Physiological and genetic characterization of the osmotic stress response in Bacillus subtilis

1994 ◽  
Vol 40 (2) ◽  
pp. 140-144 ◽  
Author(s):  
Sandra M. Ruzal ◽  
Carmen Sanchez-Rivas
Keyword(s):  
Bacillus Subtilis ◽  
Osmotic Stress ◽  
Stationary Phase ◽  
Resistant Mutant ◽  
Wild Type ◽  
Osmotic Stress Response ◽  
Mutant Phenotypes ◽  
Physiological Variations ◽  
Growth Adaptation

Bacillus subtilis cultures submitted to an osmotic upshock (1.5 M NaCl) lysed unless stationary phase had been reached. Several physiological variations were observed, such as delayed growth (adaptation), a filamentous bacterial appearance, RecA-dependent osmoresistance (SOS), and cross-induction by a previous stress (heat shock). Osmoresistance and sporulation seem to share pathways of regulation such as inhibition in the presence of glucose and glutamine and derepression in a catabolite-resistant mutant such as degUh. However, spores were not obtained on hypertonic media. Mutants of later sporulation stages (spoII, spoIII) presented a response similar to that of the wild-type parent, indicating that both processes probably shared early controls. Null mutations in any of the known key modulators of sporulation (spoOA or degU) resulted in similar levels of osmosensitivity. Sensor mutations in kinA and degS also led to strains with altered responses, the kinA mutant being even more osmosensitive than the degS mutant. Several spoOA mutant phenotypes are due to this gene's control of abrB, a regulator of stationary-phase events, and an abrB mutation relieved the osmosensitivity of the spoOA-containing mutant but had no effect on a wild-type strain.Key words: Bacillus subtilis, osmotic stress, sporulation.

scholarly journals CAND2/PMTR1 Is Required for Melatonin-Conferred Osmotic Stress Tolerance in Arabidopsis

2021 ◽  
Vol 22 (8) ◽  
pp. 4014
Author(s):  
Lin-Feng Wang ◽  
Ting-Ting Li ◽  
Yu Zhang ◽  
Jia-Xing Guo ◽  
Kai-Kai Lu ◽  
...  
Keyword(s):  
Osmotic Stress ◽  
Stress Tolerance ◽  
Wild Type Plant ◽  
Wild Type ◽  
Melatonin Receptor ◽  
Ros Scavenging ◽  
Exogenous Melatonin ◽  
Osmotic Stress Tolerance ◽  
Osmotic Stress Response ◽  
In The Wild

Osmotic stress severely inhibits plant growth and development, causing huge loss of crop quality and quantity worldwide. Melatonin is an important signaling molecule that generally confers plant increased tolerance to various environmental stresses, however, whether and how melatonin participates in plant osmotic stress response remain elusive. Here, we report that melatonin enhances plant osmotic stress tolerance through increasing ROS-scavenging ability, and melatonin receptor CAND2 plays a key role in melatonin-mediated plant response to osmotic stress. Upon osmotic stress treatment, the expression of melatonin biosynthetic genes including SNAT1, COMT1, and ASMT1 and the accumulation of melatonin are increased in the wild-type plants. The snat1 mutant is defective in osmotic stress-induced melatonin accumulation and thus sensitive to osmotic stress, while exogenous melatonin enhances the tolerance of the wild-type plant and rescues the sensitivity of the snat1 mutant to osmotic stress by upregulating the expression and activity of catalase and superoxide dismutase to repress H2O2 accumulation. Further study showed that the melatonin receptor mutant cand2 exhibits reduced osmotic stress tolerance with increased ROS accumulation, but exogenous melatonin cannot revert its osmotic stress phenotype. Together, our study reveals that CADN2 functions necessarily in melatonin-conferred osmotic stress tolerance by activating ROS-scavenging ability in Arabidopsis.

scholarly journals The Mutant Phenotype Associated With P-Element Alleles of the vestigial Locus in Drosophila melanogaster May Be Caused by a Readthrough Transcript Initiated at the P-Element Promoter

