This Article Full Text Full Text (PDF) Other Versions of this Article: JVI.01196-07v1 81/24/13354    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Stahl, M. Articles by Nassal, M. Search for Related Content PubMed PubMed Citation Articles by Stahl, M. Articles by Nassal, M.

Chaperones Activate Hepadnavirus Reverse Transcriptase by Transiently Exposing a C-Proximal Region in the Terminal Protein Domain That Contributes to RNA Binding

University Hospital Freiburg, Internal Med. 2/Molecular Biology, Hugstetter Str. 55, D-79106 Freiburg, Germany

Received 1 June 2007/ Accepted 24 September 2007

All hepatitis B viruses replicate by protein-primed reverse transcription, employing a specialized reverse transcriptase, P protein, that carries a unique terminal protein (TP) domain. To initiate reverse transcription, P protein must bind to a stem-loop, , on the pregenomic RNA template. TP then provides a Y residue for covalent attachment of the first nucleotide of an -templated DNA oligonucleotide (priming reaction) that serves to initiate full-length minus-strand DNA synthesis. binding requires the chaperone-dependent conversion of inactive P protein into an activated, metastable form designated P*. However, how P* differs structurally from P protein is not known. Here we used an in vitro reconstitution system for active duck hepatitis B virus P combined with limited proteolysis, site-specific antibodies, and defined P mutants to structurally compare nonactivated versus chaperone-activated versus primed P protein. The data show that Hsp70 action, under conditions identical to those required for functional activation, transiently exposes the C proximal TP region which is, probably directly, involved in RNA binding. Notably, after priming and RNA removal, a very similar new conformation appears stable without further chaperone activity; hence, the activation of P protein is triggered by energy-consuming chaperone action but may be completed by template RNA binding.

Published ahead of print on 3 October 2007.

This article has been cited by other articles:

• Lin, L., Wan, F., Hu, J. (2008). Functional and Structural Dynamics of Hepadnavirus Reverse Transcriptase during Protein-Primed Initiation of Reverse Transcription: Effects of Metal Ions. J. Virol. 82: 5703-5714 [Abstract] [Full Text]