The pattern of proteins produced by bacteria represents the physiological state of the organism as well as the environmental conditions encountered. Environmental stress induces the expression of ...several regulons encoding stress proteins. Extensive information about the proteins which constitute these regulons (or stimulons) and their control is available for very few bacteria, such as the Gram-positive
Bacillus subtilis and the Gram-negative
Escherichia coli (γ-proteobacteria) and is minimal for all other bacteria.
Agrobacterium tumefaciens is a Gram-negative plant pathogen of the α-proteobacteria, which constitutes the main tool for plant recombinant genetics. Our previous studies on the control of chaperone-coding operons indicated that
A. tumefaciens has unique features and combines regulatory elements from both
B. subtilis and
E. coli. Therefore, we examined the patterns of proteins induced in
A. tumefaciens by environmental changes using two-dimensional gel electrophoresis and dual-channel image analysis. Shifts to high temperature, oxidative and mild acid stresses stimulated the expression of 97 proteins. The results indicate that most of these stress-induced proteins (80/97) were specific to one stress stimulon. Only 10 proteins appear to belong to a general stress regulon.
Abstract
The pattern of proteins produced by bacteria represents the physiological state of the organism as well as the environmental conditions encountered. Environmental stress induces the ...expression of several regulons encoding stress proteins. Extensive information about the proteins which constitute these regulons (or stimulons) and their control is available for very few bacteria, such as the Gram-positive Bacillus subtilis and the Gram-negative Escherichia coli (γ-proteobacteria) and is minimal for all other bacteria. Agrobacterium tumefaciens is a Gram-negative plant pathogen of the α-proteobacteria, which constitutes the main tool for plant recombinant genetics. Our previous studies on the control of chaperone-coding operons indicated that A. tumefaciens has unique features and combines regulatory elements from both B. subtilis and E. coli. Therefore, we examined the patterns of proteins induced in A. tumefaciens by environmental changes using two-dimensional gel electrophoresis and dual-channel image analysis. Shifts to high temperature, oxidative and mild acid stresses stimulated the expression of 97 proteins. The results indicate that most of these stress-induced proteins (80/97) were specific to one stress stimulon. Only 10 proteins appear to belong to a general stress regulon.
This work is concerned with user perceived privacy and how clients (which we call data subjects here) can be empowered to control their own data consistently with their own interests. To support ...building and evaluation of privacy-aware applications, we describe a privacy ontology, how the privacy principles relate to that and how they are influenced by the core concepts as well as by each other. We use this influence of the privacy principles to evaluate the level of privacy for a particular transaction, when applying and extending the core concepts for an application domain.
A proteome study of
Agrobacterium tumefaciens exposed to plant roots demonstrated the existence of a plant-dependent stimulon. This stimulon was induced by exposure to cut roots and consists of at ...least 30 soluble proteins (p
I 4–7), including several proteins whose involvement in agrobacteria–host interactions has not been previously reported. Exposure of the bacteria to tomato roots also resulted in modification of the proteins: Ribosomal Protein L19, GroEL, AttM, and ChvE, indicating the significance of protein modifications in the interactions of agrobacteria with plants.
The
Staphylococcus aureus genome codes for a sigma factor that shows close sequence similarity to the alternative sigma factor
σ
B of
Bacillus subtilis. However, of the proteins controlling the ...activity of
σ
B in
B. subtilis only RsbU, RsbV, and RsbW are encoded in the staphylococcal genome. Therefore, the regulation of the
σ
B activity must differ between these two bacterial species. The present study was designed (i) to describe the
σ
B regulon and (ii) to identify stimuli leading to an activation of
σ
B-dependent transcription. All conditions under which
σ
B was activated in
S. aureus (heat shock, addition of MnCl
2 or NaCl, alkaline shock) required the presence of RsbU, a positive regulator of
σ
B. In contrast to
B. subtilis, a drop in the cellular ATP level caused by the addition of carbonyl cyanide
m-chlorophenylhydrazone did not lead to an activation of
σ
B in
S. aureus. Moreover, ethanol, a strong inductor of
σ
B activity in
B. subtilis, also failed to induce
σ
B in
S. aureus. Expression of
sigB and
σ
B-dependent genes was enhanced following entry into stationary phase of cells grown in complex medium (LB medium). Our DNA microarray data indicated that 122 genes are positively regulated by
σ
B under alkaline stress conditions. Interestingly, only 12% of these genes have an orthologue in the
B. subtilis σ
B regulon, suggesting that the function of the
σ
B regulon in
S. aureus is different from that in
B. subtilis. We could show that
σ
B of
S. aureus, in contrast to
B. subtilis, may have a function in more basic cellular processes such as cell envelope composition, membrane transport processes and intermediary metabolism.
