Sequence of the preprotoxin dsRNA gene of type I killer yeast: Multiple processing events produce a two-component toxin

Bostian, Keith A.; Elliott, Quentin; Bussey, Howard; Bum, Virginia; Smith, Amy; Tipper, Donald J.

doi:10.1016/0092-8674(84)90354-4

Cited by 217 publications

(121 citation statements)

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Section: Introductionmentioning

confidence: 99%

“…The genetically very well-characterized killer toxin K1 is stable within a narrow range of acidic pH, is unstable at temperatures above 25 u C, and can be inactivated by agitation. It is a heterodimeric a/b protein encoded by an M1 virus with a double-stranded RNA genome (Wickner, 1986;Martinac et al, 1990;Bostian et al, 1984;Breinig et al, 2002).Killer toxins are not restricted to Saccharomyces; they can also be found in other yeast genera: Candida, Cryptococcus, Debaryomyces, Hanseniaspora, Hansenula, Kluyveromyces, Pichia, Sporidiobolus, Tilletiopsis, Zygosaccharomyces, etc. Studies of a variety of killer toxins have shown that the characteristics of the K1 killer toxin and other toxins tend to be similar (most of them are protease-sensitive heatlabile proteins that are stable and active only at acidic pH values), while the genetic bases of killer characters are quite variable.…”

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PMKT2, a new killer toxin from Pichia membranifaciens, and its promising biotechnological properties for control of the spoilage yeast Brettanomyces bruxellensis

et al. 2009

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Pichia membranifaciens CYC 1086 secretes a killer toxin (PMKT2) that is inhibitory to a variety of spoilage yeasts and fungi of agronomical interest. The killer toxin in the culture supernatant was concentrated by ultrafiltration and purified to homogeneity by two successive steps, including native electrophoresis and HPLC gel filtration. Biochemical characterization of the toxin showed it to be a protein with an apparent molecular mass of 30 kDa and an isoelectric point of 3.7. At pH 4.5, optimal killer activity was observed at temperatures up to 20 6C. Above approximately this pH, activity decreased sharply and was barely noticeable at pH 6. The toxin concentrations present in the supernatant during optimal production conditions exerted a fungicidal effect on a variety of fungal and yeast strains. The results obtained suggest that PMKT2 has different physico-chemical properties from PMKT as well as different potential uses in the biocontrol of spoilage yeasts. PMKT2 was able to inhibit Brettanomyces bruxellensis while Saccharomyces cerevisiae was fully resistant, indicating that PMKT2 could be used in wine fermentations to avoid the development of the spoilage yeast without deleterious effects on the fermentative strain. In small-scale fermentations, PMKT2, as well as P. membranifaciens CYC 1086, was able to inhibit B. bruxellensis, verifying the biocontrol activity of PMKT2 in simulated winemaking conditions. INTRODUCTIONWorldwide, microbial growth destroys large amounts of various products, causing yield losses in the agronomical and biotechnological industries. Traditionally, biocides have been used to deal with these problems but different disadvantages such as establishment of resistant strains and suppression of natural competitors have made alternatives such as biological control necessary (Beever et al., 1989;Raposo et al., 2000). Biological control strategies include natural plant-and animal-derived compounds, as well as antagonistic micro-organisms (Ciani & Fatichenti, 2001).During recent decades, microbiological control of spoilage micro-organisms has evolved as a possibility. Many yeast strains and other micro-organisms inhibiting plant pathogens have been reported, especially within the fruit-and vegetable-producing sector, and several new products have reached the commercial market (Janisiewicz & Korsten, 2002). The suggested modes of action of biocontrol yeasts are not likely to constitute any hazard for the consumer (Janisiewicz et al., 2001;Masih & Paul, 2002;Comitini et al., 2004;Santos & Marquina, 2004a).The food and beverage industries were among the first to explore the application of killer-toxin-producing yeasts to kill spoilage micro-organisms (Lowes et al., 2000). Yeast strains often achieve competitive advantage by producing killer toxins, which kill off competing sensitive cells belonging to either the same or a different species (Young, 1987;Ciani & Fatichenti, 2001). The most thoroughly studied examples are the Saccharomyces cerevisiae toxins K1, K2 and K28; producers of these toxi...

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Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

PMKT2, a new killer toxin from Pichia membranifaciens, and its promising biotechnological properties for control of the spoilage yeast Brettanomyces bruxellensis

et al. 2009

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“…The N-terminal Pol region is necessary for genome packaging, although Gag alone is sufficient to form morphologically normal capsids (11). M1, a satellite RNA of L-A, has a dsRNA genome (1.6-1.8 kb) that encodes a protein toxin and immunity (12) but no proteins necessary for its own replication. It requires L-A for encapsidation and replication.…”

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Cap-snatching mechanism in yeast L-A double-stranded RNA virus

Fujimura

Esteban

2011

Proc. Natl. Acad. Sci. U.S.A.

