scholarly journals An Extracellular Protease of Pseudomonas fluorescens Inactivates Antibiotics of Pantoea agglomerans

2004 ◽  
Vol 94 (11) ◽  
pp. 1228-1234 ◽  
Author(s):  
L. Meadow Anderson ◽  
Virginia O. Stockwell ◽  
Joyce E. Loper
Keyword(s):  
Pseudomonas Fluorescens ◽  
Agar Plate ◽  
Pantoea Agglomerans ◽  
Extracellular Protease ◽  
Protease Production ◽  
Gene Encoding ◽  
Agar Plate Bioassay ◽  
Derivatives Of ◽  
Important Disease

Pseudomonas fluorescens A506 and Pantoea agglomerans strains Eh252 and C9-1 are biological control agents that suppress fire blight, an important disease of pear and apple caused by the bacterium Erwinia amylovora. Pseudomonas fluorescens strain A506 suppresses disease largely through competitive exclusion of E. amylovora on surfaces of blossoms, the primary infection court, whereas Pantoea agglomerans strains Eh252 and C9-1 produce antibiotics that are toxic to E. amylovora. In this study, an extracellular protease produced by A506 is characterized and evaluated for its capacity to inactivate the antibiotics produced by the strains of Pantoea agglomerans. Activity of the extracellular protease was optimal at pH 9 and inhibited by zinc- or calcium-chelators, indicating that the protease is an alkaline metalloprotease. In an agar plate bioassay, partially purified extracellular protease inactivated the antibiotics mccEh252 and herbicolin O, which are produced by Pantoea agglomerans strains Eh252 and C9-1, respectively. Derivatives of A506 deficient in extracellular protease production were obtained by transposon mutagenesis, and the aprX gene encoding the protease was cloned and sequenced. Strain A506 inactivated mccEh252 and herbicolin O in agar plate bioassays, whereas the aprX mutant did not inactivate the antibiotics. Both A506 and the aprX mutant were insensitive to antibiosis by C9-1 and Eh252; thus, the protease was not required to protect A506 from antibiosis. These data highlight a previously unknown role of the extracellular protease produced by Pseudomonas fluorescens A506 in interactions among plant-associated microbes.

scholarly journals σB Modulates Virulence Determinant Expression and Stress Resistance: Characterization of a Functional rsbU Strain Derived from Staphylococcus aureus 8325-4

2002 ◽  
Vol 184 (19) ◽  
pp. 5457-5467 ◽  
Author(s):  
Malcolm J. Horsburgh ◽  
Joanne L. Aish ◽  
Ian J. White ◽  
Les Shaw ◽  
James K. Lithgow ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Minor Role ◽  
Gene Encoding ◽  
Phenotypic Properties ◽  
Relative Level ◽  
General Stress Response ◽  
A Minor ◽  
Derivatives Of

ABSTRACT The accessory sigma factor σB controls a general stress response that is thought to be important for Staphylococcus aureus survival and may contribute to virulence. The strain of choice for genetic studies, 8325-4, carries a small deletion in rsbU, which encodes a positive regulator of σB activity. Consequently, to enable the role of σB in virulence to be addressed, we constructed an rsbU + derivative, SH1000, using a method that does not leave behind an antibiotic resistance marker. The phenotypic properties of SH1000 (8325-4 rsbU +) were characterized and compared to those of 8325-4, the rsbU mutant, parent strain. A recognition site for σB was located in the promoter region of katA, the gene encoding the sole catalase of S. aureus, by primer extension analysis. However, catalase expression and activity were similar in SH1000 (8325-4 rsbU +), suggesting that this promoter may have a minor role in catalase expression under normal conditions. Restoration of σB activity in SH1000 (8325-4 rsbU +) resulted in a marked decrease in the levels of the exoproteins SspA and Hla, and this is likely to be mediated by reduced expression of agr in this strain. By using Western blotting and a sarA-lacZ reporter assay, the levels of SarA were found to be similar in strains 8325-4 and SH1000 (8325-4 rsbU +) and sigB mutant derivatives of these strains. This finding contrasts with previous reports that suggested that SarA expression levels are altered when they are measured transcriptionally. Inactivation of sarA in each of these strains resulted in an expected decrease in agr expression; however, the relative level of agr in SH1000 (8325-4 rsbU +) remained less than the relative levels in 8325-4 and the sigB mutant derivatives. We suggest that SarA is not likely to be the effector in the overall σB-mediated effect on agr expression.

