F. Hans et al., LOCATION OF THE REPLICATION DETERMINANTS OF THE SATELLITE RNA ASSOCIATED WITH GRAPEVINE FANLEAF-NEPOVIRUS (STRAIN-F13), Biochimie, 75(7), 1993, pp. 597-603
A large satellite RNA of 1114 nucleotides, named RNA3, is always found
associated with the genomic RNAs of grapevine fanleaf virus, isolate
F13 (GFLV-F13). RNA3 encodes a non-structural protein (P3) of M(r) 37K
to which no function has previously been assigned. Full-length cDNA c
lones of RNA3 were mutated in the 5' and 3' non-coding regions and in
the 37K open reading frame. The ability of transcripts obtained from t
hese clones to be replicated was investigated by protoplast infection
in the presence of a helper virus. We demonstrate that the 5' and 3' n
on-coding regions as well as the satellite-encoded P3 protein are esse
ntial for replication of the GFLV-F13 satellite RNA. Our results sugge
st that two hydrophobic regions located at the N- and C-extremity of P
3 and a zinc-finger motif near the C-terminal extremity of P3 are prob
ably involved in the replication of this satellite. Analysis of the in
vitro translation products from transcripts of RNA3 clones of differe
nt lengths indicates that the double band formed by P3 could result fr
om phosphorylation of a part of this protein.