Genetics ◽  
2001 ◽  
Vol 157 (4) ◽  
pp. 1665-1672 ◽  
Author(s):  
Ross B Hodgetts ◽  
Sandra L O'Keefe
Keyword(s):  
Rna Secondary Structure ◽  
Insertion Site ◽  
Large Body ◽  
P Element ◽  
Wild Type ◽  
Subtle Difference ◽  
Pronounced Difference ◽  
Internal Repeat ◽  
Mutant Phenotypes

Abstract We report here the isolation of a new P-element-induced allele of the vestigial locus vg2a33, the molecular characterization of which allows us to propose a unifying explanation of the phenotypes of the large number of vestigial P-element alleles that now exists. The first P-element allele of vestigial to be isolated was vg21, which results in a very weak mutant wing phenotype that is suppressed in the P cytotype. By destabilizing vg2a33 in a dysgenic cross, we isolated the vg2a33 allele, which exhibits a moderate mutant wing phenotype and is not suppressed by the P cytotype. The new allele is characterized by a 46-bp deletion that removes the 3′-proximal copy of the 11-bp internal repeat from the P element of vg21. To understand how this subtle difference between the two alleles leads to a rather pronounced difference in their phenotypes, we mapped both the vg and P-element transcription units present in wild type and mutants. Using both 5′-RACE and S1 protection, we found that P-element transcription is initiated 19 bp farther upstream than previously thought. Using primer extension, the start of vg transcription was determined to lie 435 bp upstream of the longest cDNA recovered to date and upstream of the P-element insertion site. Our discovery that the P element is situated within the first vg exon has prompted a reassessment of the large body of genetic data on a series of alleles derived from vg21. Our current hypothesis to explain the degree of variation in the mutant phenotypes and their response to the P repressor invokes a critical RNA secondary structure in the vg transcript, the formation of which is hindered by a readthrough transcript initiated at the P-element promoter.

scholarly journals NMR and LC-MS-Based Metabolomics to Study Osmotic Stress in Lignan-Deficient Flax

Molecules ◽  
2021 ◽  
Vol 26 (3) ◽  
pp. 767
Author(s):  
Kamar Hamade ◽  
Ophélie Fliniaux ◽  
Jean-Xavier Fontaine ◽  
Roland Molinié ◽  
Elvis Otogo Nnang ◽  
...  
Keyword(s):  
Stress Response ◽  
Osmotic Stress ◽  
Biosynthetic Pathway ◽  
Potential Role ◽  
Plant Secondary Metabolites ◽  
Wild Type ◽  
Osmotic Stress Response ◽  
Transgenic Flax ◽  
Insight Into

Lignans, phenolic plant secondary metabolites, are derived from the phenylpropanoid biosynthetic pathway. Although, being investigated for their health benefits in terms of antioxidant, antitumor, anti-inflammatory and antiviral properties, the role of these molecules in plants remains incompletely elucidated; a potential role in stress response mechanisms has been, however, proposed. In this study, a non-targeted metabolomic analysis of the roots, stems, and leaves of wild-type and PLR1-RNAi transgenic flax, devoid of (+) secoisolariciresinol diglucoside ((+) SDG)—the main flaxseed lignan, was performed using 1H-NMR and LC-MS, in order to obtain further insight into the involvement of lignan in the response of plant to osmotic stress. Results showed that wild-type and lignan-deficient flax plants have different metabolic responses after being exposed to osmotic stress conditions, but they both showed the capacity to induce an adaptive response to osmotic stress. These findings suggest the indirect involvement of lignans in osmotic stress response.

scholarly journals Genetic evidence for signal transduction within the Bacillus subtilis GerA germinant receptor

2021 ◽  
Author(s):  
Jeremy D. Amon ◽  
Lior Artzi ◽  
David Z. Rudner
Keyword(s):  
Signal Transduction ◽  
Bacillus Subtilis ◽  
Signal Transduction Pathway ◽  
Dominant Negative ◽  
Bacterial Spores ◽  
Wild Type ◽  
Enrichment Strategy ◽  
Functional Receptor

