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Zhang N, Gao X, Li D, Xu L, Zhou G, Xu M, Peng L, Sun G, Pan F, Li Y, Ren R, Huang R, Yang Y, Wang Z. Sleep deprivation-induced anxiety-like behaviors are associated with alterations in the gut microbiota and metabolites. Microbiol Spectr 2024; 12:e0143723. [PMID: 38421192 PMCID: PMC10986621 DOI: 10.1128/spectrum.01437-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 02/03/2024] [Indexed: 03/02/2024] Open
Abstract
The present study aimed to characterize the gut microbiota and serum metabolome changes associated with sleep deprivation (SD) as well as to explore the potential benefits of multi-probiotic supplementation in alleviating SD-related mental health disorders. Rats were subjected to 7 days of SD, followed by 14 days of multi-probiotics or saline administration. Open-field tests were conducted at baseline, end of SD (day 7), and after 14 days of saline or multi-probiotic gavage (day 21). Metagenomic sequencing was conducted on fecal samples, and serum metabolites were measured by untargeted liquid chromatography tandem-mass spectrometry. At day 7, anxiety-like behaviors, including significant decreases in total movement distance (P = 0.0002) and staying time in the central zone (P = 0.021), were observed. In addition, increased levels of lipopolysaccharide (LPS; P = 0.028) and decreased levels of uridine (P = 0.018) and tryptophan (P = 0.01) were detected in rats after 7 days of SD. After SD, the richness of the gut bacterial community increased, and the levels of Akkermansia muciniphila, Muribaculum intestinale, and Bacteroides caecimuris decreased. The changes in the host metabolism and gut microbiota composition were strongly associated with the anxiety-like behaviors caused by SD. In addition, multi-probiotic supplementation for 14 days modestly improved the anxiety-like behaviors in SD rats but significantly reduced the serum level of LPS (P = 0.045). In conclusion, SD induces changes in the gut microbiota and serum metabolites, which may contribute to the development of chronic inflammatory responses and affect the gut-brain axis, causing anxiety-like behaviors. Probiotic supplementation significantly reduces serum LPS, which may alleviate the influence of chronic inflammation. IMPORTANCE The disturbance in the gut microbiome and serum metabolome induced by SD may be involved in anxiety-like behaviors. Probiotic supplementation decreases serum levels of LPS, but this reduction may be insufficient for alleviating SD-induced anxiety-like behaviors.
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Affiliation(s)
- Nana Zhang
- Medical School of Chinese PLA, Beijing, China
- Department of Gastroenterology and Hepatology, The First Centre of Chinese PLA General Hospital, Beijing, China
| | - Xuefeng Gao
- Shenzhen Key Laboratory of Gastrointestinal Microbiota and Disease, Integrative Microecology Clinical Center, Shenzhen Hospital of Southern Medical University, Shenzhen, Guangdong, China
- Shenzhen Clinical Research Center for Digestive Disease, Shenzhen Hospital of Southern Medical University, Shenzhen, Guangdong, China
- The Clinical Innovation & Research Center, Shenzhen Hospital, Southern Medical University, Shenzhen, Guangdong, China
| | - Donghao Li
- Department of Gastroenterology and Hepatology, The First Centre of Chinese PLA General Hospital, Beijing, China
| | - Lijuan Xu
- Department of Gastroenterology and Hepatology, The First Centre of Chinese PLA General Hospital, Beijing, China
| | - Guanzhou Zhou
- Department of Gastroenterology and Hepatology, The First Centre of Chinese PLA General Hospital, Beijing, China
| | - Mengqi Xu
- Medical School of Chinese PLA, Beijing, China
- Department of Gastroenterology and Hepatology, The First Centre of Chinese PLA General Hospital, Beijing, China
| | - Lihua Peng
- Medical School of Chinese PLA, Beijing, China
- Department of Gastroenterology and Hepatology, The First Centre of Chinese PLA General Hospital, Beijing, China
| | - Gang Sun
- Medical School of Chinese PLA, Beijing, China
- Department of Gastroenterology and Hepatology, The First Centre of Chinese PLA General Hospital, Beijing, China
| | - Fei Pan
- Medical School of Chinese PLA, Beijing, China
- Department of Gastroenterology and Hepatology, The First Centre of Chinese PLA General Hospital, Beijing, China
| | - Yan Li
- Medical School of Chinese PLA, Beijing, China
- Department of Gastroenterology and Hepatology, The First Centre of Chinese PLA General Hospital, Beijing, China
| | - Rongrong Ren
- Medical School of Chinese PLA, Beijing, China
- Department of Gastroenterology and Hepatology, The First Centre of Chinese PLA General Hospital, Beijing, China
| | - Ruolan Huang
- Department of Neurology, Shenzhen University Clinical Research Center for Neurological Diseases, Shenzhen University General Hospital, Shenzhen, China
| | - Yunsheng Yang
- Medical School of Chinese PLA, Beijing, China
- Department of Gastroenterology and Hepatology, The First Centre of Chinese PLA General Hospital, Beijing, China
| | - Zikai Wang
- Medical School of Chinese PLA, Beijing, China
