Exploitation of the Mediator complex by viruses

Rovnak, Joel; Quackenbush, Sandra L.

doi:10.1371/journal.ppat.1010422

Cited by 6 publications

(6 citation statements)

References 76 publications

(82 reference statements)

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“…In both viruses, these findings were confirmed in infected cells, where Gag was targeted to the USvRNA transcription site, presumably at the site of proviral integration. Among other transcription-related proteins, in this study we identified multiple members of the Mediator complex, which has been shown to be hijacked by other viruses and retroelements, and we demonstrated that RSV Gag colocalized and co-immunoprecipitated with Med26 (Fig4and Video S1)[36][37][38][39][40][41][42][43]. Quantitative analysis of our imaging experiments indicated that nearly half of the nuclear Gag signal was colocalized with Med26.…”

mentioning

confidence: 58%

“…The presence of multiple Mediator proteins in our dataset raised the likelihood that Gag may interact with this multiprotein complex. Furthermore, Mediator proteins have been shown to be exploited by other viruses and endogenous retroelements [36][37][38][39][40][41][42][43]. Interestingly, Med26 and Med30 are both metazoan-specific Mediator proteins, implying that Gag may display selectivity for metazoan-specific Mediator complexes over those with protozoan orthologs.…”

Section: Validation Of Rsv Gag-med26 Interactionmentioning

confidence: 99%

“…To complement those datasets, we performed affinity-tagged purification of both RSV and HIV-1 Gag, and identified nuclear interacting partners using mass spectrometry. To further explore one of the novel hits, we utilized immunoprecipitation and quantitative imaging approaches to validate the interaction of RSV Gag with Mediator complex subunit 26 (Med26), a critical component of the transcriptional Mediator complex, which is exploited by other viruses and endogenous retroelements [36][37][38][39][40][41][42][43]. Together, published studies combined with our results suggest that Gag proteins may interface with host nuclear factors to facilitate genomic RNA selection and/or influence cellular processes, including gene expression, RNA processing, splicing, nucleic acid metabolism, and/or chromatin modification.…”

Section: Introductionmentioning

confidence: 99%

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Comparative analysis of retroviral Gag-host cell interactions: focus on the nuclear interactome

Lambert,

Rice,

Maldonado

et al. 2024

Preprint

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Retroviruses exploit a variety of host proteins to assemble and release virions from in-fected cells. To date, most studies that examined possible interacting partners of retroviral Gag proteins focused on host proteins that localize primarily to the cytoplasm or plasma membrane. Given the recent findings that several full-length Gag proteins localize to the nucleus, identifying the Gag-nuclear interactome has high potential for novel findings that reveal previously un-known host processes. In this study, we systematically compared nuclear factors identified in published HIV-1 proteomic studies which had used a variety of experimental approaches. In addition, to contribute to this body of knowledge, we report results from a mass spectrometry approach using affinity-tagged (His6) HIV-1 and RSV Gag proteins mixed with nuclear extracts. Taken together, the previous studies, as well as our own, identified potential binding partners of HIV-1 and RSV Gag involved in several nuclear processes, including transcription, splicing, RNA modification, and chromatin remodeling. Although a subset of host proteins interacted with both Gag proteins, there were also unique host proteins belonging to each interactome dataset. To validate one of the novel findings, we demonstrated the interaction of RSV Gag with a member of the Mediator complex, Med26, which is required for RNA polymerase II-mediated transcription. These results provide a strong premise for future functional studies to investigate roles for these nuclear host factors that may have shared functions in the biology of both retroviruses, as well as functions specific to RSV and HIV-1, given their distinctive hosts and molecular pathology.

