Induction of autolysis in Bacillus subtilis by ochratoxin A

1978 ◽  
Vol 24 (5) ◽  
pp. 563-568 ◽  
Author(s):  
U. Singer ◽  
R. Röschenthaler
Keyword(s):  
Cell Wall ◽  
Protein Synthesis ◽  
Bacillus Subtilis ◽  
Ochratoxin A ◽  
Optical Density ◽  
Growth Phase ◽  
Exponential Growth ◽  
Rna Synthesis ◽  
Exponential Growth Phase ◽  
Cell Wall Synthesis

Ochratoxin A (OTA) added during the exponential growth phase at a concentration higher than 12 μg/ml caused autolysis of Bacillus subtilis. Optical density of cultures decreased, and at higher concentrations the cultures became sterile. Optimum OTA-induced lysis was about pH 5. At concentrations below 10 μg/ml, protein synthesis was inhibited more strongly than RNA synthesis. Cell wall synthesis was also strongly inhibited. A fraction extracted from the lysates had the property of a lysis inhibitor. The relevance of this fraction in respect to autolysis is discussed.

scholarly journals Biosynthesis and turnover of outer-membrane proteins in Escherichia coli ML308-225

1979 ◽  
Vol 182 (2) ◽  
pp. 407-412 ◽  
Author(s):  
R J Allen ◽  
G K Scott
Keyword(s):  
Escherichia Coli ◽  
Protein Synthesis ◽  
Outer Membrane ◽  
Bacterial Growth ◽  
Growth Phase ◽  
Exponential Growth ◽  
Outer Membrane Proteins ◽  
Exponential Growth Phase ◽  
Outer Membranes ◽  
Dilution Experiments

Isolated outer membranes and outer-membrane extracts from Escherichia coli ML308-225 in the early-exponential growth phase contain more protein than do corresponding preparations from late-exponential- or stationary-phase bacteria. Isotope-dilution experiments show that this is due to a loss of protein from the membrane during the exponential growth phase. Inhibition of bacterial growth and protein synthesis stabilizes the outer-membrane-protein concentration. Protein synthesis in the absence of bacterial growth results in higher concentrations of protein in the outer membrane.

scholarly journals CcpA-Independent Regulation of Expression of the Mg2+-Citrate Transporter Gene citM by Arginine Metabolism in Bacillus subtilis

2003 ◽  
Vol 185 (3) ◽  
pp. 854-859 ◽  
Author(s):  
Jessica B. Warner ◽  
Christian Magni ◽  
Juke S. Lolkema
Keyword(s):  
Bacillus Subtilis ◽  
Growth Phase ◽  
Exponential Growth ◽  
Stationary Growth Phase ◽  
Luria Bertani ◽  
Transition Phase ◽  
Exponential Growth Phase ◽  
Uptake System ◽  
Regulation Of Expression ◽  
Citrate Transporter

ABSTRACT Transcriptional regulation of the Mg2+-citrate transporter, CitM, the main citrate uptake system of Bacillus subtilis, was studied during growth in rich medium. Citrate in the growth medium was required for induction under all growth conditions. In Luria-Bertani medium containing citrate, citM expression was completely repressed during the exponential growth phase, marginally expressed in the transition phase, and highly expressed in the stationary growth phase. The repression was relieved when the cells were grown in spent Luria-Bertani medium. The addition of a mixture of 18 amino acids restored repression. l-Arginine in the mixture appeared to be solely responsible for the repression, and ornithine appeared to be an equally potent repressor of citM expression. Studies of mutant strains deficient in RocR and SigL, proteins required for the expression of the enzymes of the arginase pathway, confirmed that uptake into the cell and, most likely, conversion of arginine to ornithine were required for repression. Arginine-mediated repression was independent of a functional CcpA, the global regulator protein in carbon catabolite repression (CCR). Nevertheless, CCR-mediated repression was the major mechanism controlling the expression during exponential growth, while the newly described, CcpA-independent arginine-mediated repression was specifically apparent during the transition phase of growth.

