Structural effects of amino acid substitutions on the matrix protein of vesicular stomatitis virus

The structural effects of amino acid substitutions for Gly at position 21 in the amino-terminal segment (Lys 15-Pro 26) of the matrix (M) protein of vesicular stomatitis virus (VSV) have been investigated using conformational energy analysis. Monoclonal antibody-binding experiments and protein digestion studies of the M protein indicate that this segment is important to its ribonucleoprotein recognition and its transcription-inhibitory activity. Temperaturesensitive mutants of VSV that do not bind monoclonal antibody and that are devoid of transcription-inhibitory activity are known to have the substitution of Glu for Gly at position 21. The current findings demonstrate a significant conformational change at position 21 induced by the substitution of Glu for Gly, which could explain this alteration in antibody binding and transcription-inhibitory activity. Furthermore, the results indicate that the substitution of any noncyclic L-amino acid for Gly at position 21 may be expected to produce similar changes in M protein function.