Bacterial spores can rapidly exit dormancy through the process of germination. This process begins with the activation of nutrient receptors embedded in the spore membrane. The prototypical germinant receptor in Bacillus subtilis responds to L-alanine and is thought to be a complex of proteins encoded by the genes in the gerA operon: gerAA, gerAB, and gerAC. The GerAB subunit has recently been shown to function as the nutrient sensor, but beyond contributing to complex stability, no additional functions have been attributed to the other two subunits. Here, we investigate the role of GerAA. We resurrect a previously characterized allele of gerA (termed gerA*) that carries a mutation in gerAA and show it constitutively activates germination even in the presence of a wild-type copy of gerA. Using an enrichment strategy to screen for suppressors of gerA*, we identified mutations in all three gerA genes that restore a functional receptor. Characterization of two distinct gerAB suppressors revealed that one (gerAB-E105K) reduces the GerA complex's ability to respond to L-alanine, while another (gerAB-F259S) disrupts the germinant signal downstream of L-alanine recognition. These data argue against models in which GerAA is directly or indirectly involved in germinant sensing. Rather, our data suggest that GerAA is responsible for transducing the nutrient signal sensed by GerAB. While the steps downstream of gerAA have yet to be uncovered, these results validate the use of a dominant-negative genetic approach in elucidating the gerA signal transduction pathway.

scholarly journals Metabolic Imbalance and Sporulation in an Isocitrate Dehydrogenase Mutant of Bacillus subtilis

1999 ◽  
Vol 181 (11) ◽  
pp. 3382-3391 ◽  
Author(s):  
Kiyoshi Matsuno ◽  
Tessa Blais ◽  
Alisa W. Serio ◽  
Tyrrell Conway ◽  
Tina M. Henkin ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Stationary Phase ◽  
Isocitrate Dehydrogenase ◽  
Citrate Synthase ◽  
Divalent Cations ◽  
Mutant Cell ◽  
Stage I ◽  
Mutant Form ◽  
Wild Type ◽  
High Accumulation

ABSTRACT A Bacillus subtilis mutant with a deletion in thecitC gene, encoding isocitrate dehydrogenase, the third enzyme of the tricarboxylic acid branch of the Krebs cycle, exhibited reduced growth yield in broth medium and had greatly reduced ability to sporulate compared to the wild type due to a block at stage I, i.e., a failure to form the polar division septum. In early stationary phase, mutant cells accumulated intracellular and extracellular concentrations of citrate and isocitrate that were at least 15-fold higher than in wild-type cells. The growth and sporulation defects of the mutant could be partially bypassed by deletion of the major citrate synthase gene (citZ), by raising the pH of the medium, or by supplementation of the medium with certain divalent cations, suggesting that abnormal accumulation of citrate affects survival of stationary-phase cells and sporulation by lowering extracellular pH and chelating metal ions. While these genetic and environmental alterations were not sufficient to allow the majority of the mutant cell population to pass the stage I block (lack of asymmetric septum formation), introduction of the sof-1 mutant form of the Spo0A transcription factor, when coupled with a reduction in citrate synthesis, restored sporulation gene expression and spore formation nearly to wild-type levels. Thus, the primary factor inhibiting sporulation in a citC mutant is abnormally high accumulation of citrate, but relief of this metabolic defect is not by itself sufficient to restore competence for sporulation.

scholarly journals Regulation and Characterization of a Newly Deduced Cell Wall Hydrolase Gene (cwlJ) Which Affects Germination of Bacillus subtilis Spores

1998 ◽  
Vol 180 (6) ◽  
pp. 1375-1380 ◽  
Author(s):  
Shu Ishikawa ◽  
Kunio Yamane ◽  
Junichi Sekiguchi
Keyword(s):  
Bacillus Subtilis ◽  
Type Strain ◽  
Wild Type Strain ◽  
Catalytic Domain ◽  
Slow Release ◽  
Dipicolinic Acid ◽  
Northern Hybridization ◽  
Predicted Amino Acid Sequence ◽  
Wild Type