scholarly journals Localization of the Vegetative Cell Wall Hydrolases LytC, LytE, and LytF on the Bacillus subtilis Cell Surface and Stability of These Enzymes to Cell Wall-Bound or Extracellular Proteases

2003 ◽  
Vol 185 (22) ◽  
pp. 6666-6677 ◽  
Author(s):  
Hiroki Yamamoto ◽  
Shin-ichirou Kurosawa ◽  
Junichi Sekiguchi
Keyword(s):  
Cell Wall ◽  
Bacillus Subtilis ◽  
Cell Surface ◽  
Fusion Protein ◽  
Growth Phase ◽  
Vegetative Growth ◽  
Cell Separation ◽  
Vegetative Cell ◽  
Exponential Growth Phase ◽  
Cell Wall Hydrolases

ABSTRACT LytF, LytE, and LytC are vegetative cell wall hydrolases in Bacillus subtilis. Immunofluorescence microscopy showed that an epitope-tagged LytF fusion protein (LytF-3xFLAG) in the wild-type background strain was localized at cell separation sites and one of the cell poles of rod-shaped cells during vegetative growth. However, in a mutant lacking both the cell surface protease WprA and the extracellular protease Epr, the fusion protein was observed at both cell poles in addition to cell separation sites. This suggests that LytF is potentially localized at cell separation sites and both cell poles during vegetative growth and that WprA and Epr are involved in LytF degradation. The localization pattern of LytE-3xFLAG was very similar to that of LytF-3xFLAG during vegetative growth. However, especially in the early vegetative growth phase, there was a remarkable difference between the shape of cells expressing LytE-3xFLAG and the shape of cells expressing LytF-3xFLAG. In the case of LytF-3xFLAG, it seemed that the signals in normal rod-shaped cells were stronger than those in long-chain cells. In contrast, the reverse was found in the case of LytE-3xFLAG. This difference may reflect the dependence on different sigma factors for gene expression. The results support and extend the previous finding that LytF and LytE are cell-separating enzymes. On the other hand, we observed that cells producing LytC-3xFLAG are uniformly coated with the fusion protein after the middle of the exponential growth phase, which supports the suggestion that LytC is a major autolysin that is not associated with cell separation.

scholarly journals Temporal Expression of the Bacillus subtilis secAGene, Encoding a Central Component of the Preprotein Translocase

1999 ◽  
Vol 181 (2) ◽  
pp. 493-500 ◽  
Author(s):  
Markus Herbort ◽  
Michael Klein ◽  
Erik H. Manting ◽  
Arnold J. M. Driessen ◽  
Roland Freudl
Keyword(s):  
Bacillus Subtilis ◽  
Growth Phase ◽  
Exponential Growth ◽  
De Novo ◽  
Stationary Growth Phase ◽  
Extracellular Proteins ◽  
Exponential Growth Phase ◽  
Central Component ◽  
Temporal Expression ◽  
Stationary Growth

ABSTRACT In Bacillus subtilis, the secretion of extracellular proteins strongly increases upon transition from exponential growth to the stationary growth phase. It is not known whether the amounts of some or all components of the protein translocation apparatus are concomitantly increased in relation to the increased export activity. In this study, we analyzed the transcriptional organization and temporal expression of the secA gene, encoding a central component of the B. subtilis preprotein translocase. We found that secA and the downstream gene (prfB) constitute an operon that is transcribed from a vegetative (ςA-dependent) promoter located upstream ofsecA. Furthermore, using different independent methods, we found that secA expression occurred mainly in the exponential growth phase, reaching a maximal value almost precisely at the transition from exponential growth to the stationary growth phase. Following to this maximum, the de novo transcription ofsecA sharply decreased to a low basal level. Since at the time of maximal secA transcription the secretion activity of B. subtilis strongly increases, our results clearly demonstrate that the expression of at least one of the central components of the B. subtilis protein export apparatus is adapted to the increased demand for protein secretion. Possible mechanistic consequences are discussed.

scholarly journals A switch in surface polymer biogenesis triggers growth-phase-dependent and antibiotic-induced bacteriolysis

