scholarly journals Acyl-Homoserine Lactone Production Is More Common among Plant-Associated Pseudomonas spp. than among Soilborne Pseudomonas spp.

2001 ◽  
Vol 67 (3) ◽  
pp. 1198-1209 ◽  
Author(s):  
Miena Elasri ◽  
Sandrine Delorme ◽  
Philippe Lemanceau ◽  
Gordon Stewart ◽  
Bridget Laue ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Regulatory Protein ◽  
Enteric Bacteria ◽  
Homoserine Lactone ◽  
Gene Organization ◽  
Bacterial Strains ◽  
Gene Encoding ◽  
Reading Frame ◽  
Pseudomonas Spp ◽  
Absolute Correlation

ABSTRACT A total of 137 soilborne and plant-associated bacterial strains belonging to different Pseudomonas species were tested for their ability to synthesize N-acyl-homoserine lactones (NAHL). Fifty-four strains synthesized NAHL. Interestingly, NAHL production appears to be more common among plant-associated than among soilborne Pseudomonas spp. Indeed, 40% of the analyzed Pseudomonas syringae strains produced NAHL which were identified most often as the short-chain NAHL,N-hexanoyl-l-homoserine lactone,N-(3-oxo-hexanoyl)-homoserine lactone, andN-(3-oxo-octanoyl)-l-homoserine lactone (no absolute correlation between genomospecies of P. syringae and their ability to produce NAHL could be found). Six strains of fluorescent pseudomonads, belonging to the species P. chlororaphis, P. fluorescens, and P. putida, isolated from the plant rhizosphere produced different types of NAHL. In contrast, none of the strains isolated from soil samples were shown to produce NAHL. The gene encoding the NAHL synthase in P. syringae pv. maculicola was isolated by complementation of an NAHL-deficient Chromobacteriummutant. Sequence analysis revealed the existence of aluxI homologue that we named psmI. This gene is sufficient to confer NAHL synthesis upon its bacterial host and has strong homology to psyI and ahlI, two genes involved in NAHL production in P. syringae pv. tabaci and P. syringae pv. syringae, respectively. We identified another open reading frame that we termedpsmR, transcribed convergently in relation topsmI and partly overlapping psmI; this gene encodes a putative LuxR regulatory protein. This gene organization, with luxI and luxRhomologues facing each other and overlapping, has been found so far only in the enteric bacteria Erwinia andPantoea and in the related species P. syringae pv. tabaci.

scholarly journals Cloning and Expression of a Novel NADP(H)-Dependent Daidzein Reductase, an Enzyme Involved in the Metabolism of Daidzein, from Equol-Producing Lactococcus Strain 20-92

2010 ◽  
Vol 76 (17) ◽  
pp. 5892-5901 ◽  
Author(s):  
Yoshikazu Shimada ◽  
Setsuko Yasuda ◽  
Masayuki Takahashi ◽  
Takashi Hayashi ◽  
Norihiro Miyazawa ◽  
...  
Keyword(s):  
Amino Acid ◽  
Enteric Bacteria ◽  
Amino Acid Sequences ◽  
Soy Isoflavones ◽  
Cloning And Expression ◽  
Gene Encoding ◽  
Binding Motifs ◽  
Reading Frame ◽  
Cofactor Binding ◽  
International Patent

ABSTRACT Equol is a metabolite produced from daidzein by enteric microflora, and it has attracted a great deal of attention because of its protective or ameliorative ability against several sex hormone-dependent diseases (e.g., menopausal disorder and lower bone density), which is more potent than that of other isoflavonoids. We purified a novel NADP(H)-dependent daidzein reductase (L-DZNR) from Lactococcus strain 20-92 (Lactococcus 20-92; S. Uchiyama, T. Ueno, and T. Suzuki, international patent WO2005/000042) that is involved in the metabolism of soy isoflavones and equol production and converts daidzein to dihydrodaidzein. Partial amino acid sequences were determined from purified L-DZNR, and the gene encoding L-DZNR was cloned. The nucleotide sequence of this gene consists of an open reading frame of 1,935 nucleotides, and the deduced amino acid sequence consists of 644 amino acids. L-DZNR contains two cofactor binding motifs and an 4Fe-4S cluster. It was further suggested that L-DZNR was an NAD(H)/NADP(H):flavin oxidoreductase belonging to the old yellow enzyme (OYE) family. Recombinant histidine-tagged L-DZNR was expressed in Escherichia coli. The recombinant protein converted daidzein to (S)-dihydrodaidzein with enantioselectivity. This is the first report of the isolation of an enzyme related to daidzein metabolism and equol production in enteric bacteria.

