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Capacity for instantaneous catabolism of preferred and non-preferred carbon sources in Escherichia coli and Bacillus subtilis.

ABSTRACT: Making the right choice for nutrient consumption in an ever-changing environment is a key factor for evolutionary success of bacteria. Here we investigate the regulatory mechanisms that enable dynamic adaptation between non-preferred and preferred carbon sources for the model Gram-negative and -positive species Escherichia coli and Bacillus subtilis, respectively. We focus on the ability for instantaneous catabolism of a gluconeogenic carbon source upon growth on a glycolytic carbon source and vice versa. By following isotopic tracer dynamics on a 1-2?minute scale, we show that flux reversal from the preferred glucose to non-preferred pyruvate as the sole carbon source is primarily transcriptionally regulated. In the opposite direction, however, E. coli can reverse its flux instantaneously by means of allosteric regulation, whereas in B. subtilis this flux reversal is transcriptionally regulated. Upon removal of transcriptional regulation, B. subtilis assumes the ability of instantaneous glucose catabolism. Using an approach that combines quantitative metabolomics and kinetic modelling, we then identify the additionally necessary key metabolite-enzyme interactions that implement the instantaneous flux reversal in the transcriptionally deregulated B. subtilis, and validate the most relevant allosteric interactions.

SUBMITTER: Buffing MF

PROVIDER: S-EPMC6079084 | biostudies-other | 2018 Aug

REPOSITORIES: biostudies-other

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Capacity for instantaneous catabolism of preferred and non-preferred carbon sources in Escherichia coli and Bacillus subtilis.

Buffing Marieke F MF Link Hannes H Christodoulou Dimitris D Sauer Uwe U

Scientific reports 20180806 1

Making the right choice for nutrient consumption in an ever-changing environment is a key factor for evolutionary success of bacteria. Here we investigate the regulatory mechanisms that enable dynamic adaptation between non-preferred and preferred carbon sources for the model Gram-negative and -positive species Escherichia coli and Bacillus subtilis, respectively. We focus on the ability for instantaneous catabolism of a gluconeogenic carbon source upon growth on a glycolytic carbon source and v ...[more]

PMID: 30082753

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Project description:RasP is a predicted intramembrane metalloprotease of Bacillus subtilis that has been proposed to cleave the stress response anti-sigma factors RsiW and RsiV, the cell division protein FtsL, and remnant signal peptides within their transmembrane segments. To provide evidence for direct effects of RasP on putative substrates, we developed a heterologous coexpression system. Since expression of catalytically inactive RasP E21A inhibited expression of other membrane proteins in Escherichia coli, we added extra transmembrane segments to RasP E21A, which allowed accumulation of most other membrane proteins. A corresponding active version of RasP appeared to promiscuously cleave coexpressed membrane proteins, except those with a large periplasmic domain. However, stable cleavage products were not observed, even in clpP mutant E. coli Fusions of transmembrane segment-containing parts of FtsL and RsiW to E. coli maltose-binding protein (MBP) also resulted in proteins that appeared to be RasP substrates upon coexpression in E. coli, including FtsL with a full-length C-terminal domain (suggesting that prior cleavage by a site 1 protease is unnecessary) and RsiW designed to mimic the PrsW site 1 cleavage product (suggesting that further trimming by extracytoplasmic protease is unnecessary). Purified RasP cleaved His6-MBP-RsiW(73-118) in vitro within the RsiW transmembrane segment based on mass spectrometry analysis, demonstrating that RasP is an intramembrane protease. Surprisingly, purified RasP failed to cleave His6-MBP-FtsL(23-117). We propose that the lack of ?-helix-breaking residues in the FtsL transmembrane segment creates a requirement for the membrane environment and/or an additional protein(s) in order for RasP to cleave FtsL.IMPORTANCE Intramembrane proteases govern important signaling pathways in nearly all organisms. In bacteria, they function in stress responses, cell division, pathogenesis, and other processes. Their membrane-associated substrates are typically inferred from genetic studies in the native bacterium. Evidence for direct effects has come sometimes from coexpression of the enzyme and potential substrate in a heterologous host and rarely from biochemical reconstitution of cleavage in vitro We applied these two approaches to the B. subtilis enzyme RasP and its proposed substrates RsiW and FtsL. We discovered potential pitfalls and solutions in heterologous coexpression experiments in E. coli, providing evidence that both substrates are cleaved by RasP in vivo but, surprisingly, that only RsiW was cleaved in vitro, suggesting that FtsL has an additional requirement.

Project description:Model topology is divided into two compartments, cell programming and performance testing. The cell programming compartment is split into history and pre-treatment. History ( History I or H1: E.coli grown for 18hrs in LB flask, transferred to fresh LB flask after that. History II or H2: E.coli grown for 18hrs in LB flask, transferred to fresh LB flask for 45 min. From this flask, 0.1O.D./ml transferred to rich medium and grown for 4 hours. From this,0.1O.D./ml transferred to fresh rich medium. History III or H3: E.coli grown for 18hrs in LB flask, transferred to fresh LB flask for 45 min. From this flask, 0.1O.D./ml transferred to starvation medium and grown for 4 hours. From this,0.1O.D./ml transferred to fresh starvation medium. Pre-treatment (Pre-treatment 1(T1): 2.5g glucose/litre 5mM NH4Cl. Pre-treatment 2 (T2): 2.5g glucose/litre 0.25mM NH4Cl. Pre-treatment 3 (T3): - 0.25g glucose/litre 5mmM NH4Cl. Pre-treatment 4 (T4): 0.25g glucose/litre 0.25mM NH4Cl). Each pre-treatment given for 2.5 hours.The culture nomenclature indicates the adaptive path followed, for example, H1T1 indicates the culture has encountered history I (H1) and then transferred to pre-treatment 1 (T1).RNA was extracted for selected combinations. Performance testing : Performance testing describes the type of analysis done which is the growth pattern study onto three substrates, glucose, succinate and pyruvate. This performance testing revealed specific history-pretreatment combinations to be better suited for growth on certain substrate and some not suited for growth. The samples were harvested for RNA isolation at peak growth points and named worst_glucose, best_glucose,worst_succinate, best_succinate, worst_pyruvate and best_pyruvate according to the growth shown after testing all 12 history-pretreatment combinations. The differences in physiology were studied in details using microarray analysis of 13 samples including 3 history samples, 4 pre-treatment samples and 6 samples at performance testing level. RNA extraction was done using Qiagen RNeasy minikit (Germany). Standard Affymetrix protocol was followed for hybridization on Affymetrix E. coli Genome 2.0 Array.

Dataset Information

Capacity for instantaneous catabolism of preferred and non-preferred carbon sources in Escherichia coli and Bacillus subtilis.

Publications

Capacity for instantaneous catabolism of preferred and non-preferred carbon sources in Escherichia coli and Bacillus subtilis.

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