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Xu Y, Zeng C, Wen H, Shi Q, Zhao X, Meng Q, Li X, Xiao J. Discovery of AI-2 Quorum Sensing Inhibitors Targeting the LsrK/ HPr Protein-Protein Interaction Site by Molecular Dynamics Simulation, Virtual Screening, and Bioassay Evaluation. Pharmaceuticals (Basel) 2023; 16:ph16050737. [PMID: 37242520 DOI: 10.3390/ph16050737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 05/04/2023] [Accepted: 05/09/2023] [Indexed: 05/28/2023] Open
Abstract
Quorum sensing (QS) is a cell-to-cell communication mechanism that regulates bacterial pathogenicity, biofilm formation, and antibiotic sensitivity. Among the identified quorum sensing, AI-2 QS exists in both Gram-negative and Gram-positive bacteria and is responsible for interspecies communication. Recent studies have highlighted the connection between the phosphotransferase system (PTS) and AI-2 QS, with this link being associated with protein-protein interaction (PPI) between HPr and LsrK. Here, we first discovered several AI-2 QSIs targeting the LsrK/HPr PPI site through molecular dynamics (MD) simulation, virtual screening, and bioassay evaluation. Of the 62 compounds purchased, eight compounds demonstrated significant inhibition in LsrK-based assays and AI-2 QS interference assays. Surface plasmon resonance (SPR) analysis confirmed that the hit compound 4171-0375 specifically bound to the LsrK-N protein (HPr binding domain, KD = 2.51 × 10-5 M), and therefore the LsrK/HPr PPI site. The structure-activity relationships (SARs) emphasized the importance of hydrophobic interactions with the hydrophobic pocket and hydrogen bonds or salt bridges with key residues of LsrK for LsrK/HPr PPI inhibitors. These new AI-2 QSIs, especially 4171-0375, exhibited novel structures, significant LsrK inhibition, and were suitable for structural modification to search for more effective AI-2 QSIs.
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Affiliation(s)
- Yijie Xu
- National Engineering Research Center for Strategic Drugs, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China
| | - Chunlan Zeng
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China
| | - Huiqi Wen
- State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences, Beijing 100071, China
| | - Qianqian Shi
- National Engineering Research Center for Strategic Drugs, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China
| | - Xu Zhao
- Department of Hepatology, Fifth Medical Center of Chinese PLA General Hospital, Beijing 100039, China
| | - Qingbin Meng
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China
| | - Xingzhou Li
- National Engineering Research Center for Strategic Drugs, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China
| | - Junhai Xiao
- National Engineering Research Center for Strategic Drugs, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China
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Kumar S, Bhadane R, Shandilya S, Salo-Ahen OMH, Kapila S. Identification of HPr kinase/phosphorylase inhibitors: novel antimicrobials against resistant Enterococcus faecalis. J Comput Aided Mol Des 2022. [PMID: 35809194 DOI: 10.1007/s10822-022-00461-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2022] [Accepted: 06/14/2022] [Indexed: 12/02/2022]
Abstract
Enterococcus faecalis, a gram-positive bacterium, is among the most common nosocomial pathogens due to its limited susceptibility to antibiotics and its reservoir of the genes coding for virulence factors. Bacterial enzymes such as kinases and phosphorylases play important roles in diverse functions of a bacterial cell and, thus, are potential antibacterial drug targets. In Gram-positive bacteria, HPr Kinase/Phosphorylase (HPrK/P), a bifunctional enzyme is involved in the regulation of carbon catabolite repression by phosphorylating/dephosphorylating the histidine-containing phosphocarrier protein (HPr) at Ser46 residue. Deficiencies in HPrK/P function leads to severe defects in bacterial growth. This study aimed at identifying novel inhibitors of E. faecalis HPrK/P from a commercial compound library using structure-based virtual screening. The hit molecules were purchased and their effect on enzyme activity and growth of resistant E. faecalis was evaluated in vitro. Furthermore, docking and molecular dynamics simulations were performed to study the interactions of the hit compounds with HPrK/P. Among the identified hit molecules, two compounds inhibited the phosphorylation of HPr as well as significantly reduced the growth of resistant E. faecalis in vitro. These identified potential HPrK/P inhibitors open new research avenues towards the development of novel antimicrobials against resistant Gram-positive bacteria.
