Synthetic genetic array analysis in Saccharomyces cerevisiae provides evidence for an interaction between RAT8/DBP5 and genes encoding P-body components.
Coordination of the multiple steps of mRNA biogenesis helps to ensure proper regulation of gene expression. The Saccharomyces cerevisiae DEAD-box protein Rat8p/Dbp5p is an essential mRNA export factor that functions at the nuclear pore complex (NPC) where it is thought to remodel mRNA/protein complexes during mRNA export. Rat8p also functions in translation termination and has been implicated in functioning during early transcription. We conducted a synthetic genetic array analysis (SGA) using a strain harboring the temperature-sensitive rat8-2 allele. Although RAT8 had been shown to interact genetically with >15 other genes, we identified >40 additional genes whose disruption in a rat8-2 background causes synthetic lethality or dramatically reduced growth. Included were five that encode components of P-bodies, sites of cytoplasmic mRNA turnover and storage. Wild-type Rat8p localizes to NPCs and diffusely throughout the cell but rat8-2p localized to cytoplasmic granules at nonpermissive temperature that are distinct from P-bodies. In some genetic backgrounds, these granules also contain poly(A)-binding protein, Pab1p, and additional mRNA export factors. Although these foci are distinct from P-bodies, the two merge under heat-stress conditions. We suggest that these granules reflect defective mRNP remodeling during mRNA export and during cytoplasmic mRNA metabolism.
Scarcelli
John J
JJ
Department of Biochemistry, Dartmouth Medical School, Hanover, NH 03755, USA.
Viggiano
Susan
S
Hodge
Christine A
CA
Heath
Catherine V
CV
Amberg
David C
DC
Cole
Charles N
CN
D000483:Alleles; D003593:Cytoplasm / Q000378:metabolism; D053487:DEAD-box RNA Helicases / Q000235:genetics* / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D005813:Genes, Synthetic; D022022:Nuclear Pore / Q000378:metabolism; D029543:Nucleocytoplasmic Transport Proteins / Q000235:genetics* / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D011132:Polyribosomes / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism*
D029543:Nucleocytoplasmic Transport Proteins; D012333:RNA, Messenger; D029701:Saccharomyces cerevisiae Proteins; C492382:DBP5 protein, S cerevisiae; D053487:DEAD-box RNA Helicases