ABSTRACT The predicted amino acid sequence of Bacillus subtilis ycbQ (renamed cwlJ) exhibits high similarity to those of the deduced C-terminal catalytic domain of SleBs, the specific cortex-hydrolyzing enzyme of B. cereus and the deduced one of B. subtilis. We constructed acwlJ::lacZ fusion in the B. subtilischromosome. The β-galactosidase activity and results of Northern hybridization and primer extension analyses of the cwlJgene indicated that it is transcribed by EςE RNA polymerase. cwlJ-deficient spores responded to bothl-alanine and AGFK, the A 580 values of spore suspensions decreased more slowly than in the case of the wild-type strain, and the mutant spores released less dipicolinic acid than did those of the wild-type strain during germination. However, the mutant spores released only slightly less hexosamine than did the wild-type spores. In contrast, B. subtilis sleB spores did not release hexosamine at a significant level. While cwlJand sleB spores were able to germinate, CJSB (cwlJ sleB) spores could not germinate but exhibited initial germination reactions, e.g., partial decrease inA 580 and slow release of dipicolinic acid. CJSB spores became slightly gray after 6 h in the germinant, but their refractility was much greater than that of sleB mutant spores. The roles of the sleB and cwlJmutations in germination and spore maturation are also discussed.

scholarly journals Functional analysis of the competence transcription factor ComK of Bacillus subtilis by characterization of truncation variants

Microbiology ◽  
2006 ◽  
Vol 152 (2) ◽  
pp. 473-483 ◽  
Author(s):  
Kim A. Susanna ◽  
Fabrizia Fusetti ◽  
Andy-Mark W. H. Thunnissen ◽  
Leendert W. Hamoen ◽  
Oscar P. Kuipers
Keyword(s):  
Transcription Factor ◽  
Bacillus Subtilis ◽  
Dna Binding ◽  
Protein Interactions ◽  
Transcription Activation ◽  
Wild Type ◽  
Protein Protein Interactions ◽  
Protein Dna Interactions ◽  
Lower Protein

The competence transcription factor ComK is the master regulator of competence development in Bacillus subtilis. In the regulatory pathway, ComK is involved in different interactions: (i) protein–DNA interactions to stimulate transcription of ComK-dependent genes and (ii) protein–protein interactions, divided into interactions with other proteins and interactions between ComK proteins involving oligomerization. The fact that ComK displays different types of interactions suggests the presence of specific, distinct domains in the protein. This paper describes a search for functional domains, by constructing ComK truncation variants, which were tested for DNA binding, oligomerization and transcription activation. Truncations at the C-terminal end of ComK demonstrated the requirement of this part for transcription activation, but not for DNA binding. The C-terminal region is probably involved in oligomerization of ComK-dimers into tetramers. Surprisingly, a ComK truncation variant lacking 9 aa from the N-terminal end (ΔN9ComK) showed higher transcription activation than wild-type ComK, when expressed in Lactococcus lactis. However, in B. subtilis, transcription activation by ΔN9ComK was twofold lower than that by wild-type ComK, resulting from a five- to sixfold lower protein level of ComKΔN9. Thus, relatively, ΔN9ComK is more active in transcription activation than wild-type ComK. These results suggest that the presence of this N-terminal extension on ComK is a trade-off between high transcription activation and a thus far unidentified role in regulation of ComK.

Characterization of a norflurazon-resistant mutant of Chlamydomonas reinhardtii

Weed Science ◽  
1997 ◽  
Vol 45 (3) ◽  
pp. 374-377 ◽  
Author(s):  
Varsha Vartak ◽  
Sujata Bhargava
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Mode Of Action ◽  
Resistant Mutant ◽  
Phytoene Desaturase ◽  
Wild Type ◽  
Cross Tolerance ◽  
In The Wild ◽  
Similar Mode ◽  
Target Enzyme

A norflurazon-resistant mutant has been isolated from Chlamydomonas reinhardtii that showed a three-fold factor of resistance over wild type cultures. In comparison to wild type cultures, the mutant showed better retention of chlorophylls and carotenoids when grown in light in the presence of norflurazon. When grown in the dark, chlorophyll losses were similar, while carotenoid losses were lower than in the wild type cultures. Higher levels of phytoene accumulated in the wild type cultures in the presence of norflurazon than in the resistant cultures. The resistant cultures also showed cross tolerance to EMD-IT 5914, a herbicide with a similar mode of action. Norflurazon resistance in this alga appears to arise from alterations in the target enzyme phytoene desaturase.

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