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Wen J, Zhao X, Si F, Qi G. Surfactin, a quorum sensing signal molecule, globally affects the carbon metabolism in Bacillus amyloliquefaciens. Metab Eng Commun 2021; 12:e00174. [PMID: 34094854 DOI: 10.1016/j.mec.2021.e00174] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 04/25/2021] [Accepted: 05/07/2021] [Indexed: 12/11/2022] Open
Abstract
Surfactin, a quorum sensing signal molecule, is correlated with carbon metabolism in Bacillus amyloliquefaciens. In the present work, we found that mutation of srfA (ΔsrfA) led to an obviously changed carbon metabolism in B. amyloliquefaciens. Firstly, the PTS-glucose system was significantly increased as a feedback to glucose exhaustion. Secondly, the basic carbon metabolism such as glycolysis and TCA cycle was obviously weakened in ΔsrfA. Thirdly, the global regulator of CcpA (carbon catabolite protein A) and P ~ Ser46-HPr (seryl-phosphorylated form of histidine-containing protein) to mediate the CcpA-dependent CCR (carbon catabolite repression) were not increased, but the ability to use extracellular non- and less-preferred carbon sources was down-regulated in ΔsrfA. Fourthly, the carbon overflow metabolism such as biosynthesis of acetate was enhanced while biosynthesis of acetoin/2,3-butanediol and branched-chain amino acids were weakened in ΔsrfA. Finally, ΔsrfA could use most of non- and less-preferred carbon sources except for fatty acids, branched chain amino acids, and some organic acids (e.g. pyruvate, citrate and glutamate) after glucose exhaustion. Collectively, surfactin showed a global influence on carbon metabolism in B. amyloliquefaciens. Our studies highlighted a way to correlate quorum sensing with carbon metabolism via surfactin in Bacillus species. The quorum sensing molecule of surfactin globally influenced the carbon metabolism in B. amyloliquefaciens. The studies highlighted a way to correlate quorum sensing with carbon metabolism via surfactin in Bacillus species. Glycolysis and TCA cycle was obviously weakened after biosynthesis of surfactin was disrupted. The CcpA-dependent carbon catabolite repression was not enhanced after disruption of surfactin biosynthesis. The ability to use non-preferred carbon sources was down-regulated after disruption of surfactin biosynthesis.
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Pätzold L, Brausch AC, Bielefeld EL, Zimmer L, Somerville GA, Bischoff M, Gaupp R. Impact of the Histidine-Containing Phosphocarrier Protein HPr on Carbon Metabolism and Virulence in Staphylococcus aureus. Microorganisms 2021; 9:microorganisms9030466. [PMID: 33668335 PMCID: PMC7996215 DOI: 10.3390/microorganisms9030466] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Revised: 02/18/2021] [Accepted: 02/19/2021] [Indexed: 01/01/2023] Open
Abstract
Carbon catabolite repression (CCR) is a common mechanism pathogenic bacteria use to link central metabolism with virulence factor synthesis. In gram-positive bacteria, catabolite control protein A (CcpA) and the histidine-containing phosphocarrier protein HPr (encoded by ptsH) are the predominant mediators of CCR. In addition to modulating CcpA activity, HPr is essential for glucose import via the phosphotransferase system. While the regulatory functions of CcpA in Staphylococcus aureus are largely known, little is known about the function of HPr in CCR and infectivity. To address this knowledge gap, ptsH mutants were created in S. aureus that either lack the open reading frame or harbor a ptsH variant carrying a thymidine to guanosine mutation at position 136, and the effects of these mutations on growth and metabolism were assessed. Inactivation of ptsH altered bacterial physiology and decreased the ability of S. aureus to form a biofilm and cause infections in mice. These data demonstrate that HPr affects central metabolism and virulence in S. aureus independent of its influence on CcpA regulation.
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Affiliation(s)
- Linda Pätzold
- Institute of Medical Microbiology and Hygiene, Saarland University, D-66421 Homburg, Germany; (L.P.); (A.-C.B.); (E.-L.B.); (L.Z.); (R.G.)
| | - Anne-Christine Brausch
- Institute of Medical Microbiology and Hygiene, Saarland University, D-66421 Homburg, Germany; (L.P.); (A.-C.B.); (E.-L.B.); (L.Z.); (R.G.)
| | - Evelyn-Laura Bielefeld
- Institute of Medical Microbiology and Hygiene, Saarland University, D-66421 Homburg, Germany; (L.P.); (A.-C.B.); (E.-L.B.); (L.Z.); (R.G.)
| | - Lisa Zimmer
- Institute of Medical Microbiology and Hygiene, Saarland University, D-66421 Homburg, Germany; (L.P.); (A.-C.B.); (E.-L.B.); (L.Z.); (R.G.)
| | - Greg A. Somerville
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska, Lincoln, NE 68588, USA;
| | - Markus Bischoff
- Institute of Medical Microbiology and Hygiene, Saarland University, D-66421 Homburg, Germany; (L.P.); (A.-C.B.); (E.-L.B.); (L.Z.); (R.G.)
