A downstream polyadenylation element in human papillomavirus type 16 L2 encodes multiple GGG motifs and interacts with hnRNP H.
Production of human papillomavirus type 16 (HPV-16) virus particles is totally dependent on the differentiation-dependent induction of viral L1 and L2 late gene expression. The early polyadenylation signal in HPV-16 plays a major role in the switch from the early to the late, productive stage of the viral life cycle. Here, we show that the L2 coding region of HPV-16 contains RNA elements that are necessary for polyadenylation at the early polyadenylation signal. Consecutive mutations in six GGG motifs located 174 nucleotides downstream of the polyadenylation signal resulted in a gradual decrease in polyadenylation at the early polyadenylation signal. This caused read-through into the late region, followed by production of the late mRNAs encoding L1 and L2. Binding of hnRNP H to the various triple-G mutants correlated with functional activity of the HPV-16 early polyadenylation signal. In addition, the polyadenylation factor CStF-64 was also found to interact specifically with the region in L2 located 174 nucleotides downstream of the early polyadenylation signal. Staining of cervix epithelium with anti-hnRNP H-specific antiserum revealed high expression levels of hnRNP H in the lower layers of cervical epithelium and a loss of hnRNP H production in the superficial layers, supporting a model in which a differentiation-dependent down regulation of hnRNP H causes a decrease in HPV-16 early polyadenylation and an induction of late gene expression.
Department of Medical Biochemistry and Microbiology, Uppsala University, BMC, Box 582, Husargatan 3, 751 23 Uppsala, Sweden.
Daniel
D
Oberg
Joanna
J
Fay
Helen
H
Lambkin
Stefan
S
Schwartz
D001483:Base Sequence; D036022:Capsid Proteins / Q000235:genetics*; D002454:Cell Differentiation; D002584:Cervix Uteri / Q000166:cytology / Q000378:metabolism; D005260:Female; D006367:HeLa Cells; D034541:Heterogeneous-Nuclear Ribonucleoprotein Group F-H / Q000502:physiology*; D006801:Humans; D008969:Molecular Sequence Data; D009856:Oncogene Proteins, Viral / Q000235:genetics*; D016366:Open Reading Frames; D026723:Polyadenylation; D012313:RNA / Q000378:metabolism; D012326:RNA Splicing
D036022:Capsid Proteins; D034541:Heterogeneous-Nuclear Ribonucleoprotein Group F-H; C063316:L2 protein, Human papillomavirus type 16; D009856:Oncogene Proteins, Viral; D012313:RNA