7O24

Structure of the foamy viral protease-reverse transcriptase in complex with dsDNA.

Summary for 7O24

• Entry DOI: 10.2210/pdb7o24/pdb
• EMDB information: 12698
• Descriptor: Pr125Pol, DNA (5'-D(*AP*AP*CP*AP*GP*AP*GP*TP*GP*CP*GP*AP*CP*AP*CP*CP*TP*GP*AP*TP*TP*CP*CP*A)-3'), DNA (5'-D(*TP*GP*GP*AP*AP*TP*CP*AP*GP*GP*TP*GP*TP*CP*GP*CP*AP*CP*TP*CP*TP*G)-3') (3 entities in total)
• Functional Keywords: reverse trancscriptase, complex with dsdna, viral protein
• Biological source: White-tufted-ear marmoset simian foamy virus; More
• Total number of polymer chains: 5
• Total formula weight: 270533.01

Authors

Nowotny, M.,Czarnocki-Cieciura, M. (deposition date: 2021-03-30, release date: 2021-06-30, Last modification date: 2024-07-10)

Primary citation

Nowacka, M.,Nowak, E.,Czarnocki-Cieciura, M.,Jackiewicz, J.,Skowronek, K.,Szczepanowski, R.H.,Wohrl, B.M.,Nowotny, M.
Structures of Substrate Complexes of Foamy Viral Protease-Reverse Transcriptase.
J.Virol., 95:e0084821-e0084821, 2021

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 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.

PubMed: 34232702
DOI: 10.1128/JVI.00848-21

Experimental method

ELECTRON MICROSCOPY (4.8 Å)