- Correspondence: ; Tel.: +49-6841-162-39-63
| | - Rosmarie Gaupp
- Institute of Medical Microbiology and Hygiene, Saarland University, D-66421 Homburg, Germany; (L.P.); (A.-C.B.); (E.-L.B.); (L.Z.); (R.G.)
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Kumar S, Narayan KS, Shandilya S, Sood SK, Kapila S. Role of non-PTS dependent glucose permease (GlcU) in maintaining the fitness cost during acquisition of nisin resistance by Enterococcus faecalis. FEMS Microbiol Lett 2020; 366:5628326. [PMID: 31738414 DOI: 10.1093/femsle/fnz230] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 11/15/2019] [Indexed: 11/13/2022] Open
Abstract
Nisin is used for food preservation due to its antibacterial activity. However, some bacteria survive under the prevailing conditions owing to the acquisition of resistance. This study aimed to characterize nisin-resistant Enterococcus faecalis isolated from raw buffalo milk and investigate their fitness cost. FE-SEM, biofilm and cytochrome c assay were used for characterization. Growth kinetics, HPLC, qPCR and western blotting were performed to confer their fitness cost. Results revealed that nisin-resistant E. faecalis were morphologically different from sensitive strain and internalize more glucose. However, no significant difference was observed in the growth pattern of the resistant strain compared to that of the sensitive strain. A non-phosphotransferase glucose permease (GlcU) was found to be associated with enhanced glucose uptake. Conversely, Mpt, a major phosphotransferase system responsible for glucose uptake, did not play any role, as confirmed by gene expression studies and western blot analysis of HPr protein. The phosphorylation of His-15 residue of HPr phosphoprotein was reduced, while that of the Ser-46 residue increased with progression in nisin resistance, indicating that it may be involved in the regulation of pathogenicity. In conclusion, resistance imposes a significant fitness cost and GlcU plays a key role in maintaining the fitness cost in nisin-resistant variants.
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Affiliation(s)
- Sandeep Kumar
- Animal Biochemistry Division, National Dairy Research Institute, Karnal 132001, Haryana, India
| | - Kapil Singh Narayan
- Animal Biochemistry Division, National Dairy Research Institute, Karnal 132001, Haryana, India
| | - Shruti Shandilya
- Animal Biochemistry Division, National Dairy Research Institute, Karnal 132001, Haryana, India
| | - Shiv Kumar Sood
- Animal Biochemistry Division, National Dairy Research Institute, Karnal 132001, Haryana, India
| | - Suman Kapila
- Animal Biochemistry Division, National Dairy Research Institute, Karnal 132001, Haryana, India
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Dickmanns A, Zschiedrich CP, Arens J, Parfentev I, Gundlach J, Hofele R, Neumann P, Urlaub H, Görke B, Ficner R, Stülke J. Structural basis for the regulatory interaction of the methylglyoxal synthase MgsA with the carbon flux regulator Crh in Bacillus subtilis. J Biol Chem 2018. [PMID: 29514981 DOI: 10.1074/jbc.ra117.001289] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Utilization of energy-rich carbon sources such as glucose is fundamental to the evolutionary success of bacteria. Glucose can be catabolized via glycolysis for feeding the intermediary metabolism. The methylglyoxal synthase MgsA produces methylglyoxal from the glycolytic intermediate dihydroxyacetone phosphate. Methylglyoxal is toxic, requiring stringent regulation of MgsA activity. In the Gram-positive bacterium Bacillus subtilis, an interaction with the phosphoprotein Crh controls MgsA activity. In the absence of preferred carbon sources, Crh is present in the nonphosphorylated state and binds to and thereby inhibits MgsA. To better understand the mechanism of regulation of MgsA, here we performed biochemical and structural analyses of B. subtilis MgsA and of its interaction with Crh. Our results indicated that MgsA forms a hexamer (i.e. a trimer of dimers) in the crystal structure, whereas it seems to exist in an equilibrium between a dimer and hexamer in solution. In the hexamer, two alternative dimers could be distinguished, but only one appeared to prevail in solution. Further analysis strongly suggested that the hexamer is the biologically active form. In vitro cross-linking studies revealed that Crh interacts with the N-terminal helices of MgsA and that the Crh-MgsA binding inactivates MgsA by distorting and thereby blocking its active site. In summary, our results indicate that dimeric and hexameric MgsA species exist in an equilibrium in solution, that the hexameric species is the active form, and that binding to Crh deforms and blocks the active site in MgsA.
