FIG. 6.

Summary of the structures and in vivo mRNA-degradative activities of wild-type and mutant Vhs polypeptides and their abilities to bind eIF4H and eIF4B. The Vhs polypeptide encoded by wild-type HSV-1(KOS) is represented by the solid rectangle in line 1, and the structures of deletion and point mutants of the HSV-1(KOS) polypeptide are in lines 2 through 17. For deletion mutants, the Vhs residues included in the mutant proteins are indicated. For each point mutant, the location of the altered residue is indicated by the vertical line above the bar representing the protein. The in vivo mRNA-degradative activity of each Vhs protein is shown in the third column from the right and summarizes, in a qualitative fashion, quantitative measurements that were reported previously (14-16, 49, 57). Activity was assayed for all Vhs alleles using a cotransfection assay of Vhs activity and during virus infections for those alleles marked by an asterisk. The double plus sign indicates activity similar to that of wild-type HSV-1(KOS), and the minus sign indicates no detectable mRNA-degradative activity. The second column from the right indicates whether a Vhs protein binds (++) or does not bind (−) eIF4H and summarizes data that have been reported previously (14, 17, 18). The binding of various mutant Vhs polypeptides to GST-eIF4B was expressed relative to the binding of wild-type Vhs to GST-eIF4B, as explained in Materials and Methods, and is shown in the rightmost column.