scholarly journals hpaR, a Putative marR Family Transcriptional Regulator, Is Positively Controlled by HrpG and HrpX and Involved in the Pathogenesis, Hypersensitive Response, and Extracellular Protease Production of Xanthomonas campestris Pathovar campestris

2006 ◽  
Vol 189 (5) ◽  
pp. 2055-2062 ◽  
Author(s):  
Ke Wei ◽  
Dong-Jie Tang ◽  
Yong-Qiang He ◽  
Jia-Xun Feng ◽  
Bo-Le Jiang ◽  
...  
Keyword(s):  
Hypersensitive Response ◽  
Xanthomonas Campestris ◽  
Transcriptional Regulator ◽  
Transcriptional Regulators ◽  
Extracellular Protease ◽  
Protease Production ◽  
Phytopathogenic Bacterium ◽  
Cellular Processes ◽  
Glucuronidase Activity ◽  
Nonhost Plant

ABSTRACT The MarR family of transcriptional regulators of bacteria are involved in the regulation of many cellular processes, including pathogenesis. In this work, we have demonstrated genetically that hpaR (hpa, hrp associated), which encodes a putative MarR family regulator, is involved in the hypersensitive response (HR), pathogenicity, and extracellular protease production of the phytopathogenic bacterium Xanthomonas campestris pathovar campestris. A mutation in hpaR resulted in complete loss of virulence in the host plant cabbage, a delayed and weakened HR in the nonhost plant pepper ECW-10R, and an increase in extracellular protease production. Detection of the β-glucuronidase activity of a plasmid-driven hpaR promoter-gusA reporter revealed that the expression of hpaR is positively controlled by HrpG and HrpX and is suppressed in rich medium while being strongly induced in minimal and hrp-inducing media and inside the host. These findings indicate that hpaR belongs to the hrpG and hrpX regulon and that HrpX regulates the extracellular protease production via hpaR in X. campestris pv. campestris.

scholarly journals Identification of Two Novelhrp-Associated Genes in the hrp Gene Cluster ofXanthomonas oryzae pv. oryzae

2000 ◽  
Vol 182 (7) ◽  
pp. 1844-1853 ◽  
Author(s):  
Weiguang Zhu ◽  
Mark M. MaGbanua ◽  
Frank F. White
Keyword(s):  
Nucleotide Sequence ◽  
Gene Cluster ◽  
Hypersensitive Response ◽  
Xanthomonas Campestris ◽  
Host Plants ◽  
Xanthomonas Oryzae ◽  
Insertion Element ◽  
Nonhost Plant ◽  
Rice Leaves ◽  
Glycine Rich Protein

ABSTRACT We have cloned a hrp gene cluster fromXanthomonas oryzae pv. oryzae. Bacteria with mutations in the hrp region have reduced growth in rice leaves and lose the ability to elicit a hypersensitive response (HR) on the appropriate resistant cultivars of rice and the nonhost plant tomato. A 12,165-bp portion of nucleotide sequence from the presumed left end and extending through the hrpB operon was determined. The region was most similar to hrp genes from Xanthomonas campestris pv. vesicatoria and Ralstonia solanacearum. Two new hrp-associated loci, namedhpa1 and hpa2, were located beyond thehrpA operon. The hpa1 gene encoded a 13-kDa glycine-rich protein with a composition similar to those of harpins and PopA. The product of hpa2 was similar to lysozyme-like proteins. Perfect PIP boxes were present in the hrpB andhpa1 operons, while a variant PIP box was located upstream of hpa2. A strain with a deletion encompassinghpa1 and hpa2 had reduced pathogenicity and elicited a weak HR on nonhost and resistant host plants. Experiments using single mutations in hpa1 and hpa2indicated that the loss of hpa1 was the principal cause of the reduced pathogenicity of the deletion strain. A 1,519-bp insertion element was located immediately downstream of hpa2. Hybridization with hpa2 indicated that the gene was present in all of the strains of Xanthomonas examined. Hybridization experiments with hpa1 and IS1114indicated that these sequences were detectable in all strains ofX. oryzae pv. oryzae and some other Xanthomonasspecies.

scholarly journals The rsmA-like Gene rsmAXcc of Xanthomonas campestris pv. campestris Is Involved in the Control of Various Cellular Processes, Including Pathogenesis

