title: A minimal region in the NTPase/helicase domain of the TGBp1 plant virus movement protein is responsible for ATPase activity and cooperative RNA binding.
abstract: The TGBp1 protein, encoded in the genomes of a number of plant virus genera as the first gene of the 'triple gene block', possesses an NTPase/helicase domain characterized by seven conserved sequence motifs. It has been shown that the TGBp1 NTPase/helicase domain exhibits NTPase, RNA helicase and RNA-binding activities. In this paper, we have analysed a series of deletion and point mutants in the TGBp1 proteins encoded by Potato virus X (PVX, genus Potexvirus) and Poa semilatent virus (PSLV, genus Hordeivirus) to map functional regions responsible for their biochemical activities in vitro. It was found that, in both PVX and PSLV, the N-terminal part of the TGBp1 NTPase/helicase domain comprising conserved motifs I, Ia and II was sufficient for ATP hydrolysis, RNA binding and homologous protein-protein interactions. Point mutations in a single conserved basic amino acid residue upstream of motif I had little effect on the activities of C-terminally truncated mutants of both TGBp1 proteins. However, when introduced into the full-length NTPase/helicase domains, these mutations caused a substantial decrease in the ATPase activity of the protein, suggesting that the conserved basic amino acid residue upstream of motif I was required to maintain a reaction-competent conformation of the TGBp1 ATPase active site.
authors.affiliation: A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119992, Russia.
authors.forename: Anna D
authors.initials: AD
authors.lastname: Leshchiner
authors.affiliation: A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119992, Russia.
authors.forename: Andrey G
authors.initials: AG
authors.lastname: Solovyev
authors.affiliation: A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119992, Russia.
authors.forename: Sergey Yu
authors.initials: SY
authors.lastname: Morozov
authors.affiliation: A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119992, Russia.
authors.forename: Natalia O
authors.initials: NO
authors.lastname: Kalinina
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000378:metabolism*; D020816:Amino Acid Motifs; D009068:Movement; D010942:Plant Viruses / Q000201:enzymology*; D011485:Protein Binding; D012313:RNA / Q000378:metabolism*; D020365:RNA Helicases / Q000737:chemistry* / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: D016601:RNA-Binding Proteins; D012313:RNA; D000251:Adenosine Triphosphatases; D020365:RNA Helicases