Functional organization of enhancer (ENII) of hepatitis B virus.
A new enhancer ENII, located in the X open reading frame and immediately upstream of the core gene promoter, has recently been identified in the genome of hepatitis B virus. We have studied the functional constituents of this new enhancer in different cell lines. ENII can be divided into two functional elements, A and B, corresponding to two major binding sequences for nuclear protein factors. Element A alone gave very low activity; however, it was a modulatory element important for cell-type specificity. Element B was shown to be the basic functional element of ENII, which retained about 70% of the enhancer activity of the complete ENII in HepG2 cells. Element B can be further dissected into three subunits, B1, B2, and B3, which act synergistically. A 52-bp sequence is identified as the core sequences of element B. A model for the mechanism of ENII function is proposed.
Wu
X
X
Shanghai Institute of Biochemistry, Academia Sinica, China.
Zhu
L
L
Li
Z P
ZP
Koshy
R
R
Wang
Y
Y
D001483:Base Sequence; D001667:Binding, Competitive; D002460:Cell Line; D004279:DNA, Viral; D004742:Enhancer Elements, Genetic; D006515:Hepatitis B virus / Q000235:genetics*; D008969:Molecular Sequence Data; D014157:Transcription Factors / Q000378:metabolism
D004279:DNA, Viral; D014157:Transcription Factors