2008 ◽  
Vol 21 (4) ◽  
pp. 411-423 ◽  
Author(s):  
Nai-Xia Chao ◽  
Ke Wei ◽  
Qi Chen ◽  
Qing-Lin Meng ◽  
Dong-Jie Tang ◽  
...  
Keyword(s):  
Xanthomonas Campestris ◽  
Rna Binding ◽  
Agar Plate ◽  
Erwinia Carotovora ◽  
Polymerase Chain Reaction Analysis ◽  
Glycogen Accumulation ◽  
Cellular Processes ◽  
Nonhost Plant ◽  
Virulence Regulator ◽  
Xanthomonas Campestris Pv Campestris

RsmA is an RNA-binding protein functioning as a global post-transcriptional regulator of various cellular processes in bacteria and has been demonstrated to be an important virulence regulator in many animal bacterial pathogens. However, its function in other phytopathogenic bacteria is unclear, except for the Erwinia carotovora RsmA, which acts as a negative virulence regulator. In this work, we investigated the function of the rsmA-like gene, named rsmAXcc, of the phytopathogen Xanthomonas campestris pv. campestris. Deletion of rsmAXcc resulted in complete loss of virulence on the host plant Chinese radish, hypersensitive response on the nonhost plant pepper ECW-10R, and motility on the surface of an agar plate. The rsmAXcc mutant displayed a significant reduction in the production of extracellular amylase, endoglucanase, and polysaccharide, but a significant increase in intracellular glycogen accumulation and an enhanced bacterial aggregation and cell adhesion. Microarray hybridization and semiquantitative reverse-transcription polymerase chain reaction analysis showed that deletion of rsmAXcc led to significantly reduced expression of genes encoding the type III secretion system (T3SS), T3SS-effectors, and the bacterial aggregate dispersing enzyme endo-β-1,4-mannanase. These results suggest that rsmAXcc is involved in the control of various cellular processes, including pathogenesis of X. campestris pv. campestris.

scholarly journals The Activity of Lipid A and Core Components of Bacterial Lipopolysaccharides in the Prevention of the Hypersensitive Response in Pepper

1997 ◽  
Vol 10 (7) ◽  
pp. 926-928 ◽  
Author(s):  
Mari-Anne Newman ◽  
Michael J. Daniels ◽  
J. Maxwell Dow
Keyword(s):  
Hypersensitive Response ◽  
Xanthomonas Campestris ◽  
Lipid A ◽  
Enteric Bacteria ◽  
Core Oligosaccharide ◽  
The Core ◽  
Minimal Structure ◽  
Core Components ◽  
Pre Treatment ◽  
Bacterial Lipopolysaccharides

Pre-treatment of leaves of pepper (Capsicum annuum) with lipopolysaccharide (LPS) preparations from enteric bacteria and Xanthomonas campestris could prevent the hypersensitive response caused by an avirulent X. campestris strain. By use of a range of deep-rough mutants, the minimal structure in Salmonella LPS responsible for the elicitation of this effect was determined to be lipid A attached to a disaccharide of 2-keto-3-deoxyoctulosonate; lipid A alone and the free core oligosaccharide from a Salmonella Ra mutant were not effective. For Xanthomonas, the core oligosaccharide alone had activity although lipid A was not effective. The results suggest that pepper cells can recognize different structures within bacterial LPS to trigger alterations in plant response to avirulent pathogens.

Wool-degrading Bacillus isolates: extracellular protease production for microbial processing of fabrics

2009 ◽  
Vol 26 (6) ◽  
pp. 1047-1052 ◽  
Author(s):  
Inés Infante ◽  
Maria A. Morel ◽  
Martha C. Ubalde ◽  
Cecilia Martínez-Rosales ◽  
Silvia Belvisi ◽  
...  
Keyword(s):  
Extracellular Protease ◽  
Protease Production

scholarly journals A Technique for Precise Inoculation of the Internal Phyllosphere of Cotton with Xanthomonas campestris pv. malvacearum

