scholarly journals Pyridine-2,6-Bis(Thiocarboxylic Acid) Produced by Pseudomonas stutzeri KC Reduces and Precipitates Selenium and Tellurium Oxyanions

2006 ◽  
Vol 72 (5) ◽  
pp. 3119-3129 ◽  
Author(s):  
Anna M. Zawadzka ◽  
Ronald L. Crawford ◽  
Andrzej J. Paszczynski
Keyword(s):  
Wild Type Strain ◽  
Hydrolysis Product ◽  
Pseudomonas Stutzeri ◽  
Elemental Selenium ◽  
Bacterial Cells ◽  
Wild Type ◽  
Chemical Structures ◽  
Thiocarboxylic Acid ◽  
Insoluble Compounds ◽  
Initial Line

ABSTRACT The siderophore of Pseudomonas stutzeri KC, pyridine-2,6-bis(thiocarboxylic acid) (pdtc), is shown to detoxify selenium and tellurium oxyanions in bacterial cultures. A mechanism for pdtc's detoxification of tellurite and selenite is proposed. The mechanism is based upon determination using mass spectrometry and energy-dispersive X-ray spectrometry of the chemical structures of compounds formed during initial reactions of tellurite and selenite with pdtc. Selenite and tellurite are reduced by pdtc or its hydrolysis product H2S, forming zero-valent pdtc selenides and pdtc tellurides that precipitate from solution. These insoluble compounds then hydrolyze, releasing nanometer-sized particles of elemental selenium or tellurium. Electron microscopy studies showed both extracellular precipitation and internal deposition of these metalloids by bacterial cells. The precipitates formed with synthetic pdtc were similar to those formed in pdtc-producing cultures of P. stutzeri KC. Culture filtrates of P. stutzeri KC containing pdtc were also active in removing selenite and precipitating elemental selenium and tellurium. The pdtc-producing wild-type strain KC conferred higher tolerance against selenite and tellurite toxicity than a pdtc-negative mutant strain, CTN1. These observations support the hypothesis that pdtc not only functions as a siderophore but also is involved in an initial line of defense against toxicity from various metals and metalloids.

scholarly journals Activation and Inactivation of Pseudomonas stutzeriMethylbenzene Catabolism Pathways Mediated by a Transposable Element

1999 ◽  
Vol 65 (5) ◽  
pp. 1876-1882 ◽  
Author(s):  
Fabrizio Bolognese ◽  
Cinzia di Lecce ◽  
Enrica Galli ◽  
Paola Barbieri
Keyword(s):  
Transposable Element ◽  
Type Strain ◽  
Insertion Sequence ◽  
Wild Type Strain ◽  
Pseudomonas Stutzeri ◽  
Inverted Repeats ◽  
Wild Type ◽  
Catabolic Pathway ◽  
Catabolic Genes ◽  
Target Dna

ABSTRACT The arrangement of the genes involved in o-xylene,m-xylene, and p-xylene catabolism was investigated in three Pseudomonas stutzeri strains: the wild-type strain OX1, which is able to grow on o-xylene but not on the meta and para isomers; the mutant M1, which grows on m-xylene and p-xylene but is unable to utilize the ortho isomer; and the revertant R1, which can utilize all the three isomers of xylene. A 3-kb insertion sequence (IS) termed ISPs1, which inactivates them-xylene and p-xylene catabolic pathway inP. stutzeri OX1 and the o-xylene catabolic genes in P. stutzeri M1, was detected. No IS was detected in the corresponding catabolic regions of the P. stutzeri R1 genome. ISPs1 is present in several copies in the genomes of the three strains. It is flanked by 24-bp imperfect inverted repeats, causes the direct duplication of 8 bp in the target DNA, and seems to be related to the ISL3 family.

scholarly journals Effect of Trehalose and Trehalose Transport on the Tolerance ofClostridium perfringensto Environmental Stress in a Wild Type Strain and Its Fluoroquinolone-Resistant Mutant

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Miseon Park ◽  
Wilfrid J. Mitchell ◽  
Fatemeh Rafii
Keyword(s):  
Environmental Stress ◽  
Type Strain ◽  
Wild Type Strain ◽  
Resistant Mutant ◽  
Defined Medium ◽  
Low Ph ◽  
Bacterial Cells ◽  
Chemically Defined Medium ◽  
Wild Type ◽  
Qrt Pcr

