Dorothée Molle

Publications (3)24.43 Total impact

• Source

  Available from: Séverine Boulon

  Article: HSP90 and its R2TP/Prefoldin-like cochaperone are involved in the cytoplasmic assembly of RNA polymerase II.

  Séverine Boulon, Bérengère Pradet-Balade, Céline Verheggen, Dorothée Molle, Stéphanie Boireau, Marya Georgieva, Karim Azzag, Marie-Cécile Robert, Yasmeen Ahmad, Henry Neel, Angus I Lamond, Edouard Bertrand
  [show abstract] [hide abstract]
  ABSTRACT: RNA polymerases are key multisubunit cellular enzymes. Microscopy studies indicated that RNA polymerase I assembles near its promoter. However, the mechanism by which RNA polymerase II is assembled from its 12 subunits remains unclear. We show here that RNA polymerase II subunits Rpb1 and Rpb3 accumulate in the cytoplasm when assembly is prevented and that nuclear import of Rpb1 requires the presence of all subunits. Using MS-based quantitative proteomics, we characterized assembly intermediates. These included a cytoplasmic complex containing subunits Rpb1 and Rpb8 associated with the HSP90 cochaperone hSpagh (RPAP3) and the R2TP/Prefoldin-like complex. Remarkably, HSP90 activity stabilized incompletely assembled Rpb1 in the cytoplasm. Our data indicate that RNA polymerase II is built in the cytoplasm and reveal quality-control mechanisms that link HSP90 to the nuclear import of fully assembled enzymes. hSpagh also bound the free RPA194 subunit of RNA polymerase I, suggesting a general role in assembling RNA polymerases.
  Molecular cell 09/2010; 39(6):912-24. · 14.61 Impact Factor
• Source

  Available from: PubMed Central

  Article: A real-time view of the TAR:Tat:P-TEFb complex at HIV-1 transcription sites.

  Dorothée Molle, Paolo Maiuri, Stéphanie Boireau, Edouard Bertrand, Anna Knezevich, Alessandro Marcello, Eugenia Basyuk
  [show abstract] [hide abstract]
  ABSTRACT: HIV-1 transcription is tightly regulated: silent in long-term latency and highly active in acutely-infected cells. Transcription is activated by the viral protein Tat, which recruits the elongation factor P-TEFb by binding the TAR sequence present in nascent HIV-1 RNAs. In this study, we analyzed the dynamic of the TAR:Tat:P-TEFb complex in living cells, by performing FRAP experiments at HIV-1 transcription sites. Our results indicate that a large fraction of Tat present at these sites is recruited by Cyclin T1. We found that in the presence of Tat, Cdk9 remained bound to nascent HIV-1 RNAs for 71s. In contrast, when transcription was activated by PMA/ionomycin, in the absence of Tat, Cdk9 turned-over rapidly and resided on the HIV-1 promoter for only 11s. Thus, the mechanism of trans-activation determines the residency time of P-TEFb at the HIV-1 gene, possibly explaining why Tat is such a potent transcriptional activator. In addition, we observed that Tat occupied HIV-1 transcription sites for 55s, suggesting that the TAR:Tat:P-TEFb complex dissociates from the polymerase following transcription initiation, and undergoes subsequent cycles of association/dissociation.
  Retrovirology 02/2007; 4:36. · 6.47 Impact Factor
• Article: Phosphorylation of the HTLV-1 matrix L-domain-containing protein by virus-associated ERK-2 kinase.

  Bénédicte Hémonnot, Dorothée Molle, Martine Bardy, Bernard Gay, Daniel Laune, Christian Devaux, Laurence Briant
  [show abstract] [hide abstract]
  ABSTRACT: L-domain-containing proteins from animal retroviruses play a critical role in the recruitment of the host cell endocytic machinery that is required for retroviruses budding. We recently demonstrated that phosphorylation of the p6(gag) protein containing the L-domain of the human immunodeficiency virus type 1 regulates viral assembly and budding. Here, we investigated whether or not the L-domain-containing protein from another human retrovirus, namely the matrix protein of the human T-cell leukemia virus type 1, that contains the canonical PTAP and PPPY L-domain motifs, shares similar functional properties. We found that MA is phosphorylated at several sites. We identified one phosphorylated amino acid in the HTLV-1 MA protein as being S105, located in the close vicinity to the L-domain sequence. S105 phosphorylation was found to be mediated by the cellular kinase ERK-2 that is incorporated within HTLV-1 virus particles in an active form. Mutation of the ERK-2 target S105 residue into an alanine was found to decrease viral release and budding efficiency of the HTLV-1(ACH) molecular clone from transfected cells. Our data thus support the postulate that phosphorylation of retroviral L-domain proteins is a common feature to retroviruses that participates in the regulation of viral budding.
  Virology 07/2006; 349(2):430-9. · 3.35 Impact Factor