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79 Publications visible to you, out of a total of 79
Penicillin-binding protein folding is dependent on the PrsA peptidyl-prolyl cis-trans isomerase in Bacillus subtilis

Abstract (Expand)

Summary The PrsA protein is a membrane-anchored peptidyl-prolyl cis-trans isomerase in Bacillus subtilis and most other Gram-positive bacteria. It catalyses the post-translocational folding of exported … proteins and is essential for normal growth of B. subtilis. We studied the mechanism behind this indispensability. We could construct a viable prsA null mutant in the presence of a high concentration of magnesium. Various changes in cell morphology in the absence of PrsA suggested that PrsA is involved in the biosynthesis of the cylindrical lateral wall. Consistently, four penicillin-binding proteins (PBP2a, PBP2b, PBP3 and PBP4) were unstable in the absence of PrsA, while muropeptide analysis revealed a 2% decrease in the peptidoglycan cross-linkage index. Misfolded PBP2a was detected in PrsA-depleted cells, indicating that PrsA is required for the folding of this PBP either directly or indirectly. Furthermore, strongly increased uniform staining of cell wall with a fluorescent vancomycin was observed in the absence of PrsA. We also demonstrated that PrsA is a dimeric or oligomeric protein which is localized at distinct spots organized in a helical pattern along the cell membrane. These results suggest that PrsA is essential for normal growth most probably as PBP folding is dependent on this PPIase.

Authors: Hanne-Leena Hyyryläinen, , Kathleen Dahncke, Milla Pietiäinen, Pascal Courtin, Marika Vitikainen, Raili Seppala, Andreas Otto, Dörte Becher, Marie-Pierre Chapot-Chartier, , Vesa P Kontinen

Date Published: 4th May 2010

Publication Type: Not specified

Physical interactions between tricarboxylic acid cycle enzymes in Bacillus subtilis: Evidence for a metabolon

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The majority of all proteins of a living cell is active in complexes rather than in an isolated way. These protein-protein interactions are of high relevance for many biological functions. In addition … to many well established protein complexes an increasing number of protein-protein interactions, which form rather transient complexes has recently been discovered. The formation of such complexes seems to be a common feature especially for metabolic pathways. In the Gram-positive model organism Bacillus subtilis, we identified a protein complex of three citric acid cycle enzymes. This complex consists of the citrate synthase, the isocitrate dehydrogenase, and the malate dehydrogenase. Moreover, fumarase and aconitase interact with malate dehydrogenase and with each other. These five enzymes catalyze sequential reaction of the TCA cycle. Thus, this interaction might be important for a direct transfer of intermediates of the TCA cycle and thus for elevated metabolic fluxes via substrate channeling. In addition, we discovered a link between the TCA cycle and gluconeogenesis through a flexible interaction of two proteins: the association between the malate dehydrogenase and phosphoenolpyruvate carboxykinase is directly controlled by the metabolic flux. The phosphoenolpyruvate carboxykinase links the TCA cycle with gluconeogenesis and is essential for B. subtilis growing on gluconeogenic carbon sources. Only under gluconeogenic growth conditions an interaction of these two proteins is detectable and disappears under glycolytic growth conditions.

Authors: Frederik M Meyer, Jan Gerwig, Elke Hammer, Christina Herzberg, Fabian M Commichau, ,

Date Published: 20th Aug 2010

Publication Type: Not specified

Physiological proteomics and stress/starvation responses in Bacillus subtilis and Staphylococcus aureus

Abstract (Expand)

Gel-based proteomics is a useful approach for visualizing the responses of bacteria to stress and starvation stimuli. In order to face stress/starvation, bacteria have developed very complicated gene … expression networks. A proteomic view of stress/starvation responses, however, is only a starting point which should promote follow-up studies aimed at the comprehensive description of single regulons, their signal transduction pathways on the one hand, and their adaptive functions on the other, and finally their integration into complex gene expression networks. This "road map of physiological proteomics" will be demonstrated for the general stress regulon controlled by sigma(B) in Bacillus subtilis and the oxygen starvation response with Rex as a master regulator in Staphylococcus aureus.

Authors: , Alexander Reder, Stephan Fuchs, Martin Pagels, Susanne Engelmann

Date Published: 20th Feb 2009

Publication Type: Not specified

Protein transport across and into cell membranes in bacteria and archaea

Abstract (Expand)

In the three domains of life, the Sec, YidC/Oxa1, and Tat translocases play important roles in protein translocation across membranes and membrane protein insertion. While extensive studies have been … performed on the endoplasmic reticular and Escherichia coli systems, far fewer studies have been done on archaea, other Gram-negative bacteria, and Gram-positive bacteria. Interestingly, work carried out to date has shown that there are differences in the protein transport systems in terms of the number of translocase components and, in some cases, the translocation mechanisms and energy sources that drive translocation. In this review, we will describe the different systems employed to translocate and insert proteins across or into the cytoplasmic membrane of archaea and bacteria.

Authors: Jijun Yuan, Jessica C Zweers, , Ross E Dalbey

Date Published: 16th Jun 2009

Publication Type: Not specified

Proteolysis of beta-galactosidase following SigmaB activation in Bacillus subtilis

Abstract (Expand)

In Bacillus subtilis the σB mediated general stress response provides protection against various environmental and energy related stress conditions. To better understand the general stress response, … we need to explore the mechanism by which the components interact. Here, we performed experiments in B. subtilis wild type and mutant strains to test and validate a mathematical model of the dynamics of σB activity. In the mutant strain BSA115, σB transcription is inducible by the addition of IPTG and negative control of σB activity by the anti-sigma factor RsbW is absent. In contrast to our expectations of a continuous β-galactosidase activity from a ctc::lacZ fusion, we observed a transient activity in the mutant. To explain this experimental finding, we constructed mathematical models reflecting different hypotheses regarding the regulation of σB and β-galactosidase dynamics. Only the model assuming instability of either ctc::lacZ mRNA or β-galactosidase protein is able to reproduce the experiments in silico. Subsequent Northern blot experiments revealed stable high-level ctc::lacZ mRNA concentrations after the induction of the σB response. Therefore, we conclude that protein instability following σB activation is the most likely explanation for the experimental observations. Our results thus support the idea that B. subtilis increases the cytoplasmic proteolytic degradation to adapt the proteome in face of environmental challenges following activation of the general stress response. The findings also have practical implications for the analysis of stress response dynamics using lacZ reporter gene fusions, a frequently used strategy for the σB response.

Authors: , , , , Georg Homuth, ,

Date Published: 2012

Publication Type: Not specified

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