scholarly journals New Insights into the Potential Cytotoxic Role of Bacillus cytotoxicus Cytotoxin K-1

Toxins ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 698
Author(s):  
Klèma Marcel Koné ◽  
Pauline Hinnekens ◽  
Jelena Jovanovic ◽  
Andreja Rajkovic ◽  
Jacques Mahillon
Keyword(s):  
Bacillus Cereus ◽  
Tetrazolium Salt ◽  
Wild Type ◽  
Foodborne Outbreak ◽  
Pathogenic Role ◽  
Bacillus Cereus Group ◽  
Mtt Method ◽  
High Cytotoxicity ◽  
Type Strains

The thermotolerant representative of the Bacillus cereus group, Bacillus cytotoxicus, reliably harbors the coding gene of cytotoxin K-1 (CytK-1). This protein is a highly cytotoxic variant of CytK toxin, initially recovered from a diarrheal foodborne outbreak that caused the death of three people. In recent years, the cytotoxicity of B. cytotoxicus has become controversial, with some strains displaying a high cytotoxicity while others show no cytotoxicity towards cell lines. In order to better circumscribe the potential pathogenic role of CytK-1, knockout (KO) mutants were constructed in two B. cytotoxicus strains, E8.1 and E28.3. The complementation of the cytK-1 KO mutation was implemented in a mutant strain lacking in the cytK-1 gene. Using the tetrazolium salt (MTT) method, cytotoxicity tests of the cytK-1 KO and complemented mutants, as well as those of their wild-type strains, were carried out on Caco-2 cells. The results showed that cytK-1 KO mutants were significantly less cytotoxic than the parental wild-type strains. However, the complemented mutant was as cytotoxic as the wild-type, suggesting that CytK-1 is the major cytotoxicity factor in B. cytotoxicus.

Characterization of the Role of the FluG Protein in Asexual Development of Aspergillus nidulans

Genetics ◽  
2001 ◽  
Vol 158 (3) ◽  
pp. 1027-1036 ◽  
Author(s):  
Cletus A D'Souza ◽  
Bee Na Lee ◽  
Thomas H Adams
Keyword(s):  
Aspergillus Nidulans ◽  
Negative Influence ◽  
Asexual Development ◽  
Wild Type ◽  
Significant Similarity ◽  
Developmental Defects ◽  
Asexual Sporulation ◽  
Type Strains

Abstract We showed previously that a ΔfluG mutation results in a block in Aspergillus nidulans asexual sporulation and that overexpression of fluG activates sporulation in liquid-submerged culture, a condition that does not normally support sporulation of wild-type strains. Here we demonstrate that the entire N-terminal region of FluG (∼400 amino acids) can be deleted without affecting sporulation, indicating that FluG activity resides in the C-terminal half of the protein, which bears significant similarity with GSI-type glutamine synthetases. While FluG has no apparent role in glutamine biosynthesis, we propose that it has an enzymatic role in sporulation factor production. We also describe the isolation of dominant suppressors of ΔfluG(dsg) that should identify components acting downstream of FluG and thereby define the function of FluG in sporulation. The dsgA1 mutation also suppresses the developmental defects resulting from ΔflbA and dominant activating fadA mutations, which both cause constitutive induction of the mycelial proliferation pathway. However, dsgA1 does not suppress the negative influence of these mutations on production of the aflatoxin precursor, sterigmatocystin, indicating that dsgA1 is specific for asexual development. Taken together, our studies define dsgA as a novel component of the asexual sporulation pathway.

scholarly journals Modification Strategy of D-leucine Residue Addition on a Novel Peptide from Odorrana schmackeri, with Enhanced Bioactivity and In Vivo Efficacy

Toxins ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 611
Author(s):  
Aifang Yao ◽  
Yingxue Ma ◽  
Xiaoling Chen ◽  
Mei Zhou ◽  
Xinping Xi ◽  
...  
Keyword(s):  
Methicillin Resistant Staphylococcus Aureus ◽  
Therapeutic Potential ◽  
Wild Type ◽  
Anticancer Activities ◽  
Gram Positive Bacteria ◽  
Leucine Residue ◽  
Low Cytotoxicity ◽  
High Cytotoxicity

