Interaction between the movement protein of barley yellow dwarf virus and the cell nuclear envelope: role of a putative amphiphilic alpha-helix at the N-terminus of the movement protein.
The open reading frame 4 (ORF 4) gene product of barley yellow dwarf virus (BYDV) may act as a movement protein (MP) by assisting the transport of viral genomic RNA across the nuclear envelope (NE) of host plant cells. To investigate interactions between BYDV MP and the NE, wild-type and mutant open reading frame (ORF 4)-green fluorescent protein (GFP) fusion cistrons were expressed in insect cells. A fusion protein expressed by the wild-type ORF 4-GFP cistron associated with the NE and caused protrusions from its surface. The fusion protein expressed by the mutant ORF 4-GFP cistron lacked a putative amphiphilic alpha-helix at its N-terminus and although associating with the NE, showed decreased levels of protrusions. A peptide homologue of this putative alpha-helix induced an increase of 7 degrees C in the phase transition temperature of dimyrystoyl phosphatidylserine (DMPS) membranes, accompanied by a decrease in membrane fluidity, but exhibited no significant interaction with either dimyristoyl phosphatidylcholine (DMPC) or dimyristoyl phosphatidylethanolamine (DMPE) membranes. These results strongly support the view that BYDV MP may interact with the NE to help transport viral genomic RNA into the nuclear compartment. This function of BYDV MP appears to involve protrusions on the surface of the NE and may require the presence of an N-terminal amphiphilic alpha-helix, which is speculated to destabilize membranes, thereby assisting the entry of BYDV-GAV into the nuclear compartment.
Liu
Kunfan
K
Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
Xia
Zongliang
Z
Zhang
Yan
Y
Wen
Yuxiang
Y
Wang
Daowen
D
Brandenburg
Klaus
K
Harris
Frederick
F
Phoenix
David Andrew
DA
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D017793:Luteovirus / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D009685:Nuclear Envelope / Q000378:metabolism; D053830:Plant Viral Movement Proteins; D017433:Protein Structure, Secondary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
D053830:Plant Viral Movement Proteins; D011993:Recombinant Fusion Proteins; D014764:Viral Proteins