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Josué Flores-Kim ◽  
Genevieve S Dobihal ◽  
Andrew Fenton ◽  
David Z Rudner ◽  
Thomas G Bernhardt
Keyword(s):  
Cell Wall ◽  
Streptococcus Pneumoniae ◽  
Growth Phase ◽  
Exponential Growth ◽  
Cell Wall Synthesis ◽  
Phase Growth ◽  
Gram Positive ◽  
Osmotic Lysis ◽  
Penicillin Treatment ◽  
Lipoteichoic Acids

Penicillin and related antibiotics disrupt cell wall synthesis to induce bacteriolysis. Lysis in response to these drugs requires the activity of cell wall hydrolases called autolysins, but how penicillins misactivate these deadly enzymes has long remained unclear. Here, we show that alterations in surface polymers called teichoic acids (TAs) play a key role in penicillin-induced lysis of the Gram-positive pathogen Streptococcus pneumoniae (Sp). We find that during exponential growth, Sp cells primarily produce lipid-anchored TAs called lipoteichoic acids (LTAs) that bind and sequester the major autolysin LytA. However, penicillin-treatment or prolonged stationary phase growth triggers the degradation of a key LTA synthase, causing a switch to the production of wall-anchored TAs (WTAs). This change allows LytA to associate with and degrade its cell wall substrate, thus promoting osmotic lysis. Similar changes in surface polymer assembly may underlie the mechanism of antibiotic- and/or growth phase-induced lysis for other important Gram-positive pathogens.

scholarly journals SigM, an Extracytoplasmic Function Sigma Factor of Bacillus subtilis, Is Activated in Response to Cell Wall Antibiotics, Ethanol, Heat, Acid, and Superoxide Stress

2003 ◽  
Vol 185 (12) ◽  
pp. 3491-3498 ◽  
Author(s):  
Penny D. Thackray ◽  
Anne Moir
Keyword(s):  
Cell Wall ◽  
Bacillus Subtilis ◽  
Exponential Growth ◽  
Sigma Factor ◽  
Promoter Region ◽  
Normal Cell ◽  
Tween 20 ◽  
Exponential Growth Phase ◽  
Extracytoplasmic Function Sigma Factor ◽  
Triton X

ABSTRACT The extracytoplasmic function sigma M of Bacillus subtilis is required for normal cell growth under salt stress. It is expressed maximally during exponential growth and is further induced by the addition of 0.7 M NaCl. The promoter region of the sigM operon contains two promoters; one (PA) is sigma A dependent, and the other (PM) is sigma M dependent. These have been placed separately at the amy locus, directing expression of a lacZ reporter gene. Only the PM fusion responded to salt induction. This promoter, which was responsive to the level of active sigma M in the cell, was also induced by 5% ethanol, by vancomycin, bacitracin, or phosphomycin (inhibitors of cell wall biosynthesis; 2 μg per ml), and by heat shock of 50°C for 10 min. It was very strongly induced by acid (pH 4.3) and 80 μM paraquat, but after a 15- to 30-min delay. There was no induction by alkali (pH 9), 5 mM H2O2, the detergents 0.1% Triton X-100 and 0.1% Tween 20, or 50 μM monensin. In addition to their reduced tolerance to salt, null mutants of sigM were unable to grow at pH 4.3 and lysed after exposure to 5% ethanol. Genes regulated by SigM were also tested for their response to pH 4.3, 5% ethanol, and 2 μg of vancomycin per ml. Expression of the genes may have been activated by increased levels of sigma M, but at least some were also subject to additional controls, as they responded to one type of stress but not another. Expression of yrhJ, which encodes a cytochrome P450/NADPH reductase, was induced in response to acid and vancomycin. yraA expression was acid, ethanol, and vancomycin induced, whereas yjbD showed only ethanol induction. YraA protein was extremely important to acid survival—a mutation in yraA, like a sigM mutation, resulted in the failure of B. subtilis to grow at pH 4.3. Sigma M is therefore involved in maintaining membrane and cell wall integrity in response to several different stresses in exponential growth phase and is activated by such stresses.

scholarly journals Interplay of CodY and ScoC in the Regulation of Major Extracellular Protease Genes of Bacillus subtilis

