Kinetic studies of killer toxin K1 binding to yeast cells indicate two receptor populations

1994 ◽  
Vol 162 (3) ◽  
pp. 211-214 ◽  
Author(s):  
Helena Kurzweilov� ◽  
Karel Sigler
Keyword(s):  
Killer Toxin ◽  
Kinetic Studies ◽  
Yeast Cells

Kluyveromyces lactis killer toxin inhibits adenylate cyclase of sensitive yeast cells

Nature ◽  
1983 ◽  
Vol 304 (5925) ◽  
pp. 464-466 ◽  
Author(s):  
Yuji Sugisaki ◽  
Norio Gunge ◽  
Kenji Sakaguchi ◽  
Makari Yamasaki ◽  
Gakuzo Tamura
Keyword(s):  
Adenylate Cyclase ◽  
Kluyveromyces Lactis ◽  
Killer Toxin ◽  
Yeast Cells

Killer Toxins of Yeasts: Inhibitors of Fermentation and Their Adsorption

1987 ◽  
Vol 50 (3) ◽  
pp. 234-238 ◽  
Author(s):  
FERDINAND RADLER ◽  
MANFRED SCHMITT
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Wall ◽  
Yeast Cell ◽  
Cell Walls ◽  
Killer Toxin ◽  
Yeast Cells ◽  
Toxin Concentration ◽  
Commercial Preparation ◽  
Killer Toxins ◽  
Original Amount

The killer toxin (KT 28), a glycoprotein of Saccharomyces cerevisiae strain 28, was almost completely adsorbed by bentonite, when applied at a concentration of 1 g per liter. No significant differences were found between several types of bentonite. Killer toxin KT 28 is similarly adsorbed by intact yeast cells or by a commercial preparation of yeast cell walls that has been recommended to prevent stuck fermentations. An investigation of the cell wall fractions revealed that the toxin KT 28 was mainly adsorbed by mannan, that removed the toxin completely. The alkali-soluble and the alkali-insoluble β-1,3- and β-1,6-D-glucans lowered the toxin concentration to one tenth of the original amount. The killer toxin of the type K1 of S. cerevisiae was adsorbed much better by glucans than by mannan.

scholarly journals Raphia-Microorganism Composite Biosorbent for Lead Ion Removal from Aqueous Solutions

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7482
Author(s):  
Paweł Staroń ◽  
Jarosław Chwastowski
Keyword(s):  
Aqueous Solutions ◽  
Kinetic Studies ◽  
Sorption Process ◽  
Yeast Cells ◽  
Lead Ion ◽  
Removal Capacity ◽  
New Information ◽  
Microbial Resources ◽  
Nonlinear Equilibrium ◽  
Spectroscopy Studies

This study investigated the possibility of obtaining a raphia-microorganism composite for removing lead ions from aqueous solutions using immobilized yeast cells Saccharomyces cerevisiae on Raphia farinifera fibers. The obtained biocomposite was characterized using scanning electron microscopy and Fourier transform infrared spectroscopy. Studies were conducted to determine the influence of contact time, initial concentration of Pb(II), and pH allowed for the selection of nonlinear equilibrium and kinetic models. The results showed that the biocomposite had a better Pb(II) removal capacity in comparison to the raphia fibers alone, and its maximum Pb(II) adsorption capacity was 94.8 mg/g. The model that best describes Pb(II) sorption was the Temkin isotherm model, while kinetic studies confirmed the chemical nature of the sorption process following the Elovich model. The obtained research results provide new information on the full use of the adsorption function of biomass and the ubiquitous microbial resources and their use in the remediation of aqueous environments contaminated with heavy metals.

scholarly journals Immunolocalization of Kex2 protease identifies a putative late Golgi compartment in the yeast Saccharomyces cerevisiae.