- Department of Gastroenterology and Hepatology, The First Centre of Chinese PLA General Hospital, Beijing, China
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2
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Mardoukhi MSY, Rapp J, Irisarri I, Gunka K, Link H, Marienhagen J, de Vries J, Stülke J, Commichau FM. Metabolic rewiring enables ammonium assimilation via a non-canonical fumarate-based pathway. Microb Biotechnol 2024; 17:e14429. [PMID: 38483038 PMCID: PMC10938345 DOI: 10.1111/1751-7915.14429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 01/16/2024] [Accepted: 02/09/2024] [Indexed: 03/17/2024] Open
Abstract
Glutamate serves as the major cellular amino group donor. In Bacillus subtilis, glutamate is synthesized by the combined action of the glutamine synthetase and the glutamate synthase (GOGAT). The glutamate dehydrogenases are devoted to glutamate degradation in vivo. To keep the cellular glutamate concentration high, the genes and the encoded enzymes involved in glutamate biosynthesis and degradation need to be tightly regulated depending on the available carbon and nitrogen sources. Serendipitously, we found that the inactivation of the ansR and citG genes encoding the repressor of the ansAB genes and the fumarase, respectively, enables the GOGAT-deficient B. subtilis mutant to synthesize glutamate via a non-canonical fumarate-based ammonium assimilation pathway. We also show that the de-repression of the ansAB genes is sufficient to restore aspartate prototrophy of an aspB aspartate transaminase mutant. Moreover, in the presence of arginine, B. subtilis mutants lacking fumarase activity show a growth defect that can be relieved by aspB overexpression, by reducing arginine uptake and by decreasing the metabolic flux through the TCA cycle.
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Affiliation(s)
| | - Johanna Rapp
- Interfaculty Institute for Microbiology and Infection Medicine TübingenUniversity of TübingenTübingenGermany
| | - Iker Irisarri
- Department of Applied Bioinformatics, Institute of Microbiology and Genetics, GZMBGeorg‐August‐University GöttingenGöttingenGermany
- Campus Institute Data ScienceUniversity of GöttingenGöttingenGermany
| | - Katrin Gunka
- Department of General Microbiology, Institute for Microbiology and Genetics, GZMBGeorg‐August‐University GöttingenGöttingenGermany
| | - Hannes Link
- Interfaculty Institute for Microbiology and Infection Medicine TübingenUniversity of TübingenTübingenGermany
| | - Jan Marienhagen
- Institute of Bio‐ and Geosciences, IBG‐1: BiotechnologyForschungszentrum JülichJülichGermany
- Institut of BiotechnologyRWTH Aachen UniversityAachenGermany
| | - Jan de Vries
- Department of Applied Bioinformatics, Institute of Microbiology and Genetics, GZMBGeorg‐August‐University GöttingenGöttingenGermany
- Campus Institute Data ScienceUniversity of GöttingenGöttingenGermany
| | - Jörg Stülke
- Department of General Microbiology, Institute for Microbiology and Genetics, GZMBGeorg‐August‐University GöttingenGöttingenGermany
| | - Fabian M. Commichau
- FG Molecular Microbiology, Institute for BiologyUniversity of HohenheimStuttgartGermany
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3
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Koirala P, Doody C, Blackwell H, Chandler JR. Regulation of an antibiotic resistance efflux pump by quorum sensing and a TetR-family repressor in Chromobacterium subtsugae. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.02.556004. [PMID: 37693375 PMCID: PMC10491235 DOI: 10.1101/2023.09.02.556004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
The soil bacterium Chromobacterium substugae uses a single LuxI-R-type quorum-sensing system, CviI-R, to regulate genes in a cell density-dependent manner. CviI synthesizes the signal N-hexanoyl-homoserine lactone (C6-HSL) and CviR is a C6-HSL-responsive cytoplasmic transcription regulator. C6-HSL-bound CviR activates dozens of genes, for example the cdeAB-oprM cluster coding for an efflux pump conferring antibiotic resistance. The cdeAB-oprM genes are also regulated by an antibiotic-responsive transcription factor, CdeR, which represses expression of these genes. We are interested in understanding how C. subtsugae integrates different environmental cues to regulate antibiotic resistance. In this study, we sought to delineate the mechanism of regulation of the cdeAB-oprM genes by CviR and CdeR. In recombinant E. coli, the cdeA promoter is activated by CviR and repressed by CdeR. We identify non-overlapping sequence elements in the cdeA promoter that are required for CviR activation and CdeR repression, respectively. We also examined the role of CdeR in modulating cdeA activation by C6-HSL in C. subtsugae. We show that CviR and CdeR can independently modulate transcription from the cdeA promoter in C. subtsugae, consistent with the conclusion that CviR and CdeR regulate the cdeAB-oprM genes by interacting directly with different binding sites in the cdeA promoter. These results contribute to a molecular understanding of how the cdeAB-oprM genes are regulated and provide new insight into how C. subtsugae integrates different environmental cues to regulate antibiotic resistance.
