The Measles Virus Fusion Protein Transmembrane Region Modulates Availability of an Active Glycoprotein Complex and Fusion Efficiency

Bimolecular Complementation of Paramyxovirus Fusion and Hemagglutinin-Neuraminidase Proteins Enhances Fusion: Implications for the Mechanism of Fusion Triggering

“…Regardless, these correlations prove neither model definitively, and interpretation of the results is confounded by the fact that some observations do not fit into this breakdown easily. A mutation in the active site of NDV HN can block fusion without preventing F-HN association (33), some HeV G stalk mutants with decreased fusion lose F association (4), and some MeV F transmembrane mutants with enhanced fusion show improved F1-H association (40). In addition, NA treatment of cells to remove the receptor resulted in enhanced NDV F-HN coIP, consistent with the clamp model (36).…”

Trimeric Transmembrane Domain Interactions in Paramyxovirus Fusion Proteins

“…TM-TM interactions could also influence triggering of membrane fusion. Interactions with the viral attachment protein are hypothesized to trigger fusion for most paramyxovirus F proteins (2, 3) except for HMPV F (67), and altered association of the measles attachment protein with the cleaved fusogenic F 1 ϩ F 2 protein was observed when specific mutations were introduced into the F TM domain (17). Alterations in TM-TM association due to attachment protein interactions or alterations in the lipid environment could regulate the dissociation of the heptad repeat B coiled-coil needed to reach the final fusogenic structure (Fig.…”

“…A number of studies have observed that modifications to the TM domain can result in modulation of class I viral fusion protein activity (12)(13)(14)(15)(16)(17)(18), including impairment of fusion pore opening or enlargement (13-15, 19 -21) or alterations in the efficiency of fusion promotion (18,22,23). Recent studies have also demonstrated an important role for the TM domains of class II fusion proteins (24) and reovirus fusion-associated small transmembrane (FAST) proteins (25) in the fusion process.…”

Previously Unrecognized Amino Acid Substitutions in the Hemagglutinin and Fusion Proteins of Measles Virus Modulate Cell-Cell Fusion, Hemadsorption, Virus Growth, and Penetration Rate

“…Another possibility is that the H(N481Y/H495R) protein might have some defects in functional interaction with the F protein. Several reports indicated that the formation of the F-H protein complex influences the fusion function of MV (6,28,34). Experiments are now under way to examine the formation of the F-H protein complex to elucidate this point.…”