Structure of a membrane-binding domain from a non-enveloped animal virus: insights into the mechanism of membrane permeability and cellular entry.
The gamma(1)-peptide is a 21-residue lipid-binding domain from the non-enveloped Flock House virus (FHV). Unlike enveloped viruses, the entry of non-enveloped viruses into cells is believed to occur without membrane fusion. In this study, we performed NMR experiments to establish the solution structure of a membrane-binding peptide from a small non-enveloped icosahedral virus. The three-dimensional structure of the FHV gamma(1)-domain was determined at pH 6.5 and 4.0 in a hydrophobic environment. The secondary and tertiary structures were evaluated in the context of the capacity of the peptide for permeabilizing membrane vesicles of different lipid composition, as measured by fluorescence assays. At both pH values, the peptide has a kinked structure, similar to the fusion domain from the enveloped viruses. The secondary structure was similar in three different hydrophobic environments as follows: water/trifluoroethanol, SDS, and membrane vesicles of different compositions. The ability of the peptide to induce vesicle leakage was highly dependent on the membrane composition. Although the gamma-peptide shares some structural properties to fusion domains of enveloped viruses, it did not induce membrane fusion. Our results suggest that small protein components such as the gamma-peptide in nodaviruses (such as FHV) and VP4 in picornaviruses have a crucial role in conducting nucleic acids through cellular membranes and that their structures resemble the fusion domains of membrane proteins from enveloped viruses.
Maia
Lenize F
LF
Programa de Biologia Estrutrural, Instituto de Bioquímica Médica and Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, RJ, Brazil.
Soares
Márcia R
MR
Valente
Ana P
AP
Almeida
Fabio C L
FC
Oliveira
Andréa C
AC
Gomes
Andre M O
AM
Freitas
Monica S
MS
Schneemann
Anette
A
Johnson
John E
JE
Silva
Jerson L
JL
D000818:Animals; D002462:Cell Membrane / Q000821:virology*; D002463:Cell Membrane Permeability; D002942:Circular Dichroism; D006863:Hydrogen-Ion Concentration; D008055:Lipids / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry; D008561:Membrane Fusion; D008968:Molecular Conformation; D010455:Peptides / Q000737:chemistry; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D014270:Trifluoroethanol / Q000737:chemistry
D008055:Lipids; D008081:Liposomes; D010455:Peptides; D012967:Sodium Dodecyl Sulfate; D014270:Trifluoroethanol