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.

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 Enhanced production of exopolysaccharide matrix and biofilm by a menadione-auxotrophic Staphylococcus aureus small-colony variant

2010 ◽  
Vol 59 (5) ◽  
pp. 521-527 ◽  
Author(s):  
Rachna Singh ◽  
Pallab Ray ◽  
Anindita Das ◽  
Meera Sharma
Keyword(s):  
Staphylococcus Aureus ◽  
Tricarboxylic Acid Cycle ◽  
Surface Hydrophobicity ◽  
Tricarboxylic Acid ◽  
Polysaccharide Intercellular Adhesin ◽  
Wild Type ◽  
Small Colony Variant ◽  
Enhanced Production ◽  
Small Colony

The role of Staphylococcus aureus small-colony variants (SCVs) in the pathogenesis of biofilm-associated infections remains unclear. This study investigated the mechanism behind increased biofilm-forming potential of a menadione-auxotrophic Staphylococcus aureus SCV compared with the wild-type parental strain, as recently reported by our laboratory. SCVs displayed an autoaggregative phenotype, with a greater amount of polysaccharide intercellular adhesin (PIA), significantly reduced tricarboxylic acid cycle activity and a decreased susceptibility to aminoglycosides and cell-wall inhibitors compared with wild-type. The biofilms formed by the SCV were highly structured, consisting of large microcolonies separated by channels, and contained more biomass as well as significantly more PIA than wild-type biofilms. The surface hydrophobicity of the two phenotypes was similar. Thus, the autoaggregation and increased biofilm-forming capacity of menadione-auxotrophic Staphylococcus aureus SCVs in this study was related to the enhanced production of PIA in these variants.

Murine T Lymphocytes Incapable of Producing Macrophage Inhibitory Protein-1 Are Impaired in Causing Graft-Versus-Host Disease Across a Class I But Not Class II Major Histocompatibility Complex Barrier

Blood ◽  
1999 ◽  
Vol 93 (1) ◽  
pp. 43-50 ◽  
Author(s):  
Jonathan S. Serody ◽  
Donald N. Cook ◽  
Suzanne L. Kirby ◽  
Elizabeth Reap ◽  
Thomas C. Shea ◽  
...  
Keyword(s):  
T Cell ◽  
T Lymphocytes ◽  
Graft Versus Host Disease ◽  
Class Ii ◽  
Class I ◽  
Wild Type ◽  
Inhibitory Protein ◽  
Host Disease ◽  
Graft Versus Host

Abstract The routine use of bone marrow transplantation is limited by the occurrence of acute and chronic graft-versus-host disease (GVHD). Current approaches to decreasing the occurrence of GVHD after allogeneic transplantation use T-cell depletion, use immunosuppressive agents, or block costimulatory molecule function. The role of proteins in the recruitment of alloreactive lymphocytes has not been well characterized. Chemokines are a large family of proteins that mediate recruitment of mononuclear cells in vitro and in vivo. To investigate the role of T-cell production of the chemokine macrophage inhibitory protein-1 (MIP-1) in the occurrence of GVHD, splenocytes either from wild-type or from MIP-1−/− mice were administered to class I (B6.C-H2bm1) and class II disparate mice (B6-C-H2bm12). The incidence and severity of GVHD was markedly reduced in bm1 mice receiving splenocytes from MIP-1−/− mice as compared with mice receiving wild-type splenocytes. Bm1 mice receiving MIP-1−/− splenocytes had significantly less weight loss and markedly reduced inflammatory responses in the lung and liver than mice receiving C57BL/6 splenocytes. Bm1 mice receiving MIP-1−/− splenocytes had a markedly decreased production of antichromatin autoantibodies and impaired generation of bm1-specific T lymphocytes versus wild-type mice. However, MIP-1−/− splenocytes easily induced GVHD when administered to bm12 mice. This data show that blockade of chemokine production or function may provide a new approach to the prevention or treatment of GVHD but that chemokines that recruit both CD4+ and CD8+ lymphocytes may need to be targeted.

scholarly journals On the Role of Myosin-II in Cytokinesis: Division ofDictyostelium Cells under Adhesive and Nonadhesive Conditions

1997 ◽  
Vol 8 (12) ◽  
pp. 2617-2629 ◽  
Author(s):  
Ji-Hong Zang ◽  
Guy Cavet ◽  
James H. Sabry ◽  
Peter Wagner ◽  
Sheri L. Moores ◽  
...  
Keyword(s):  
Cell Division ◽  
Light Chain ◽  
Binding Sites ◽  
Myosin Ii ◽  
Hydrophobic Surface ◽  
Wild Type ◽  
Daughter Cells ◽  
Adhesive Surface ◽  
Spatial And Temporal Changes