1991 ◽  
Vol 113 (3) ◽  
pp. 527-538 ◽  
Author(s):  
K Redding ◽  
C Holcomb ◽  
R S Fuller
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Secretory Pathway ◽  
Killer Toxin ◽  
Proteolytic Processing ◽  
Yeast Cells ◽  
Yeast Saccharomyces Cerevisiae ◽  
Golgi Compartment ◽  
Membrane Bound ◽  
Gene Structures ◽  
Stage Analysis

The Kex2 protein of the yeast Saccharomyces cerevisiae is a membrane-bound, Ca2(+)-dependent serine protease that cleaves the precursors of the mating pheromone alpha-factor and the M1 killer toxin at pairs of basic residues during their transport through the secretory pathway. To begin to characterize the intracellular locus of Kex2-dependent proteolytic processing, we have examined the subcellular distribution of Kex2 protein in yeast by indirect immunofluorescence. Kex2 protein is located at multiple, discrete sites within wild-type yeast cells (average, 3.0 +/- 1.7/mother cell). Qualitatively similar fluorescence patterns are observed at elevated levels of expression, but no signal is found in cells lacking the KEX2 gene. Structures containing Kex2 protein are not concentrated at a perinuclear location, but are distributed throughout the cytoplasm at all phases of the cell cycle. Kex2-containing structures appear in the bud at an early, premitotic stage. Analysis of conditional secretory (sec) mutants demonstrates that Kex2 protein ordinarily progresses from the ER to the Golgi but is not incorporated into secretory vesicles, consistent with the proposed localization of Kex2 protein to the yeast Golgi complex.

scholarly journals In Vitro and In Vivo Anti-Candida Activity and Structural Analysis of Killer Peptide (KP)-Derivatives

2021 ◽  
Vol 7 (2) ◽  
pp. 129
Author(s):  
Tecla Ciociola ◽  
Thelma A. Pertinhez ◽  
Tiziano De Simone ◽  
Walter Magliani ◽  
Elena Ferrari ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Low Cost ◽  
Chemical Properties ◽  
Killer Toxin ◽  
Variable Region ◽  
Antifungal Drugs ◽  
Yeast Cells ◽  
Morphological Alterations

The previously described decapeptide AKVTMTCSAS (killer peptide, KP), derived from the variable region of a recombinant yeast killer toxin-like anti-idiotypic antibody, proved to exert a variety of antimicrobial, antiviral, and immunomodulatory activities. It also showed a peculiar self-assembly ability, likely responsible for the therapeutic effect in animal models of systemic and mucosal candidiasis. The present study analyzed the biological and structural properties of peptides derived from KP by substitution or deletion of the first residue, leaving unchanged the remaining amino acids. The investigated peptides proved to exert differential in vitro and/or in vivo anti-Candida activity without showing toxic effects on mammalian cells. The change of the first residue in KP amino acidic sequence affected the conformation of the resulting peptides in solution, as assessed by circular dichroism spectroscopy. KP-derivatives, except one, were able to induce apoptosis in yeast cells, like KP itself. ROS production and changes in mitochondrial transmembrane potential were also observed. Confocal and transmission electron microscopy studies allowed to establish that selected peptides could penetrate within C. albicans cells and cause gross morphological alterations. Overall, the physical and chemical properties of the first residue were found to be important for peptide conformation, candidacidal activity and possible mechanism of action. Small antimicrobial peptides could be exploited for the development of a new generation of antifungal drugs, given their relative low cost and ease of production as well as the possibility of devising novel delivery systems.

Significance of the lag phase in K1 killer toxin action on sensitive yeast cells

1995 ◽  
Vol 40 (2) ◽  
pp. 213-215 ◽  
Author(s):  
H. Kurzweilová ◽  
K. Sigler
Keyword(s):  
Killer Toxin ◽  
Yeast Cells ◽  
Lag Phase

scholarly journals Analysis of Yeast Killer Toxin K1 Precursor Processing via Site-Directed Mutagenesis: Implications for Toxicity and Immunity

mSphere ◽  
2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Stefanie Gier ◽  
Manfred J. Schmitt ◽  
Frank Breinig
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Secretory Pathway ◽  
Killer Toxin ◽  
Site Directed Mutagenesis ◽  
Yeast Cells ◽  
Bacterial Toxin ◽  
Α Subunit ◽  
Content Type ◽  
Killer Yeast ◽  
Immunity Mechanism

