Molecular cloning, sequencing, functional analysis and expression in E. coli of major core protein gene (S3) of rice dwarf virus Chinese isolate

Zhang, F.; Li, Y.; Liu, Y.; An, C.; Chen, Z.

Acta Virologica 41(3): 161-168

1997


ISSN/ISBN: 0001-723X
PMID: 9385405
Accession: 002898567

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Abstract
The complete nucleotide sequence of major core protein gene (segment S3) of rice dwarf phytoreovirus (RDV) Chinese isolate was determined after cDNA cloning from the viral genomic RNA. Sequence analysis showed that the cloned fragment is 3195 bp and contains a single open reading frame (ORF), encoding the major core protein (P3) (Mr of 114 K). The nucleotide and deduced amino acid sequences of S3 of this isolate shared significant homology (94.1 and 97%, respectively) with those of S3 of the Japanese isolate. At the amino acid level, P3 of RDV Chinese isolate shared significant homology with P3 of rice gall dwarf phytoreovirus (RGDV), significant regional homology with the rotavirus VP4 protein which forms spikes on the virus particles and has been identified as a protein involved in the activation of the rotavirus penetration, and homology with spheroidin of amsacta entomopoxvirus (SPH), which is the major protein of the occlusion body, with clp-like ATP-dependent protease binding subunit and with ATP-dependent protease ATP-binding subunit. Amino acid sequence analysis also showed that P3 contained RNA-dependent RNA polymerase (RDRP) motif-like elements such as DXXXD, SGXXXXXXN, GDD and ENXXXY. It is suggested that P3 is a multifunctional protein which has important functions in virus formation, virus replication and virus penetration. The full length cDNA sequence of RDV S3, and a partial one which covers nucleotides 1004-3195 were cloned into bacterial expression vector pTrcHisB. The full length cDNA sequence was not expressed in Escherichia coli, but the partial sequence was successfully expressed.