scholarly journals Characterization of Regulatory Pathways in Xylella fastidiosa: Genes and Phenotypes Controlled by algU

2007 ◽  
Vol 73 (21) ◽  
pp. 6748-6756 ◽  
Author(s):  
Xiang Yang Shi ◽  
C. Korsi Dumenyo ◽  
Rufina Hernandez-Martinez ◽  
Hamid Azad ◽  
Donald A. Cooksey
Keyword(s):  
Microarray Analysis ◽  
Biofilm Formation ◽  
Xylella Fastidiosa ◽  
Bacterial Pathogens ◽  
Regulatory Gene ◽  
Cell Aggregation ◽  
Wild Type ◽  
Regulatory Pathways ◽  
In The Wild ◽  
Bacterial Mutants

ABSTRACT Many virulence genes in plant bacterial pathogens are coordinately regulated by “global” regulatory genes. Conducting DNA microarray analysis of bacterial mutants of such genes, compared with the wild type, can help to refine the list of genes that may contribute to virulence in bacterial pathogens. The regulatory gene algU, with roles in stress response and regulation of the biosynthesis of the exopolysaccharide alginate in Pseudomonas aeruginosa and many other bacteria, has been extensively studied. The role of algU in Xylella fastidiosa, the cause of Pierce's disease of grapevines, was analyzed by mutation and whole-genome microarray analysis to define its involvement in aggregation, biofilm formation, and virulence. In this study, an algU::nptII mutant had reduced cell-cell aggregation, attachment, and biofilm formation and lower virulence in grapevines. Microarray analysis showed that 42 genes had significantly lower expression in the algU::nptII mutant than in the wild type. Among these are several genes that could contribute to cell aggregation and biofilm formation, as well as other physiological processes such as virulence, competition, and survival.

scholarly journals Hik36–Hik43 and Rre6 act as a two-component regulatory system to control cell aggregation in Synechocystis sp. PCC6803

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Kota Kera ◽  
Yuichiro Yoshizawa ◽  
Takehiro Shigehara ◽  
Tatsuya Nagayama ◽  
Masaru Tsujii ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Morphological Changes ◽  
Response Regulator ◽  
Control Cell ◽  
Regulatory System ◽  
Cell Aggregation ◽  
Wild Type ◽  
Type Iv ◽  
Two Component ◽  
In The Wild

Abstract In response to environmental stress the model cyanobacterium, Synechocystis sp. PCC6803 can switch from a planktonic state to autoaggregation and biofilm formation. The precise mechanism of this transition remains unknown. Here we investigated the role of a candidate two-component regulatory system (TCS) in controlling morphological changes, as a way to understand the intermediate molecular steps that are part of the signaling pathway. A bacterial two-hybrid assay showed that the response regulator Rre6 formed a TCS together with a split histidine kinase consisting of Hik36 and Hik43. Individual disruption mutants displayed autoaggregation in a static culture. In contrast, unlike in the wild type, high salinity did not induce biofilm formation in Δhik36, Δhik43 and Δrre6. The expression levels of exopolysaccharide (EPS) production genes were higher in Δhik36 and Δhik43, compared with the wild type, but lower in Δrre6, suggesting that the TCS regulated EPS production in Synechocystis. Rre6 interacted physically with the motor protein PilT2, that is a component of the type IV pilus system. This interaction was enhanced in a phosphomimic version of Rre6. Taken together, Hik36–Hik43–Rre6 function as an upstream component of the pili-related signal transduction cascade and control the prevention of cell adhesion and biofilm formation.

scholarly journals Characterization of Regulatory Pathways in Xylella fastidiosa: Genes and Phenotypes Controlled by gacA

2009 ◽  
Vol 75 (8) ◽  
pp. 2275-2283 ◽  
Author(s):  
Xiang Yang Shi ◽  
C. Korsi Dumenyo ◽  
Rufina Hernandez-Martinez ◽  
Hamid Azad ◽  
Donald A. Cooksey
Keyword(s):  
Pseudomonas Syringae ◽  
Biofilm Formation ◽  
Xylella Fastidiosa ◽  
Cell Aggregation ◽  
Toxin Gene ◽  
Tomato Dc3000 ◽  
Disease Symptoms ◽  
Regulatory Pathways ◽  
Physiological Processes