2016 ◽  
Vol 198 (6) ◽  
pp. 907-920 ◽  
Author(s):  
Giulia Barbieri ◽  
Alessandra M. Albertini ◽  
Eugenio Ferrari ◽  
Abraham L. Sonenshein ◽  
Boris R. Belitsky
Keyword(s):  
Gene Expression ◽  
Bacillus Subtilis ◽  
Growth Phase ◽  
Exponential Growth ◽  
Degradation Products ◽  
Transcriptional Regulator ◽  
Complex Medium ◽  
Exponential Growth Phase ◽  
Content Type ◽  
In Cells

ABSTRACTAprE and NprE are two major extracellular proteases inBacillus subtiliswhose expression is directly regulated by several pleiotropic transcriptional factors, including AbrB, DegU, ScoC, and SinR. In cells growing in a rich, complex medium, theaprEandnprEgenes are strongly expressed only during the post-exponential growth phase; mutations in genes encoding the known regulators affect the level of post-exponential-phase gene expression but do not permit high-level expression during the exponential growth phase. Using DNA-binding assays and expression and mutational analyses, we have shown that the genes for both exoproteases are also under strong, direct, negative control by the global transcriptional regulator CodY. However, because CodY also repressesscoC, little or no derepression ofaprEandnprEwas seen in acodYnull mutant due to overexpression ofscoC. Thus, CodY is also an indirect positive regulator of these genes by limiting the synthesis of a second repressor. In addition, in cells growing under conditions that activate CodY, ascoCnull mutation had little effect onaprEornprEexpression; full effects ofscoCorcodYnull mutations could be seen only in the absence of the other regulator. However, even thecodY scoCdouble mutant did not show high levels ofaprEandnprEgene expression during exponential growth phase in a rich, complex medium. Only a third mutation, inabrB, allowed such expression. Thus, three repressors can contribute to reducing exoprotease gene expression during growth in the presence of excess nutrients.IMPORTANCEThe majorBacillus subtilisexoproteases, AprE and NprE, are important metabolic enzymes whose genes are subject to complex regulation by multiple transcription factors. We show here that expression of theaprEandnprEgenes is also controlled, both directly and indirectly, by CodY, a global transcriptional regulator that responds to the intracellular pools of amino acids. Direct CodY-mediated repression explains a long-standing puzzle, that is, why exoproteases are not produced when cells are growing exponentially in a medium containing abundant quantities of proteins or their degradation products. Indirect regulation ofaprEandnprEthrough CodY-mediated repression of thescoCgene, encoding another pleiotropic repressor, serves to maintain a significant level of repression of exoprotease genes when CodY loses activity.

A particulate chitin synthase from Aspergillus flavus Link: the properties, location, and levels of activity in mycelium and regenerating protoplast preparations

1976 ◽  
Vol 22 (7) ◽  
pp. 915-921 ◽  
Author(s):  
P. M. Moore ◽  
J. F. Peberdy
Keyword(s):  
Protein Synthesis ◽  
Carbon Source ◽  
Aspergillus Flavus ◽  
Growth Phase ◽  
Exponential Growth ◽  
Incubation Temperature ◽  
Specific Activity ◽  
Chitin Synthase ◽  
Exponential Growth Phase ◽  
Net Protein

Chitin synthase (EC 2.4.1.16) has been characterized in Aspergillus flavus. A Km value of 2.5 mM was obtained for the substrate UDPGlcNAc. The enzyme had a requirement for GlcNAc, and Mg2+ and activity was increased in the presence of soluble chitodextrins F1 and F2. The optimum activity was obtained using Tris–HCl buffer, pH 7.5, with a secondary peak at pH 6.2 and an incubation temperature of 29.5 °C.Distribution patterns of chitin synthase in protoplasts and mycelial material were very similar. The highest specific activity was found in a 200 000 × g fraction.Enzyme levels in growing mycelium increased during the exponential growth phase after which they declined. Activity also increased during the early stages of regeneration of both conidial and mycelial protoplasts, despite an initial lack in net protein synthesis. Chitin synthase levels were also dependent upon the carbon source available during regeneration.

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