scholarly journals Knot Formation Caused by Pseudomonas syringae subsp. savastanoi on Olive Plants Is hrp-Dependent

2004 ◽  
Vol 94 (5) ◽  
pp. 484-489 ◽  
Author(s):  
A. Sisto ◽  
M. G. Cipriani ◽  
M. Morea
Keyword(s):  
Sequence Analysis ◽  
Pseudomonas Syringae ◽  
Open Reading Frame ◽  
Gene Encoding ◽  
Disease Symptoms ◽  
Phytopathogenic Bacteria ◽  
Reading Frame ◽  
Nonhost Plant ◽  
Induced Mutant

The virulence of Pseudomonas syringae subsp. savastanoi, which causes hyperplastic symptoms (knots) on olive plants, is associated with secreted phytohormones. We identified a Tn5-induced mutant of P. syringae subsp. savastanoi that did not cause disease symptoms on olive plants although it was still able to produce phytohormones. In addition, the mutant failed to elicit a hypersensitive response in a nonhost plant. Molecular characterization of the mutant revealed that a single Tn5 insertion occurred within an open reading frame encoding a protein 92% identical to the HrcC protein of P. syringae pv. syringae. Moreover, sequence analysis revealed that the gene encoding the HrcC protein in P. syringae subsp. savastanoi was part of an operon that included five genes arranged as in other phytopathogenic bacteria. These results imply that hrp/hrc genes are functional in P. syringae subsp. savastanoi and that they play a key role in the pathogenicity of this plant pathogen.

scholarly journals Regulation of AHL Production and Its Contribution to Epiphytic Fitness in Pseudomonas syringae

2004 ◽  
Vol 17 (5) ◽  
pp. 521-531 ◽  
Author(s):  
Beatriz Quiñones ◽  
Catherine J. Pujol ◽  
Steven E. Lindow
Keyword(s):  
Pseudomonas Syringae ◽  
Large Cell ◽  
Homoserine Lactone ◽  
Dependent Manner ◽  
High Cell ◽  
Differential Survival ◽  
Gene Encoding ◽  
Fitness Traits ◽  
Tn5 Mutants ◽  
Cell Concentrations

Pseudomonas syringae forms large cell aggregates that are more stress tolerant than solitary cells during epiphytic growth on plants. The differential survival of aggregates on leaves suggests that epiphytic fitness traits may be controlled in a density-dependent manner via cell-cell signaling. We investigated this hypothesis in P. syringae B728a. Synthesis of N-acyl-homoserine lactone (AHL), 3-oxo-hexanoyl homo-serine lactone, and the expression of the gene encoding AHL synthase ahlI were maximal at high cell concentrations. The expression of the AHL regulator ahlR, in contrast, was similar at all cell concentrations. A screen of Tn5 mutants revealed that P. syringae B728a requires a novel transcriptional activator for AHL production. This regulator, which belongs to the TetR family, was also required for epiphytic fitness and has been designated AefR (for AHL and epiphytic fitness regulator). The expression of ahlI was greatly reduced in both aefR¯ and gacA¯ mutants and was completely restored in either mutant after addition of exogenous AHL. In contrast, the expression of aefR was not reduced in either gacS¯ or gacA¯ mutants. Thus, AefR appears to positively regulate AHL production independently of the regulators GacS/GacA and also controls traits in P. syringae B728a that are required for epiphytic colonization.

scholarly journals Cloning and Characterization of the Genes Encoding a Cytochrome P450 (PipA) Involved in Piperidine and Pyrrolidine Utilization and Its Regulatory Protein (PipR) in Mycobacterium smegmatis mc2155

