SKI2

..The superkiller 2 (ski2), ski3, ski6, ski7, and ski8 mutations enhance the expression of the poly(A)(-) mRNAs of yeast RNA viruses...

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..This finding suggests that the cytoplasmic and nuclear forms of the exosome represent two functionally different complexes involved in distinct 3'-to-5' processing and degradation reactions...

..Thus, Ski7p G protein appears to function as a signal-coupling factor between the two multi-complexes operating in the 3'-to-5' mRNA-decay pathway...

..We also show that the SKI2, SKI3, SKI6/RRP41, SKI8 and RRP4 gene products are required for 3' to 5' decay of mRNA...

..These data suggest that the activation of 3'-to-5' directed NMD is mediated through the interaction between Upf1p and the Ski7p N domain...

..In addition, inactivating the Ski complex by mutating conserved residues in the DEVH helicase motif of Ski2 did not abrogate its interaction with Ski7p, indicating that Ski2p function is not necessary for this interaction.

..Such a process would allow periodic sampling of the 3' UTR, which can diverge rapidly, for novel and beneficial protein extensions...

..We suggest that mechanisms of regeneration identified in this mutant screen may reveal fundamental differences between the mechanisms that establish differentiated cells during embryogenesis, and those involved in larval or adult growth...

..This system efficiently degrades mRNAs that are prematurely polyadenylated within the coding region and prevents their expression...

..Further, we show that the proteasome and Ski7p affected expression of nonstop reporter genes independently of each other. In addition, our results implicate inositol 1,3,4,5,6-pentakisphosphate as an inhibitor of nonstop mRNA decay...

The yeast Ski complex assists the exosome in the degradation of mRNA. The Ski complex consists of three components; Ski2, Ski3, and Ski8, believed to be present in a 1:1:1 stoichiometry...

..These results underscore the importance of Lsm1p-7p-Pat1p complex-mRNA interaction for mRNA decay in vivo and imply that the oligo(A) tail mediated enhancement of such interaction is crucial in that process...

..Our results demonstrate that improper histone stoichiometry leads to genomic instability and highlight the importance of regulating histone mRNA decay in the tight control of histone levels in yeast...

..of RAI1 is synthetically lethal with the rat1-1(ts) mutation and shows genetic interaction with a deletion of SKI2 but not XRN1...

The SKI2 gene is part of a host system that represses the copy number of the L-A double-stranded RNA (dsRNA) virus and its satellites M and X dsRNA, of the L-BC dsRNA virus, and of the single-stranded replicon 20S RNA...

..approach to study the role of SEP1/XRN1 in mitotic yeast cells, we identified mutations in the genes superkiller 2 (SKI2) and superkiller 3 (SKI3) as synthetically lethal with an sep1 null mutation...

..A screen for bypass suppressors of the inviability of xrn1 ski2 double mutants identified dominant alleles of RAT1, encoding an exoribonuclease homologous with Xrn1p...

..A variant killer plasmid is described that confers the superkiller phenotype and, like chromosomal ski mutations, makes several mak genes dispensable for plasmid replication...

..The virus propagation phenotype of mak21-1 is suppressed by ski2 or ski6 mutations, each of which derepresses translation of non-poly(A) mRNA.

..system because a single ski7 mutation derepresses the expression of non-poly(A) mRNA as much as a quadruple ski2 ski3 ski7 ski8 mutation, and the effect of the overexpression of Ski7p is not obtained unless other SKI genes are ..

..SKI1) encodes a cytoplasmic 5'-exoribonuclease responsible for the majority of cytoplasmic RNA turnover, whereas SKI2, SKI3, and SKI8 are required for normal 3'-degradation of mRNA and for repression of translation of poly(A) minus ..

..Mutations in ski2, ski3, ski4, ski6, ski7, and ski8 result in increased M copy number at 30 degrees C and prevent the cells from ..

..The SKI2 antiviral gene represses the copy numbers of the L-A and L-BC viruses and the 20S RNA replicon, apparently by ..

..We conclude that recognition of NMD substrates by the Upf surveillance complex can target mRNAs to rapid deadenylation and exosome-mediated degradation...

..Deletion of two nonessential putative RNA helicases (genes SKI2 and SLH1) makes poly(A) dispensable for translation...

..A ski1 mutation results in a decreased rate of cell growth. The kex1 and kex2 mutations are epistatic to each ski mutation...

..Understanding these pathways and how they are integrated with other cellular pathways will provide the intellectual underpinning for investigators carrying out translational research. ..

..Two models accounting for these results are that this complex is required for normal 60S function or that this complex acts in a 3'-mRNA degradation pathway. Experiments will be carried out to distinguish between these two models. ..

..synthetically lethal with xrn alleles (Aim 1) and to characterize the mutants obtained (including the already known SKI2 gene) in RNA turnover and translation, in vivo (Aim 2) and in vitro (Aim 4)...

..3) Determine the function of Arx1 p and Reilp, two functionally related proteins that act at the polypeptide exit tunnel on the nascent large ribosomal subunit during export and as it enters the cytoplasmic pool of active subunits. ..