Brevinins are a well-characterised, frog-skin-derived, antimicrobial peptide (AMP) family, but their applications are limited by high cytotoxicity. In this study, a wild-type des-Leu2 brevinin peptide, named brevinin-1OS (B1OS), was identified from Odorrana schmackeri. To explore the significant role of the leucine residue at the second position, two variants, B1OS-L and B1OS-D-L, were designed by adding L-leucine and D-leucine residues at this site, respectively. The antibacterial and anticancer activities of B1OS-L and B1OS-D-L were around ten times stronger than the parent peptide. The activity of B1OS against the growth of Gram-positive bacteria was markedly enhanced after modification. Moreover, the leucine-modified products exerted in vivo therapeutic potential in an methicillin-resistant Staphylococcus aureus (MRSA)-infected waxworm model. Notably, the single substitution of D-leucine significantly increased the killing speed on lung cancer cells, where no viable H838 cells survived after 2 h of treatment with B1OS-D-L at 10 μM with low cytotoxicity on normal cells. Overall, our study suggested that the conserved leucine residue at the second position from the N-terminus is vital for optimising the dual antibacterial and anticancer activities of B1OS and proposed B1OS-D-L as an appealing therapeutic candidate for development.

scholarly journals Pathogenic Role of Bacillus Cereus in Wound Infections in the Tropics

1987 ◽  
Vol 80 (8) ◽  
pp. 480-481 ◽  
Author(s):  
M S Dryden
Keyword(s):  
Bacillus Cereus ◽  
Clinical Findings ◽  
Costa Rican ◽  
High Rate ◽  
Wound Infections ◽  
Pathogenic Role ◽  
Infected Wounds ◽  
The Tropics ◽  
Nose And Throat

A bacteriological survey was undertaken on clinically infected traumatic wounds amongst a group of young and fit Operation Raleigh members, who were living and working in a remote area of Costa Rican rain forest. All infected wounds were swabbed before treatment and, where possible, at intervals during treatment. Swabs were also obtained from the nose and throat of each patient. All swabs were stored by desiccation in sterile silica gel for culture at a later date. Culture revealed a high rate of isolation of Bacillus cereus from the wounds. The organism was commonly isolated in pure and heavy growth. Contamination by B. cereus was considered and excluded experimentally. Preliminary toxological studies have shown that the majority of the isolates produce a necrotic exotoxin, in keeping with the clinical findings. These results suggest that B. cereus caused significant sepsis in this series of traumatic wounds.

scholarly journals The Role of Ethylene Production in Virulence of Pseudomonas syringae pvs. glycinea and phaseolicola

2001 ◽  
Vol 91 (5) ◽  
pp. 511-518 ◽  
Author(s):  
Helge Weingart ◽  
Henriette Ullrich ◽  
Klaus Geider ◽  
Beate Völksch
Keyword(s):  
Pseudomonas Syringae ◽  
Ethylene Production ◽  
Type Strain ◽  
Wild Type Strain ◽  
Wild Type ◽  
In Planta ◽  
Population Sizes ◽  
Soybean Plants ◽  
Type Strains

The importance of ethylene production for virulence of Pseudomonas syringae pvs. glycinea and phaseolicola was assayed by comparing bacterial multiplication and symptom development in bean and soybean plants inoculated with ethylene-negative (efe) mutants and wild-type strains. The efe mutants of Pseudomonas syringae pv. glycinea were significantly reduced in their ability to grow in planta. However, the degree of reduction was strain-dependent. Population sizes of efe mutant 16/83-E1 that did not produce the phototoxin coronatine were 10- and 15-fold lower than those of the wild-type strain on soybean and on bean, and 16/83-E1 produced very weak symptoms compared with the wild-type strain. The coronatine-producing efe mutant 7a/90-E1 reached fourfold and twofold lower population sizes compared with the wild-type strain on soybean and bean, respectively, and caused disease symptoms typical of the wild-type strain. Experiments with ethylene-insensitive soybeans confirmed these results. The virulence of the wild-type strains was reduced to the same extent in ethylene-insensitive soybean plants as the virulence of the efe mutants in ethylene-susceptible soybeans. In contrast, the virulence of Pseudomonas syringae pv. phaseolicola was not affected by disruption of the efe gene.

