TY - JOUR
T1 - A novel expression selection approach allows precise mapping of the hepatitis B virus enhancer
AU - Tognoni, Angelo
AU - Cattaneo, Roberto
AU - Serfling, Edgar
AU - Schaffner, Walter
N1 - Funding Information:
ACKNOWLEDGEMENTS A.T. thanks the Istituto Pasteur-Fondazione Cenci-Bolognetti for financial support. We thank Hans Will and Heinz Schaller and also J. de Villiers and J. Banerji for communicating unpublished information. We are indebted to Maria Jasin, Patrick Matthias and Max L. Birnstiel for critical reading of the manuscript. Mike Fried has independently coined the term "expression selection" to describe the selection of host cell DNA substituting for polyoma virus enhancer/promoter sequences in stable transformation assays (62). Finally we thank Fritz Ochsenbein and Silvia Oberholzer for the preparation of the excellent graphics and for operating the word processor, respectively. This work was supported by the Swiss National Research Foundation and the Kanton Zurich.
PY - 1985/10/25
Y1 - 1985/10/25
N2 - We have used a novel approach called expression selection to precisely define the hepatitis B virus (HBV) enhancer. Expression selection is based on a shuttle vector containing an enhancerless SV40 T antigen gene, the SV40 origin of replication and a plasmid replicon. This vector is linearized, ligated with the sonicated DNA to be analyzed and transfected into eukaryotic cells, where only plasmids which have incorporated an enhancer can express T antigen and therefore replicate. Vectors amplified by replication are selectively rescued in E.coli and their inserts analyzed. When we performed this protocol with HBV DNA we rescued two overlapping fragments of 166 and 214 bp which in HBV DNA map about 500 bp upstream of the core antigen mRNA initiation site and 1150 bp downstream of the surface antigen mRNA initiation site. These results were confirmed by conventional deletion mapping. When compared to the SV40 enhancer in nonhepatic cell lines, the HBV enhancer is only 5 to 10% as active; nevertheless, it also acts in an orientation-independent manner and in a position downstream of a gene. The HBV enhancer is situated in the coding region of the potential reverse transcriptase, and thus is the first enhancer identified to map in a protein-coding region.
AB - We have used a novel approach called expression selection to precisely define the hepatitis B virus (HBV) enhancer. Expression selection is based on a shuttle vector containing an enhancerless SV40 T antigen gene, the SV40 origin of replication and a plasmid replicon. This vector is linearized, ligated with the sonicated DNA to be analyzed and transfected into eukaryotic cells, where only plasmids which have incorporated an enhancer can express T antigen and therefore replicate. Vectors amplified by replication are selectively rescued in E.coli and their inserts analyzed. When we performed this protocol with HBV DNA we rescued two overlapping fragments of 166 and 214 bp which in HBV DNA map about 500 bp upstream of the core antigen mRNA initiation site and 1150 bp downstream of the surface antigen mRNA initiation site. These results were confirmed by conventional deletion mapping. When compared to the SV40 enhancer in nonhepatic cell lines, the HBV enhancer is only 5 to 10% as active; nevertheless, it also acts in an orientation-independent manner and in a position downstream of a gene. The HBV enhancer is situated in the coding region of the potential reverse transcriptase, and thus is the first enhancer identified to map in a protein-coding region.
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U2 - 10.1093/nar/13.20.7457
DO - 10.1093/nar/13.20.7457
M3 - Article
C2 - 2997748
AN - SCOPUS:0022432508
VL - 13
SP - 7457
EP - 7472
JO - Nucleic Acids Research
JF - Nucleic Acids Research
SN - 0305-1048
IS - 20
ER -