Adenovirus type 2 polypeptide synthesis in arginine-deprived cells

Abstract

Among the exogenous amino acids which are essential for mammalian cell growth in vitro, only arginine (arg) is absolutely required for productive infection by nuclear DNA viruses. As previously reported, when arg-deprived KB cells are infected with adenovirus type 2, both viral DNA and viral structural proteins are synthesized at appropriate times in the virus growth cycle, but virion assembly does not occur. Quantitative study of the polypeptides made late in infection by electrophoresis under denaturing conditions show that (1) all the polypeptides synthesized in arg + cultures are also identified in arg − cultures; (2) overall synthesis is reduced 70–75%; (3) neither a disproportionate reduction of one or more polypeptides nor enhanced degradation is observed. An equivalent reduction in virus polypeptide synthesis is seen in isoleucine-starved cells as well as a similarly reduced rate of protein synthesis, but significant yields (1000 FFU/cell) of virus progeny are obtained. Since no alteration in the proportions of the various viral polypeptides could be detected and since similar amounts were adequate to support virus production in isoleucine-deficient cells, the arg-sensitive function cannot occur at the level of synthesis. This suggests the possibility that an as yet undefined arg-sensitive host function may be a critical prerequisite in virus assembly.