Foamy Virus Gag p71-p68 Cleavage Is Required for Template Switch of the Reverse Transcriptase

Spannaus, Ralf; Schneider, Anna; Hartl, Maximilian J.; Wöhrl, Birgitta M.; Bodem, Jochen

doi:10.1128/jvi.00833-13

Cited by 9 publications

(12 citation statements)

References 12 publications

(10 reference statements)

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“…The fact, that in the virus the situation is the other way round, that is, complete Pol but incomplete Gag cleavage is observed, implies that cleavage of Gag is somehow circumvented during virus assembly or maturation. We have shown previously that partial Gag processing is required for the first template switch during reverse transcription . Thus, we conclude that in vivo during virus maturation, the Gag p68/p3 cleavage site is less accessible than the Pol RT/IN site, leading to delayed and therefore only partial Gag cleavage.…”

Section: Discussionmentioning

confidence: 60%

“…Bound pregenomic viral RNA or the Gag p71 folding topology might be the cause for steric hindrance. We postulate, that this slowdown is a regulatory feature to control the precise order of events during virus assembly and maturation since the virus has to guarantee that IN is cleaved off from Pol before reverse transcription starts to be able to create active IN tetramers . These are required in the next round of infection to integrate the double‐stranded DNA into the host genome.…”

Section: Discussionmentioning

confidence: 99%

“…We postulate, that this slowdown is a regulatory feature to control the precise order of events during virus assembly and maturation since the virus has to guarantee that IN is cleaved off from Pol before reverse transcription starts to be able to create active IN tetramers. 5,39 These are required in the next round of infection to integrate the double-stranded DNA into the host genome. Premature start of the reverse transcription process will result in destruction of the PARM secondary structure required for PR activity and thus noninfectious virus.…”

Section: Discussionmentioning

confidence: 99%

“…Finally, we demonstrate that SFVmac PR does not discriminate between the Gag and Pol cleavage sites in vitro , although in the virus Pol is completely cleaved into PR‐RT and IN, whereas the Gag p68/p3 cleavage is incomplete. Consequently, we hypothesize that in the viral context, complete cleavage is prevented by steric hindrance and/or additional factors to control the correct sequence of events essential for virus maturation.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, FV p3 deletion mutants are able to replicate, while FVs with an inactive Gag p68=p3 cleavage site are not, demonstrating the necessity for a tight control of PR activity during FV assembly and maturation. [5][6][7][8][9] We have shown previously, that the isolated PR domain from simian FV from macaques (SFVmac) is a monomer of about 12 kDa, which has to dimerize to be active. 3,10,11 In the mature PR-RT, the PR is located Nterminally of the RT.…”

Section: Introductionmentioning

confidence: 99%

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Structural requirements for enzymatic activities of foamy virus protease‐reverse transcriptase

et al. 2013

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Reverse transcriptases (RTs) are pivotal in the life cycle of retroviruses and convert the genomic viral RNA into double-stranded DNA. The RT polymerase domain is subdivided into fingers, palm, thumb, and the connection subdomain, which links the polymerase to the C-terminal RNase H domain. In contrast to orthoretroviruses, mature RT of foamy viruses harbors the protease (PR) domain at its N-terminus (PR-RT). Therefore and due to low homology to other RTs, it is difficult to define the boundaries and functions of the (sub)domains. We introduced N- and C-terminal deletions into simian foamy virus PR-RT to investigate the impact of the truncations on the catalytic activities. Both, the RNase H domain and the connection subdomain contribute substantially to polymerase integrity and stability as well as to polymerase activity and substrate binding. The 42 amino acids long region C-terminal of the PR is important for polymerase stability and activity. PR activation via binding of PR-RT to viral RNA requires the presence of the full length PR-RT including the RNase H domain. In vitro, the cleavage efficiencies of FV PR for the Gag and Pol cleavage site are comparable, even though in virus particles only the Pol site is cleaved to completion suggesting that additional factors control PR activity and that virus maturation needs to be strictly regulated.

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Section: Discussionmentioning

confidence: 60%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Structural requirements for enzymatic activities of foamy virus protease‐reverse transcriptase

et al. 2013

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Specific RNA–protein interactions in the replication of foamy viruses (FVs)

Rethwilm

2013

Current Opinion in Virology

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Determination of the protease cleavage site repertoire—The RNase H but not the RT domain is essential for foamy viral protease activity

Spannaus

Bodem

2014

Virology

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In contrast to orthoretroviruses, the foamy virus protease is only active as a protease-reverse transcriptase fusion protein and requires viral RNA for activation. Maturation of foamy viral proteins seems to be restricted to a single cleavage site in Gag and Pol. We provide evidence that unprocessed Gag is required for optimal infectivity, which is unique among retroviruses. Analyses of the cleavage site sequences of the Gag and Pol cleavage sites revealed a high similarity compared to those of Lentiviruses. We show that positions P2׳ and P2 are invariant and that Gag and Pol cleavage sites are processed with similar efficiencies. The RNase H domain is essential for protease activity, but can functionally be substituted by RNase H domains of other retroviruses. Thus, the RNase H domain might be involved in the stabilization of the protease dimer, while the RT domain is essential for RNA dependent protease activation.

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Foamy Virus Gag p71-p68 Cleavage Is Required for Template Switch of the Reverse Transcriptase

Cited by 9 publications

References 12 publications

Structural requirements for enzymatic activities of foamy virus protease‐reverse transcriptase

Structural requirements for enzymatic activities of foamy virus protease‐reverse transcriptase

Specific RNA–protein interactions in the replication of foamy viruses (FVs)

Determination of the protease cleavage site repertoire—The RNase H but not the RT domain is essential for foamy viral protease activity

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