Reversible block in intracellular transport and budding of mutant vesicular stomatitis virus glycoproteins

Abstract

The blocks in intracellular maturation of glycoprotein (G protein) synthesized by two temperature-sensitive vesicular stomatite's virus (VSV) mutants are reversible. Our earlier work demonstrated that at 40°, the nonpermissive temperature, mutant is L513(V) G protein accumulates in the rough endoplasmic reticulum. Here we show that when the temperature is lowered the high-mannose oligosaccharides on a significant fraction of ts L513(V) G protein, synthesized at 40°, will be modified to the complex type. Moreover, when the temperature is lowered is L513(V) G protein accumulated at 40° will mature to the cell surface, as evidenced by its accessibility to extracellular trinitrobenzene sulfonate, and into virions. G protein synthesized at 40° in is L511(V)-infected cells undergoes most of the processing events characteristic of the Golgi complex. Although we reported previously that no is L511(V) G protein reaches the plasma membrane at 40°, we now find, using more sensitive techniques, that an appreciable fraction does reach the cell surface. ts L511(V) G protein is lost from the cells but is not incorporated into virions. However, an appreciable fraction of the is L511(V) G protein which accumulates in cells at 40° will mature into virions when the temperature is lowered. These results exclude irreversible denaturation of mutant G proteins as a cause of the block in intracellular maturation and virus budding.