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J. Virol., 01 1998, 201-208, Vol 72, No. 1
CQ Zeng, MK Estes, A Charpilienne and J Cohen
The innermost core of rotavirus is composed of VP2, which forms a protein
layer that surrounds the two minor proteins VP1 and VP3, and the genome of
11 segments of double-stranded RNA. This inner core layer surrounded by
VP6, the major capsid protein, constitutes double-layered particles that
are transcriptionally active. Each gene encoding a structural protein of
double-layered particles has been cloned into baculovirus recombinants and
expressed in insect cells. Previously, we showed that coexpression of
different combinations of the structural proteins of rotavirus
double-layered particles results in the formation of virus-like particles
(VLPs), and each VLP containing VP1, the presumed RNA-dependent RNA
polymerase, possesses replicase activity as assayed in an in vitro
template-dependent assay system (C. Q.-Y. Zeng, M. J. Wentz, J. Cohen, M.
E. Estes, and R. F. Ramig, J. Virol. 70:2736- 2742, 1996). This work
reports construction and characterization of VLPs containing a truncated
VP2 (VPdelta2, containing amino acids [aa] Met-93 to 880). Expression of
VPdelta2 alone resulted in the formation of single-layered delta2-VLPs.
Coexpression of VPdelta2 with VP6 produced double-layered delta2/6-VLPs.
VLPs formed by coexpression of VPdelta2 and VP1 or VP3, or both VP1 and
VP3, resulted in the formation of VLPs lacking both VP1 and VP3. The
presence of VP6 with VPdelta2 did not result in encapsidation of VP1 and
VP3. To determine the domain of VP2 required for binding VP1, far-Western
blot analyses using a series of truncated VP2 constructs were performed to
test their ability to bind VP1. These analyses showed that (i) full-length
VP2 (aa 1 to 880) binds to VP1, (ii) any N-terminal truncation lacking aa 1
to 25 fails to bind VP1, and (iii) a C-terminal 296-aa truncated VP2
construct (aa 1 to 583) maintains the ability to bind VP1. These analyses
indicate that the N terminus of rotavirus VP2 is necessary for the
encapsidation of VP1 and VP3.
Copyright © 1998, American Society for Microbiology
The N terminus of rotavirus VP2 is necessary for encapsidation of VP1 and VP3
Division of Molecular Virology, Baylor College of Medicine, Houston, Texas 77030, USA. qzeng@bmc.tmc.edu
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