ABSTRACT K1 represents a heterodimeric A/B toxin secreted by virus-infected Saccharomyces cerevisiae strains. In a two-staged receptor-mediated process, the ionophoric activity of K1 leads to an uncontrolled influx of protons, culminating in the breakdown of the cellular transmembrane potential of sensitive cells. K1 killer yeast necessitate not only an immunity mechanism saving the toxin-producing cell from its own toxin but, additionally, a molecular system inactivating the toxic α subunit within the secretory pathway. In this study, different derivatives of the K1 precursor were constructed to analyze the biological function of particular structural components and their influence on toxin activity as well as the formation of protective immunity. Our data implicate an inactivation of the α subunit during toxin maturation and provide the basis for an updated model of K1 maturation within the host cell’s secretory pathway. IMPORTANCE The killer phenotype in the baker’s yeast Saccharomyces cerevisiae relies on two double-stranded RNA viruses that are persistently present in the cytoplasm. As they carry the same receptor populations as sensitive cells, killer yeast cells need—in contrast to various bacterial toxin producers—a specialized immunity mechanism. The ionophoric killer toxin K1 leads to the formation of cation-specific pores in the plasma membrane of sensitive yeast cells. Based on the data generated in this study, we were able to update the current model of toxin processing, validating the temporary inactivation of the toxic α subunit during maturation in the secretory pathway of the killer yeast.

scholarly journals Isolation, Purification, and Characterization of a Killer Protein from Schwanniomyces occidentalis

2000 ◽  
Vol 66 (12) ◽  
pp. 5348-5352 ◽  
Author(s):  
Wen-Bao Chen ◽  
Yuh-Fehng Han ◽  
Shung-Chang Jong ◽  
Shenq-Chyi Chang
Keyword(s):  
Protein Identification ◽  
Periodic Acid ◽  
Killer Toxin ◽  
Yeast Cells ◽  
Periodic Acid Schiff ◽  
Killer Activity ◽  
Schwanniomyces Occidentalis ◽  
Molecular Masses ◽  
Killer Protein

ABSTRACT The yeast Schwanniomyces occidentalis produces a killer toxin lethal to sensitive strains of Saccharomyces cerevisiae. Killer activity is lost after pepsin and papain treatment, suggesting that the toxin is a protein. We purified the killer protein and found that it was composed of two subunits with molecular masses of approximately 7.4 and 4.9 kDa, respectively, but was not detectable with periodic acid-Schiff staining. A BLAST search revealed that residues 3 to 14 of the 4.9-kDa subunit had 75% identity and 83% similarity with killer toxin K2 from S. cerevisiaeat positions 271 to 283. Maximum killer activity was between pH 4.2 and 4.8. The protein was stable between pH 2.0 and 5.0 and inactivated at temperatures above 40�C. The killer protein was chromosomally encoded. Mannan, but not β-glucan or laminarin, prevented sensitive yeast cells from being killed by the killer protein, suggesting that mannan may bind to the killer protein. Identification and characterization of a killer strain of S. occidentalis may help reduce the risk of contamination by undesirable yeast strains during commercial fermentations.

scholarly journals Synthetic lethality of sep1 (xrn1) ski2 and sep1 (xrn1) ski3 mutants of Saccharomyces cerevisiae is independent of killer virus and suggests a general role for these genes in translation control.

1995 ◽  
Vol 15 (5) ◽  
pp. 2719-2727 ◽  
Author(s):  
A W Johnson ◽  
R D Kolodner
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Synthetic Lethality ◽  
Rna Virus ◽  
Dna Recombination ◽  
Killer Toxin ◽  
Yeast Cells ◽  
Temperature Sensitive ◽  
Translation Control ◽  
General Role ◽  
Synthetic Cell

Strand exchange protein 1 (Sep1) (also referred to as exoribonuclease I [Xrn1]) from Saccharomyces cerevisiae has been implicated in DNA recombination, RNA turnover, karyogamy, and G4 DNA pairing among other disparate cellular processes. Using a genetic 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. The SKI genes are thought to comprise an intracellular antiviral system controlling the expression of killer toxin from double-stranded RNA virus found in many yeast strains. However, the lethality of sep1 ski2 and sep1 ski3 mutants was independent of the L-A and M viruses, suggesting that the SKI genes act in a general cellular process in addition to virus control. We propose that Sep1/Xrn1 and Ski2 both act to block translation on transcripts targeted for degradation. Using a temperature-sensitive allele of SEP1/XRN1, we show that double mutants display a synthetic cell cycle arrest in late G1 at Start.

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