scholarly journals Mutations in the lrpE Gene of Ralstonia solanacearum Affects Hrp Pili Production and Virulence

2006 ◽  
Vol 19 (8) ◽  
pp. 884-895 ◽  
Author(s):  
Yukio Murata ◽  
Naoyuki Tamura ◽  
Kazuhiro Nakaho ◽  
Takafumi Mukaihara
Keyword(s):  
Cell Surface ◽  
Growth Phase ◽  
Ralstonia Solanacearum ◽  
Vascular System ◽  
Exponential Growth Phase ◽  
Bacterial Cells ◽  
Wild Type ◽  
Bacterial Surface ◽  
Bacterial Morphology ◽  
In The Wild

The Ralstonia solanacearum hrpB-regulated gene lrpE (hpx5/brg24) encodes a PopC-like leucine-rich repeat (LRR) protein that carries 11 tandem LRR in the central region. Defects in the lrpE gene slightly reduced the virulence of R. solanacearum on host plants and changed the bacterial morphology leading to the formation of large aggregates in a minimal medium. The aggregation in the ΔlrpE background required the presence of a functional Hrp type III secretion system. In wild-type R. solanacearum, Hrp pili disappeared from the bacterial surface at the end of the exponential growth phase, when the pili form into long bundles. However, even in the late growth phase, bundled Hrp pili were still observed on the cell surface of the ΔlrpE mutant. Such bundles were entangled and anchored the mutant cells in the aggregates. In contrast to PopC, LrpE accumulated in bacterial cells and did not translocate into plant cells as an effector protein. The expression levels of hrp genes increased three- to fivefold in the ΔlrpE background compared with those in the wild type. We propose that LrpE may negatively regulate the production of Hrp pili on the cell surface of R. solanacearum to disperse bacterial cells from aggregates. In turn, dispersal may contribute to the movement of the pathogen in the plant vascular system and, as a consequence, the pathogenicity of R. solanacearum.

scholarly journals Recent Progress in the Study of Peroxiredoxin in the Harmful Algal Bloom Species Chattonella marina

Antioxidants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 162
Author(s):  
Yohei Shimasaki ◽  
Koki Mukai ◽  
Yuki Takai ◽  
Xuchun Qiu ◽  
Yuji Oshima
Keyword(s):  
Oxidative Stress ◽  
Growth Phase ◽  
Critical Role ◽  
High Irradiance ◽  
Growth Potential ◽  
Exponential Growth Phase ◽  
Wild Type ◽  
Chattonella Marina ◽  
Strong Light ◽  
Expression Strain

Peroxiredoxin (Prx) is a relatively recently discovered antioxidant enzyme family that scavenges peroxides and is known to be present in organisms from biological taxa ranging from bacteria to multicellular eukaryotes, including photosynthetic organisms. Although there have been many studies of the Prx family in higher plants, green algae, and cyanobacteria, few studies have concerned raphidophytes and dinoflagellates, which are among the eukaryotic algae that cause harmful algal blooms (HABs). In our proteomic study using 2-D electrophoresis, we found a highly expressed 2-Cys peroxiredoxin (2-CysPrx) in the raphidophyte Chattonella marina var. antiqua, a species that induces mass mortality of aquacultured fish. The abundance of the C. marina 2-CysPrx enzyme was highest in the exponential growth phase, during which photosynthetic activity was high, and it then decreased by about a factor of two during the late stationary growth phase. This pattern suggested that 2-CysPrx is a key enzyme involved in the maintenance of high photosynthesis activity. In addition, the fact that the depression of photosynthesis by excessively high irradiance was more severe in the 2-CysPrx low-expression strain (wild type) than in the normal-expression strain (wild type) of C. marina suggested that 2-CysPrx played a critical role in protecting the cell from oxidative stress caused by exposure to excessively high irradiance. In the field of HAB research, estimates of growth potential have been desired to predict the population dynamics of HABs for mitigating damage to fisheries. Therefore, omics approaches have recently begun to be applied to elucidate the physiology of the growth of HAB species. In this review, we describe the progress we have made using a molecular physiological approach to identify the roles of 2-CysPrx and other antioxidant enzymes in mitigating environmental stress associated with strong light and high temperatures and resultant oxidative stress. We also describe results of a survey of expressed Prx genes and their growth-phase-dependent behavior in C. marina using RNA-seq analysis. Finally, we speculate about the function of these genes and the ecological significance of 2-CysPrx, such as its involvement in circadian rhythms and the toxicity of C. marina to fish.