1999 ◽  
Vol 181 (11) ◽  
pp. 3419-3426 ◽  
Author(s):  
Pascal Poupin ◽  
Véronique Ducrocq ◽  
Sylvie Hallier-Soulier ◽  
Nicole Truffaut
Keyword(s):  
Cytochrome P450 ◽  
Mycobacterium Smegmatis ◽  
Regulatory Protein ◽  
Gene Replacement ◽  
Open Reading Frames ◽  
Cytochrome P450 Enzyme ◽  
Insertion Element ◽  
Gene Encoding ◽  
Reading Frame ◽  
New Family

ABSTRACT Transposon mutagenesis of Mycobacterium smegmatismc2155 enabled the isolation of a mutant strain (called LGM1) altered in the regulation of piperidine and pyrrolidine utilization. The complete nucleotide sequence of the gene inactivated in mutant LGM1 was determined from the wild-type strain. This gene (pipR) encoded a member of the GntR family of bacterial regulatory proteins. An insertion element (IS1096), previously described for M. smegmatis, was detected downstream of the gene pipR. Three additional open reading frames were found downstream of IS1096. The first open reading frame (pipA) appeared to encode a protein identified as a cytochrome P450 enzyme. This gene is the first member of a new family, CYP151. By a gene replacement experiment, it was demonstrated that the cytochrome P450 pipA gene is required for piperidine and pyrrolidine utilization in M. smegmatis mc2155. Genes homologous topipA were detected by hybridization in several, previously isolated, morpholine-degrading mycobacterial strains. A gene encoding a putative [3Fe-4S] ferredoxin (orf1) and a truncated gene encoding a putative glutamine synthetase (orf2′) were found downstream of pipA.

scholarly journals OpaR, a Homolog of Vibrio harveyi LuxR, Controls Opacity of Vibrio parahaemolyticus

1998 ◽  
Vol 180 (12) ◽  
pp. 3166-3173 ◽  
Author(s):  
Linda L. McCarter
Keyword(s):  
Vibrio Parahaemolyticus ◽  
Vibrio Harveyi ◽  
Regulatory Protein ◽  
Cell Types ◽  
Colony Morphology ◽  
Genomic Alteration ◽  
Gene Encoding ◽  
Reading Frame ◽  
Large Gene ◽  
Transcriptional Regulatory

ABSTRACT Vibrio parahaemolyticus is an organism well adapted to communal life on surfaces. When grown on a surface or in a viscous layer, the bacterium induces a large gene system and differentiates to swarmer cells capable of movement over and colonization of surfaces.V. parahaemolyticus displays additional phenotypic versatility manifested as variable colony morphology, switching between translucent and opaque colony types. Although not itself luminescent,V. parahaemolyticus produces autoinducer molecules capable of inducing luminescence in Vibrio harveyi. To examine the role of quorum signaling in the lifestyles of V. parahaemolyticus, the functional homolog of the gene encoding theV. harveyi autoinducer-controlled transcriptional regulatory protein LuxR was cloned. Sequence analysis of the clone predicted an open reading frame with a deduced product 96% identical to LuxR. Introduction of the clone carrying the luxR-like locus into V. parahaemolyticus dramatically affected colony morphology, converting a translucent strain to an opaque one. When the coding sequence for the luxR homolog was placed under the control of the Ptac promoter, conversion to the opaque phenotype became inducible by isopropyl-β-d-thiogalactopyranoside. Allelic disruption of the luxR-like gene on the chromosome of an opaque strain produced a translucent strain proficient in swarming ability. Primer extension mapping demonstrated opaRtranscription in opaque but not translucent cell types. It is postulated that this gene, which has been named opaR, encodes a transcription factor controlling cell type. The underlying genetic basis for opaque-translucent variation may be the consequence of a genomic alteration detected in the opaR locus of opaque and translucent strains.

