scholarly journals Deletion of the Transcriptional Regulator MucR in Brucella canis Affects Stress Responses and Bacterial Virulence

2021 ◽  
Vol 8 ◽  
Author(s):  
Jiali Sun ◽  
Hao Dong ◽  
Xiaowei Peng ◽  
Yufu Liu ◽  
Hui Jiang ◽  
...  
Keyword(s):  
Mutant Strain ◽  
Stress Responses ◽  
Transcriptional Regulator ◽  
Normal Growth ◽  
Growth Stress ◽  
Bacterial Virulence ◽  
Infection Model ◽  
Phenotypic Properties ◽  
Bacterial Flagellum ◽  
Brucella Canis

The transcriptional regulator MucR is related to normal growth, stress responses and Brucella virulence, and affects the expression of various virulence-related genes in smooth-type Brucella strains. However, the function of MucR in the rough-type Brucella canis remains unknown. In this study, we discovered that MucR protein was involved in resistance to heat stress, iron-limitation, and various antibiotics in B. canis. In addition, the expression level of various bacterial flagellum-related genes was altered in mucR mutant strain. Deletion of this transcriptional regulator in B. canis significantly affected Brucella virulence in RAW264.7 macrophage and mice infection model. To gain insight into the genetic basis for distinctive phenotypic properties exhibited by mucR mutant strain, RNA-seq was performed and the result showed that various genes involved in translation, ribosomal structure and biogenesis, signal transduction mechanisms, energy production, and conversion were significantly differently expressed in ΔmucR strain. Overall, these studies have not only discovered the phenotype of mucR mutant strain but also preliminarily uncovered the molecular mechanism between the transcriptional regulator MucR, stress response and bacterial virulence in B. canis.

scholarly journals The AraC Family Transcriptional Regulator Rv1931c Plays a Role in the Virulence of Mycobacterium tuberculosis

2004 ◽  
Vol 72 (9) ◽  
pp. 5483-5486 ◽  
Author(s):  
Cristiane C. Frota ◽  
K. G. Papavinasasundaram ◽  
Elaine O. Davis ◽  
M. Joseph Colston
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Mutant Strain ◽  
Transcriptional Regulator ◽  
Infection Model ◽  
Mouse Infection Model ◽  
Mouse Infection ◽  
Arac Family

ABSTRACT A Mycobacterium tuberculosis strain disrupted in the AraC homologue Rv1931c was isolated. The mutant strain exhibited reduced survival both in macrophages and in a mouse infection model, with survival being restored on complementation with the Rv1931c gene. These results suggest that Rv1931c regulates genes important for virulence of M. tuberculosis.

scholarly journals Integrated Transcriptomic and Proteomic Analyses Reveal the Role of NprR in Bacillus anthracis Extracellular Protease Expression Regulation and Oxidative Stress Responses

2020 ◽  
Vol 11 ◽  
Author(s):  
Yanchun Wang ◽  
Na Jiang ◽  
Bowen Wang ◽  
Haoxia Tao ◽  
Xin Zhang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Bacillus Anthracis ◽  
Mutant Strain ◽  
Stress Responses ◽  
Protease Activity ◽  
Deletion Mutant ◽  
Transcriptional Regulator ◽  
Proteomic Analyses ◽  
Oxidative Stress Responses ◽  
Go Terms

NprR is a protein of Bacillus anthracis that exhibits moonlighting functions as either a phosphatase or a neutral protease regulator that belongs to the RNPP family. We previously observed that the extracellular protease activity of an nprR deletion mutant significantly decreased within in vitro cultures. To identify the genes within the regulatory network of nprR that contribute to its protease activity, integrated transcriptomic and proteomic analyses were conducted here by comparing the nprR deletion mutant and parent strains. A total of 366 differentially expressed genes (DEGs) between the strains were observed via RNA-seq analysis. In addition, label-free LC-MS/MS analysis revealed 503 differentially expressed proteins (DEPs) within the intracellular protein fraction and 213 extracellular DEPs with significant expressional differences between the strains. The majority of DEGs and DEPs were involved in environmental information processing and metabolism. Integrated transcriptomic and proteomic analyses indicated that oxidation-reduction-related GO terms for intracellular DEPs and endopeptidase-related GO terms for extracellular DEPs were significantly enriched in the mutant strain. Notably, many genes involved in protease activity were largely downregulated in the nprR deletion mutant cultures. Moreover, western blot analysis revealed that the major extracellular neutral protease Npr599 was barely expressed in the nprR deletion mutant strain. The mutant also exhibited impaired degradation of protective antigen, which is a major B. anthracis toxin component, thereby resulting in higher protein yields. Concomitantly, another global transcriptional regulator, SpxA1, was also dramatically downregulated in the nprR deletion mutant, resulting in higher sensitivity to oxidative and disulfide stress. These data consequently indicate that NprR is a transcriptional regulator that controls genes whose products function as extracellular proteases and also is involved in oxidative stress responses. This study thus contributes to a more comprehensive understanding of the biological function of NprR, and especially in the middle growth stages of B. anthracis.

