Filter and export

Publications

What is a Publication?
79 Publications visible to you, out of a total of 79
T-box-mediated control of the anabolic proline biosynthetic genes of Bacillus subtilis

Abstract (Expand)

Bacillus subtilis possesses interlinked routes for the synthesis of proline. The ProJ-ProA-ProH route is responsible for the production of proline as an osmoprotectant, and the ProB-ProA-ProI route … provides proline for protein synthesis. We show here that the transcription of the anabolic proBA and proI genes is controlled in response to proline limitation via a T-box-mediated termination/antitermination regulatory mechanism, a tRNA-responsive riboswitch. Primer extension analysis revealed mRNA leader transcripts of 270 and 269 nt for the proBA and proI genes, respectively, both of which are synthesized from SigA-type promoters. These leader transcripts are predicted to fold into two mutually exclusive secondary mRNA structures, forming either a terminator or an antiterminator configuration. Northern blot analysis allowed the detection of both the leader and the full-length proBA and proI transcripts. Assessment of the level of the proBA transcripts revealed that the amount of the full-length mRNA species strongly increased in proline-starved cultures. Genetic studies with a proB-treA operon fusion reporter strain demonstrated that proBA transcription is sensitively tied to proline availability and is derepressed as soon as cellular starvation for proline sets in. Both the proBA and the proI leader sequences contain a CCU proline-specific specifier codon prone to interact with the corresponding uncharged proline-specific tRNA. By replacing the CCU proline specifier codon in the proBA T-box leader with UUC, a codon recognized by a Phe-specific tRNA, we were able to synthetically re-engineer the proline-specific control of proBA transcription to a control that was responsive to starvation for phenylalanine.

Authors: Jeanette Brill, , Harald Putzer,

Date Published: 13th Jan 2011

Publication Type: Not specified

The DEAD-box RNA helicases in Bacillus subtilis have multiple functions and act independent from each other

Abstract (Expand)

DEAD-box RNA helicases play important roles in remodeling RNA molecules and in facilitating a variety of RNA-protein interactions that are key to many essential cellular processes. In spite of the … importance of RNA, our knowledge about RNA helicases is only limited. In this study we investigated the role of the four DEAD-box RNA helicases in Gram positive model-organism Bacillus subtilis. A strain deleted of all RNA helicases is able to grow at 37°C but not at lower temperatures. Especially the deletion of cshA, cshB or yfmL lead to cold-sensitive phenotypes. Moreover, these mutant strains exhibit unique defects in ribosome biogenesis suggesting distinct functions for the individual enzymes in this process. Based on protein accumulation, severity of the cold-sensitive phenotype and the interaction with components of the RNA degradosome, CshA is the major RNA helicase of B. subtilis. To unravel the functions of CshA in addition to ribosome biogenesis we conducted microarray analysis and identified the ysbAB and frlBONMD mRNAs as targets that are strongly affected by the deletion of the cshA gene. Our findings suggest that the different helicases make distinct contributions to the physiology of B. subtilis. Ribosome biogenesis and RNA degradation are two of their major tasks in B. subtilis.

Authors: Martin Lehnik-Habrink, Leonie Rempeters, Akos T Kovács, Christoph Wrede, Claudia Baierlein, Heike Krebber, ,

Date Published: 24th Nov 2012

Publication Type: Not specified

The large mechanosensitive channel MscL determines bacterial susceptibility to the bacteriocin sublancin 168

Abstract (Expand)

Bacillus subtilis strain 168 produces the extremely stable and broad-spectrum lantibiotic sublancin 168. Known sublancin 168-susceptible organisms include important pathogens, such as Staphylococcus … aureus. Nevertheless, since its discovery, the mode of action of sublancin 168 has remained elusive. The present studies were, therefore, aimed at the identification of cellular determinants for bacterial susceptibility toward sublancin 168. Growth inhibition and competition assays on plates and in liquid cultures revealed that sublancin 168-mediated growth inhibition of susceptible B. subtilis and S. aureus cells is affected by the NaCl concentration in the growth medium. Added NaCl did not influence the production, activity, or stability of sublancin 168 but, instead, lowered the susceptibility of sensitive cells toward this lantibiotic. Importantly, the susceptibility of B. subtilis and S. aureus cells toward sublancin 168 was shown to depend on the presence of the large mechanosensitive channel of conductance MscL. In contrast, MscL was not involved in susceptibility toward the bacteriocin nisin or Pep5. Taken together, our unprecedented results demonstrate that MscL is a critical and specific determinant in bacterial sublancin 168 susceptibility that may serve either as a direct target for this lantibiotic or as a gate of entry to the cytoplasm.

