THE MULTIMERIC NONSTRUCTURAL NS2 PROTEINS OF BLUETONGUE VIRUS, AFRICAN HORSESICKNESS VIRUS, AND EPIZOOTIC HEMORRHAGIC-DISEASE VIRUS DIFFER IN THEIR SINGLE-STRANDED RNA-BINDING ABILITY
Jm. Uitenweerde et al., THE MULTIMERIC NONSTRUCTURAL NS2 PROTEINS OF BLUETONGUE VIRUS, AFRICAN HORSESICKNESS VIRUS, AND EPIZOOTIC HEMORRHAGIC-DISEASE VIRUS DIFFER IN THEIR SINGLE-STRANDED RNA-BINDING ABILITY, Virology, 209(2), 1995, pp. 624-632
The structure and single-stranded (ss) RNA-binding by the nonstructura
l protein NS2 of three different orbiviruses were studied and compared
. African horsesickness virus (AHSV), bluetongue virus (BTV), and epiz
ootic hemorrhagic disease virus (EHDV) were analyzed in recombinant ba
culovirus-infected cells and in cells infected with BTV and AHSV. Sedi
mentation analysis and nonreducing SDS-PAGE revealed that NS2 of all t
hree orbiviruses is a 7S multimer with both inter- and intramolecular
disulfide bonds, probably consisting of six or more NS2 molecules. The
7S NS2 multimer of all three viruses binds ssRNA but there is a marke
d disparity in the ssRNA-binding ability between the three proteins. A
t physiological salt concentration, BN NS2 binds ssRNA very efficientl
y, whereas AHSV NS2 shows only a low efficiency for binding ssRNA. EHD
V NS2 binds with intermediate efficiency. The result was the same irre
spective of whether poly(U)-Sepharose or viral mRNA was used, indicati
ng that ssRNA-binding by NS2 is nonspecific. The difference in RNA-bin
ding ability may be related to the alpha-helix content of the respecti
ve proteins. NS2 of BTV has the highest predicted alpha-helix content
followed by EHDV and AHSV. The ability of the NS2 proteins to form vir
us inclusion body-like structures in baculovirus-infected cells is not
affected by the ssRNA-binding disparity. (C) 1995 Academic Press, Inc
.