scholarly journals Hypothetical Protein Avin_16040 as the S-Layer Protein of Azotobacter vinelandii and Its Involvement in Plant Root Surface Attachment

2015 ◽  
Vol 81 (21) ◽  
pp. 7484-7495 ◽  
Author(s):  
Pauline Woan Ying Liew ◽  
Bor Chyan Jong ◽  
Nazalan Najimudin
Keyword(s):  
Cell Surface ◽  
Deletion Mutant ◽  
Azotobacter Vinelandii ◽  
Plant Root ◽  
Hypothetical Protein ◽  
Surface Hydrophobicity ◽  
Root Surface ◽  
Bacterial Cells ◽  
Wild Type ◽  
Content Type

ABSTRACTA proteomic analysis of a soil-dwelling, plant growth-promotingAzotobacter vinelandiistrain showed the presence of a protein encoded by the hypotheticalAvin_16040gene when the bacterial cells were attached to theOryza sativaroot surface. AnAvin_16040deletion mutant demonstrated reduced cellular adherence to the root surface, surface hydrophobicity, and biofilm formation compared to those of the wild type. By atomic force microscopy (AFM) analysis of the cell surface topography, the deletion mutant displayed a cell surface architectural pattern that was different from that of the wild type.Escherichia colitransformed with the wild-typeAvin_16040gene displayed on its cell surface organized motifs which looked like the S-layer monomers ofA. vinelandii. The recombinantE. colialso demonstrated enhanced adhesion to the root surface.

scholarly journals Fate of Glycosylphosphatidylinositol (GPI)-Less Procyclin and Characterization of Sialylated Non-GPI-Anchored Surface Coat Molecules of Procyclic-Form Trypanosoma brucei

2009 ◽  
Vol 8 (9) ◽  
pp. 1407-1417 ◽  
Author(s):  
Maria Lucia Sampaio Güther ◽  
Kenneth Beattie ◽  
Douglas J. Lamont ◽  
John James ◽  
Alan R. Prescott ◽  
...  
Keyword(s):  
Cell Surface ◽  
Trypanosoma Brucei ◽  
Gel Filtration ◽  
Apparent Molecular Weight ◽  
Life Cycle Stage ◽  
Galactose Oxidase ◽  
Surface Coat ◽  
Wild Type ◽  
In The Wild ◽  
P Type

ABSTRACT A Trypanosoma brucei TbGPI12 null mutant that is unable to express cell surface procyclins and free glycosylphosphatidylinositols (GPI) revealed that these are not the only surface coat molecules of the procyclic life cycle stage. Here, we show that non-GPI-anchored procyclins are N-glycosylated, accumulate in the lysosome, and appear as proteolytic fragments in the medium. We also show, using lectin agglutination and galactose oxidase-NaB3H4 labeling, that the cell surface of the TbGPI12 null parasites contains glycoconjugates that terminate in sialic acid linked to galactose. Following desialylation, a high-apparent-molecular-weight glycoconjugate fraction was purified by ricin affinity chromatography and gel filtration and shown to contain mannose, galactose, N-acetylglucosamine, and fucose. The latter has not been previously reported in T. brucei glycoproteins. A proteomic analysis of this fraction revealed a mixture of polytopic transmembrane proteins, including P-type ATPase and vacuolar proton-translocating pyrophosphatase. Immunolocalization studies showed that both could be labeled on the surfaces of wild-type and TbGPI12 null cells. Neither galactose oxidase-NaB3H4 labeling of the non-GPI-anchored surface glycoconjugates nor immunogold labeling of the P-type ATPase was affected by the presence of procyclins in the wild-type cells, suggesting that the procyclins do not, by themselves, form a macromolecular barrier.

scholarly journals Null Mutations of Group A Streptococcus Orphan Kinase RocA: Selection in Mouse Infection and Comparison with CovS Mutations in Alteration of In Vitro and In Vivo Protease SpeB Expression and Virulence

2016 ◽  
Vol 85 (1) ◽  
Author(s):  
Wenchao Feng ◽  
Dylan Minor ◽  
Mengyao Liu ◽  
Jinquan Li ◽  
Suzanne L. Ishaq ◽  
...  
Keyword(s):  
Gene Expression ◽  
Growth Phase ◽  
Virulence Genes ◽  
Expression Patterns ◽  
Mouse Skin ◽  
Exponential Growth Phase ◽  
Wild Type ◽  
Subcutaneous Infection ◽  
Group A

