A genetic screen in Saccharomyces cerevisiae identifies new genes that interact with mex67-5, a temperature-sensitive allele of the gene encoding the mRNA export receptor.
The Mex67p protein, together with Mtr2p, functions as the mRNA export receptor in Saccharomyces cerevisiae by interacting with both mRNA and nuclear pore complexes. To identify genes that interact functionally with MEX67, we used transposon insertion to search for mutations that suppressed the temperature-sensitive mex67-5 allele. Four suppressors are described here. The screen revealed that mutant Mex67-5p, but not wild-type Mex67p, is a target of the nuclear protein quality control mediated by San1p, a ubiquitin-protein ligase that participates in degradation of aberrant chromatin-associated proteins. Our finding that overexpression of the SPT6 gene alleviates the growth defects of the mex67-5 strain, together with the impairment of poly(A)(+) RNA export caused by depletion of Spt6p or the related protein Iws1p/Spn1p, supports the mechanism proposed in mammalian cells for Spt6-mediated co-transcriptional loading of mRNA export factors during transcription elongation. Finally, our results also uncovered genetic connections between Mex67p and the poly(A) nuclease complex and with components of chromatin boundary elements.
Estruch
Francisco
F
Department of Biochemistry and Molecular Biology, Universitat de Valencia, c/Dr. Moliner, 50, Burjassot (Valencia), 46100, Spain. estruch@uv.es
Peiró-Chova
Lorena
L
Gómez-Navarro
Natalia
N
Durbán
Jordi
J
Hodge
Christine
C
Del Olmo
Marcellí
M
Cole
Charles N
CN
D000483:Alleles; D001483:Base Sequence; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism; D004271:DNA, Fungal / Q000235:genetics; D005095:Exoribonucleases / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D005800:Genes, Fungal; D056488:Histone Chaperones; D008954:Models, Biological; D016254:Mutagenesis, Insertional; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D029543:Nucleocytoplasmic Transport Proteins / Q000235:genetics* / Q000378:metabolism; D010957:Plasmids / Q000235:genetics; D012331:RNA, Fungal / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D013696:Temperature; D035602:Transcriptional Elongation Factors; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism
D002868:Chromosomal Proteins, Non-Histone; D004271:DNA, Fungal; D005095:Exoribonucleases; D056488:Histone Chaperones; D009687:Nuclear Proteins; D029543:Nucleocytoplasmic Transport Proteins; D012331:RNA, Fungal; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; D035602:Transcriptional Elongation Factors; D044767:Ubiquitin-Protein Ligases; C106898:MEX67 protein, S cerevisiae; C065456:SPT6 protein, S cerevisiae; C508095:YTA7 protein, S cerevisiae; C500396:SAN1 protein, S cerevisiae