scholarly journals Extracellular Protease of Pseudomonas fluorescens CHA0, a Biocontrol Factor with Activity against the Root-Knot Nematode Meloidogyne incognita

2005 ◽  
Vol 71 (9) ◽  
pp. 5646-5649 ◽  
Author(s):  
Imran Ali Siddiqui ◽  
Dieter Haas ◽  
Stephan Heeb
Keyword(s):  
Pseudomonas Fluorescens ◽  
Meloidogyne Incognita ◽  
Regulatory Gene ◽  
Extracellular Protease ◽  
Root Knot Nematode ◽  
Gene Encoding ◽  
Egg Hatching ◽  
Biocontrol Activity ◽  
Culture Supernatants

ABSTRACT In Pseudomonas fluorescens CHA0, mutation of the GacA-controlled aprA gene (encoding the major extracellular protease) or the gacA regulatory gene resulted in reduced biocontrol activity against the root-knot nematode Meloidogyne incognita during tomato and soybean infection. Culture supernatants of strain CHA0 inhibited egg hatching and induced mortality of M. incognita juveniles more strongly than did supernatants of aprA and gacA mutants, suggesting that AprA protease contributes to biocontrol.

scholarly journals Pengaruh Rizobakteri dalam Meningkatkan Kandungan Asam Salisilat dan Total Fenol Tanaman terhadap Penekanan Nematoda Puru Akar

2018 ◽  
Vol 9 (2) ◽  
pp. 54
Author(s):  
Kristiana Sri Wijayanti ◽  
Bambang Tri Rahardjo ◽  
Toto Himawan
Keyword(s):  
Bacillus Subtilis ◽  
Salicylic Acid ◽  
Pseudomonas Fluorescens ◽  
Dry Weight ◽  
Hibiscus Cannabinus ◽  
Total Phenols ◽  
Root Knot Nematode ◽  
Meloidogyne Spp ◽  
Important Disease

<p> </p><p>Penyakit puru akar pada tanaman kenaf (Hibiscus cannabinus L.) yang disebabkan oleh nematoda Meloidogyne spp. mengakibatkan penurunan kualitas dan kuantitas serat. Kolonisasi rizobakteri dalam rizosfer berperan sebagai antagonis yang dapat dimanfaatkan dalam ketahanan tanaman terhadap patogen.  Peran rizobakteri sebagai bioprotektan dapat menurunkan populasi nematoda yang akan mempengaruhi perkembangan patogen penyebab penyakit. Penelitian ini bertujuan untuk mengevaluasi rizobakteri yang potensial dalam meningkatkan ketahanan tanaman kenaf terhadap infeksi nematoda Meloidogyne spp. melalui pembentukan metabolit sekunder diantaranya kandungan total fenol dan asam salisilat. Aplikasi<br /> rizobakteri dengan cara perendaman dan tanpa perendaman baik secara tunggal maupun konsorsium.  Rizobakteri yang digunakan terdiri dari 3 jenis yaitu Pseudomonas fluorescens, Bacillus subtilis, dan Azotobacter sp. Pengamatan kandungan total fenol dan asam salisilat diamati pada 15 dan 25 hari setelah inokulasi dengan menggunakan alat spektrofotometer. Peningkatan total fenol dan asam salisilat tertinggi diperoleh ketika benih kenaf direndam dengan bakteri P. fluorescens berturut-turut sebesar 513,45% dan 235,99%. Terdapat peningkatan bobot kering tanaman kenaf dengan aplikasi rizobakteri dibandingkan dengan kontrol.</p><p> </p><p><strong><em>Effect </em></strong><strong><em>of Rhizobacteria  in Content  of Salicylic Acid and </em></strong><strong><em>Total Phenol </em></strong><strong><em>of Kenaf </em></strong><strong><em>Against </em></strong><strong><em>Nematodes</em></strong><strong><em> Infections</em></strong></p><p align="center"> </p><p><em>Root knoot disease of kenaf caused by nematodes Meloidogyne spp. is an important disease since it lowers quality and quantity of the fiber. Colonization of rhizobacteria in rhizosphere acts as an antagonist that can be utilized in plant resistance to pathogens. The role of rhizobacteria as a bioprotectan could reduce nematode population, and thus affect development of the disease. This study aimed to evaluate the potency of rhizobacteria in improving kenaf resistance against root knot nematode by inhibiting the production of total phenols and salicylic acid. Application of rhizobacteria was done by soaking or without soaking kenaf seeds either singly or in consortium. There were three rhizobacteria used in this study, i.e: Pseudomonas fluorescens, Bacillus subtilis, and Azotobacter sp. The content of total phenols and salicylic acid was observed at 15 and 25 days after inoculation using a spectrophotometer. The highest elevation level of total phenols and salicylic acid was obtained when kenaf seeds were soaked in P. fluorescens 513,45% and 235,99% respectively. There is an increase dry weight of kenaf with aplication of rhizobacteria compared with controls.</em></p>