ABSTRACT The xylem-limited, insect-transmitted bacterium Xylella fastidiosa causes Pierce's disease in grapes through cell aggregation and vascular clogging. GacA controls various physiological processes and pathogenicity factors in many gram-negative bacteria, including biofilm formation in Pseudomonas syringae pv. tomato DC3000. Cloned gacA of X. fastidiosa was found to restore the hypersensitive response and pathogenicity in gacA mutants of P. syringae pv. tomato DC3000 and Erwinia amylovora. A gacA mutant of X. fastidiosa (DAC1984) had significantly reduced abilities to adhere to a glass surface, form biofilm, and incite disease symptoms on grapevines, compared with the parent (A05). cDNA microarray analysis identified 7 genes that were positively regulated by GacA, including xadA and hsf, predicted to encode outer membrane adhesion proteins, and 20 negatively regulated genes, including gumC and an antibacterial polypeptide toxin gene, cvaC. These results suggest that GacA of X. fastidiosa regulates many factors, which contribute to attachment and biofilm formation, as well as some physiological processes that may enhance the adaptation and tolerance of X. fastidiosa to environmental stresses and the competition within the host xylem.

scholarly journals Spermidine Inversely Influences Surface Interactions and Planktonic Growth in Agrobacterium tumefaciens

2016 ◽  
Vol 198 (19) ◽  
pp. 2682-2691 ◽  
Author(s):  
Yi Wang ◽  
Sok Ho Kim ◽  
Ramya Natarajan ◽  
Jason E. Heindl ◽  
Eric L. Bruger ◽  
...  
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Biofilm Formation ◽  
Direct Synthesis ◽  
Wild Type ◽  
Cyclic Diguanylate ◽  
Content Type ◽  
Exogenous Addition ◽  
In The Wild ◽  
Growth Requirement ◽  
Transposon Insertions

ABSTRACTIn bacteria, the functions of polyamines, small linear polycations, are poorly defined, but these metabolites can influence biofilm formation in several systems. Transposon insertions in an ornithine decarboxylase (odc) gene inAgrobacterium tumefaciens, predicted to direct synthesis of the polyamine putrescine from ornithine, resulted in elevated cellulose. Null mutants forodcgrew somewhat slowly in a polyamine-free medium but exhibited increased biofilm formation that was dependent on cellulose production. Spermidine is an essential metabolite inA. tumefaciensand is synthesized from putrescine inA. tumefaciensvia the stepwise actions of carboxyspermidine dehydrogenase (CASDH) and carboxyspermidine decarboxylase (CASDC). Exogenous addition of either putrescine or spermidine to theodcmutant returned biofilm formation to wild-type levels. Low levels of exogenous spermidine restored growth to CASDH and CASDC mutants, facilitating weak biofilm formation, but this was dampened with increasing concentrations. Norspermidine rescued growth for theodc, CASDH, and CASDC mutants but did not significantly affect their biofilm phenotypes, whereas in the wild type, it stimulated biofilm formation and depressed spermidine levels. Theodcmutant produced elevated levels of cyclic diguanylate monophosphate (c-di-GMP), exogenous polyamines modulated these levels, and expression of a c-di-GMP phosphodiesterase reversed the enhanced biofilm formation. Prior work revealed accumulation of the precursors putrescine and carboxyspermidine in the CASDH and CASDC mutants, respectively, but unexpectedly, both mutants accumulated homospermidine; here, we show that this requires a homospermidine synthase (hss) homologue.IMPORTANCEPolyamines are small, positively charged metabolites that are nearly ubiquitous in cellular life. They are often essential in eukaryotes and more variably in bacteria. Polyamines have been reported to influence the surface-attached biofilm formation of several bacteria. InAgrobacterium tumefaciens, mutants with diminished levels of the polyamine spermidine are stimulated for biofilm formation, and exogenous provision of spermidine decreases biofilm formation. Spermidine is also essential forA. tumefaciensgrowth, but the related polyamine norspermidine exogenously rescues growth and does not diminish biofilm formation, revealing that the growth requirement and biofilm control are separable. Polyamine control of biofilm formation appears to function via effects on the cellular second messenger cyclic diguanylate monophosphate, regulating the transition from a free-living to a surface-attached lifestyle.