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The 5′ cap structure (m 7 GpppX-) is an essential feature of eukaryotic mRNA required for mRNA stability and efficient translation. Influenza virus furnishes its mRNA with this structure by a capsnatching mechanism, in which the viral polymerase cleaves host mRNA endonucleolytically 10-13 nucleotides from the 5′ end and utilizes the capped fragment as a primer to synthesize viral transcripts. Here we report a unique cap-snatching mechanism by which the yeast double-stranded RNA totivirus L-A furnishes its transcript with a cap structure derived from mRNA. Unlike influenza virus, L-A transfers only m 7 Gp from the cap donor to the 5′ end of the viral transcript, thus preserving the 5′ α-and β-phosphates of the transcript in the triphosphate linkage of the final product. This in vitro capping reaction requires His154 of the coat protein Gag, a residue essential for decapping of host mRNA and known to form m 7 Gp-His adduct. Furthermore, the synthesis of capped viral transcripts in vivo and their expression were greatly compromised by the Arg154 mutation, indicating the involvement of Gag in the cap-snatching reaction. The overall reaction and the structure around the catalytic site in Gag resemble those of guanylyltransferase, a key enzyme of cellular mRNA capping, suggesting convergent evolution. Given that Pol of L-A is confined inside the virion and unable to access host mRNA in the cytoplasm, the structural protein Gag rather than Pol catalyzing this unique cap-snatching reaction exemplifies the versatility as well as the adaptability of eukaryotic RNA viruses.transcription | Saccharomyces cerevisiae | killer toxin E ukaryotic mRNA is capped at the 5′ end by a 7-methyl GMP moiety via an inverted 5′-5′ triphosphate linkage (m 7 GpppX) (1, 2). The cap structure is required for mRNA stability and efficient translation. Capping of the RNA 5′ end is accomplished in cells and for most viruses in three sequential catalytic reactions (3, 4): removal of the 5′ γ-phosphate by RNA triphosphatase, addition of GMP from GTP by guanylyltransferase, and methylation of the added GMP by methyltransferase. Influenza virus, how-

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“…Maturation of these bioactive peptides occurs by sequential action of trypsin-like and earboxypeptidase.B-like enzymes Ill. Although until recently only a few prohormones were known to be processed at monobasic cleavage sites, at present a large number of monobasic cleavages are found throughout the animal kingdom [2][3][4][5][6]. Table I shows the list of precursors and the amino acid sequence around the monobasic cleavage site.…”

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Consensus sequence for processing of peptide precursors at monobasic sites

1991

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'm{,¢.o/~gr. New ) 'ork {:nireratt.r Medi¢',d (~t;ter. N Y lO01d. USA R~¢civ~d 2 January Iggl Many regulat:ory p~ptid¢ pr¢c:ursors undergo post.trandationai pro~sstnj at moan. ,tad,or dibasic: residues, Compari:~nn of amino acids around the lnon,ohasi~ cleavage site~ sult=ests that these clear qles follow certain ~etiucnce motif~t anti t:a. be described as the rule~ that ttovern monobasi¢ gleav;l~e~: (i) a basic amino acid is present at either .L 5, or ? amino acids N.terminal 1o the ¢leavaje site, tii.) hydrophnbi¢ aliphatic amino aetds tleucine, isoleucine, valine, or methiontnc) are never pre~ent in the position C-terminal to the monobali¢ amino acid at the cleavage site, till) a t:ystcine i~ =lever present in the vicinity ol" the cleavase site. and (iv) an aromatic amino acid is never pre~em at the position N.terminal tt~ the monobasic amino acid at the cleavage ~ite. h~ addition to the~e rule~, the monobasi¢ clcavaltes follow certain tendencies: (i) the amino acid at tile cleavage ~it¢ tends to In: predominantly arginin¢, tii} the amino ttcid at the po~ition C.tcrrainal to the cleavage site tends to M striae, ahmine or 81ycine in more than 60"~ of the cases. (Sill the amino acid at either ~. 5. or ? petition N.tcrminal to the cleavage site tends to t~ aritiaine. (iv} aromatic amino a,id, ale rare at the position C.terminal to th¢ mon0basi¢ amino acid at the clcavag© site, and iv) aliphatie amino acids tend to ~ in tl~¢ two positlon~ N.terminal to and the two position, C-terminal to the cleavig~ ~ite. except as noted above. When compared with a htr~e number of sequenc=:~ t:0ntaininB single basic amino acids, these rules and tendencies are eu pable of not only correctly predicting the pro¢cssin$ sites, hut also are cap;IbM of excluding most of" the single basic: sequences that are known to be uncleared. Many of these rules can al~o be applied to corre*:tly predict the dab=tile and multibasic cleavage sites su~scstintl that the rule= and tendencies could govern endoproteolytic processing at tit, monobasic, dibasic and multibasic site~.

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Sequence of the preprotoxin dsRNA gene of type I killer yeast: Multiple processing events produce a two-component toxin

Cited by 217 publications

References 48 publications

PMKT2, a new killer toxin from Pichia membranifaciens, and its promising biotechnological properties for control of the spoilage yeast Brettanomyces bruxellensis

PMKT2, a new killer toxin from Pichia membranifaciens, and its promising biotechnological properties for control of the spoilage yeast Brettanomyces bruxellensis

Cap-snatching mechanism in yeast L-A double-stranded RNA virus

Consensus sequence for processing of peptide precursors at monobasic sites

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