Influence of the poly(A) tail and putative polyadenylation signal on the infectivity of white clover mosaic potexvirus.
A series of mutations has been constructed in a cDNA clone of white clover mosaic virus (WCIMV) which decreases the poly(A) tail length of run-off transcripts from 74 to 27, 10 or zero 3'-terminal (A) residues. Although transcripts with short poly(A) tails were less infectious than wild-type RNA, complete removal of the (A) tail did not abolish infectivity. Addition of nonviral nucleotides to the 3' terminus of transcripts with no 3'-terminal (A) residues eliminated infectivity. Heterogenous-length poly(A) tails, indistinguishable from the wild type, were synthesized de novo in plants inoculated with transcripts with no 3'-terminal (A) residues, demonstrating the presence of a poly(A) polymerase activity in WCIMV-infected tissue. Mutation of a putative polyadenylation motif found in the 3' noncoding region of WCIMV decreased the efficiency of polyadenylation of the progeny of transcripts with 10 3'-terminal (A) residues. The same mutation in transcripts with no 3'-terminal (A) residues abolished infectivity.
Guilford
P J
PJ
DSIR Plant Protection, Mt. Albert Research Centre, Auckland, New Zealand.
Beck
D L
DL
Forster
R L
RL
D003001:Cloning, Molecular; D004252:DNA Mutational Analysis; D009841:Oligonucleotides / Q000737:chemistry; D010942:Plant Viruses / Q000235:genetics* / Q000472:pathogenicity; D011061:Poly A / Q000235:genetics*; D012328:RNA Viruses / Q000235:genetics* / Q000472:pathogenicity; D012367:RNA, Viral / Q000235:genetics*; D012045:Regulatory Sequences, Nucleic Acid; D013329:Structure-Activity Relationship
D009841:Oligonucleotides; D012367:RNA, Viral; D011061:Poly A