We have investigated the role of myosin in cytokinesis inDictyostelium cells by examining cells under both adhesive and nonadhesive conditions. On an adhesive surface, both wild-type and myosin-null cells undergo the normal processes of mitotic rounding, cell elongation, polar ruffling, furrow ingression, and separation of daughter cells. When cells are denied adhesion through culturing in suspension or on a hydrophobic surface, wild-type cells undergo these same processes. However, cells lacking myosin round up and polar ruffle, but fail to elongate, furrow, or divide. These differences show that cell division can be driven by two mechanisms that we term Cytokinesis A, which requires myosin, and Cytokinesis B, which is cell adhesion dependent. We have used these approaches to examine cells expressing a myosin whose two light chain-binding sites were deleted (ΔBLCBS-myosin). Although this myosin is a slower motor than wild-type myosin and has constitutively high activity due to the abolition of regulation by light-chain phosphorylation, cells expressing ΔBLCBS-myosin were previously shown to divide in suspension ( Uyeda et al., 1996 ). However, we suspected their behavior during cytokinesis to be different from wild-type cells given the large alteration in their myosin. Surprisingly, ΔBLCBS-myosin undergoes relatively normal spatial and temporal changes in localization during mitosis. Furthermore, the rate of furrow progression in cells expressing a ΔBLCBS-myosin is similar to that in wild-type cells.

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.

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.

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 Role of the White Collar 1 Photoreceptor in Carotenogenesis, UV Resistance, Hydrophobicity, and Virulence of Fusarium oxysporum

2008 ◽  
Vol 7 (7) ◽  
pp. 1227-1230 ◽  
Author(s):  
M. Carmen Ruiz-Roldán ◽  
Victoriano Garre ◽  
Josep Guarro ◽  
Marçal Mariné ◽  
M. Isabel G. Roncero
Keyword(s):  
Fusarium Oxysporum ◽  
White Collar ◽  
Surface Hydrophobicity ◽  
Uv Resistance ◽  
Uv Treatment ◽  
Tomato Plants ◽  
Knockout Mutants ◽  
Aerial Hyphae ◽  
Infection Experiments

ABSTRACT Knockout mutants of Fusarium oxysporum lacking the putative photoreceptor Wc1 were impaired in aerial hyphae, surface hydrophobicity, light-induced carotenogenesis, photoreactivation after UV treatment, and upregulation of photolyase gene transcription. Infection experiments with tomato plants and immunodepressed mice revealed that Wc1 is dispensable for pathogenicity on plants but required for full virulence on mammals.

Murine T Lymphocytes Incapable of Producing Macrophage Inhibitory Protein-1 Are Impaired in Causing Graft-Versus-Host Disease Across a Class I But Not Class II Major Histocompatibility Complex Barrier

Blood ◽  
1999 ◽  
Vol 93 (1) ◽  
pp. 43-50 ◽  
Author(s):  
Jonathan S. Serody ◽  
Donald N. Cook ◽  
Suzanne L. Kirby ◽  
Elizabeth Reap ◽  
Thomas C. Shea ◽  
...  
Keyword(s):  
T Cell ◽  
T Lymphocytes ◽  
Graft Versus Host Disease ◽  
Class Ii ◽  
Class I ◽  
Wild Type ◽  
Inhibitory Protein ◽  
Host Disease ◽  
Graft Versus Host

The routine use of bone marrow transplantation is limited by the occurrence of acute and chronic graft-versus-host disease (GVHD). Current approaches to decreasing the occurrence of GVHD after allogeneic transplantation use T-cell depletion, use immunosuppressive agents, or block costimulatory molecule function. The role of proteins in the recruitment of alloreactive lymphocytes has not been well characterized. Chemokines are a large family of proteins that mediate recruitment of mononuclear cells in vitro and in vivo. To investigate the role of T-cell production of the chemokine macrophage inhibitory protein-1 (MIP-1) in the occurrence of GVHD, splenocytes either from wild-type or from MIP-1−/− mice were administered to class I (B6.C-H2bm1) and class II disparate mice (B6-C-H2bm12). The incidence and severity of GVHD was markedly reduced in bm1 mice receiving splenocytes from MIP-1−/− mice as compared with mice receiving wild-type splenocytes. Bm1 mice receiving MIP-1−/− splenocytes had significantly less weight loss and markedly reduced inflammatory responses in the lung and liver than mice receiving C57BL/6 splenocytes. Bm1 mice receiving MIP-1−/− splenocytes had a markedly decreased production of antichromatin autoantibodies and impaired generation of bm1-specific T lymphocytes versus wild-type mice. However, MIP-1−/− splenocytes easily induced GVHD when administered to bm12 mice. This data show that blockade of chemokine production or function may provide a new approach to the prevention or treatment of GVHD but that chemokines that recruit both CD4+ and CD8+ lymphocytes may need to be targeted.

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