σ
B-dependent genes identified by the DNA microarray approach were subjected to detailed transcriptional analyses using primer extension and Northern blot techniques. These analyses confirmed our DNA microarray data and furthermore revealed different regulatory groups of
σ
B-dependent genes.
The Staphylococcus aureus genome codes for a sigma factor that shows close sequence similarity to the alternative sigma factor sigmaB of Bacillus subtilis. However, of the proteins controlling the ...activity of sigmaB in B. subtilis only RsbU, RsbV, and RsbW are encoded in the staphylococcal genome. Therefore, the regulation of the sigmaB activity must differ between these two bacterial species. The present study was designed (i) to describe the sigmaB regulon and (ii) to identify stimuli leading to an activation of sigmaB-dependent transcription. All conditions under which sigmaB was activated in S. aureus (heat shock, addition of MnCl2 or NaCl, alkaline shock) required the presence of RsbU, a positive regulator of sigmaB. In contrast to B. subtilis, a drop in the cellular ATP level caused by the addition of carbonyl cyanide m-chlorophenylhydrazone did not lead to an activation of sigmaB in S. aureus. Moreover, ethanol, a strong inductor of sigmaB activity in B. subtilis, also failed to induce sigmaB in S. aureus. Expression of sigB and sigmaB-dependent genes was enhanced following entry into stationary phase of cells grown in complex medium (LB medium). Our DNA microarray data indicated that 122 genes are positively regulated by sigmaB under alkaline stress conditions. Interestingly, only 12% of these genes have an orthologue in the B. subtilis sigmaB regulon, suggesting that the function of the sigmaB regulon in S. aureus is different from that in B. subtilis. We could show that sigmaB of S. aureus, in contrast to B. subtilis, may have a function in more basic cellular processes such as cell envelope composition, membrane transport processes and intermediary metabolism. sigmaB-dependent genes identified by the DNA microarray approach were subjected to detailed transcriptional analyses using primer extension and Northern blot techniques. These analyses confirmed our DNA microarray data and furthermore revealed different regulatory groups of sigmaB-dependent genes.
The expression of many virulence determinants in Staphylococcus aureus is tightly coordinated generally by global regulatory elements such as accessory gene regulator (agr), staphylococcal accessory ...regulator and the alternative sigma factor sigmaB. We have compared the two-dimensional (2-D) protein pattern of extracellular protein extracts of wild-type cells with the 2-D patterns of the respective regulatory mutants in order to identify proteins whose amount is influenced by a mutation in agr or sigB. In order to quantify changes in the level of interesting proteins we used the Ettan-fluorescence difference gel electrophoresis technique (Amersham Biosciences). As in most bacteria, the amount of extracellular proteins was strongly regulated and increased mainly in the stationary phase of growth at high cell densities. By comparing the extracellular protein pattern of the RN6390 rsbU strain with that of an isogenic agr mutant RN6911 we show that the level of about 70 protein spots changed in the mutant. To analyze the role of sigmaB in virulence gene expression an RsbU+ (RN6390 RsbU+) derivative was included in this study. The protein pattern of the RsbU+ strain (RN6390 RsbU+) was very similar to that of the Deltaagr/DeltarsbU mutant strain (RN6911) indicating an opposing effect of agr and rsbU on the expression of the same genes.
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