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ISSN
1672-9145
Acta Biochim Biophys Sin 2005,
37(1): 55–60
CN 31-1940/Q
RNA-binding Domain of the Key Structural Protein P7 for the Rice
dwarf virus Particle Assembly
Bo-Xiong ZHONG1,2*,
Yan-Wei SHEN1, and Toshihiro OMURA2
1Department of Bioresource Science, College of Animal Science,
Zhejiang University, Hangzhou 310029, China;
2National Agricultural Research Center, Tsukuba, Ibaraki 305, Japan
Abstract The Rice dwarf virus (RDV) P7 structural protein is
the key protein in the RDV particle assembly. The P7 protein was digested
partially or completely by Staphylococcus aureus V8 protease and/or Pseudomonas
fragi Asp-N protease. The molecular mass and the N-terminal amino acid
sequence of the polypeptide fragments of the P7
protein were determined by SDS-PAGE and the Edman degradation method,
respectively. Then the polypeptides were located in the deduced amino acid
sequence of the RDV P7 protein based on the nucleotide sequence information,
with the knowledge of the specific cleavage sites of the Staphylococcus
aureus V8 and Pseudomonas fragi Asp-N protease, and the two RNA-binding
domains in the P7 protein were identified. Domain 1 was located in the residue
128249 containing 122 amino acids and domain 2 was located in the residue
325355 containing 31 amino acids. Thus, these two domains may play an important
role in the virus particle assembly by contributing to the packaging of viral
dsRNAs inside the particles. The two domains may be novel RNA-binding domains,
because no amino acid sequences highly similar to the conservative sequences of
known dsRNA-binding domains reported so far. The similarity between the motif
of domain 1 and the motif of the DNA-binding protein suggests that the
DNA-binding activity of the RDV P7 protein may be due to this sequence. The
similarity between the motif of domain 1 and the motif of the RNA polymerase
domain suggests that the P7 protein may also play a role in RNA synthesis,
besides its function in the assembly and subsequent packaging of viral dsRNA
into core particles.
Key words RDV; RNA-binding protein;
protein functional domain; virion assembly; RNA polymerase
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Received: September 24, 2004 Accepted: November 10,
2004
*Corresponding author: Tel, 86-571-86971302; Fax, 86-571-86971302;
E-mail, [email protected]