Mutagenic DNA repair potential in Pseudomonas spp., and characterization of the rulABPc operon from the highly mutable strain Pseudomonas cichorii 302959

2004 ◽  
Vol 50 (1) ◽  
pp. 29-39 ◽  
Author(s):  
Shouan Zhang ◽  
George W Sundin
Keyword(s):  
Dna Repair ◽  
Pseudomonas Syringae ◽  
Burkholderia Cepacia ◽  
Phylogenetic Analyses ◽  
Acid Resistance ◽  
Enteric Bacteria ◽  
Ultraviolet B ◽  
Pseudomonas Cichorii ◽  
Pseudomonas Spp ◽  
Mutagenic Dna Repair

We assessed the tolerance to ultraviolet B (UVB; 290-320 nm) radiation and UVB-induced mutability in 28 Pseudomonas spp. and four Burkholderia cepacia strains. The UVB survival of 23 (72%) of the strains was elevated (>46% survival following irradiation with a 2250 J m-2 dose), and 17 (53%) strains were defined as mutable by UVB. A mutagenic DNA repair determinant was cloned and characterized from the highly mutable strain P. cichorii 302959 and shown by sequence analysis to be an allele of rulAB, a mutagenic DNA repair determinant previously characterized from Pseudomonas syringae. Phylogenetic analyses of RulA- and RulB-related sequences indicated that the sequences identified in environmental bacteria shared a common ancestor with UmuDC-like sequences from enteric bacteria but were considerably diverged. The dynamics of UVB-induced mutability to nalidixic acid resistance (NalR) and rifampicin resistance (RifR) were studied in replicate populations of P. cichorii 302959 subjected to a daily UVB dose of 2250 J m-2 for 14 consecutive days. While there was an initial spike in the frequency of NalR and RifR mutants recovered on Days 1 and 2 of two separate experiments, the frequencies were sharply reduced and then fluctuated throughout the duration of both experiments. These experimental results are intriguing because they point to the possibility that P. cichorii possesses additional mechanisms to curtail the induction of spontaneous mutants following repeated episodes of UVB irradiation.Key words: phyllosphere, UVB survival, UVB mutability, long-term mutability, translesion synthesis, Y family DNA polymerase.

scholarly journals GIT1, a Gene Encoding a Novel Transporter for Glycerophosphoinositol in Saccharomyces cerevisiae

Genetics ◽  
1998 ◽  
Vol 149 (4) ◽  
pp. 1707-1715 ◽  
Author(s):  
J L Patton-Vogt ◽  
S A Henry
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Regulatory Gene ◽  
Sugar Transport ◽  
Open Reading Frame ◽  
Gene Encoding ◽  
Reading Frame ◽  
Membrane Spanning ◽  
Membrane Spanning Domains ◽  
Uptake And Metabolism ◽  
Cells Cultured

Abstract Phosphatidylinositol catabolism in Saccharomyces cerevisiae cells cultured in media containing inositol results in the release of glycerophosphoinositol (GroPIns) into the medium. As the extracellular concentration of inositol decreases with growth, the released GroPIns is transported back into the cell. Exploiting the ability of the inositol auxotroph, ino1, to use exogenous GroPIns as an inositol source, we have isolated mutants (Git−) defective in the uptake and metabolism of GroPIns. One mutant was found to be affected in the gene encoding the transcription factor, SPT7. Mutants of the positive regulatory gene INO2, but not of its partner, INO4, also have the Git− phenotype. Another mutant was complemented by a single open reading frame (ORF) termed GIT1 (glycerophosphoinositol). This ORF consists of 1556 bp predicted to encode a polypeptide of 518 amino acids and 57.3 kD. The predicted Git1p has similarity to a variety of S. cerevisiae transporters, including a phosphate transporter (Pho84p), and both inositol transporters (Itr1p and Itr2p). Furthermore, Git1p contains a sugar transport motif and 12 potential membrane-spanning domains. Transport assays performed on a git1 mutant together with the above evidence indicate that the GIT1 gene encodes a permease involved in the uptake of GroPIns.

scholarly journals Global versus Local Regulatory Roles for Lrp-Related Proteins: Haemophilus influenzae as a Case Study

2001 ◽  
Vol 183 (13) ◽  
pp. 4004-4011 ◽  
Author(s):  
Devorah Friedberg ◽  
Michael Midkiff ◽  
Joseph M. Calvo
Keyword(s):  
Amino Acid ◽  
Haemophilus Influenzae ◽  
Regulatory Protein ◽  
Enteric Bacteria ◽  
Regulatory Role ◽  
Regulatory Function ◽  
Ecological Niches ◽  
E Coli ◽  
Sequence Identity ◽  
Related Proteins

