Accumulation of viruslike particles in a yeast mutant lacking a mitochondrial pore protein.

Dihanich, Melitta; Tuinen, E van; Lambris, John D.; Marshallsay, B

doi:10.1128/mcb.9.3.1100

Cited by 37 publications

(26 citation statements)

References 29 publications

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“…Its cytoplasmic location (12) makes it unlikely that it can use cellular enzymes to modify its mRNA, and viral transcripts made in vitro lack both modifications, although a single uncoded A (or G) residue is found at the 3Ј end of both viral strands (7,54).…”

Section: May Stimulate Translation Of the Poly(a)mentioning

confidence: 99%

Decoying the Cap² mRNA Degradation System by a Double-Stranded RNA Virus and Poly(A)² mRNA Surveillance by a Yeast Antiviral System

Masison

Blanc

Ribas

et al. 1995

Molecular and Cellular Biology

132

157

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The major coat protein of the L-A double-stranded RNA virus of Saccharomyces cerevisiae covalently binds m 7 GMP from 5 capped mRNAs in vitro. We show that this cap binding also occurs in vivo and that, while this activity is required for expression of viral information (killer toxin mRNA level and toxin production) in a wild-type strain, this requirement is suppressed by deletion of SKI1/XRN1/SEP1. We propose that the virus creates decapped cellular mRNAs to decoy the 533 exoribonuclease specific for cap ؊ RNA encoded by XRN1. The SKI2 antiviral gene represses the copy numbers of the L-A and L-BC viruses and the 20S RNA replicon, apparently by specifically blocking translation of viral RNA. We show that SKI2, SKI3, and SKI8 inhibit translation of electroporated luciferase and ␤-glucuronidase mRNAs in vivo, but only if they lack the 3 poly(A) structure. Thus, L-A decoys the SKI1/XRN1/SEP1 exonuclease directed at 5 uncapped ends, but translation of the L-A poly(A) ؊ mRNA is repressed by Ski2,3,8p. The SKI2-SKI3-SKI8 system is more effective against cap ؉ poly(A) ؊ mRNA, suggesting a (nonessential) role in blocking translation of fragmented cellular mRNAs.

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Section: May Stimulate Translation Of the Poly(a)mentioning

confidence: 99%

Decoying the Cap² mRNA Degradation System by a Double-Stranded RNA Virus and Poly(A)² mRNA Surveillance by a Yeast Antiviral System

Masison

Blanc

Ribas

et al. 1995

Molecular and Cellular Biology

132

157

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“…As chronicled in a recent publication, Dihanich et al sought to identify the 86-kDa protein and the gene encoding it (15). They determined that the 86-kDa protein is, surprisingly, the coat protein of the yeast double-stranded RNA viruslike particle, which is a product of the L-A dsRNA itself (31) rather than the product of a yeast nuclear gene.…”

mentioning

confidence: 99%

“…Mutations in another nuclear gene, POR, which encodes the mitochondrial outer membrane protein porin, result in a phenotype similar to that of the nucl mutant strains. por mutant strains also overproduce the 86-kDa viruslike particle coat protein (14,15 …”

mentioning

confidence: 99%

Overproduction of yeast viruslike particles by strains deficient in a mitochondrial nuclease.

Liu¹,

Dieckmann²

1989

Mol. Cell. Biol.

