Role of matrix protein in assembling the membrane of vesicular stomatitis virus: reconstitution of matrix protein with negatively charged phospholipid vesicles.

The matrix (M) protein of vesicular stomatitis virus (VSV) was reconstituted into phospholipid vesicles by detergent dialysis. Reconstitution of the positively charged M protein occurred only in the presence of negatively charged phospholipids such as phosphatidylserine, phosphatidic acid, or phosphatidylinositol. Preformed vesicles containing negatively charged phospholipids also bound free M protein. Derivatization of the positively charged lysines in M protein with acetic anhydride or succinic anhydride prevented M protein reconstitution but did not affect the biological property of M protein to inhibit in vitro VSV transcription. An additional indication of the electrostatic nature of the M protein binding to the vesicles was that M protein could not be reconstituted in the presence of 0.5 M NaCl. Nonelectrostatic forces also appear to be involved in the association of the M protein with vesicles, since previously reconstituted M protein remained associated with the vesicles upon subsequent exposure to 0.5 M NaCl.