RECONSTITUTION OF THE INFLUENZA-VIRUS M(2) ION-CHANNEL IN LIPID BILAYERS

Citation
Mt. Tosteson et al., RECONSTITUTION OF THE INFLUENZA-VIRUS M(2) ION-CHANNEL IN LIPID BILAYERS, The Journal of membrane biology, 142(1), 1994, pp. 117-126
Citations number
43
Categorie Soggetti
Cytology & Histology
ISSN journal
00222631
Volume
142
Issue
1
Year of publication
1994
Pages
117 - 126
Database
ISI
SICI code
0022-2631(1994)142:1<117:ROTIMI>2.0.ZU;2-1
Abstract
M(2), an integral membrane protein of influenza A virus, was purified from either influenza A virus infected CV-1 cells or from Spodoptera f rugiperda (Sf9) cells infected with a recombinant-M(2) baculovirus. Th e purified protein, when incorporated into phospholipid bilayer membra nes, produced ion-permeable channels with the following characteristic s: (1) The channels appeared in bursts during which unit conductances of diverse magnitudes (25-500 pS) were observed. (2) The most probable open state was usually the lowest unit conductance (25-90 pS). (3) Th e channels were selective for cations; t(Na) = 0.75 when 150 mM NaCl b athed both sides of the membrane. (4) Amantadine reduced the probabili ty of opening of the high conductance state and also the conductance o f the most probable state. (5) Reducing pH increased the mean current through the open channel as well as the conductance of the most probab le state. (6) The sequence of selectivity for group IA monovalent cati ons was Rb > K > Cs similar to Na > Li. The pH activation, amantadine block and ion selectivity of the M(2) protein ion channel in bilayers are consistent with those observed on expression of the M(2) protein i n oocytes of Xenopus laevis as well as for those predicted for the pro posed role of an ion channel in the uncoating process of influenza vir us. The finding that the M(2) protein has intrinsic ion channel activi ty supports the hypothesis that it has ion channel activity in the inf luenza virus particle.