Trehalose has been shown to protect bacterial cells from environmental stress. Its uptake and osmoprotective effect inClostridium perfringenswere investigated by comparing wild typeC. perfringensATCC 13124 with a fluoroquinolone- (gatifloxacin-) resistant mutant. In a chemically defined medium, trehalose and sucrose supported the growth of the wild type but not that of the mutant. Microarray data and qRT-PCR showed that putative genes for the phosphorylation and transport of sucrose and trehalose (via phosphoenolpyruvate-dependent phosphotransferase systems, PTS) and some regulatory genes were downregulated in the mutant. The wild type had greater tolerance than the mutant to salts and low pH; trehalose and sucrose further enhanced the osmotolerance of the wild type to NaCl. Expression of the trehalose-specific PTS was lower in the fluoroquinolone-resistant mutant. Protection ofC. perfringensfrom environmental stress could therefore be correlated with the ability to take up trehalose.

Pathogenic potential of a collagenase gene fromAeromonas veronii

2008 ◽  
Vol 54 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Hyun-Ja Han ◽  
Tatsuo Taki ◽  
Hidehiro Kondo ◽  
Ikuo Hirono ◽  
Takashi Aoki
Keyword(s):  
Mutant Strain ◽  
Type Strain ◽  
Pathogenic Bacteria ◽  
Wild Type Strain ◽  
Collagenolytic Activity ◽  
Bacterial Cells ◽  
Wild Type ◽  
Pathogenic Potential ◽  
Collagenase Gene

The role of collagenase as a mechanism of bacterial pathogenicity in some pathogenic bacteria has been reported. The information on the role of collagenase in Aeromonas spp. pathogenesis is scant. In the present study, a mutant Aeromonas veronii RY001 that is deficient in the putative collagenase gene acg was constructed and compared with the wild-type strain for virulence factors. Bacterial cells and cell-free extracellular products of the mutant had significantly less collagenolytic activity, but there were not significant differences in caseinolytic, gelatinolytic, and elastolytic activities. Adhesion and invasion abilities of the mutant strain on epithelioma papillosum of carp cells was only 56% of that of the wild-type strain, and the cytotoxicity of the mutant strain to epithelioma papillosum of carp cells was only 42% of that of the wild-type strain. The LD50values of the wild-type strain were determined as 1.6 × 106and 3.5 × 105cfu in goldfish and mice, respectively, whereas the mutant RY001 strain showed slightly higher values (i.e., 2.8 × 106and 1.4 × 106cfu in goldfish and mice, respectively). These results indicated the involvement of the collagenase gene in the pathogenesis of A. veronii.

scholarly journals Inhibition of Phagocytosis by Haemophilus ducreyi Requires Expression of the LspA1 and LspA2 Proteins

2003 ◽  
Vol 71 (10) ◽  
pp. 5994-6003 ◽  
Author(s):  
Merja Vakevainen ◽  
Steven Greenberg ◽  
Eric J. Hansen
Keyword(s):  
Type Strain ◽  
Wild Type Strain ◽  
Rabbit Model ◽  
Inhibitory Effect ◽  
Haemophilus Ducreyi ◽  
Bacterial Cells ◽  
Wild Type ◽  
Temperature Dependent ◽  
Live Bacterial Cells

ABSTRACT Haemophilus ducreyi previously has been shown to inhibit the phagocytosis of both secondary targets and itself by certain cells in vitro. Wild-type H. ducreyi strain 35000HP contains two genes, lspA1 and lspA2, whose encoded protein products are predicted to be 456 and 543 kDa, respectively. An isogenic mutant of H. ducreyi 35000HP with inactivated lspA1 and lspA2 genes has been shown to exhibit substantially decreased virulence in the temperature-dependent rabbit model for chancroid. This lspA1 lspA2 mutant was tested for its ability to inhibit phagocytosis of immunoglobulin G-opsonized particles by differentiated HL-60 and U-937 cells and by J774A.1 cells. The wild-type strain H. ducreyi 35000HP readily inhibited phagocytosis, whereas the lspA1 lspA2 mutant was unable to inhibit phagocytosis. Similarly, the wild-type strain was resistant to phagocytosis, whereas the lspA1 lspA2 mutant was readily engulfed by phagocytes. This inhibitory effect of wild-type H. ducreyi on phagocytic activity was primarily associated with live bacterial cells but could also be found, under certain conditions, in concentrated H. ducreyi culture supernatant fluids that lacked detectable outer membrane fragments. Both the wild-type strain and the lspA1 lspA2 mutant attached to phagocytes at similar levels. These results indicate that the LspA1 and LspA2 proteins of H. ducreyi are involved, directly or indirectly, in the antiphagocytic activity of this pathogen, and they provide a possible explanation for the greatly reduced virulence of the lspA1 lspA2 mutant.

