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The amino‐terminal domain of the hepadnaviral P‐gene encodes the terminal protein (genome‐linked protein) believed to prime reverse transcription.
Author(s) -
Bartenschlager R.,
Schaller H.
Publication year - 1988
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1988.tb03315.x
Subject(s) - biology , gene , microbiology and biotechnology , transcription (linguistics) , dna , genetics , open reading frame , genome , peptide sequence , virology , philosophy , linguistics
A series of antisera directed against amino acid sequences from different segments of the duck hepatitis B virus (DHBV) P‐gene were shown to immunoprecipitate DHBV DNA molecules that were covalently linked to the DHBV DNA terminal protein. Restriction analysis and sizing after protease treatment demonstrated that the P‐gene proteins were bound to the 5′‐end of the DHBV DNA minus‐strand which was mapped to a G‐residue in the centre of the repeat sequence DR1. Resistance to alkali treatment indicated a phosphodiester linkage to tyrosine between protein and DNA. Limited protease treatment prior to immunoprecipitation cleaved C‐terminal P‐proteins from the viral DNA, indicating that the terminal protein forms a separate domain encoded in the N‐terminal part of the P‐gene. Functional analysis of a deletion mutant confirmed the notion that a non‐essential spacer separates the terminal protein from the polymerase domain residing in the C‐terminal half of the P‐gene. Thus, the major proteins required for hepadnaviral reverse transcription, namely the primer, DNA polymerase, and possibly also RNase H, appear to be synthesized as a polyprotein precursor which is at least initially linked as such to its first DNA product.