Biochemical and Genetic Characterization of an Extracellular Protease from Pseudomonas fluorescensCY091

1998 ◽  
Vol 64 (3) ◽  
pp. 914-921 ◽  
Author(s):  
Ching-Hsing Liao ◽  
Daniel E. McCallus
Keyword(s):  
Enzyme Activity ◽  
Genomic Region ◽  
Exchange Chromatography ◽  
Extracellular Protease ◽  
Protease Production ◽  
Heat Inactivation ◽  
Gene Encoding ◽  
Conserved Sequence ◽  
Putative Protease

ABSTRACT Pseudomonas fluorescens CY091 cultures produce an extracellular protease with an estimated molecular mass of 50 kDa. Production of this enzyme (designated AprX) was observed in media containing CaCl2 or SrCl2 but not in media containing ZnCl2, MgCl2, or MnCl2. The requirement of Ca2+ (or Sr2+) for enzyme production was concentration dependent, and the optimal concentration for production was determined to be 0.35 mM. Following ammonium sulfate precipitation and ion-exchange chromatography, the AprX in the culture supernatant was purified to near electrophoretic homogeneity. Over 20% of the enzyme activity was retained in the AprX sample which had been heated in boiling water for 10 min, indicating that the enzyme is highly resistant to heat inactivation. The enzyme activity was almost completely inhibited in the presence of 1 mM 1,10-phenanthroline, but only 30% of the activity was inhibited in the presence of 1 mM EGTA. The gene encoding AprX was cloned from the genome of P. fluorescens CY091 by isolating cosmid clones capable of restoring the protease production in a nonproteolytic mutant of strain CY091. The genomic region of strain CY091 containing the aprX gene was located within a 7.3-kb DNA fragment. Analysis of the complete nucleotide sequence of this 7.3-kb fragment revealed the presence of a cluster of genes required for the production of extracellular AprX inP. fluorescens and Escherichia coli. The AprX protein showed 50 to 60% identity in amino acid sequence to the related proteases produced by Pseudomonas aeruginosa andErwinia chrysanthemi. Two conserved sequence domains possibly associated with Ca2+ and Zn2+ binding were identified. Immediately adjacent to the aprXstructural gene, a gene (inh) encoding a putative protease inhibitor and three genes (aprD, aprE, andaprF), possibly required for the transport of AprX, were also identified. The organization of the gene cluster involved in the synthesis and secretion of AprX in P. fluorescens CY091 appears to be somewhat different from that previously demonstrated inP. aeruginosa and E. chrysanthemi.

scholarly journals Xylanase B and an arabinofuranosidase from Pseudomonas fluorescens subsp. cellulosa contain identical cellulose-binding domains and are encoded by adjacent genes

1990 ◽  
Vol 272 (2) ◽  
pp. 369-376 ◽  
Author(s):  
L E Kellett ◽  
D M Poole ◽  
L M Ferreira ◽  
A J Durrant ◽  
G P Hazlewood ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Pseudomonas Fluorescens ◽  
Crystalline Cellulose ◽  
Amino Acid Residues ◽  
Gene Encoding ◽  
Reading Frame ◽  
Conserved Sequence ◽  
Binding Domains ◽  
Cellulose Binding ◽  
Derivatives Of