scholarly journals Deletion of the Gene Encoding p60 in Listeria monocytogenes Leads to Abnormal Cell Division and Loss of Actin-Based Motility

2003 ◽  
Vol 71 (6) ◽  
pp. 3473-3484 ◽  
Author(s):  
Sabine Pilgrim ◽  
Annette Kolb-Mäurer ◽  
Ivaylo Gentschev ◽  
Werner Goebel ◽  
Michael Kuhn
Keyword(s):  
Listeria Monocytogenes ◽  
Epithelial Cells ◽  
Type Strain ◽  
Wild Type Strain ◽  
Essential Gene ◽  
Bacterial Cells ◽  
Wild Type ◽  
Septum Formation ◽  
Intracellular Movement ◽  
Cell Spread

ABSTRACT Protein p60 encoded by the iap gene is regarded as an essential gene product of Listeria monocytogenes. Here we report, however, the successful construction of a viable iap deletion mutant of L. monocytogenes EGD. The mutant, which produces no p60, shows abnormal septum formation and tends to form short filaments and hooked forms during logarithmic growth. These abnormal bacterial cells break into almost normal sized single bacteria in the late-stationary-growth phase. The iap mutant is strongly attenuated in a mouse model after intravenous injection, demonstrating the importance of p60 during infection, and the invasiveness of the Δiap mutant for 3T6 fibroblasts and Caco-2 epithelial cells is slightly reduced. Upon uptake by epithelial cells and macrophages, the iap mutant escapes from the phagosome into the cytosol with the same efficiency as the wild-type strain, and the mutant bacteria also grow intracellularly at a rate similar to that of the wild-type strain. Intracellular movement and cell-to-cell spread are drastically reduced in various cell lines, since the iap-negative bacteria fail to induce the formation of actin tails. However, the bacteria are covered with actin filaments. Most intracellular bacteria show a nonpolar and uneven distribution of ActA around the cell, in contrast to that for the wild-type strain, where ActA is concentrated at the old pole. In an iap+ revertant strain that produces wild-type levels of p60, intracellular movement, cell-to-cell spread, and polar distribution of ActA are fully restored. In vitro analysis of ActA distribution on the filaments of the Δiap strain shows that the loss of bacterial septum formation leads to ActA accumulation at the presumed division sites. In the light of data presented here and elswhere, we propose to rename iap (invasion-associated protein) cwhA (cell wall hydrolase A).

scholarly journals Transcriptional Regulation of the pdt Gene Cluster of Pseudomonas stutzeri KC Involves an AraC/XylS Family Transcriptional Activator (PdtC) and the Cognate Siderophore Pyridine-2,6-Bis(Thiocarboxylic Acid)

2006 ◽  
Vol 72 (11) ◽  
pp. 6994-7002 ◽  
Author(s):  
Sergio E. Morales ◽  
Thomas A. Lewis
Keyword(s):  
Gene Cluster ◽  
Molecular Mechanisms ◽  
Pseudomonas Stutzeri ◽  
Transcriptional Activator ◽  
Wild Type ◽  
Transcriptional Reporter ◽  
Reverse Transcription Pcr ◽  
Thiocarboxylic Acid ◽  
Transcriptional Units ◽  
Necessary And Sufficient