A role for rhamnolipid in biofilm dispersion

Biofilms ◽  
2004 ◽  
Vol 1 (2) ◽  
pp. 91-99 ◽  
Author(s):  
S. R. Schooling ◽  
U. K. Charaf ◽  
D. G. Allison ◽  
P. Gilbert
Keyword(s):  
Surface Tension ◽  
Quorum Sensing ◽  
Biofilm Formation ◽  
Culture Medium ◽  
High Cell Density ◽  
Culture Media ◽  
Homoserine Lactone ◽  
Wild Type ◽  
In The Wild ◽  
Biofilm Dispersion

Biofilms are often considered as localized zones of high cell density. Quorum sensing provides a means for control of population processes and has been implicated in the regulation of biofilm activities. We present a role for quorum sensing in programmed detachment and dispersal processes. Biofilms of Pseudomonas aeruginosa PAO1 and its isogenic homoserine lactone (HSL) mutant P. aeruginosa PAO-JP2 were grown in batch culture on glass substrata; differences were found in the rate and extent of formation of biofilm. Climax communities were observed for PAO1 at 24 h. These were later accompanied by foaming, a drop in the surface tension of culture media and dispersal of the biofilm, after which no subsequent biofilm accretion occurred. PAO-JP2 cultures reformed biofilm post-detachment and did not foam. Prevention of biofilm reformation in the wild type was related to some component excreted into the culture medium. Rhamnolipid, a biosurfactant regulated by quorum sensing, was detected in PAO1 cultures. When rhamnolipid was added to freshly inoculated substrata, biofilm formation was inhibited. At 20 h, PAO1 biofilms were transferred to medium with added rhamnolipid: biofilm was relatively unaffected. Biofilm events were also studied in medium supplemented with N-butyryl-L-homoserine lactone, which is involved in the regulation of rhamnolipid synthesis. Both strains exhibited similar trends of rapid biofilm formation and dramatic changes in the rate and extent of biofilm accretion. In both cases, there was premature foaming, lowered surface tension and elevated rhamnolipid levels. A role for HSLs in maintenance of biofilm and events leading to dispersion of cells is proposed. This role would encompass dispersion but not necessarily detachment of cells from biofilm and supports a new function for rhamnolipid in pathogenesis, whereby rhamnolipid would promote the dissemination of cells from a nidus of infection.

scholarly journals Proteins Associated with the Myxococcus xanthus Extracellular Matrix

2007 ◽  
Vol 189 (21) ◽  
pp. 7634-7642 ◽  
Author(s):  
Patrick D. Curtis ◽  
James Atwood ◽  
Ron Orlando ◽  
Lawrence J. Shimkets
Keyword(s):  
Extracellular Matrix ◽  
Biofilm Formation ◽  
Myxococcus Xanthus ◽  
Sodium Dodecyl ◽  
Wild Type ◽  
Fruiting Body Formation ◽  
Ecm Proteins ◽  
Chromatography Tandem Mass Spectrometry ◽  
Liquid Chromatography Tandem Mass ◽  
In The Wild

ABSTRACT Fruiting body formation of Myxococcus xanthus, like biofilm formation of many other organisms, involves the production of an extracellular matrix (ECM). While the polysaccharide component has been studied, the protein component has been largely unexplored. Proteins associated with the ECM were solubilized from purified ECM by boiling with sodium dodecyl sulfate and were identified by liquid chromatography-tandem mass spectrometry of tryptic fragments. The ECM is enriched in proteins of novel function; putative functions were assigned for only 5 of the 21 proteins. Thirteen putative ECM proteins had lipoprotein secretion signals. The genes for many ECM proteins were disrupted in the wild-type (WT), fibA, and pilA backgrounds. Disruption of the MXAN4860 gene had no effect in the WT or fibA background but in the pilA background resulted in a 24-h delay in aggregation and sporulation compared to its parent. The results of this study show that the M. xanthus ECM proteome is diverse and novel.

scholarly journals Regulation of Hydrogen Peroxide-Dependent Gene Expression in Rhodobacter sphaeroides: Regulatory Functions of OxyR

2007 ◽  
Vol 189 (10) ◽  
pp. 3784-3792 ◽  
Author(s):  
Tanja Zeller ◽  
Mobarak A. Mraheil ◽  
Oleg V. Moskvin ◽  
Kuanyu Li ◽  
Mark Gomelsky ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Rhodobacter Sphaeroides ◽  
Expression Patterns ◽  
Class Iii ◽  
Wild Type ◽  
Binding Studies ◽  
Regulatory Pathways ◽  
Mutant Strains ◽  
In The Wild

ABSTRACT Genome-wide transcriptome profiling was used to reveal hydrogen peroxide (H2O2)-dependent regulatory mechanisms in the facultatively photosynthetic bacterium Rhodobacter sphaeroides. In this study we focused on the role of the OxyR protein, a known regulator of the H2O2 response in bacteria. The transcriptome profiles of R. sphaeroides wild-type and oxyR mutant strains that were exposed to 1 mM H2O2 for 7 min or were not exposed to H2O2 were analyzed. Three classes of OxyR-dependent genes were identified based on their expression patterns in the wild type of oxyR mutant strains with differing predicted roles of oxidized and reduced OxyR as activators of transcription. DNA binding studies revealed that OxyR binds upstream of class I genes, which are induced by H2O2 and exhibit similar basal levels of expression in the wild-type and oxyR mutant strains. The effect of OxyR on class II genes, which are also induced by H2O2 but exhibit significantly lower basal levels of expression in the wild-type strain than in the mutant, is indirect. Interestingly, reduced OxyR also activates expression of few genes (class III). The role of reduced OxyR as an activator is shown for the first time. Our data reveal that the OxyR-mediated response is fast and transient. In addition, we found that additional regulatory pathways are involved in the H2O2 response.