Authors: Thijs R H M Kouwen, Erik N Trip, Emma L Denham, Mark J J B Sibbald, Jean-Yves F Dubois,

Date Published: 8th Sep 2009

Publication Type: Not specified

The role of dynamic stimulation pattern in the analysis of bistable intracellular networks

Abstract (Expand)

Bistable systems play an important role in the functioning of living cells. Depending on the strength of the necessary positive feedback one can distinguish between (irreversible) "one-way … switch" or (reversible) "toggle-switch" type behavior. Besides the well- established steady-state properties, some important characteristics of bistable systems arise from an analysis of their dynamics. We demonstrate that a supercritical stimulus amplitude is not sufficient to move the system from the lower (off-state) to the higher branch (on-state) for either a step or a pulse input. A switching surface is identified for the system as a function of the initial condition, input pulse amplitude and duration (a supercritical signal). We introduce the concept of bounded autonomy for single level systems with a pulse input. Towards this end, we investigate and characterize the role of the duration of the stimulus. Furthermore we show, that a minimal signal power is also necessary to change the steady state of the bistable system. This limiting signal power is independent of the applied stimulus and is determined only by systems parameters. These results are relevant for the design of experiments, where it is often difficult to create a defined pattern for the stimulus. Furthermore, intracellular processes, like receptor internalization, do manipulate the level of stimulus such that level and duration of the stimulus is conducive to characteristic behavior.

Authors: , Sree N Sreenath, Radina P Soebiyanto, Jayant Avva, Kwang-Hyun Cho,

Date Published: 17th Jan 2007

Publication Type: Not specified

The Spx paralogue MgsR (YqgZ) controls a subregulon within the general stress response of Bacillus subtilis

Abstract (Expand)

The alternative sigma factor sigma(B) of Bacillus subtilis is responsible for the induction of the large general stress regulon comprising approximately 150-200 genes. YqgZ, a member of the sigma(B) … regulon, resembles the global regulator Spx of the diamide stress regulon in B. subtilis. In this work we conducted a comprehensive transcriptome and proteome analysis of the B. subtilis wild-type 168 and its isogenic DeltasigB and DeltayqgZ mutants following exposure to 4% (v/v) ethanol stress, which led to the characterization of a 'subregulon' within the general stress response that is regulated by YqgZ. Activation and induction of sigma(B) are necessary but not sufficient for a full expression of all general stress genes. Expression of 53 genes was found to be positively regulated and the expression of 18 genes was negatively affected by YqgZ. The identification of the negatively regulated group represents a so far uncharacterized regulatory phenomenon observed in the DeltasigB mutant background that can now be attributed to the function of YqgZ. Due to the strict sigma(B)-dependent expression of YqgZ it was renamed to MgsR (modulator of the general stress response).

Authors: Alexander Reder, Dirk Höper, Christin Weinberg, Ulf Gerth, Martin Fraunholz,

Date Published: 14th Jul 2008

Publication Type: Not specified

Towards the development of Bacillus subtilis as a cell factory for membrane proteins and protein complexes

Abstract (Expand)

ABSTRACT: BACKGROUND: The Gram-positive bacterium Bacillus subtilis is an important producer of high quality industrial enzymes and a few eukaryotic proteins. Most of these proteins are secreted into … the growth medium, but successful examples of cytoplasmic protein production are also known. Therefore, one may anticipate that the high protein production potential of B. subtilis can be exploited for protein complexes and membrane proteins to facilitate their functional and structural analysis. The high quality of proteins produced with B. subtilis results from the action of cellular quality control systems that efficiently remove misfolded or incompletely synthesized proteins. Paradoxically, cellular quality control systems also represent bottlenecks for the production of various heterologous proteins at significant concentrations. CONCLUSION: While inactivation of quality control systems has the potential to improve protein production yields, this could be achieved at the expense of product quality. Mechanisms underlying degradation of secretory proteins are nowadays well understood and often controllable. It will therefore be a major challenge for future research to identify and modulate quality control systems of B. subtilis that limit the production of high quality protein complexes and membrane proteins, and to enhance those systems that facilitate assembly of these proteins.

Authors: Jessica C Zweers, Imrich Barák, Dörte Becher, Arnold Jm Driessen, , Vesa P Kontinen, Manfred J Saller, L'udmila Vavrová,

Date Published: 2nd Dec 2007

Publication Type: Not specified

Trigger enzymes: bifunctional proteins active in metabolism and in controlling gene expression

Abstract (Expand)

All regulatory processes require components that sense the environmental or metabolic conditions of the cell, and sophisticated sensory proteins have been studied in great detail. During the last few … years, it turned out that enzymes can control gene expression in response to the availability of their substrates. Here, we review four different mechanisms by which these enzymes interfere with regulation in bacteria. First, some enzymes have acquired a DNA-binding domain and act as direct transcription repressors by binding DNA in the absence of their substrates. A second class is represented by aconitase, which can bind iron responsive elements in the absence of iron to control the expression of genes involved in iron homoeostasis. The third class of these enzymes is sugar permeases of the phosphotransferase system that control the activity of transcription regulators by phosphorylating them in the absence of the specific substrate. Finally, a fourth class of regulatory enzymes controls the activity of transcription factors by inhibitory protein-protein interactions. We suggest that the enzymes that are active in the control of gene expression should be designated as trigger enzymes. An analysis of the occurrence of trigger enzymes suggests that the duplication and subsequent functional specialization is a major pattern in their evolution.

Authors: Fabian M Commichau,

Date Published: 11th Dec 2007

Publication Type: Not specified

Powered by
 (v.1.15.2)
About FAIRDOMHub | Funding and Programmes | Credits | Terms & Conditions | Imprint | Cookie preferences
Copyright © 2008 - 2024 The University of Manchester and HITS gGmbH