Pml39, a novel protein of the nuclear periphery required for nuclear retention of improper messenger ribonucleoparticles.
Using a genetic screen, we have identified a previously uncharacterized Saccharomyces cerevisiae open reading frame (renamed PML39) that displays a specific interaction with nucleoporins of the Nup84 complex. Localization of a Pml39-green fluorescent protein (GFP) fusion and two-hybrid studies revealed that Pml39 is mainly docked to a subset of nuclear pore complexes opposite to the nucleolus through interactions with Mlp1 and Mlp2. The absence of Pml39 leads to a specific leakage of unspliced mRNAs that is not enhanced upon MLP1 deletion. In addition, overexpression of PML39-GFP induces a specific trapping of mRNAs transcribed from an intron-containing reporter and of the heterogenous nuclear ribonucleoprotein Nab2 within discrete nuclear domains. In a nup60delta mutant, Pml39 is mislocalized together with Mlp1 and Mlp2 in intranuclear foci that also recruit Nab2. Moreover, pml39delta partially rescues the thermosensitive phenotypes of messenger ribonucleoparticles (mRNPs) assembly mutants, indicating that PML39 deletion also bypasses the requirement for normally assembled mRNPs. Together, these data indicate that Pml39 is an upstream effector of the Mlps, involved in the retention of improper mRNPs in the nucleus before their export.
Palancade
Benoît
B
Pores Nucléaires et Transport Nucléocytoplasmique, Unité Mixte de Recherche 144 Centre National de la Recherche Scientifique, Paris Cedex, France. palancad@curie.fr
Zuccolo
Michela
M
Loeillet
Sophie
S
Nicolas
Alain
A
Doye
Valérie
V
D002467:Cell Nucleus / Q000378:metabolism; D017353:Gene Deletion; D034441:Heterogeneous-Nuclear Ribonucleoproteins / Q000378:metabolism; D007438:Introns; D008954:Models, Biological; D028861:Nuclear Pore Complex Proteins / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D029543:Nucleocytoplasmic Transport Proteins / Q000378:metabolism; D016366:Open Reading Frames; D034443:RNA Transport; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism; D012261:Ribonucleoproteins / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
D034441:Heterogeneous-Nuclear Ribonucleoproteins; C080988:MLP1 protein, S cerevisiae; C119200:MLP2 protein, S cerevisiae; C080773:NAB2 protein, S cerevisiae; C097894:NUP84 protein, S cerevisiae; D028861:Nuclear Pore Complex Proteins; D009687:Nuclear Proteins; D029543:Nucleocytoplasmic Transport Proteins; C495208:Nup60 protein, S cerevisiae; C507830:Pml39 protein, S cerevisiae; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; D029701:Saccharomyces cerevisiae Proteins; C105887:YRA1 protein, S cerevisiae; C026452:messenger ribonucleoprotein