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Saccharomyces cerevisiae strains are often host to several types of cytoplasmic double-stranded RNA (dsRNA) genomes, some of which are encapsidated by the L-A dsRNA product, an 86,000-dalton coat protein.Here we present the finding that nuclear recessive mutations in the NUCI gene, which encodes the major nonspecific nuclease of yeast mitochondria, resulted in at least a 10-fold increase in amounts of the L-A dsRNA and its encoded coat protein. The effect of nucl mutations on L-A abundance was completely suppressed in strains that also hosted the killer-toxin-encoding M dsRNA. Both NUCI and nuci strains containing the L-A genome exhibited an increase in coat protein abundance and a concomitant increase in L-A dsRNA when the cells were grown on a nonfermentable carbon source rather than on glucose, an effect independent of the increase in coat protein due to nuci mutations or to the absence of M. The increase in L-A expression in nuci strains was similar to that observed in strains with mutations in the nuclear gene encoding the most abundant outer mitochondrial membrane protein, porin. nuci mutations did not affect the level of porin in the mitochondrial outer membrane. Since the effect of mutations in nuci was to alter the copy number of the L-A coat protein genome rather than to change the level of the M toxin genome (as do mak and ski mutations), these mutations define a new class of nuclear genes affecting yeast dsRNA abundance.Most Saccharomyces cerevisiae strains are host to one or more double-stranded RNAs (dsRNAs) (2, 35; for a review, see reference 39). The L-A and M dsRNAs are associated with cytoplasmic virus-like particles and are responsible for conferring the killer phenotype (2, 30). Killer strains secrete a toxin encoded on dsRNAs of the M type (1.8 or 1.5 kilobases [kb]) that can kill sensitive yeast strains (3, 4). The coat proteins that encapsidate the dsRNAs are encoded on the separate L-A genome, which is 4.5 kb in length (1,19,20,31). That host functions are necessary for maintenance and propagation of the dsRNAs is evidenced by the myriad of nuclear genes defined by mutations that eliminate toxin production (MAK [maintenance of killer]) (1,36,40) or enhance the killer phenotype (SKI [superkiller]) (27,33). mak mutations result in the loss of either the toxin-encoding M genome alone or both the L and M genomes, whereas ski mutations result in an increased copy number of the toxinencoding M genome and therefore bestow an enhanced killer phenotype.Here, we present the finding that mutations in a nuclear gene resulted in an increased copy number of the L-A type genome and an overabundance of one product of that genome, the 86-kilodalton (kDa) coat protein. Furthermore, we show that the L-A copy number increased in mutant strains only when M, the toxin-encoding genome, was absent. These nuclear mutations are in the NUCI gene, which encodes the major nonspecific nuclease in yeast mitochondria (5,34,41). We created such a mutation in the course of our studies on CBPI, which is adjacent to NUCI ...

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“…We found only three yeast proteins that begin with MLRF (and none beginning with MLAF, MLRA, or MWRF), a-ketoglutarate dehydrogenase (KGD1) (15), fumarate hydratase (FUMJ) (25), and a 37-kDa mitochondrial ribosomal protein (MRPJ) (14). These are all mitochondrial proteins, and this may explain the mild growth defect of mak3 mutants on nonfermentable carbon sources (1,21). The signal for MAK3 acetylation would be part of the import signal sequence which is usually removed on entry into the mitochondrion.…”

mentioning

confidence: 99%

“…This modification is necessary for assembly of L-A virus particles (22 AMK3 N-acetyltransferase is also responsible for modifying one or more proteins involved in respiration (1,21).…”

mentioning

confidence: 99%

Yeast MAK3 N-acetyltransferase recognizes the N-terminal four amino acids of the major coat protein (gag) of the L-A double-stranded RNA virus