ABSTRACT Group A Streptococcus (GAS) acquires mutations of the virulence regulator CovRS in human and mouse infections, and these mutations result in the upregulation of virulence genes and the downregulation of the protease SpeB. To identify in vivo mutants with novel phenotypes, GAS isolates from infected mice were screened by enzymatic assays for SpeB and the platelet-activating factor acetylhydrolase Sse, and a new type of variant that had enhanced Sse expression and normal levels of SpeB production was identified (the variants had a phenotype referred to as enhanced Sse activity [SseA+] and normal SpeB activity [SpeBA+]). SseA+ SpeBA+ variants had transcript levels of CovRS-controlled virulence genes comparable to those of a covS mutant but had no covRS mutations. Genome resequencing of an SseA+ SpeBA+ isolate identified a C605A nonsense mutation in orphan kinase gene rocA, and 6 other SseA+ SpeBA+ isolates also had nonsense mutations or small indels in rocA. RocA and CovS mutants had similar levels of enhancement of the expression of CovRS-controlled virulence genes at the exponential growth phase; however, mutations of RocA but not mutations of CovS did not result in the downregulation of speB transcription at stationary growth phase or in subcutaneous infection of mice. GAS with RocA and CovS mutations caused greater enhancement of the expression of hasA than spyCEP in mouse skin infection than wild-type GAS did. RocA mutants ranked between wild-type GAS and CovS mutants in skin invasion, inhibition of neutrophil recruitment, and virulence in subcutaneous infection of mice. Thus, GAS RocA mutants can be selected in subcutaneous infections in mice and exhibit gene expression patterns and virulences distinct from those of CovS mutants. The findings provide novel information for understanding GAS fitness mutations in vivo, virulence gene regulation, in vivo gene expression, and virulence.

scholarly journals INFLUENCE OF NANOCARBOXYLATES OF MICROELEMENTS ON RHIZOBIUM RADIOBACTER 204 GROWTH-REGULATING ACTIVITY

2015 ◽  
Vol 22 ◽  
pp. 3-8
Author(s):  
С. Ф. Козар ◽  
Є. П. Симоненко ◽  
В. О. Линник ◽  
V. H. Kaplunenko
Keyword(s):  
Growth Phase ◽  
Exponential Growth ◽  
Liquid Culture ◽  
Culture Medium ◽  
Exponential Growth Phase ◽  
Bacterial Cells ◽  
Rhizobium Radiobacter ◽  
Bacteria Growth ◽  
Liquid Culture Medium ◽  
Growth Regulating Activity

The results of studies of the influence of nanocarboxylates (citrates) of microelements on Rhizobium radiobacter 204 growth-regulating activities are presented. It was found that increasing bacteria growth-regulating activity is achieved by the content of citrates of Zinc (Zn), Copper (Cu), Manganese (Mn), Iron (Fe) and Molybdenum (Mo) in culture medium in complex. It was shown that the use of nanocarboxylates of microelements while cultivating the investigated strain contributes to the increase of bacterial cells titre in a liquid culture medium by 1 billion/cm3. It was revealed that the cultivation of R. radiobacter 204 under the action of citrates of microelements helps extent the exponential growth phase of these bacteria by 12 hours. According to the research results an optimized liquid culture medium was proposed for bacteria culturing.

scholarly journals Both galactosaminogalactan and α-1,3-glucan contribute to aggregation of Aspergillus oryzae hyphae in liquid culture

2019 ◽  
Author(s):  
Ken Miyazawa ◽  
Akira Yoshimi ◽  
Motoaki Sano ◽  
Fuka Tabata ◽  
Asumi Sugahara ◽  
...  
Keyword(s):  
Filamentous Fungi ◽  
Aspergillus Oryzae ◽  
Double Mutant ◽  
Liquid Culture ◽  
Bacterial Cells ◽  
Wild Type ◽  
Hydrogen Bond Formation ◽  
Relative Contribution ◽  
In The Wild ◽  
Increase Productivity