scholarly journals Crp-Like Protein Plays Both Positive and Negative Roles in Regulating the Pathogenicity of Bacterial Pustule Pathogen Xanthomonas axonopodis pv. glycines

2019 ◽  
Vol 109 (7) ◽  
pp. 1171-1183 ◽  
Author(s):  
Wei Guo ◽  
Jie Gao ◽  
Qingshan Chen ◽  
Bojun Ma ◽  
Yuan Fang ◽  
...  
Keyword(s):  
Cell Motility ◽  
Biofilm Formation ◽  
Type Strain ◽  
Wild Type Strain ◽  
Extracellular Polysaccharide ◽  
Polymerase Chain Reaction Analysis ◽  
Single Copy ◽  
Wild Type ◽  
Cell Wall Degrading Enzymes ◽  
In The Wild

The global regulator Crp-like protein (Clp) is positively involved in the production of virulence factors in some of the Xanthomonas spp. However, the functional importance of Clp in X. axonopodis pv. glycines has not been investigated previously. Here, we showed that deletion of clp led to significant reduction in the virulence of X. axonopodis pv. glycines in soybean, which was highly correlated with the drastic reductions in carbohydrates utilization, extracellular polysaccharide (EPS) production, biofilm formation, cell motility, and synthesis of cell wall degrading enzymes (CWDEs). These significantly impaired properties in the clp mutant were completely rescued by a single-copy integration of the wild-type clp into the mutant chromosome via homologous recombination. Interestingly, overexpression of clp in the wild-type strain resulted in significant increases in cell motility and synthesis of the CWDEs. To our surprise, significant reductions in carbohydrates utilization, EPS production, biofilm formation, and the protease activity were observed in the wild-type strain overexpressing clp, suggesting that Clp also plays a negative role in these properties. Furthermore, quantitative reverse transcription polymerase chain reaction analysis suggested that clp was positively regulated by the diffusible signal factor-mediated quorum-sensing system and the HrpG/HrpX cascade. Taken together, our results reveal that Clp functions as both activator and repressor in multiple biological processes in X. axonopodis pv. glycines that are essential for its full virulence.

scholarly journals Genome-Wide Evaluation of the Interplay between Caenorhabditis elegans and Yersinia pseudotuberculosis duringIn VivoBiofilm Formation

2014 ◽  
Vol 83 (1) ◽  
pp. 17-27 ◽  
Author(s):  
George W. P. Joshua ◽  
Steve Atkinson ◽  
Robert J. Goldstone ◽  
Hannah L. Patrick ◽  
Richard A. Stabler ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Biofilm Formation ◽  
Yersinia Pseudotuberculosis ◽  
Regulatory Gene ◽  
Transcriptomic Analysis ◽  
Wild Type ◽  
Content Type ◽  
C Elegans ◽  
Regulatory Cascade ◽  
Genome Wide

The formation of an incapacitating biofilm onCaenorhabditis elegansbyYersinia pseudotuberculosisrepresents a tractable model for investigating the genetic basis for host-pathogen interplay during the biofilm-mediated infection of a living surface. Previously we established a role for quorum sensing (QS) and the master motility regulator, FlhDC, in biofilm formation byY. pseudotuberculosisonC. elegans. To obtain further genome-wide insights, we used transcriptomic analysis to obtain comparative information onC. elegansin the presence and absence of biofilm and on wild-typeY. pseudotuberculosisandY. pseudotuberculosisQS mutants. Infection ofC. eleganswith the wild-typeY. pseudotuberculosisresulted in the differential regulation of numerous genes, including a distinct subset of nematode C-lectin (clec) and fatty acid desaturase (fat) genes. Evaluation of the correspondingC. elegansclec-49andfat-3deletion mutants showed delayed biofilm formation and abolished biofilm formation, respectively. Transcriptomic analysis ofY. pseudotuberculosisrevealed that genes located in both of the histidine utilization (hut) operons were upregulated in both QS andflhDCmutants. In addition, mutation of the regulatory genehutCresulted in the loss of biofilm, increased expression offlhDC, and enhanced swimming motility. These data are consistent with the existence of a regulatory cascade in which the Hut pathway links QS andflhDC. This work also indicates that biofilm formation byY. pseudotuberculosisonC. elegansis an interactive process during which the initial attachment/recognition ofYersiniato/byC. elegansis followed by bacterial growth and biofilm formation.