ABSTRACT In order to gain an understanding of the molecular mechanisms dictating production of the siderophore and dechlorination agent pyridine-2,6-bis(thiocarboxylic acid) (PDTC), we have begun characterization of a gene found in the pdt gene cluster of Pseudomonas stutzeri KC predicted to have a regulatory role. That gene product is an AraC family transcriptional activator, PdtC. Quantitative reverse transcription-PCR and expression of transcriptional reporter fusions were used to assess a role for pdtC in the transcription of pdt genes. PdtC and an upstream, promoter-proximal DNA segment were required for wild-type levels of expression from the promoter of a predicted biosynthesis operon (P pdt F ). At least two other transcriptional units within the pdt cluster were also dependent upon pdtC for expression at wild-type levels. The use of a heterologous, Pseudomonas putida host demonstrated that pdtC and an exogenously added siderophore were necessary and sufficient for expression from the pdtF promoter, i.e., none of the PDTC utilization genes within the pdt cluster were required for transcriptional signaling. Tests using the promoter of the pdtC gene in transcriptional reporter fusions indicated siderophore-dependent negative autoregulation similar to that seen with other AraC-type regulators of siderophore biosynthesis and utilization genes. The data increase the repertoire of siderophore systems known to be regulated by this type of transcriptional activator and have implications for PDTC signaling.

scholarly journals Effects of Mutations of RAD50, RAD51, RAD52, and Related Genes on Illegitimate Recombination in Saccharomyces cerevisiae

Genetics ◽  
1996 ◽  
Vol 142 (2) ◽  
pp. 383-391 ◽  
Author(s):  
Yasumasa Tsukamoto ◽  
Jun-ichi Kato ◽  
Hideo Ikeda
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Quantitative Analysis ◽  
Structural Analysis ◽  
Recombination Rate ◽  
Type Strain ◽  
Negative Selection ◽  
Wild Type Strain ◽  
Illegitimate Recombination ◽  
Wild Type ◽  
In The Wild

Abstract To examine the mechanism of illegitimate recombination in Saccharomyces cerevisiae, we have developed a plasmid system for quantitative analysis of deletion formation. A can1 cyh2 cell carrying two negative selection markers, the CAN1 and CYH2 genes, on a YCp plasmid is sensitive to canavanine and cycloheximide, but the cell becomes resistant to both drugs when the plasmid has a deletion over the CAN1 and CYH2 genes. Structural analysis of the recombinant plasmids obtained from the resistant cells showed that the plasmids had deletions at various sites of the CAN1-CYH2 region and there were only short regions of homology (1-5 bp) at the recombination junctions. The results indicated that the deletion detected in this system were formed by illegitimate recombination. Study on the effect of several rad mutations showed that the recombination rate was reduced by 30-, 10-, 10-, and 10-fold in the rad52, rad50, mre11, and xrs2 mutants, respectively, while in the rud51, 54, 55, and 57 mutants, the rate was comparable to that in the wild-type strain. The rad52 mutation did not affect length of homology at junction sites of illegitimate recombination.

scholarly journals The role of Zur-regulated lipoprotein A in bacterial morphology, antimicrobial susceptibility, and production of outer membrane vesicles in Acinetobacter baumannii

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Nayeong Kim ◽  
Hyo Jeong Kim ◽  
Man Hwan Oh ◽  
Se Yeon Kim ◽  
Mi Hyun Kim ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Mutant Strain ◽  
Antimicrobial Susceptibility ◽  
Type Strain ◽  
Wild Type Strain ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Wild Type ◽  
Bacterial Morphology

Abstract Background Zinc uptake-regulator (Zur)-regulated lipoprotein A (ZrlA) plays a role in bacterial fitness and overcoming antimicrobial exposure in Acinetobacter baumannii. This study further characterized the zrlA gene and its encoded protein and investigated the roles of the zrlA gene in bacterial morphology, antimicrobial susceptibility, and production of outer membrane vesicles (OMVs) in A. baumannii ATCC 17978. Results In silico and polymerase chain reaction analyses showed that the zrlA gene was conserved among A. baumannii strains with 97–100% sequence homology. Recombinant ZrlA protein exhibited a specific enzymatic activity of D-alanine-D-alanine carboxypeptidase. Wild-type A. baumannii exhibited more morphological heterogeneity than a ΔzrlA mutant strain during stationary phase. The ΔzrlA mutant strain was more susceptible to gentamicin than the wild-type strain. Sizes and protein profiles of OMVs were similar between the wild-type and ΔzrlA mutant strains, but the ΔzrlA mutant strain produced 9.7 times more OMV particles than the wild-type strain. OMVs from the ΔzrlA mutant were more cytotoxic in cultured epithelial cells than OMVs from the wild-type strain. Conclusions The present study demonstrated that A. baumannii ZrlA contributes to bacterial morphogenesis and antimicrobial resistance, but its deletion increases OMV production and OMV-mediated host cell cytotoxicity.

