular vesicular transport, participates in the replication cycle of the virus, influencing the correct processing of viral glycoproteins VP7 and NSP4, and the assembly of the virus surface proteins VP7 and VP4.

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Item Type:Journal Article, refereed, original work
Communities & Collections:05 Vetsuisse Faculty > Institute of Veterinary Anatomy
05 Vetsuisse Faculty > Institute of Virology
Dewey Decimal Classification:570 Life sciences; biology
Scopus Subject Areas:Life Sciences > Microbiology
Life Sciences > Immunology
Life Sciences > Insect Science
Life Sciences > Virology
Uncontrolled Keywords:Immunology, Insect Science, Microbiology, Virology
Language:English
Date:12 September 2019
Deposited On:19 Jul 2019 07:48
Last Modified:29 Jul 2020 11:01
Publisher:American Society for Microbiology
ISSN:0022-538X
OA Status:Hybrid
Free access at:PubMed ID. An embargo period may apply.
Publisher DOI:https://doi.org/10.1128/jvi.01062-19
PubMed ID:31270230

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