ABSTRACT
We have analyzed polypeptides synthesized in a coupled in vitro transcription and translation system in response to detergent-disrupted Tacaribe virus. Analysis of the major Tacaribe virus-specified product by two-dimensional polyacrylamide gel electrophoresis indicated that it had an isoelectric point similar to that of the Tacaribe nucleocapsid polypeptide N; however, the in vitro product had an approximate mol. wt. of 73 000, compared to a mol. wt. of 68 000 for the N protein. The 73 000 dalton product was found to yield proteolytic cleavage products with similar electrophoretic mobilities to those obtained from the virion P and N proteins. These results, as well as pulse-chase experiments in Tacaribe virus-infected cells, suggest that a 73 000 dalton polypeptide may be processed to yield the N polypeptide. The polypeptides synthesized in the coupled system depended on the amount and type of virus added; addition of purified Shark River (SR) virus, a member of the Patois group of bunyaviruses, resulted in synthesis of a polypeptide of mol. wt. 22 000 which corresponds to the SR nucleocapsid protein.
Subject(s)
Arenaviridae/genetics , Viral Proteins/biosynthesis , Cell-Free System , Isoelectric Point , Molecular Weight , Protein Biosynthesis , RNA-Directed DNA Polymerase/metabolism , Transcription, GeneticABSTRACT
Two virus-induced polypeptides designated p79 (mol wt, 79,000) and p105 (mol wt, 105,000) in BHK21 or Vero cells infected with Tacaribe (Tac) virus have been identified. Both polypeptides were found in immune precipitates with antiserum to Tac virus, suggesting that they are virus specific. Two-dimensional gel analysis of Tac virus-infected Vero cell extracts indicated that p79 and p105 were acidic proteins which did not comigrate with any polypeptides from uninfected cells. Neither of the polypeptides was found to be phosphorylated under conditions in which phosphorylation of the N (nucleocapsid) protein was detected. Comparison of one-dimensional peptide maps of the p79 polypeptide and the nucleoprotein indicated that they are unrelated in primary sequences.
