Self-aggregation
of the Structural Protein Encoded by Rice Ragged Stunt Oryzavirus Genome
Segment 8
LU Hui-Juan, SHAO Chao-Gang, GONG Zu-Xun*
(Key Laboratory of Proteomics, Institute of Biochemistry and Cell Biology,
Shanghai Institutes for Biological Sciences, the Chinese Academy of Sciences，
Shanghai 200031,China )
Abstract Rice ragged
stunt oryzavirus (RRSV) is a member of the genus oryzavirus within the family
Reoviridae. Its genome consists of ten segments of dsRNA. The functions of all
products encoded by these viral genome segments, except one encoded by S9, have
not yet been elucidated. In the present study, the ORF of S 8 of
RRSV-Philippines isolate was sequenced and expressed in E. coli. The 67
kD product of S8 could be self-cleaved into two fragments with molecular
weights of 43 kD and 26 kD. Western blotting indicated that both 67 kD and 43
kD products were major structural proteins of the virus. It was also found that
the 67 kD protein could selfaggregate into aggregates with higher sedimentation
rate in sucrose gradients during centrifugation. Moreover, the self-aggregation
process could be accelerated by the complex of S6 product and genome dsRNAs of
RRSV. These results suggest that the S8 products, 67 kD or 43 kD, may be the
structural components of the viral inner-capsid.
Key words RRSV; P8; structural protein; selfcleavage;
selfaggregation
*Corresponding author: Tel,
86-21-64374430-5220; Fax, 86-21-64746510; e-mail, [email protected]