scholarly journals An AraC-Type Transcriptional Regulator Encoded on the Enterococcus faecalis Pathogenicity Island Contributes to Pathogenesis and Intracellular Macrophage Survival

2008 ◽  
Vol 76 (12) ◽  
pp. 5668-5676 ◽  
Author(s):  
Phillip S. Coburn ◽  
Arto S. Baghdayan ◽  
GT Dolan ◽  
Nathan Shankar
Keyword(s):  
Enterococcus Faecalis ◽  
Mutant Strain ◽  
Biofilm Formation ◽  
Transcriptional Regulator ◽  
Pathogenicity Island ◽  
Nucleotide Sequence Analysis ◽  
Infection Model ◽  
Wild Type ◽  
Altered Expression

ABSTRACT A gene encoding a putative AraC-type transcriptional regulator was identified on the 153-kb pathogenicity island (PAI) found among virulent Enterococcus faecalis strains. In an effort to understand the function of this regulator, designated PerA (for pathogenicity island-encoded regulator), we first examined the expression of the perA gene in the original PAI strain MMH594 and in an unrelated clinical isolate E99 by reverse transcription-PCR. Interestingly, expression analysis revealed no detectable perA transcript in MMH594, whereas a transcript was observed in strain E99. Nucleotide sequence analysis revealed that this altered expression between the two strains was attributable to the differential location of an IS1191 element within the putative promoter region upstream of the perA gene. In order to determine the role of this putative regulator in E. faecalis pathogenesis, a perA-deficient mutant was created in strain E99, and the wild-type and mutant pair were compared for phenotypic differences. In in vitro biofilm assays, the mutant strain showed a significantly higher level of growth medium-specific biofilm formation compared to the wild type. However, in a murine intraperitoneal infection model, the mutant strain was significantly less pathogenic. The mutant was also attenuated for survival within macrophages in vitro. These findings highlight the importance of PerA as a regulator of biofilm formation and survival within macrophages and is likely a regulator controlling determinants important to pathogenesis.

scholarly journals Versatile Physiological Functions of Plant GSK3-Like Kinases

Genes ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 697
Author(s):  
Juan Mao ◽  
Wenxin Li ◽  
Jing Liu ◽  
Jianming Li
Keyword(s):  
Stress Responses ◽  
Glycogen Synthase ◽  
Plant Stress ◽  
Normal Growth ◽  
Growth Conditions ◽  
Genetic Studies ◽  
Physiological Functions ◽  
Environmental Signals ◽  
Plant Stress Responses ◽  
Diverse Plant

The plant glycogen synthase kinase 3 (GSK3)-like kinases are highly conserved protein serine/threonine kinases that are grouped into four subfamilies. Similar to their mammalian homologs, these kinases are constitutively active under normal growth conditions but become inactivated in response to diverse developmental and environmental signals. Since their initial discoveries in the early 1990s, many biochemical and genetic studies were performed to investigate their physiological functions in various plant species. These studies have demonstrated that the plant GSK3-like kinases are multifunctional kinases involved not only in a wide variety of plant growth and developmental processes but also in diverse plant stress responses. Here we summarize our current understanding of the versatile physiological functions of the plant GSK3-like kinases along with their confirmed and potential substrates.

scholarly journals Regulation of the Bacillus subtilis bcrC Bacitracin Resistance Gene by Two Extracytoplasmic Function σ Factors