2003 ◽  
Vol 93 (10) ◽  
pp. 1204-1208 ◽  
Author(s):  
N. Kangatharalingam ◽  
Margaret L. Pierce ◽  
Margaret Essenberg
Keyword(s):  
Xanthomonas Campestris ◽  
Bacterial Population ◽  
Guard Cells ◽  
Distilled Water ◽  
Circular Area ◽  
Phytopathogenic Bacterium ◽  
Spongy Mesophyll ◽  
Adaxial Surface ◽  
Custom Made ◽  
Palisade Cells

A technique was developed to inoculate uniformly and gently the internal phyllosphere from the upper surface of cotton leaves with the phytopathogenic bacterium Xanthomonas campestris pv. malvacearum. The inoculum consisted of 2 to 3 × 107 CFU/ml in CaCO3-saturated sterile distilled water containing 0.02%, vol/vol, of the wetting agent Silwet L-77. A custom-made inoculation apparatus was employed to immerse a circular area of the adaxial surface of a leaf in inoculum for 90 s. This resulted in uniform, passive entry of bacteria into the substomatal chambers, producing an endophytic bacterial population of 2 × 104 CFU/cm2. Microscopic signs of infection were visible 48 to 72 h after inoculation. In susceptible leaves, uniformly distributed water-soaked spots were observed 7 to 8 days after inoculation. When the technique was used on resistant leaves, the autofluorescence that is characteristic of hypersensitively necrotic cells developed in the guard cells and palisade cells lining substomatal chambers, but not in the underlying spongy mesophyll.

scholarly journals Volatile organic compounds produced by the phytopathogenic bacteriumXanthomonas campestrispv.vesicatoria85-10

2012 ◽  
Vol 8 ◽  
pp. 579-596 ◽  
Author(s):  
Teresa Weise ◽  
Marco Kai ◽  
Anja Gummesson ◽  
Armin Troeger ◽  
Stephan von Reuß ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Xanthomonas Campestris ◽  
Analytical Data ◽  
Reference Sample ◽  
Petri Dish ◽  
Plant Interactions ◽  
Phytopathogenic Bacterium ◽  
Emission Profile ◽  
Volatile Organic ◽  
Sample Application

Xanthomonas campestrisis a phytopathogenic bacterium and causes many diseases of agricultural relevance. Volatiles were shown to be important in inter- and intraorganismic attraction and defense reactions. Recently it became apparent that also bacteria emit a plethora of volatiles, which influence other organisms such as invertebrates, plants and fungi. As a first step to study volatile-based bacterial–plant interactions, the emission profile ofXanthomonas c.pv.vesicatoria85-10 was determined by using GC/MS and PTR–MS techniques. More than 50 compounds were emitted by this species, the majority comprising ketones and methylketones. The structure of the dominant compound, 10-methylundecan-2-one, was assigned on the basis of its analytical data, obtained by GC/MS and verified by comparison of these data with those of a synthetic reference sample. Application of commercially available decan-2-one, undecan-2-one, dodecan-2-one, and the newly synthesized 10-methylundecan-2-one in bi-partite Petri dish bioassays revealed growth promotions in low quantities (0.01 to 10 μmol), whereas decan-2-one at 100 μmol caused growth inhibitions of the fungusRhizoctonia solani. Volatile emission profiles of the bacteria were different for growth on media (nutrient broth) with or without glucose.

scholarly journals The Transcriptional Regulator VqmA Increases Expression of the Quorum-Sensing Activator HapR in Vibrio cholerae

2006 ◽  
Vol 188 (7) ◽  
pp. 2446-2453 ◽  
Author(s):  
Zhi Liu ◽  
Ansel Hsiao ◽  
Adam Joelsson ◽  
Jun Zhu
Keyword(s):  
Quorum Sensing ◽  
Vibrio Cholerae ◽  
Diarrheal Disease ◽  
Constitutive Expression ◽  
Physiological Role ◽  
Transcriptional Regulator ◽  
Protease Production ◽  
Dependent Manner ◽  
Cell Densities

