Membrane insertion and topology of the p7B movement protein of Melon Necrotic Spot Virus (MNSV).
Cell-to-cell movement of the Melon Necrotic Spot Virus (MNSV) is controlled by two small proteins working in trans, an RNA-binding protein (p7A) and an integral membrane protein (p7B) separated by an amber stop codon. p7B contains a single hydrophobic region. Membrane integration of this region was observed when inserted into model proteins in the presence of microsomal membranes. Furthermore, we explored the topology and targeting mechanisms of full-length p7B. Here we present evidence that p7B integrates in vitro into the ER membrane cotranslationally and with an Nt-cytoplasmic/Ct-luminal orientation. The observed topology was monitored in vivo by fusing GFP to the Ct of p7B, enabling the overexpression in Escherichia coli cultures. Finally, the topology of a putative p14 movement protein was established by replacing the amber stop codon located between p7A and p7B.
Martínez-Gil
Luis
L
Departament de Bioquímica i Biologia Molecular, Universitat de València. E-46 100, Burjassot, Spain.
Saurí
Ana
A
Vilar
Marçal
M
Pallás
Vicente
V
Mingarro
Ismael
I
D019184:Carmovirus / Q000235:genetics / Q000378:metabolism*; D019662:Cucurbitaceae / Q000821:virology*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000032:analysis / Q000235:genetics; D008565:Membrane Proteins / Q000378:metabolism; D053830:Plant Viral Movement Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014764:Viral Proteins / Q000235:genetics
D008565:Membrane Proteins; D053830:Plant Viral Movement Proteins; D014764:Viral Proteins; D049452:Green Fluorescent Proteins