AbstractFilamentous fungi generally form aggregated hyphal pellets in liquid culture. We previously reported that α-1,3-glucan-deficient mutants of Aspergillus nidulans did not form hyphal pellets and their hyphae were fully dispersed, and we suggested that α-1,3-glucan functions in hyphal aggregation. Yet, Aspergillus oryzae α-1,3-glucan-deficient (AGΔ) mutants still form small pellets; therefore, we hypothesized that another factor responsible for forming hyphal pellets remains in these mutants. Here, we identified an extracellular matrix polysaccharide galactosaminogalactan (GAG) as such a factor. To produce a double mutant of A. oryzae (AG-GAGΔ), we disrupted the genes required for GAG biosynthesis in an AGΔ mutant. Hyphae of the double mutant were fully dispersed in liquid culture, suggesting that GAG is involved in hyphal aggregation in A. oryzae. Addition of partially purified GAG fraction to the hyphae of the AG-GAGΔ strain resulted in formation of mycelial pellets. Acetylation of the amino group in galactosamine of GAG weakened GAG aggregation, suggesting that hydrogen bond formation by this group is important for aggregation. Genome sequences suggest that α-1,3-glucan, GAG, or both are present in many filamentous fungi and thus may function in hyphal aggregation in these fungi. We also demonstrated that production of a recombinant polyesterase, CutL1, was higher in the AG-GAGΔ strain than in the wild-type and AGΔ strains. Thus, controlling hyphal aggregation factors of filamentous fungi may increase productivity in the fermentation industry.ImportanceProduction using filamentous fungi is an important part of the fermentation industry, but hyphal aggregation in these fungi in liquid culture limits productivity compared with that of yeast or bacterial cells. We found that galactosaminogalactan and α-1,3-glucan both function in hyphal aggregation in Aspergillus oryzae, and that the hyphae of a double mutant deficient in both polysaccharides become fully dispersed in liquid culture. We also revealed the relative contribution of α-1,3-glucan and galactosaminogalactan to hyphal aggregation. Recombinant protein production was higher in the double mutant than in the wild-type strain. Our research provides a potential technical innovation for the fermentation industry that uses filamentous fungi, as regulation of the growth characteristics of A. oryzae in liquid culture may increase productivity.

scholarly journals Cell Surface Interactions of Rhizobium Bacteroids and Other Bacterial Strains with Symbiosomal and Peribacteroid Membrane Components from Pea Nodules

2004 ◽  
Vol 17 (2) ◽  
pp. 216-223 ◽  
Author(s):  
Luis Bolaños ◽  
Miguel Redondo-Nieto ◽  
Rafael Rivilla ◽  
Nicholas J. Brewin ◽  
Ildefonso Bonilla
Keyword(s):  
Cell Surface ◽  
Rhizobium Leguminosarum ◽  
Close Association ◽  
Extracellular Polysaccharide ◽  
Staining Reaction ◽  
Bacterial Cells ◽  
Bacterial Strains ◽  
Peribacteroid Membrane ◽  
Bacterial Surface ◽  
Antibody Staining

Samples of Rhizobium bacteroids isolated from pea nodule symbiosomes reacted positively with a monoclonal antibody recognizing N-linked glycan epitopes on plant glycoproteins associated with the peribacteroid membrane and peribacteroid fluid. An antiserum recognizing the symbiosomal lectin-like glycoprotein PsNLEC-1 also reacted positively. Samples of isolated bacteroids also reacted with an antibody recognizing a glycolipid component of the peribacteroid membrane and plasma membrane. Bacterial cells derived from free-living cultures then were immobilized on nitrocellulose sheets and tested for their ability to associate with components of plant extracts derived from nodule fractionation. A positive antibody-staining reaction indicated that both PsNLEC-1 and membrane glycolipid had become associated with the bacterial surface. A range of rhizobial strains with mutants affecting cell surface polysaccharides all showed similar interactions with PsNLEC-1 and associated plant membranes, with the exception of strain B659 (a deep-rough lipopolysaccharide mutant of Rhizobium leguminosarum). However, the presence of a capsule of extracellular polysaccharide apparently prevented interactions between rhizobial cells and these plant components. The importance of a close association between peribacteroid membranes, PsNLEC-1, and the bacterial surface is discussed in the context of symbiosome development.

scholarly journals Variants of vaccinia virus hemagglutinin altered in intracellular transport.

1986 ◽  
Vol 6 (11) ◽  
pp. 3734-3745 ◽  
Author(s):  
H Shida
Keyword(s):  
Golgi Apparatus ◽  
Cell Surface ◽  
Vaccinia Virus ◽  
Intracellular Transport ◽  
Cytoplasmic Domain ◽  
Slow Movement ◽  
Wild Type ◽  
Sequence Analyses ◽  
In The Wild ◽  
Virus Mutant

Two classes of revertants were isolated from a vaccinia virus mutant whose hemagglutinins (HAs) accumulate on nuclear envelopes and rough endoplasmic reticulums. The HAs of one of the revertants had the same phenotype as the wild type, i.e., rapid and efficient movement to the cell surface. The HAs of the second class had biphasic transport: rapid export to the cell surface as in the wild type and slow movement to the medial cisternae of the Golgi apparatus. Biochemical and nucleotide sequence analyses showed that the HAs of all the mutants examined that have defects in transport from the rough endoplasmic reticulum to the Golgi apparatus have altered cytoplasmic domains and that the HAs of the second class of revertants lack the whole cytoplasmic domain, while the HAs of the first class of revertants have a wild-type cytoplasmic domain.

