The Matrix Protein of Marburg Virus Is Transported to the Plasma Membrane along Cellular Membranes: Exploiting the Retrograde Late Endosomal Pathway

Abstract

. 76:1825-1838, 2002). The present study revealed that VP40 is bound to cellular membranes rapidly after synthesis. Time course studies were performed to trace the distribution of VP40 during the course of expression. First, VP40 was homogenously distributed throughout the cytoplasm, although the majority of protein (70%) was already membrane associated. Next, VP40 accumulated in MVBs and in tubular protrusions emerging from MVBs. Finally, VP40 appeared in a patch-like pattern beneath the plasma membrane. These morphological results were supported by iodixanol density gradient analyses. The majority of VP40-positive membranes were first detected comigrating with small vesicles. VP40 was then shifted to fractions containing endosomal marker proteins, and later, to fractions containing plasma membrane marker proteins. Blocking of protein synthesis by use of cycloheximide at the time when VP40 was mainly associated with the small vesicles did not prevent the redistribution of VP40 to the late endosomes and further to the plasma membrane. The inhibition of intracellular vesicular trafficking by monensin significantly reduced the appearance of VP40 at the plasma membrane. In conclusion, we suggest that the transport of the Marburg virus matrix protein VP40 involves its accumulation in MVBs followed by the redistribution of VP40-enriched membrane clusters to the plasma membrane.

Multivesicular Bodies as a Platform for Formation of the Marburg Virus Envelope

“…Colocalization of VP40 and the endosomal marker was almost complete and also comprised GP-negative clusters that had a perinuclear location. We have shown previously that VP40 is intracellularly associated with the late endosomal compartment and can be detected in perinuclear and peripheral MVBs (30,31). The present findings indicate that GP is redirected to the peripheral but not to the perinuclear VP40-positive MVBs.…”

“…We have shown recently that GP is transported along the exocytotic pathway whereas VP40 is transported along the retrograde late endosomal pathway (5,30). It is obvious that the routes of GP and VP40 intersect at a particular point, since the two proteins need to be sorted into the same membrane subcompartment from which VLPs containing the two proteins are released.…”

“…The open reading frames of VP40 or GP (for reference, see EMBL Nucleotide Sequence Database accession number Z12132) were cloned into the mammalian expression vector pCAGGS, using the restriction enzymes SmaI and NotI. The generated plasmids contain VP40 or GP genes under the control of the chicken beta-actin promoter and were verified via sequencing (29,30,38).…”

“…VP40 is the major matrix protein of MARV and has recently been shown to use the retrograde late endosomal route for its transport to the plasma membrane. VP40 is initially a soluble protein, which associates with membranes early after synthesis; it then accumulates in multivesicular bodies (MVBs) with a perinuclear location and is subsequently transported to the cell periphery (30). Upon coexpression with GP, VP40 formed virus-like particles (VLPs) that were released into the cell culture supernatant (47).…”

Rice dwarf virus is engulfed into and released via vesicular compartments in cultured insect vector cells

“…Monensin is a carboxylic ionophore that arrests vesicular transport at a site distal to the proximal portion of the Golgi complex (Tartakoff, 1983). These two inhibitors have been extensively used to inhibit vesicular transport of several viruses (Blank et al, 2000;Boulanger et al, 2000;Suikkanen et al, 2003;Kolesnikova et al, 2004;Bugarcic & Taylor, 2006). Two hours p.i.…”