The complete nucleotide sequence of the Pseudomonas fluorescens subsp. cellulosa xynB gene, encoding an endo-beta-1,4-xylanase (xylanase B; XYLB) has been determined. The structural gene consists of an open reading frame (ORF) of 1775 bp coding for a protein of Mr 61,000. A second ORF (xynC) of 1712 bp, which starts 148 bp downstream of xynB, encodes a protein, designated xylanase C (XYLC), of Mr 59,000. XYLB hydrolyses oat spelt xylan to xylobiose and xylose, whereas XYLC releases only arabinose from the same substrate. Thus XYLB is a typical xylanase and XYLC is an arabinofuranosidase. Both enzymes bind to crystalline cellulose (Avicel), but not to xylan. The nucleotide sequences between residues 114 and 931 of xynB and xynC were identical, as were amino acid residues 39-311 of XYLB and XYLC. This conserved sequence is reiterated elsewhere in the P. fluorescens subsp. cellulosa genome. Truncated derivatives of XYLB and XYLC, in which the conserved sequence had been deleted, retained catalytic activity, but did not exhibit cellulose binding. A hybrid gene in which the 5′ end of xynC, encoding residues 1-110 of XYLC, was fused to the Escherichia coli pho A' gene (encodes mature alkaline phosphatase) directed the synthesis of a fusion protein which exhibited alkaline phosphatase activity and bound to cellulose.

Imaging of Pancreatic-Neuroendocrine Tumours: An Outline of Conventional Radiological Techniques

2019 ◽  
Vol 12 (2) ◽  
pp. 135-155 ◽  
Author(s):  
Muhammad Affan Zamir ◽  
Wasim Hakim ◽  
Siraj Yusuf ◽  
Robert Thomas
Keyword(s):  
Neuroendocrine Tumours ◽  
Treatment Options ◽  
Advantages And Disadvantages ◽  
Imaging Characteristics ◽  
Fundamental Understanding ◽  
Pancreatic Neuroendocrine Tumours ◽  
Direct Management ◽  
Important Disease ◽  
Similar Imaging

IIntroduction: Pancreatic Neuroendocrine Tumours (p-NETs) are an important disease entity and comprise of peptide-secreting tumours often with a functional syndrome. : Accounting for a small percentage of all pancreatic tumours, they have a good overall survival rate when diagnosed early, with surgery being curative. The role of nuclear medicine in the diagnosis and treatment of these tumours is evident. However, the vast majority of patients will require extensive imaging in the form of conventional radiological techniques. It is important for clinicians to have a fundamental understanding of the p-NET appearances to aid prompt identification and to help direct management through neoplastic staging. Methods: This article will review the advantages and disadvantages of conventional radiological techniques in the context of p-NETs and highlight features that these tumours exhibit. Conclusion: Pancreatic neuroendocrine tumours are a unique collection of neoplasms that have markedly disparate clinical features but similar imaging characteristics. Most p-NETs are small and welldefined with homogenous enhancement following contrast administration, although larger and less welldifferentiated tumours can demonstrate areas of necrosis and cystic architecture with heterogeneous enhancement characteristics. : Prognosis is generally favourable for these tumours with various treatment options available. However, conventional radiological techniques will remain the foundation for the initial diagnosis and staging of these tumours, and a grasp of these modalities is extremely important for physicians.

The role of secondary alcoholic groups of D-galacturonan in its degradation with exo-D-galacturonanase

1980 ◽  
Vol 45 (2) ◽  
pp. 427-434 ◽  
Author(s):  
Kveta Heinrichová ◽  
Rudolf Kohn
Keyword(s):  
Acetyl Derivative ◽  
Competitive Inhibitor ◽  
Hydroxyl Groups ◽  
Pectic Acid ◽  
Substrate Complex ◽  
Enzyme Substrate ◽  
The Individual ◽  
Degradation Degree ◽  
Derivatives Of