ABSTRACT Lrp (leucine-responsive regulatory protein) plays a global regulatory role in Escherichia coli, affecting expression of dozens of operons. Numerous lrp-related genes have been identified in different bacteria and archaea, includingasnC, an E. coli gene that was the first reported member of this family. Pairwise comparisons of amino acid sequences of the corresponding proteins shows an average sequence identity of only 29% for the vast majority of comparisons. By contrast, Lrp-related proteins from enteric bacteria show more than 97% amino acid identity. Is the global regulatory role associated withE. coli Lrp limited to enteric bacteria? To probe this question we investigated LrfB, an Lrp-related protein fromHaemophilus influenzae that shares 75% sequence identity with E. coli Lrp (highest sequence identity among 42 sequences compared). A strain of H. influenzae having anlrfB null allele grew at the wild-type growth rate but with a filamentous morphology. A comparison of two-dimensional (2D) electrophoretic patterns of proteins from parent and mutant strains showed only two differences (comparable studies withlrp + and lrp E. coli strains by others showed 20 differences). The abundance of LrfB in H. influenzae, estimated by Western blotting experiments, was about 130 dimers per cell (compared to 3,000 dimers per E. colicell). LrfB expressed in E. coli replaced Lrp as a repressor of the lrp gene but acted only to a limited extent as an activator of the ilvIH operon. Thus, although LrfB resembles Lrp sufficiently to perform some of its functions, its low abundance is consonant with a more local role in regulating but a few genes, a view consistent with the results of the 2D electrophoretic analysis. We speculate that an Lrp having a global regulatory role evolved to help enteric bacteria adapt to their ecological niches and that it is unlikely that Lrp-related proteins in other organisms have a broad regulatory function.

scholarly journals Phenotypically and Genotypically Heterogeneous Strains of Pseudomonas syringae Associated With Alfalfa Leaf Spot Disease in Iran

Plant Disease ◽  
2019 ◽  
Vol 103 (12) ◽  
pp. 3199-3208 ◽  
Author(s):  
Maryam Ansari ◽  
S. Mohsen Taghavi ◽  
Sadegh Zarei ◽  
Soraya Mehrb-Moghadam ◽  
Hamzeh Mafakheri ◽  
...  
Keyword(s):  
Host Range ◽  
Pseudomonas Syringae ◽  
Leaf Spot ◽  
Phylogenetic Analyses ◽  
Housekeeping Genes ◽  
Pcr Primers ◽  
Phylogenetic Position ◽  
Leaf Spot Disease ◽  
Bacterial Strains ◽  
Alfalfa Leaf

In this study, we provide a polyphasic characterization of 18 Pseudomonas spp. strains associated with alfalfa leaf spot symptoms in Iran. All of the strains were pathogenic on alfalfa, although the aggressiveness and symptomology varied among the strains. All strains but one were pathogenic on broad bean, cucumber, honeydew, and zucchini, whereas only a fraction of the strains were pathogenic on sugar beet, tomato, and wheat. Syringomycin biosynthesis genes (syrB1 and syrP) were detected using the corresponding PCR primers in all of the strains isolated from alfalfa. Phylogenetic analyses using the sequences of four housekeeping genes (gapA, gltA, gyrB, and rpoD) revealed that all of the strains except one (Als34) belong to phylogroup 2b of P. syringae sensu lato, whereas strain Als34 placed within phylogroup 1 close to the type strain of P. syringae pv. apii. Among the phylogroup 2b strains, nine strains were phylogenetically close to the P. syringae pv. aptata clade, whereas the remainder were scattered among P. syringae pv. atrofaciens and P. syringae pv. syringae strains. Pathogenicity and host range assays of the bacterial strains evaluated in this study on a set of taxonomically diverse plant species did not allow us to assign a “pathovar” status to the alfalfa strains. However, these results provide novel insight into the host range and phylogenetic position of the alfalfa-pathogenic members of P. syringae sensu lato, and they reveal that phenotypically and genotypically heterogeneous strains of the pathogen cause bacterial leaf spot of alfalfa.

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