Multiple serine phosphorylation sites on the 30 kDa TMV cell-to-cell movement protein synthesized in tobacco protoplasts.
p30, the protein required for cell-to-cell movement of tobacco mosaic virus (TMV), has a slightly reduced mobility on SDS-polyacrylamide gels when isolated by immunoprecipitation from TMV-infected protoplasts compared with that of p30 translated from viral RNA in vitro. Further investigation established a probable cause for the difference in mobility between the two: protoplasts incorporate [32P]orthophosphate into p30 at multiple sites, predominantly as phosphoserine. Tryptic peptide mapping reveals at least five internal phosphopeptides in p30, besides the C-terminal tryptic phosphopeptide already reported, involving at least two distinct domains of the protein (at residues 61-114 and residues 212-231), which may be substrates for different protein kinases. These structural results are consistent with a three-domain model for the TMV movement protein with two regulatory domains similar to that recently proposed on genetic grounds for dianthovirus movement proteins.
Haley
A
A
MRC Laboratory of Molecular Biology, Cambridge, UK.
Hunter
T
T
Kiberstis
P
P
Zimmern
D
D
D010449:Peptide Mapping; D010750:Phosphoproteins / Q000096:biosynthesis*; D010766:Phosphorylation; D010768:Phosphoserine / Q000032:analysis*; D053830:Plant Viral Movement Proteins; D010947:Plants, Toxic; D011523:Protoplasts / Q000821:virology; D014026:Nicotiana / Q000821:virology*; D014027:Tobacco Mosaic Virus / Q000378:metabolism*; D014764:Viral Proteins / Q000096:biosynthesis*
D010750:Phosphoproteins; D053830:Plant Viral Movement Proteins; D014764:Viral Proteins; D010768:Phosphoserine