ABSTRACT Vibrio cholerae is the causative agent of the severe diarrheal disease cholera. A number of environmental stimuli regulate virulence gene expression in V. cholerae, including quorum-sensing signals. At high cell densities, quorum sensing in V. cholerae invokes a series of signal transduction pathways in order to activate the expression of the master regulator HapR, which then represses the virulence regulon and biofilm-related genes and activates protease production. In this study, we identified a transcriptional regulator, VqmA (VCA1078), that activates hapR expression at low cell densities. Under in vitro inducing conditions, constitutive expression of VqmA represses the virulence regulon in a HapR-dependent manner. VqmA increases hapR transcription as measured by the activity of the hapR-lacZ reporter, and it increases HapR production as measured by Western blotting. Using a heterogenous luxCDABE cosmid, we found that VqmA stimulates quorum-sensing regulation at lower cell densities and that this stimulation bypasses the known LuxO-small-RNA regulatory circuits. Furthermore, we showed that VqmA regulates hapR transcription directly by binding to its promoter region and that expression of vqmA is cell density dependent and autoregulated. The physiological role of VqmA is also discussed.

scholarly journals The Novel Streptococcal Transcriptional Regulator XtgS Negatively Regulates Bacterial Virulence and Directly Represses PseP Transcription

2020 ◽  
Vol 88 (10) ◽  
Author(s):  
Guangjin Liu ◽  
Tingting Gao ◽  
Xiaojun Zhong ◽  
Jiale Ma ◽  
Yumin Zhang ◽  
...  
Keyword(s):  
Strong Association ◽  
Challenge Test ◽  
Transcriptional Regulator ◽  
Transcriptional Regulators ◽  
Negative Regulator ◽  
Broad Host Range ◽  
Bacterial Survival ◽  
Mobility Shift ◽  
Upstream Gene ◽  
Content Type

ABSTRACT Streptococcus agalactiae (group B streptococcus [GBS]) has received continuous attention for its involvement in invasive infections and its broad host range. Transcriptional regulators have an important impact on bacterial adaptation to various environments. Research on transcriptional regulators will shed new light on GBS pathogenesis. In this study, we identified a novel XRE-family transcriptional regulator encoded on the GBS genome, designated XtgS. Our data demonstrate that XtgS inactivation significantly increases bacterial survival in host blood and animal challenge test, suggesting that it is a negative regulator of GBS pathogenicity. Further transcriptomic analysis and quantitative reverse transcription-PCR (qRT-PCR) mainly indicated that XtgS significantly repressed transcription of its upstream gene pseP. Based on electrophoretic mobility shift and lacZ fusion assays, we found that an XtgS homodimer directly binds a palindromic sequence in the pseP promoter region. Meanwhile, the PseP and XtgS combination naturally coexists in diverse Streptococcus genomes and has a strong association with sequence type, serotype diversification and host adaptation of GBS. Therefore, this study reveals that XtgS functions as a transcriptional regulator that negatively affects GBS virulence and directly represses PseP expression, and it provides new insights into the relationships between transcriptional regulator and genome evolution.

scholarly journals The mechanism of MYB transcriptional regulation by MLL-AF9 oncoprotein

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Lu Cao ◽  
Partha Mitra ◽  
Thomas J. Gonda
Keyword(s):  
Cell Proliferation ◽  
Transcriptional Regulation ◽  
Acute Myeloid Leukaemia ◽  
Promoter Region ◽  
Transcriptional Regulator ◽  
Transcriptional Regulators ◽  
Therapeutic Approaches ◽  
New Therapeutic Approaches ◽  
H3k79 Methylation ◽  
Acute Myeloid

AbstractAcute leukaemias express high levels of MYB which are required for the initiation and maintenance of the disease. Inhibition of MYB expression or activity has been shown to suppress MLL-fusion oncoprotein-induced acute myeloid leukaemias (AML), which are among the most aggressive forms of AML, and indeed MYB transcription has been reported to be regulated by the MLL-AF9 oncoprotein. This highlights the importance of understanding the mechanism of MYB transcriptional regulation in these leukaemias. Here we have demonstrated that the MLL-AF9 fusion protein regulates MYB transcription directly at the promoter region, in part by recruiting the transcriptional regulator kinase CDK9, and CDK9 inhibition effectively suppresses MYB expression as well as cell proliferation. However, MYB regulation by MLL-AF9 does not require H3K79 methylation mediated by the methyltransferase DOT1L, which has also been shown to be a key mediator of MLL-AF9 leukemogenicity. The identification of specific, essential and druggable transcriptional regulators may enable effective targeting of MYB expression, which in turn could potentially lead to new therapeutic approaches for acute myeloid leukaemia with MLL-AF9.

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