Evidence for two nonoverlapping functional domains in the potato virus X 25K movement protein.
To study subdomain organization of the potato virus X (PVX) movement protein (MP) encoded by the first gene in the triple gene block (TGB), we mutated the 25-kDa TGBp1 protein. The N-terminal deletion of the helicase motifs I, IA, and II resulted in loss of the ATPase activity and RNA binding. A frameshift mutation truncating the C-terminal motifs V and VI gave rise to increase of the TGBp1 ATPase activity and had little effect on RNA binding in vitro. Fusions of the green fluorescent protein with 25-kDa MP and its derivative lacking motifs V-VI exhibited similar fluorescence patterns in epidermal cells of Nicotiana benthamiana leaves. Cell-to-cell movement of the 25K-deficient PVX genome was not complemented by the TGBp1 of Plantago asiatica mosaic potexvirus (PlAMV) but was efficiently complemented by a chimeric TGBp1 consisting of the N-terminal part of PlAMV protein (motifs I-IV) and the PVX-specific C-terminal part (motifs V-VI). These results suggest that NTP hydrolysis, RNA binding, and targeting to the specific cellular compartment(s) are associated with the N-terminal domain of the TGBp1 including the helicase motifs I-IV and that the C-terminal domain is involved in specific interactions with other virus proteins.
A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, 119899, Russia.
S Y
SY
Morozov
A G
AG
Solovyev
N O
NO
Kalinina
O N
ON
Fedorkin
O V
OV
Samuilova
J
J
Schiemann
J G
JG
Atabekov
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000595:Amino Acid Sequence; D004265:DNA Helicases / Q000378:metabolism; D016368:Frameshift Mutation; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D053830:Plant Viral Movement Proteins; D017863:Potexvirus / Q000235:genetics; D012313:RNA / Q000378:metabolism; D013329:Structure-Activity Relationship; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*
D053830:Plant Viral Movement Proteins; D014764:Viral Proteins; D012313:RNA; D000251:Adenosine Triphosphatases; D004265:DNA Helicases