THE HEPATITIS-B VIRUS POST TRANSCRIPTIONAL REGULATORY ELEMENT CONTAINS A HIGHLY STABLE RNA SECONDARY STRUCTURE

Hepatitis B virus (HBV) transcripts contain a sequence known as the po sttranscriptional regulatory element (PRE). This element was shown to facilitate the nuclear export of the S gene transcripts, to partially substitute for the human immunodeficiency virus (HIV-1) Rev-response e lement (RRE), and to bind two cellular factors, Within the genetically defined PRE (approximately 450 nucleotides), we identified a highly s table secondary structural element of 313 nucleotides in length termed PRE(313). The energy values of the PRE(313) are similar to those of t he RRE of HIV-1 and significantly lower than those of other portions o f HBV RNA. A comparison of human HBV subtypes shows strong conservatio n of the PRE(313) in terms of energy and structure, providing further evidence for the biological significance of the genetically defined PR E and the PRE(313) in particular. The structural model for the PRE(313 ) described in this study may help in identifying crucial components o f the transport mechanism of transcripts of HBV. (C) 1997 Academic Pre ss.