A block in full-length transcript maturation in cells nonpermissive for B19 parvovirus.
Vertebrate parvoviruses share a similar genomic organization, with the capsid proteins encoded by genes on the right side and nonstructural proteins encoded by genes on the left side. The temporal and cell-specific appearances of these two types of gene products are regulated by a variety of genetic mechanisms. Rodent parvovirus structural proteins, for example, are encoded by a separate promoter which is positively regulated by nonstructural-gene products. In contrast, for the human B19 parvovirus, the analogous structural-gene promoter is nonfunctional, and both left- and right-side transcripts originate from a single promoter and are highly processed. Using a combination of sensitive RNA analyses of wild-type and mutant templates, we have found that the relative abundance of these alternatively processed transcripts appears to be governed by unique postinitiation events. In permissive cells, the steady-state level of right-side structural-gene transcripts predominates over that of left-side nonstructural-gene transcripts. In nonpermissive cells transfected with the B19 virus genome, nonstructural-gene transcripts predominate. Removal of 3' processing signals located in the middle of the viral genome increases transcription of the far right side. Disruption of a polyadenylation signal in this region makes readthrough of full-length right-side transcripts possible. These results suggest that the abundance of B19 virus RNAs is determined by active 3' processing and is coupled to DNA template replication.
Liu
J M
JM
Clinical Hematology Branch, National Heart, Lung, and Blood Institute, Bethesda, Maryland 20892.
Green
S W
SW
Shimada
T
T
Young
N S
NS
D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D002213:Capsid / Q000235:genetics*; D036022:Capsid Proteins; D002460:Cell Line; D004261:DNA Replication; D004279:DNA, Viral / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides; D016376:Oligonucleotides, Antisense; D010321:Parvoviridae / Q000235:genetics* / Q000502:physiology; D016133:Polymerase Chain Reaction / Q000379:methods; D011401:Promoter Regions, Genetic; D012367:RNA, Viral / Q000235:genetics*; D015183:Restriction Mapping; D013698:Templates, Genetic; D014158:Transcription, Genetic; D014162:Transfection; D014758:Viral Core Proteins / Q000235:genetics*; D017361:Viral Nonstructural Proteins
D036022:Capsid Proteins; D004279:DNA, Viral; D009838:Oligodeoxyribonucleotides; D016376:Oligonucleotides, Antisense; D012367:RNA, Viral; D014758:Viral Core Proteins; D017361:Viral Nonstructural Proteins