scholarly journals Involvement of Stress-Related GenespolBandPA14_46880in Biofilm Formation of Pseudomonas aeruginosa

2014 ◽  
Vol 82 (11) ◽  
pp. 4746-4757 ◽  
Author(s):  
Sahar A. Alshalchi ◽  
Gregory G. Anderson
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Acute Infection ◽  
Regulatory Gene ◽  
Chronic Infections ◽  
Content Type ◽  
Abiotic Surfaces ◽  
Mutant Strains ◽  
In The Wild ◽  
Airway Cells

ABSTRACTChronic infections ofPseudomonas aeruginosaare generally established through production of biofilm. During biofilm formation, production of an extracellular matrix and establishment of a distinct bacterial phenotype make these infections difficult to eradicate. However, biofilm studies have been hampered by the fact that most assays utilize nonliving surfaces as biofilm attachment substrates. In an attempt to better understand the mechanisms behindP. aeruginosabiofilm formation, we performed a genetic screen to identify novel factors involved in biofilm formation on biotic and abiotic surfaces. We found that deletion of genespolBandPA14_46880reduced biofilm formation significantly compared to that in the wild-type strain PA14 in an abiotic biofilm system. In a biotic biofilm model, wherein biofilms form on cultured airway cells, the ΔpolBand ΔPA14_46880strains showed increased cytotoxic killing of the airway cells independent of the total number of bacteria bound. Notably, deletion mutant strains were more resistant to ciprofloxacin treatment. This phenotype was linked to decreased expression ofalgR, an alginate transcriptional regulatory gene, under ciprofloxacin pressure. Moreover, we found that pyocyanin production was increased in planktonic cells of mutant strains. These results indicate that inactivation ofpolBandPA14_46880may inhibit transition ofP. aeruginosafrom a more acute infection lifestyle to the biofilm phenotype. Future investigation of these genes may lead to a better understanding ofP. aeruginosabiofilm formation and chronic biofilm infections.

scholarly journals Role of Cyclic di-GMP in Xylella fastidiosa Biofilm Formation, Plant Virulence, and Insect Transmission

2010 ◽  
Vol 23 (10) ◽  
pp. 1356-1363 ◽  
Author(s):  
Subhadeep Chatterjee ◽  
Nabil Killiny ◽  
Rodrigo P. P. Almeida ◽  
Steven E. Lindow
Keyword(s):  
Cell Density ◽  
Intracellular Signaling ◽  
Biofilm Formation ◽  
Extracellular Enzymes ◽  
Xylella Fastidiosa ◽  
Amorphous Layer ◽  
Extracellular Polysaccharides ◽  
Wild Type ◽  
A Cell

Xylella fastidiosa must coordinately regulate a variety of traits contributing to biofilm formation, host plant and vector colonization, and transmission between plants. Traits such as production of extracellular polysaccharides (EPS), adhesins, extracellular enzymes, and pili are expressed in a cell-density-dependent fashion mediated by a cell-to-cell signaling system involving a fatty acid diffusible signaling factor (DSF). The expression of gene PD0279 (which has a GGDEF domain) is downregulated in the presence of DSF and may be involved in intracellular signaling by modulating the levels of cyclic di-GMP. PD0279, designated cyclic di-GMP synthase A (cgsA), is required for biofilm formation, plant virulence, and vector transmission. cgsA mutants exhibited a hyperadhesive phenotype in vitro and overexpressed gumJ, hxfA, hxfB, xadA, and fimA, which promote attachment of cells to surfaces and, hence, biofilm formation. The mutants were greatly reduced in virulence to grape albeit still transmissible by insect vectors, although at a reduced level compared with transmission rates of the wild-type strain, despite the fact that similar numbers of cells of the cgsA mutant were acquired by the insects from infected plants. High levels of EPS were measured in cgsA mutants compared with wild-type strains, and scanning electron microscopy analysis also revealed a thicker amorphous layer surrounding the mutants. Overexpression of cgsA in a cgsA-complemented mutant conferred the opposite phenotypes in vitro. These results suggest that decreases of cyclic di-GMP result from the accumulation of DSF as cell density increases, leading to a phenotypic transition from a planktonic state capable of colonizing host plants to an adhesive state that is insect transmissible.

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