2002 ◽  
Vol 184 (22) ◽  
pp. 6123-6129 ◽  
Author(s):  
Min Cao ◽  
John D. Helmann
Keyword(s):  
Bacillus Subtilis ◽  
Resistance Gene ◽  
Mutant Strain ◽  
Stress Responses ◽  
Double Mutant ◽  
De Novo ◽  
De Novo Synthesis ◽  
Gene Encoding ◽  
Single Promoter ◽  
Higher Sensitivity

ABSTRACT Bacitracin resistance is normally conferred by either of two major mechanisms, the BcrABC transporter, which pumps out bacitracin, or BacA, an undecaprenol kinase that provides C55-isoprenyl phosphate by de novo synthesis. We demonstrate that the Bacillus subtilis bcrC (ywoA) gene, encoding a putative bacitracin transport permease, is an important bacitracin resistance determinant. A bcrC mutant strain had an eightfold-higher sensitivity to bacitracin. Expression of bcrC initiated from a single promoter site that could be recognized by either of two extracytoplasmic function (ECF) σ factors, σX or σM. Bacitracin induced expression of bcrC, and this induction was dependent on σM but not on σX. Under inducing conditions, expression was primarily dependent on σM. As a consequence, a sigM mutant was fourfold more sensitive to bacitracin, while the sigX mutant was only slightly sensitive. A sigX sigM double mutant was similar to a bcrC mutant in sensitivity. These results support the suggestion that one function of B. subtilis ECF σ factors is to coordinate antibiotic stress responses.

scholarly journals The zinc transporter ZnuABC is critical for the virulence of Chromobacterium violaceum and contributes to diverse zinc-dependent physiological processes

2021 ◽  
Author(s):  
Renato E. R. S. Santos ◽  
Waldir P. da Silva Júnior ◽  
Simone A. Harrison ◽  
Eric P Skaar ◽  
Walter J. Chazin ◽  
...  
Keyword(s):  
Mutant Strain ◽  
Zinc Uptake ◽  
Chromobacterium Violaceum ◽  
Host Protein ◽  
Infection Model ◽  
Uptake System ◽  
Environmental Bacterium ◽  
Mouse Infection Model ◽  
Synthetic Metal

Chromobacterium violaceum is a ubiquitous environmental bacterium that causes sporadic life-threatening infections in humans. How C. violaceum acquires zinc to colonize environmental and host niches is unknown. In this work, we demonstrated that C. violaceum employs the zinc uptake system ZnuABC to overcome zinc limitation in the host, ensuring the zinc supply for several physiological demands. Our data indicated that the C. violaceum ZnuABC transporter is encoded in a zur-CV_RS15045-CV_RS15040-znuCBA operon. This operon was repressed by the zinc uptake regulator Zur and derepressed in the presence of the host protein calprotectin (CP) and the synthetic metal chelator EDTA. A ΔznuCBA mutant strain showed impaired growth under these zinc-chelated conditions. Moreover, the deletion of znuCBA provoked a reduction in violacein production, swimming motility, biofilm formation, and bacterial competition. Remarkably, the ΔznuCBA mutant strain was highly attenuated for virulence in an in vivo mouse infection model and showed a low capacity to colonize the liver, grow in the presence of CP, and resist neutrophil killing. Overall, our findings demonstrate that ZnuABC is essential for C. violaceum virulence, contributing to subvert the zinc-based host nutritional immunity.

scholarly journals Identification of Key Genes in ‘Luang Pratahn’, Thai Salt-Tolerant Rice, Based on Time-Course Data and Weighted Co-expression Networks

2021 ◽  
Vol 12 ◽  
Author(s):  
Pajaree Sonsungsan ◽  
Pheerawat Chantanakool ◽  
Apichat Suratanee ◽  
Teerapong Buaboocha ◽  
Luca Comai ◽  
...  
Keyword(s):  
Salt Stress ◽  
Salt Tolerance ◽  
Stress Responses ◽  
Time Course ◽  
Rice Variety ◽  
Enrichment Analysis ◽  
Normal Growth ◽  
Growth Conditions ◽  
Pathway Enrichment Analysis ◽  
Key Genes