RNA processing and expression of an intron-encoded protein in yeast mitochondria: role of a conserved dodecamer sequence

1987 ◽  
Vol 7 (7) ◽  
pp. 2530-2537 ◽  
Author(s):  
H Zhu ◽  
I G Macreadie ◽  
R A Butow
Keyword(s):  
Rna Processing ◽  
Rrna Gene ◽  
Yeast Mitochondria ◽  
Wild Type ◽  
Reading Frame ◽  
Processing Activity ◽  
Novel Processing ◽  
Type Strains ◽  
Upstream Exon

The 3' ends of most Saccharomyces cerevisiae mitochondrial mRNAs terminate at a conserved dodecamer sequence, 5'-AAUAAUAUUCUU-3', of unknown function. We have studied the consequences of mutations within a dodecamer found in an 1,143-base-pair optional intron of the mitochondrial large (21S) rRNA gene on RNA processing. The dodecamer is situated at the 3' end of an expressed open reading frame (ORF) within that intron, and the mutations are two adjacent transversions that extend the intron ORF by 51 nucleotides. The strain harboring these mutations, L5-10-1, is defective in biased intron transmission in crosses to strains that lack the intron, as are other mutants which contain nucleotide changes within the ORF (I. G. Macreadie, R. M. Scott, A. R. Zinn, and R. A. Butow, Cell 41:395-402, 1985). However, unlike these other mutants, wild-type strains, or petites which retain the intron allele, L5-10-1 is defective in processing at the intron dodecamer. In addition, L5-10-1 lacks a prominent 2.7-kilobase RNA containing both intron and exon sequences and at least two of four RNAs that correspond to various forms of the excised intron. We propose that these RNAs, missing in L5-10-1 but present in all other strains examined, arise in part by processing at the intron dodecamer. In addition, in all strains examined, we have detected a novel processing activity in which precursor 21S rRNA transcripts are cleaved in the upstream exon, about 1,500 nucleotides from the 5' end of the RNA. This activity, together with 3' intron dodecamer cleavage, probably accounts for the 2.7-kilobase RNA species, a candidate for the mRNA for the intron-encoded protein.

scholarly journals Allele Substitution of the Streptokinase Gene Reduces the Nephritogenic Capacity of Group A Streptococcal Strain NZ131

2000 ◽  
Vol 68 (3) ◽  
pp. 1019-1025 ◽  
Author(s):  
Annika Nordstrand ◽  
W. Michael McShan ◽  
Joseph J. Ferretti ◽  
Stig E. Holm ◽  
Mari Norgren
Keyword(s):  
Allelic Variant ◽  
Wild Type ◽  
Poststreptococcal Glomerulonephritis ◽  
Acute Poststreptococcal Glomerulonephritis ◽  
Site Specific Integration ◽  
Allele Substitution ◽  
Group A ◽  
Type Strains ◽  
Streptococcal Strain

ABSTRACT To investigate the role of allelic variants of streptokinase in the pathogenesis of acute poststreptococcal glomerulonephritis (APSGN), site-specific integration plasmids were constructed, which contained either the non-nephritis-associated streptokinase gene (skc5) from the group C streptococcal strainStreptococcus equisimilis H46A or the nephritis-associated streptokinase gene (ska1) from the group A streptococcal nephritogenic strain NZ131. The plasmids were introduced by electroporation and homologous recombination into the chromosome of an isogenic derivative of strain NZ131, in which the streptokinase gene had been deleted and which had thereby lost its nephritogenic capacity in a mouse model of APSGN. The introduction of a non-nephritis-associated allelic variant of streptokinase did not rescue the nephritogenic capacity of the strain. The mutant and the wild-type strains produced equivalent amounts of streptokinase. Complementation of the ska deletion derivative with the original ska allele reconstituted the nephritogenicity of wild-type NZ131. The findings support the hypothesis that the role of streptokinase in the pathogenesis of APSGN is related to the allelic variant of the protein.

scholarly journals 2,4,6-Trinitrotoluene Reduction by an Fe-Only Hydrogenase in Clostridium acetobutylicum

2003 ◽  
Vol 69 (3) ◽  
pp. 1542-1547 ◽  
Author(s):  
Mary M. Watrous ◽  
Sandra Clark ◽  
Razia Kutty ◽  
Shouqin Huang ◽  
Frederick B. Rudolph ◽  
...  
Keyword(s):  
Clostridium Acetobutylicum ◽  
Cell System ◽  
Hydrogenase Activity ◽  
Wild Type ◽  
Reduction Activity ◽  
Saturation Kinetics ◽  
A Cell ◽  
Type Strains ◽  
Late Growth