The effect of exo-D-galacturonanase from carrot on O-acetyl derivatives of pectic acid of variousacetylation degree was studied. Substitution of hydroxyl groups at C(2) and C(3) of D-galactopyranuronic acid units influences the initial rate of degradation, degree of degradation and its maximum rate, the differences being found also in the time of limit degradations of the individual O-acetyl derivatives. Value of the apparent Michaelis constant increases with increase of substitution and value of Vmax changes. O-Acetyl derivatives act as a competitive inhibitor of degradation of D-galacturonan. The extent of the inhibition effect depends on the degree of substitution. The only product of enzymic reaction is D-galactopyranuronic acid, what indicates that no degradation of the terminal substituted unit of O-acetyl derivative of pectic acid takes place. Substitution of hydroxyl groups influences the affinity of the enzyme towards the modified substrate. The results let us presume that hydroxyl groups at C(2) and C(3) of galacturonic unit of pectic acid are essential for formation of the enzyme-substrate complex.

scholarly journals The Role of Mitochondria in Carcinogenesis

2021 ◽  
Vol 22 (10) ◽  
pp. 5100
Author(s):  
Paulina Kozakiewicz ◽  
Ludmiła Grzybowska-Szatkowska ◽  
Marzanna Ciesielka ◽  
Jolanta Rzymowska
Keyword(s):  
Prostate Cancer ◽  
Mitochondrial Dna ◽  
Nuclear Dna ◽  
Dna Polymorphisms ◽  
Gene Encoding ◽  
Dna Mutations ◽  
Nadh Ubiquinone Oxidoreductase ◽  
Gene Coi ◽  
The Impact

The mitochondria are essential for normal cell functioning. Changes in mitochondrial DNA (mtDNA) may affect the occurrence of some chronic diseases and cancer. This process is complex and not entirely understood. The assignment to a particular mitochondrial haplogroup may be a factor that either contributes to cancer development or reduces its likelihood. Mutations in mtDNA occurring via an increase in reactive oxygen species may favour the occurrence of further changes both in mitochondrial and nuclear DNA. Mitochondrial DNA mutations in postmitotic cells are not inherited, but may play a role both in initiation and progression of cancer. One of the first discovered polymorphisms associated with cancer was in the gene NADH-ubiquinone oxidoreductase chain 3 (mt-ND3) and it was typical of haplogroup N. In prostate cancer, these mutations and polymorphisms involve a gene encoding subunit I of respiratory complex IV cytochrome c oxidase subunit 1 gene (COI). At present, a growing number of studies also address the impact of mtDNA polymorphisms on prognosis in cancer patients. Some of the mitochondrial DNA polymorphisms occur in both chronic disease and cancer, for instance polymorphism G5913A characteristic of prostate cancer and hypertension.

scholarly journals Controlled Transcription of Regulator Gene carS by Tet-on or by a Strong Promoter Confirms Its Role as a Repressor of Carotenoid Biosynthesis in Fusarium fujikuroi

2020 ◽  
Vol 9 (1) ◽  
pp. 71
Author(s):  
Julia Marente ◽  
Javier Avalos ◽  
M. Carmen Limón
Keyword(s):  
Wild Strain ◽  
Ring Finger ◽  
Carotenoid Biosynthesis ◽  
Negative Regulator ◽  
Fusarium Fujikuroi ◽  
Structural Genes ◽  
Gene Encoding ◽  
In The Wild ◽  
Set Up

Carotenoid biosynthesis is a frequent trait in fungi. In the ascomycete Fusarium fujikuroi, the synthesis of the carboxylic xanthophyll neurosporaxanthin (NX) is stimulated by light. However, the mutants of the carS gene, encoding a protein of the RING finger family, accumulate large NX amounts regardless of illumination, indicating the role of CarS as a negative regulator. To confirm CarS function, we used the Tet-on system to control carS expression in this fungus. The system was first set up with a reporter mluc gene, which showed a positive correlation between the inducer doxycycline and luminescence. Once the system was improved, the carS gene was expressed using Tet-on in the wild strain and in a carS mutant. In both cases, increased carS transcription provoked a downregulation of the structural genes of the pathway and albino phenotypes even under light. Similarly, when the carS gene was constitutively overexpressed under the control of a gpdA promoter, total downregulation of the NX pathway was observed. The results confirmed the role of CarS as a repressor of carotenogenesis in F. fujikuroi and revealed that its expression must be regulated in the wild strain to allow appropriate NX biosynthesis in response to illumination.

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