title: Insights into mRNP biogenesis provided by new genetic interactions among export and transcription factors.
abstract: BACKGROUND
  The various steps of mRNP biogenesis (transcription, processing and export) are interconnected. It has been shown that the transcription machinery plays a pivotal role in mRNP assembly, since several mRNA export factors are recruited during transcription and physically interact with components of the transcription machinery. Although the shuttling DEAD-box protein Dbp5p is concentrated on the cytoplasmic fibrils of the NPC, previous studies demonstrated that it interacts physically and genetically with factors involved in transcription initiation.
  
  
  RESULTS
  We investigated the effect of mutations affecting various components of the transcription initiation apparatus on the phenotypes of mRNA export mutant strains. Our results show that growth and mRNA export defects of dbp5 and mex67 mutant strains can be suppressed by mutation of specific transcription initiation components, but suppression was not observed for mutants acting in the very first steps of the pre-initiation complex (PIC) formation.
  
  
  CONCLUSIONS
  Our results indicate that mere reduction in the amount of mRNP produced is not sufficient to suppress the defects caused by a defective mRNA export factor. Suppression occurs only with mutants affecting events within a narrow window of the mRNP biogenesis process. We propose that reducing the speed with which transcription converts from initiation and promoter clearance to elongation may have a positive effect on mRNP formation by permitting more effective recruitment of partially-functional mRNP proteins to the nascent mRNP.
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Universitat de Valencia, Burjassot, Spain. estruch@uv.es
authors.forename: Francisco
authors.initials: F
authors.lastname: Estruch
authors.forename: Christine
authors.initials: C
authors.lastname: Hodge
authors.forename: Natalia
authors.initials: N
authors.lastname: Gómez-Navarro
authors.forename: Lorena
authors.initials: L
authors.lastname: Peiró-Chova
authors.forename: Catherine V
authors.initials: CV
authors.lastname: Heath
authors.forename: Charles N
authors.initials: CN
authors.lastname: Cole
mesh_terms: D021581:Active Transport, Cell Nucleus; D000483:Alleles; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D022022:Nuclear Pore / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D029543:Nucleocytoplasmic Transport Proteins / Q000235:genetics / Q000378:metabolism; D012319:RNA Polymerase II / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D012261:Ribonucleoproteins / Q000235:genetics* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: C106898:MEX67 protein, S cerevisiae; D009687:Nuclear Proteins; D029543:Nucleocytoplasmic Transport Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C026452:messenger ribonucleoprotein; D012319:RNA Polymerase II; C492382:DBP5 protein, S cerevisiae; D053487:DEAD-box RNA Helicases