ABSTRACT The role of hydrogenase on the reduction of 2,4,6-trinitrotoluene (TNT) in Clostridium acetobutylicum was evaluated. An Fe-only hydrogenase was isolated and identified by using TNT reduction activity as the selection basis. The formation of hydroxylamino intermediates by the purified enzyme corresponded to expected products for this reaction, and saturation kinetics were determined with a Km of 152 μM. Comparisons between the wild type and a mutant strain lacking the region encoding an alternative Fe-Ni hydrogenase determined that Fe-Ni hydrogenase activity did not significantly contribute to TNT reduction. Hydrogenase expression levels were altered in various strains, allowing study of the role of the enzyme in TNT reduction rates. The level of hydrogenase activity in a cell system correlated (R 2 = 0.89) with the organism's ability to reduce TNT. A strain that overexpressed the hydrogenase activity resulted in maintained TNT reduction during late growth phases, which it is not typically observed in wild type strains. Strains exhibiting underexpression of hydrogenase produced slower TNT rates of reduction correlating with the determined level of expression. The isolated Fe-only hydrogenase is the primary catalyst for reducing TNT nitro substituents to the corresponding hydroxylamines in C. acetobutylicum in whole-cell systems. A mechanism for the reaction is proposed. Due to the prevalence of hydrogenase in soil microbes, this research may enhance the understanding of nitroaromatic compound transformation by common microbial communities.

scholarly journals Repellents have functionally replaced hydrophobins in mediating attachment to a hydrophobic surface and in formation of hydrophobic aerial hyphae in Ustilago maydis

Microbiology ◽  
2006 ◽  
Vol 152 (12) ◽  
pp. 3607-3612 ◽  
Author(s):  
Wieke R. Teertstra ◽  
Heine J. Deelstra ◽  
Miroslav Vranes ◽  
Ralph Bohlmann ◽  
Regine Kahmann ◽  
...  
Keyword(s):  
Hydrophobic Surface ◽  
Ustilago Maydis ◽  
Surface Hydrophobicity ◽  
Class I ◽  
Wild Type ◽  
Repeat Sequences ◽  
Recognition Sites ◽  
Aerial Hyphae ◽  
Type Strains

Ustilago maydis contains one repellent and two class I hydrophobin genes in its genome. The repellent gene rep1 has been described previously. It encodes 11 secreted repellent peptides that result from the cleavage of a precursor protein at KEX2 recognition sites. The hydrophobin gene hum2 encodes a typical class I hydrophobin of 117 aa, while hum3 encodes a hydrophobin that is preceded by 17 repeat sequences. These repeats are separated, like the repellent peptides, by KEX2 recognition sites. Gene hum2, but not hum3, was shown to be expressed in a cross of two compatible wild-type strains, suggesting a role of the former hydrophobin gene in aerial hyphae formation. Indeed, aerial hyphae formation was reduced in a Δhum2 cross. However, the reduction in aerial hyphae formation was much more dramatic in the Δrep1 cross. Moreover, colonies of the Δrep1 cross were completely wettable, while surface hydrophobicity was unaffected and only slightly reduced in the Δhum2 and the Δhum2Δhum3 cross, respectively. It was also shown that the repellents and not the hydrophobins are involved in attachment of hyphae to hydrophobic Teflon. Deleting either or both hydrophobin genes in the Δrep1 strains did not further affect aerial hyphae formation, surface hydrophobicity and attachment. From these data it is concluded that hydrophobins of U. maydis have been functionally replaced, at least partially, by repellents.

scholarly journals Role of the PDR Gene Network in Yeast Susceptibility to the Antifungal Antibiotic Mucidin

2000 ◽  
Vol 44 (2) ◽  
pp. 418-420 ◽  
Author(s):  
Dana Michalkova-Papajova ◽  
Margita Obernauerova ◽  
Julius Subik
Keyword(s):  
Transcriptional Regulation ◽  
Gene Network ◽  
Wild Type ◽  
Gain Of Function ◽  
Antifungal Antibiotic ◽  
Yeast Strains ◽  
Yeast Mutants ◽  
Type Strains ◽  
Higher Sensitivity

ABSTRACT Yeast strains disrupted in the PDR1, PDR3, or PDR5 gene, but not in SNQ2, exhibited higher sensitivity to mucidin (strobilurin A) than did the isogenic wild-type strains. Different gain-of-function mutations in the PDR1and PDR3 genes rendered yeast mutants resistant to this antibiotic. Mucidin induced PDR5 expression, but the changes in the expression of SNQ2 were only barely detectable. The results indicate that PDR5 provides the link between transcriptional regulation by PDR1 andPDR3 and mucidin resistance of yeast.

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