A cytoplasmic region of the NSP4 enterotoxin of rotavirus is involved in retention in the endoplasmic reticulum.
The rotavirus genome encodes two glycoproteins, one structural (VP7) and one non-structural (NSP4), both of which mature and remain in the endoplasmic reticulum (ER). While three amino acids in the N terminus have been proposed to function as a retention signal for VP7, no information is yet available on how NSP4 remains associated with the ER. In this study, we have investigated the ER retention motif of NSP4 by producing various C-terminal truncations. Deleting the C terminus by 52 amino acids did not change the intracellular distribution of NSP4, but an additional deletion of 38 amino acids diminished the ER retention and resulted in the expression of NSP4 on the cell surface. Brefeldin A treatment prevented NSP4 from reaching the cell surface, suggesting that C-terminal truncated plasma membrane NSP4 is transported through the normal secretory pathway. On the basis of these results, we propose that the region between amino acids 85 and 123 in the cytoplasmic region of NSP4 are involved in ER retention.
Mirazimi
Ali
A
Department of Virology, Swedish Institute for Infectious Disease Control/Karolinska Institute, 171 82 Solna, Sweden.
Magnusson
Karl-Eric
KE
Division of Medical Microbiology, Department of Molecular and Clinical Medicine, University of Linköping, Sweden.
Svensson
Lennart
L
Division of Medical Microbiology, Department of Molecular and Clinical Medicine, University of Linköping, Sweden.|Department of Virology, Swedish Institute for Infectious Disease Control/Karolinska Institute, 171 82 Solna, Sweden.
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D020126:Brefeldin A / Q000494:pharmacology; D002460:Cell Line; D012321:DNA-Directed RNA Polymerases; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D017353:Gene Deletion; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012401:Rotavirus / Q000378:metabolism*; D017361:Viral Nonstructural Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication
D011500:Protein Synthesis Inhibitors; D017361:Viral Nonstructural Proteins; D020126:Brefeldin A; D012321:DNA-Directed RNA Polymerases