Comparative studies of an asporogenic mutant and a wild type strain of Clostridium botulinum type E

1972 ◽  
Vol 18 (1) ◽  
pp. 29-34 ◽  
Author(s):  
A. C. Emeruwa ◽  
R. Z. Hawirko
Keyword(s):  
Optical Density ◽  
Growth Phase ◽  
Comparative Studies ◽  
Type Strain ◽  
Clostridium Botulinum ◽  
Wild Type Strain ◽  
Wild Type ◽  
Botulinum Type ◽  
Clostridium Botulinum Type E ◽  
In The Wild

An asporogenic mutant of Clostridium botulinum type E, ATCC 9564, was recovered on liver veal agar, which had been supplemented with MnSO4 (0.13 mM) and mercaptoacetate (0.2%). Growth in TPG measured by optical density increased exponentially for the two strains during the first 11 h. But subsequently, the optical density of the wild type rapidly declined while the sp− mutant showed a more gradual decrease. The pH decreased significantly during growth but remained unaltered at pH 5–6 during sporulation. The DPA synthesis in the sp+ strain paralleled the appearance of refractile spores, while the sp− strain showed no measurable amounts of DPA. Protease and antibiotic activities were detected late in the log growth phase of the wild type. Gas–solid chromatography showed that during growth and sporulation the mercaptoethanol and CO2 content declined significantly in the wild type, but remained unchanged in the sp− mutant, whereas N2O was evolved concurrently with sporulation. This study has provided us with an effective method for the isolation of asporogenic mutants of C. botulinum, as well as a basis for the analysis of the events which occur during the stages of sporulation.

SubMICs of penicillin and erythromycin enhance biofilm formation and hydrophobicity of Corynebacterium diphtheriae strains

2013 ◽  
Vol 62 (5) ◽  
pp. 754-760 ◽  
Author(s):  
D. L. R. Gomes ◽  
R. S. Peixoto ◽  
E. A. B. Barbosa ◽  
F. Napoleão ◽  
P. S. Sabbadini ◽  
...  
Keyword(s):  
Cell Surface ◽  
Surface Properties ◽  
Biofilm Formation ◽  
Antimicrobial Agents ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Corynebacterium Diphtheriae ◽  
Surface Charges ◽  
Bacterial Surface ◽  
Bacterial Morphology

Subinhibitory concentrations (subMICs) of antibiotics may alter bacterial surface properties and change microbial physiology. This study aimed to investigate the effect of a subMIC (⅛ MIC) of penicillin (PEN) and erythromycin (ERY) on bacterial morphology, haemagglutinating activity, cell-surface hydrophobicity (CSH) and biofilm formation on glass and polystyrene surfaces, as well as the distribution of cell-surface acidic anionic residues of Corynebacterium diphtheriae strains (HC01 tox − strain; CDC-E8392 and 241 tox + strains). All micro-organisms tested were susceptible to PEN and ERY. Growth in the presence of PEN induced bacterial filamentation, whereas subMIC of ERY caused cell-size reduction of strains 241 and CDC-E8392. Adherence to human erythrocytes was reduced after growth in the presence of ERY, while CSH was increased by a subMIC of both antibiotics in bacterial adherence to n-hexadecane assays. Conversely, antibiotic inhibition of biofilm formation was not observed. All strains enhanced biofilm formation on glass after treatment with ERY, while only strain 241 increased glass adherence after cultivation in the presence of PEN. Biofilm production on polystyrene surfaces was improved by ⅛ MIC of ERY. After growth in the presence of both antimicrobial agents, strains 241 and CDC-E8392 exhibited anionic surface charges with focal distribution. In conclusion, subMICs of PEN and ERY modified bacterial surface properties and enhanced not only biofilm formation but also cell-surface hydrophobicity. Antibiotic-induced biofilm formation may contribute to the inconsistent success of antimicrobial therapy for C. diphtheriae infections.

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