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confidence: 58%

Section: Validation Of Rsv Gag-med26 Interactionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Comparative analysis of retroviral Gag-host cell interactions: focus on the nuclear interactome

Lambert,

Rice,

Maldonado

et al. 2024

Preprint

View full text Add to dashboard Cite

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“…The presence of multiple Mediator proteins in our dataset raised the likelihood that Gag may interact with this multiprotein complex. Furthermore, Mediator proteins have been shown to be exploited by other viruses and endogenous retroelements [38][39][40][41][42][43][44][45]. Interestingly, Med26 and Med30 are both metazoan-specific Mediator proteins, implying that Gag may display selectivity for metazoan-specific Mediator complexes over those with protozoan orthologs.…”

Section: Validation Of Rsv Gag-med26 Interactionmentioning

confidence: 99%

“…To complement those datasets, we performed affinity-tagged purification of both RSV and HIV-1 Gag, and identified nuclear interacting partners using mass spectrometry. To further explore one of the novel hits, we utilized immunoprecipitation and quantitative imaging approaches to validate the interaction of RSV Gag with Mediator complex subunit 26 (Med26; AlphaFold Protein Structure Database [36,37], entry O95402), a critical component of the transcriptional Mediator complex, which is exploited by other viruses and endogenous retroelements [38][39][40][41][42][43][44][45]. Together, published studies combined with our results suggest that Gag proteins may interface with host nuclear factors to facilitate genomic RNA selection and/or influence cellular processes, including gene expression, RNA processing, splicing, nucleic acid metabolism, and/or chromatin modification.…”

Section: Introductionmentioning

confidence: 99%

Comparative analysis of retroviral Gag-host cell interactions: focus on the nuclear interactome

Lambert,

Rice,

Maldonado

et al. 2024

Retrovirology

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Retroviruses exploit host proteins to assemble and release virions from infected cells. Previously, most studies focused on interacting partners of retroviral Gag proteins that localize to the cytoplasm or plasma membrane. Given that several full-length Gag proteins have been found in the nucleus, identifying the Gag-nuclear interactome has high potential for novel findings involving previously unknown host processes. Here we systematically compared nuclear factors identified in published HIV-1 proteomic studies and performed our own mass spectrometry analysis using affinity-tagged HIV-1 and RSV Gag proteins mixed with nuclear extracts. We identified 57 nuclear proteins in common between HIV-1 and RSV Gag, and a set of nuclear proteins present in our analysis and ≥ 1 of the published HIV-1 datasets. Many proteins were associated with nuclear processes which could have functional consequences for viral replication, including transcription initiation/elongation/termination, RNA processing, splicing, and chromatin remodeling. Examples include facilitating chromatin remodeling to expose the integrated provirus, promoting expression of viral genes, repressing the transcription of antagonistic cellular genes, preventing splicing of viral RNA, altering splicing of cellular RNAs, or influencing viral or host RNA folding or RNA nuclear export. Many proteins in our pulldowns common to RSV and HIV-1 Gag are critical for transcription, including PolR2B, the second largest subunit of RNA polymerase II (RNAPII), and LEO1, a PAF1C complex member that regulates transcriptional elongation, supporting the possibility that Gag influences the host transcription profile to aid the virus. Through the interaction of RSV and HIV-1 Gag with splicing-related proteins CBLL1, HNRNPH3, TRA2B, PTBP1 and U2AF1, we speculate that Gag could enhance unspliced viral RNA production for translation and packaging. To validate one putative hit, we demonstrated an interaction of RSV Gag with Mediator complex member Med26, required for RNA polymerase II-mediated transcription. Although 57 host proteins interacted with both Gag proteins, unique host proteins belonging to each interactome dataset were identified. These results provide a strong premise for future functional studies to investigate roles for these nuclear host factors that may have shared functions in the biology of both retroviruses, as well as functions specific to RSV and HIV-1, given their distinctive hosts and molecular pathology. Graphical Abstract

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Mediator complex in transcription regulation and DNA repair: Relevance for human diseases

Maalouf,

Alberti,

Soutourina

2024

DNA Repair

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Exploitation of the Mediator complex by viruses

Cited by 6 publications

References 76 publications

Comparative analysis of retroviral Gag-host cell interactions: focus on the nuclear interactome

Comparative analysis of retroviral Gag-host cell interactions: focus on the nuclear interactome

Comparative analysis of retroviral Gag-host cell interactions: focus on the nuclear interactome

Mediator complex in transcription regulation and DNA repair: Relevance for human diseases

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