1993

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The MAK3 gene of Saccharomyces cerevisiae encodes an N-acetyltransferase whose acetylation of the N terminus of the L-A double-stranded RNA virus major coat protein (gag) is necessary for viral assembly. We show that the first 4 amino acids of the L-A gag protein sequence, MLRF, are a portable signal for N-terminal acetylation by MA4K3. Amino acids 2, 3, and 4 are each important for acetylation by the MAK3 enzyme. In yeast cells, only three mitochondrial proteins are known to have the MAK3 acetylation signal, suggesting an explanation for the slow growth of mak3 mutants on nonfermentable carbon sources.Most proteins made in eukaryotes are N-terminally acetylated, but the role of these modifications and the signals determining them are, in most cases, unclear (reviewed in references 5 and 17). There are at least three enzymes in Saccharomyces cerevisiae that perform this process. The enzyme responsible for most acetylations is encoded by two genes, NATI (also called AAAJ) and ARDI (7, 13). While NAT1 encodes peptides of the purified major N-acetyltransferase (7), the sequence ofARDJ (24) strongly suggests that it encodes a catalytic subunit of an acetyltransferase (21), and the requirement for both NAT1 and ARDJ in stoichiometric amounts suggests the enzyme has two subunits (13). Although the NATJ-ARDI system is responsible for acetylation of about 20% of all yeast proteins (10), mutants in either gene (or both) are viable, showing slowed growth, defects in repression of the HML mating locus, and failure to sporulate or to enter Go (9,13,24). This indicates that most proteins modified by this system do not need the modification for function. Based on in vitro and in vivo studies, the NA T1 (AAAI)-ARD1 system modifies mainly proteins whose initiator methionine has been removed leaving an N-terminal serine, threonine, glycine, or alanine (8,18,20). Although changing a protein's second amino acid residue can change its acetylation either in vivo or in vitro (4,8,12,23), this is clearly not the only determinant of acetylation (8,17,23).A second yeast N-acetyltransferase, capable of modifying N-terminal methionine, has also been described (11). This activity is present in mutants lacking the NATI-ARD1 activity, and, based on data to date, seems to prefer a penultimate D, E, or N residue (11, 18).The MAK3 gene encodes a protein methionine N-acetyltransferase responsible for the acetylation of the N-terminus of gag, the major coat protein of the L-A double-stranded RNA virus of S. cerevisiae (21,22 AMK3 N-acetyltransferase is also responsible for modifying one or more proteins involved in respiration (1, 21).We previously showed that the first 13 amino acids of the L-A major coat protein, when attached to the N-terminus of 13-galactosidase, are a sufficient signal to allow N-acetylation of the fusion protein by AMK3 and to block N-acetylation of the 3-galactosidase by other yeast systems (22). In this work, we further dissected the specificity of the AL4K3 activity, and, on the basis of the results, suggest an explanati...

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Accumulation of viruslike particles in a yeast mutant lacking a mitochondrial pore protein.

Cited by 37 publications

References 29 publications

Decoying the Cap² mRNA Degradation System by a Double-Stranded RNA Virus and Poly(A)² mRNA Surveillance by a Yeast Antiviral System

Decoying the Cap² mRNA Degradation System by a Double-Stranded RNA Virus and Poly(A)² mRNA Surveillance by a Yeast Antiviral System

Overproduction of yeast viruslike particles by strains deficient in a mitochondrial nuclease.

Yeast MAK3 N-acetyltransferase recognizes the N-terminal four amino acids of the major coat protein (gag) of the L-A double-stranded RNA virus

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Accumulation of viruslike particles in a yeast mutant lacking a mitochondrial pore protein.

Cited by 37 publications

References 29 publications

Decoying the Cap2 mRNA Degradation System by a Double-Stranded RNA Virus and Poly(A)2 mRNA Surveillance by a Yeast Antiviral System

Decoying the Cap2 mRNA Degradation System by a Double-Stranded RNA Virus and Poly(A)2 mRNA Surveillance by a Yeast Antiviral System

Overproduction of yeast viruslike particles by strains deficient in a mitochondrial nuclease.

Yeast MAK3 N-acetyltransferase recognizes the N-terminal four amino acids of the major coat protein (gag) of the L-A double-stranded RNA virus

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Decoying the Cap² mRNA Degradation System by a Double-Stranded RNA Virus and Poly(A)² mRNA Surveillance by a Yeast Antiviral System

Decoying the Cap² mRNA Degradation System by a Double-Stranded RNA Virus and Poly(A)² mRNA Surveillance by a Yeast Antiviral System