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Title | Structures of Substrate Complexes of Foamy Viral Protease-Reverse Transcriptase. |
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Journal, issue, pages | J Virol, Vol. 95, Issue 18, Page e0084821, Year 2021 |
Publish date | Aug 25, 2021 |
Authors | Marzena Nowacka / Elżbieta Nowak / Mariusz Czarnocki-Cieciura / Justyna Jackiewicz / Krzysztof Skowronek / Roman H Szczepanowski / Birgitta M Wöhrl / Marcin Nowotny / |
PubMed Abstract | Reverse transcriptases (RTs) use their DNA polymerase and RNase H activities to catalyze the conversion of single-stranded RNA to double-stranded DNA (dsDNA), a crucial process for the replication of ...Reverse transcriptases (RTs) use their DNA polymerase and RNase H activities to catalyze the conversion of single-stranded RNA to double-stranded DNA (dsDNA), a crucial process for the replication of retroviruses. Foamy viruses (FVs) possess a unique RT, which is a fusion with the protease (PR) domain. The mechanism of substrate binding by this enzyme has been unknown. Here, we report a crystal structure of monomeric full-length marmoset FV (MFV) PR-RT in complex with an RNA/DNA hybrid substrate. We also describe a structure of MFV PR-RT with an RNase H deletion in complex with a dsDNA substrate in which the enzyme forms an asymmetric homodimer. Cryo-electron microscopy reconstruction of the full-length MFV PR-RT-dsDNA complex confirmed the dimeric architecture. These findings represent the first structural description of nucleic acid binding by a foamy viral RT and demonstrate its ability to change its oligomeric state depending on the type of bound nucleic acid. Reverse transcriptases (RTs) are intriguing enzymes converting single-stranded RNA to dsDNA. Their activity is essential for retroviruses, which are divided into two subfamilies differing significantly in their life cycles: and . The latter family is much more ancient and comprises five genera. A unique feature of foamy viral RTs is that they contain N-terminal protease (PR) domains, which are not present in orthoretroviral enzymes. So far, no structural information for full-length foamy viral PR-RT interacting with nucleic substrates has been reported. Here, we present crystal and cryo-electron microscopy structures of marmoset foamy virus (MFV) PR-RT. These structures revealed the mode of binding of RNA/DNA and dsDNA substrates. Moreover, unexpectedly, the structures and biochemical data showed that foamy viral PR-RT can adopt both a monomeric configuration, which is observed in our structures in the presence of an RNA/DNA hybrid, and an asymmetric dimer arrangement, which we observed in the presence of dsDNA. |
External links | J Virol / PubMed:34232702 / PubMed Central |
Methods | EM (single particle) / X-ray diffraction |
Resolution | 3.09 - 4.8 Å |
Structure data | EMDB-12698, PDB-7o24: PDB-7o0g: PDB-7o0h: |
Chemicals | ChemComp-HOH: |
Source |
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Keywords | VIRAL PROTEIN / reverse trancscriptase / complex with RNA-DNA / complex with dsDNA |