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Affiliation(s)
| | | | - Johannes Arens
- From the Departments of Molecular Structural Biology and
| | - Iwan Parfentev
- the Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany, and.,the Bioanalytics Group, Institute for Clinical Chemistry, University Medical Center Göttingen, 37075 Göttingen, Germany
| | - Jan Gundlach
- General Microbiology, GZMB, Georg-August-University Göttingen, 37077 Göttingen, Germany
| | - Romina Hofele
- the Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany, and.,the Bioanalytics Group, Institute for Clinical Chemistry, University Medical Center Göttingen, 37075 Göttingen, Germany
| | - Piotr Neumann
- From the Departments of Molecular Structural Biology and
| | - Henning Urlaub
- the Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany, and.,the Bioanalytics Group, Institute for Clinical Chemistry, University Medical Center Göttingen, 37075 Göttingen, Germany
| | - Boris Görke
- General Microbiology, GZMB, Georg-August-University Göttingen, 37077 Göttingen, Germany
| | - Ralf Ficner
- From the Departments of Molecular Structural Biology and
| | - Jörg Stülke
- General Microbiology, GZMB, Georg-August-University Göttingen, 37077 Göttingen, Germany,
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Liu L, Chen S, Wu J. Phosphoenolpyruvate:glucose phosphotransferase system modification increases the conversion rate during L-tryptophan production in Escherichia coli. J Ind Microbiol Biotechnol 2017; 44:1385-1395. [PMID: 28726163 DOI: 10.1007/s10295-017-1959-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 06/09/2017] [Indexed: 11/27/2022]
Abstract
Escherichia coli FB-04(pta1), a recombinant L-tryptophan production strain, was constructed in our laboratory. However, the conversion rate (L-tryptophan yield per glucose) of this strain is somewhat low. In this study, additional genes have been deleted in an effort to increase the conversion rate of E. coli FB-04(pta1). Initially, the pykF gene, which encodes pyruvate kinase I (PYKI), was inactivated to increase the accumulation of phosphoenolpyruvate, a key L-tryptophan precursor. The resulting strain, E. coli FB-04(pta1)ΔpykF, showed a slightly higher L-tryptophan yield and a higher conversion rate in fermentation processes. To further improve the conversion rate, the phosphoenolpyruvate:glucose phosphotransferase system (PTS) was disrupted by deleting the ptsH gene, which encodes the phosphocarrier protein (HPr). The levels of biomass, L-tryptophan yield, and conversion rate of this strain, E. coli FB-04(pta1)ΔpykF/ptsH, were especially low during fed-batch fermentation process, even though it achieved a significant increase in conversion rate during shake-flask fermentation. To resolve this issue, four HPr mutations (N12S, N12A, S46A, and S46N) were introduced into the genomic background of E. coli FB-04(pta1)ΔpykF/ptsH, respectively. Among them, the strain harboring the N12S mutation (E. coli FB-04(pta1)ΔpykF-ptsHN12S) showed a prominently increased conversion rate of 0.178 g g-1 during fed-batch fermentation; an increase of 38.0% compared with parent strain E. coli FB-04(pta1). Thus, mutation of the genomic of ptsH gene provided an alternative method to weaken the PTS and improve the efficiency of carbon source utilization.
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Affiliation(s)
- Lina Liu
- State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, China.,School of Biotechnology and Key Laboratory of Industrial Biotechnology Ministry of Education, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, China
| | - Sheng Chen
- State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, China.,School of Biotechnology and Key Laboratory of Industrial Biotechnology Ministry of Education, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, China
| | - Jing Wu
- State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, China. .,School of Biotechnology and Key Laboratory of Industrial Biotechnology Ministry of Education, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, China.
