CONFORMATIONAL FLEXIBILITY AND POLYMERIZATION OF VESICULAR STOMATITIS-VIRUS MATRIX PROTEIN

The matrix protein of vesicular stomatitis virus (VSV) plays a pivotal role in viral assembly. We previously demonstrated the ability of M p rotein to self-associate at low salt concentrations. Now, we show the ability of M protein to polymerize in the presence of ZnCl2 in a nucle ation-dependent manner. Analysis of kinetics revealed that the nuclei are probably made of three or four molecules of M. These results are c onsistent with the idea that in vitro self association of M protein is not due to amorphous aggregation but rather reflects an intrinsic abi lity of M to polymerize. Using attenuated total reflectance Fouler tra nsform infrared spectroscopy, we showed that M polymerization is assoc iated with an increase in the P-sheet content of the protein. We propo se a model explaining both the apparent M protein solubility in infect ed cells and how M polymerization could promote viral assembly. Data a vailable for other negative strand viruses suggest that M polymerizati on may be the general basis of viral assembly. (C) 1997 Academic Press Limited.