In vitro dissection of the membrane and RNP binding activities of influenza virus M1 protein

Spontaneous proteolysis of influenza virus M1 protein during crystallisatio n has defined an N-terminal domain of amino acids 1-164. Full-length M1, th e N-terminal domain, and the C-terminal part of M1 (residues 165-252) were produced in Escherichia coil in vitro tests showed that only full-length M1 and its N-terminal domain bind to negatively charged liposomes and that on ly full-length M1 and its C-terminal part bind to RNP. However, only full-l ength M1 had transcription inhibition activity. Several independent experim ental approaches indicate that in vitro transcription inhibition occurs thr ough polymerisation/aggregation of M1 onto RNP, or of M1 onto M1 already bo und to RNP, rather than by binding to a specific active site on the nucleop rotein or the polymerase. The structure/function of influenza virus M1 will be compared with that of the Ebola virus matrix protein, VP40. (C) 2001 Ac ademic Press.