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Park YH, Um SH, Song S, Seok YJ, Ha NC. Structural basis for the sequestration of the anti-σ(70) factor Rsd from σ(70) by the histidine-containing phosphocarrier protein HPr. ACTA ACUST UNITED AC 2015; 71:1998-2008. [PMID: 26457424 DOI: 10.1107/s1399004715013759] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 07/20/2015] [Indexed: 11/10/2022]
Abstract
Histidine-containing phosphocarrier protein (HPr) is a general component of the bacterial phosphoenolpyruvate:sugar phosphotransferase system (PTS) involved in the phosphorylation-coupled transport of numerous sugars called PTS sugars. HPr mainly exists in a dephosphorylated form in the presence of PTS sugars in the medium, while its phosphorylation increases in the absence of PTS sugars. A recent study revealed that the dephosphorylated form of HPr binds and antagonizes the function of the antisigma factor Rsd. This anti-sigma factor sequesters the housekeeping sigma factor σ(70) to facilitate switching of the sigma subunit on RNA polymerase from σ(70) to the stress-responsive sigma factor σ(S) in stationary-phase cells. In this study, the structure of the complex of Rsd and HPr was determined at 2.1 Å resolution and revealed that the binding site for HPr on the surface of Rsd partly overlaps with that for σ(70). The localization of the phosphorylation site on HPr at the binding interface for Rsd explains why phosphorylation of HPr abolishes its binding to Rsd. The mutation of crucial residues involved in the HPr-Rsd interaction significantly influenced the competition between HPr and σ(70) for binding to Rsd both in vitro and in vivo. The results provide a structural basis for the linkage of global gene regulation to nutrient availability in the external environment.
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Affiliation(s)
- Young Ha Park
- Department of Biological Sciences and Institute of Microbiology, Seoul National University, Seoul 151-742, Republic of Korea
| | - Si Hyeon Um
- Department of Agricultural Biotechnology, Center for Food Safety and Toxicology, Research Institute for Agricultural and Life Sciences, Seoul National University, Seoul 151-921, Republic of Korea
| | - Saemee Song
- Department of Agricultural Biotechnology, Center for Food Safety and Toxicology, Research Institute for Agricultural and Life Sciences, Seoul National University, Seoul 151-921, Republic of Korea
| | - Yeong Jae Seok
- Department of Biological Sciences and Institute of Microbiology, Seoul National University, Seoul 151-742, Republic of Korea
| | - Nam Chul Ha
- Department of Agricultural Biotechnology, Center for Food Safety and Toxicology, Research Institute for Agricultural and Life Sciences, Seoul National University, Seoul 151-921, Republic of Korea
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Matsuoka Y, Shimizu K. Catabolite regulation analysis of Escherichia coli for acetate overflow mechanism and co-consumption of multiple sugars based on systems biology approach using computer simulation. J Biotechnol 2013; 168:155-73. [PMID: 23850830 DOI: 10.1016/j.jbiotec.2013.06.023] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 06/21/2013] [Accepted: 06/28/2013] [Indexed: 11/16/2022]
Abstract
It is quite important to understand the basic principle embedded in the main metabolism for the interpretation of the fermentation data. For this, it may be useful to understand the regulation mechanism based on systems biology approach. In the present study, we considered the perturbation analysis together with computer simulation based on the models which include the effects of global regulators on the pathway activation for the main metabolism of Escherichia coli. Main focus is the acetate overflow metabolism and the co-fermentation of multiple carbon sources. The perturbation analysis was first made to understand the nature of the feed-forward loop formed by the activation of Pyk by FDP (F1,6BP), and the feed-back loop formed by the inhibition of Pfk by PEP in the glycolysis. Those together with the effect of transcription factor Cra caused by FDP level affected the glycolysis activity. The PTS (phosphotransferase system) acts as the feed-back system by repressing the glucose uptake rate for the increase in the glucose uptake rate. It was also shown that the increased PTS flux (or glucose consumption rate) causes PEP/PYR ratio to be decreased, and EIIA-P, Cya, cAMP-Crp decreased, where cAMP-Crp in turn repressed TCA cycle and more acetate is formed. This was further verified by the detailed computer simulation. In the case of multiple carbon sources such as glucose and xylose, it was shown that the sequential utilization of carbon sources was observed for wild type, while the co-consumption of multiple carbon sources with slow consumption rates were observed for the ptsG mutant by computer simulation, and this was verified by experiments. Moreover, the effect of a specific gene knockout such as Δpyk on the metabolic characteristics was also investigated based on the computer simulation.
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Affiliation(s)
- Yu Matsuoka
- Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, Iizuka, Fukuoka 820-8502, Japan
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