Salinity is an important environmental factor causing a negative effect on rice production. To prevent salinity effects on rice yields, genetic diversity concerning salt tolerance must be evaluated. In this study, we investigated the salinity responses of rice (Oryza sativa) to determine the critical genes. The transcriptomes of ‘Luang Pratahn’ rice, a local Thai rice variety with high salt tolerance, were used as a model for analyzing and identifying the key genes responsible for salt-stress tolerance. Based on 3' Tag-Seq data from the time course of salt-stress treatment, weighted gene co-expression network analysis was used to identify key genes in gene modules. We obtained 1,386 significantly differentially expressed genes in eight modules. Among them, six modules indicated a significant correlation within 6, 12, or 48h after salt stress. Functional and pathway enrichment analysis was performed on the co-expressed genes of interesting modules to reveal which genes were mainly enriched within important functions for salt-stress responses. To identify the key genes in salt-stress responses, we considered the two-state co-expression networks, normal growth conditions, and salt stress to investigate which genes were less important in a normal situation but gained more impact under stress. We identified key genes for the response to biotic and abiotic stimuli and tolerance to salt stress. Thus, these novel genes may play important roles in salinity tolerance and serve as potential biomarkers to improve salt tolerance cultivars.

scholarly journals A Suppressor Mutation That Creates a Faster and More Robust σE Envelope Stress Response

2016 ◽  
Vol 198 (17) ◽  
pp. 2345-2351 ◽  
Author(s):  
Anna Konovalova ◽  
Jaclyn A. Schwalm ◽  
Thomas J. Silhavy
Keyword(s):  
Stress Response ◽  
Stress Responses ◽  
Novel Mutation ◽  
Signal Transduction Pathway ◽  
Normal Growth ◽  
Internal Stresses ◽  
Content Type ◽  
Envelope Stress ◽  
Genetic Perturbations ◽  
Periplasmic Stress

ABSTRACTThe σE envelope stress response is an essential signal transduction pathway which detects and removes mistargeted outer membrane (OM) β-barrel proteins (OMPs) in the periplasm ofEscherichia coli. It relies on σE, an alternative sigma factor encoded by therpoEgene. Here we report a novel mutation, a nucleotide change of C to A in the third base of the second codon, which increases levels of σE (rpoE_S2R). TherpoE_S2Rmutation does not lead to the induction of the stress response during normal growth but instead changes the dynamics of induction upon periplasmic stress, resulting in a faster and more robust response. This allows cells to adapt faster to the periplasmic stress, avoiding lethal accumulation of unfolded OMPs in the periplasm caused by severe defects in the OMP assembly pathway.IMPORTANCESurvival of bacteria under conditions of external or internal stresses depends on timely induction of stress response signaling pathways to regulate expression of appropriate genes that function to maintain cellular homeostasis. Previous studies have shown that strong preinduction of envelope stress responses can allow bacteria to survive a number of lethal genetic perturbations. In our paper, we describe a unique mutation that enhances kinetics of the σE envelope stress response pathway rather than preinducing the response. This allows bacteria to quickly adapt to sudden and severe periplasmic stress.

scholarly journals Genetic functions of the NAIP family of inflammasome receptors for bacterial ligands in mice

2016 ◽  
Vol 213 (5) ◽  
pp. 647-656 ◽  
Author(s):  
Yue Zhao ◽  
Jianjin Shi ◽  
Xuyan Shi ◽  
Yupeng Wang ◽  
Fengchao Wang ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Type Iii Secretion ◽  
Physiological Function ◽  
Shigella Flexneri ◽  
Critical Role ◽  
Bacterial Virulence ◽  
Infection Model ◽  
Inflammasome Activation ◽  
Inflammatory Damage

Biochemical studies suggest that the NAIP family of NLR proteins are cytosolic innate receptors that directly recognize bacterial ligands and trigger NLRC4 inflammasome activation. In this study, we generated Naip5−/−, Naip1−/−, and Naip2−/− mice and showed that bone marrow macrophages derived from these knockout mice are specifically deficient in detecting bacterial flagellin, the type III secretion system needle, and the rod protein, respectively. Naip1−/−, Naip2−/−, and Naip5−/− mice also resist lethal inflammasome activation by the corresponding ligand. Furthermore, infections performed in the Naip-deficient macrophages have helped to define the major signal in Legionella pneumophila, Salmonella Typhimurium and Shigella flexneri that is detected by the NAIP/NLRC4 inflammasome. Using an engineered S. Typhimurium infection model, we demonstrate the critical role of NAIPs in clearing bacterial infection and protecting mice from bacterial virulence–induced lethality. These results provide definitive genetic evidence for the important physiological function of NAIPs in antibacterial defense and inflammatory damage–induced lethality in mice.

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