scholarly journals FixJ family regulator AcfR of Azorhizobium caulinodans is involved in symbiosis with the host plant

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Wei Liu ◽  
Xue Bai ◽  
Yan Li ◽  
Haikun Zhang ◽  
Xiaoke Hu
Keyword(s):  
Signal Transduction ◽  
Host Plant ◽  
Type Strain ◽  
Wild Type Strain ◽  
Response Regulator ◽  
Azorhizobium Caulinodans ◽  
Wild Type ◽  
Response Regulators ◽  
Free Living ◽  
Two Component

Abstract Background A wide variety of bacterial adaptative responses to environmental conditions are mediated by signal transduction pathways. Two-component signal transduction systems are one of the predominant means used by bacteria to sense the signals of the host plant and adjust their interaction behaviour. A total of seven open reading frames have been identified as putative two-component response regulators in the gram-negative nitrogen-fixing bacteria Azorhizobium caulinodans ORS571. However, the biological functions of these response regulators in the symbiotic interactions between A. caulinodans ORS571 and the host plant Sesbania rostrata have not been elucidated to date. Results In this study, we identified and investigated a two-component response regulator, AcfR, with a phosphorylatable N-terminal REC (receiver) domain and a C-terminal HTH (helix-turn-helix) LuxR DNA-binding domain in A. caulinodans ORS571. Phylogenetic analysis showed that AcfR possessed close evolutionary relationships with NarL/FixJ family regulators. In addition, six histidine kinases containing HATPase_c and HisKA domains were predicted to interact with AcfR. Furthermore, the biological function of AcfR in free-living and symbiotic conditions was elucidated by comparing the wild-type strain and the ΔacfR mutant strain. In the free-living state, the cell motility behaviour and exopolysaccharide production of the ΔacfR mutant were significantly reduced compared to those of the wild-type strain. In the symbiotic state, the ΔacfR mutant showed a competitive nodule defect on the stems and roots of the host plant, suggesting that AcfR can provide A. caulinodans with an effective competitive ability for symbiotic nodulation. Conclusions Our results showed that AcfR, as a response regulator, regulates numerous phenotypes of A. caulinodans under the free-living conditions and in symbiosis with the host plant. The results of this study help to elucidate the involvement of a REC + HTH_LuxR two-component response regulator in the Rhizobium-host plant interaction.

scholarly journals Mab_3083c Is a Homologue of RNase J and Plays a Role in Colony Morphotype, Aggregation, and Sliding Motility of Mycobacterium abscessus

2021 ◽  
Vol 9 (4) ◽  
pp. 676
Author(s):  
Ting-Yu Liu ◽  
Sheng-Hui Tsai ◽  
Jenn-Wei Chen ◽  
Yu-Ching Wang ◽  
Shiau-Ting Hu ◽  
...  
Keyword(s):  
Type Strain ◽  
Wild Type Strain ◽  
Opportunistic Pathogen ◽  
Mycobacterium Abscessus ◽  
Colony Morphology ◽  
Clinical Strain ◽  
Immunocompromised Patients ◽  
Clinical Infection ◽  
Wild Type ◽  
Sliding Motility

Mycobacterium abscessus is an opportunistic pathogen causing human diseases, especially in immunocompromised patients. M. abscessus strains with a rough morphotype are more virulent than those with a smooth morphotype. Morphotype switch may occur during a clinical infection. To investigate the genes involved in colony morphotype switching, we performed transposon mutagenesis in a rough clinical strain of M. abscessus. A morphotype switching mutant (smooth) named mab_3083c::Tn was obtained. This mutant was found to have a lower aggregative ability and a higher sliding motility than the wild type strain. However, its glycopeptidolipid (GPL) content remained the same as those of the wild type. Complementation of the mutant with a functional mab_3083c gene reverted its morphotype back to rough, indicating that mab_3083c is associated with colony morphology of M. abscessus. Bioinformatic analyses showed that mab_3083c has a 75.4% identity in amino acid sequence with the well-characterized ribonuclease J (RNase J) of M. smegmatis (RNase JMsmeg). Complementation of the mutant with the RNase J gene of M. smegmatis also switched its colony morphology from smooth back to rough. These results suggest that Mab_3083c is a homologue of RNase J and involved in regulating M. abscessus colony morphotype switching.

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