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Affiliation(s)
- Pratik Koirala
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045 USA
| | - Cassie Doody
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706 USA
| | - Helen Blackwell
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706 USA
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4
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Hao N, Donnelly AJ, Dodd IB, Shearwin KE. When push comes to shove - RNA polymerase and DNA-bound protein roadblocks. Biophys Rev 2023; 15:355-366. [PMID: 37396453 PMCID: PMC10310618 DOI: 10.1007/s12551-023-01064-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 05/21/2023] [Indexed: 07/04/2023] Open
Abstract
In recent years, transcriptional roadblocking has emerged as a crucial regulatory mechanism in gene expression, whereby other DNA-bound obstacles can block the progression of transcribing RNA polymerase (RNAP), leading to RNAP pausing and ultimately dissociation from the DNA template. In this review, we discuss the mechanisms by which transcriptional roadblocks can impede RNAP progression, as well as how RNAP can overcome these obstacles to continue transcription. We examine different DNA-binding proteins involved in transcriptional roadblocking and their biophysical properties that determine their effectiveness in blocking RNAP progression. The catalytically dead CRISPR-Cas (dCas) protein is used as an example of an engineered programmable roadblock, and the current literature in understanding the polarity of dCas roadblocking is also discussed. Finally, we delve into a stochastic model of transcriptional roadblocking and highlight the importance of transcription factor binding kinetics and its resistance to dislodgement by an elongating RNAP in determining the strength of a roadblock.
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Affiliation(s)
- Nan Hao
- Department of Molecular and Biomedical Science, School of Biological Sciences, The University of Adelaide, Adelaide, SA 5005 Australia
| | - Alana J. Donnelly
- Department of Molecular and Biomedical Science, School of Biological Sciences, The University of Adelaide, Adelaide, SA 5005 Australia
| | - Ian B. Dodd
- Department of Molecular and Biomedical Science, School of Biological Sciences, The University of Adelaide, Adelaide, SA 5005 Australia
| | - Keith E. Shearwin
- Department of Molecular and Biomedical Science, School of Biological Sciences, The University of Adelaide, Adelaide, SA 5005 Australia
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5
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Pal B, Gupta AK. Reservoir crowding in a resource-constrained exclusion process with a dynamic defect. Phys Rev E 2022; 106:044130. [PMID: 36397510 DOI: 10.1103/physreve.106.044130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 10/03/2022] [Indexed: 06/16/2023]
Abstract
To understand the complicated transport processes that occur in biological and physical systems, we investigate a constrained totally asymmetric simple exclusion process with a stochastic defect particle. The defect particle might randomly emerge or vanish, resulting in a dynamic defect, and slows down the flow of moving particles when attached to the lattice. Using a mean-field technique, we examine the steady-state characteristics and boundary-layer analysis is provided to comprehend the properties of finite system. In a simplification, our theoretical method unifies three different parameter used to define the defect dynamics into one parameter termed the obstruction factor. It is found that the defect kinetics lead to emergence of phases where the current is defect restricted. The system shows nine phases overall, including bulk-induced and boundary-induced shock phases, with the phase schema showing no more than eight phases depending on the dynamics. We found that variation of obstruction does not lead to qualitative transition in the system, whereas the change in constraint on total particles affect the system qualitatively. All the theoretical outcomes have been validated using extensive Monte Carlo simulations.
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Affiliation(s)
- Bipasha Pal
- Department of Mathematics, Indian Institute of Technology Ropar, Rupnagar 140001, Punjab, India
| | - Arvind Kumar Gupta
- Department of Mathematics, Indian Institute of Technology Ropar, Rupnagar 140001, Punjab, India
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6
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Alternative σ Factors Regulate Overlapping as Well as Distinct Stress Response and Metabolic Functions in Listeria monocytogenes under Stationary Phase Stress Condition. Pathogens 2021; 10:pathogens10040411. [PMID: 33915780 PMCID: PMC8066629 DOI: 10.3390/pathogens10040411] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 03/23/2021] [Accepted: 03/26/2021] [Indexed: 12/13/2022] Open
Abstract
Listeria monocytogenes can regulate and fine-tune gene expression, to adapt to diverse stress conditions encountered during foodborne transmission. To further understand the contributions of alternative sigma (σ) factors to the regulation of L. monocytogenes gene expression, RNA-Seq was performed on L. monocytogenes strain 10403S and five isogenic mutants (four strains bearing in-frame null mutations in three out of four alternative σ factor genes, ΔCHL, ΔBHL, ΔBCL, and ΔBCH, and one strain bearing null mutations in all four genes, ΔBCHL), grown to stationary phase. Our data showed that 184, 35, 34, and 20 genes were positively regulated by σB, σL, σH, and σC (posterior probability > 0.9 and Fold Change (FC) > 5.0), respectively. Moreover, σB-dependent genes showed the highest FC (based on comparisons between the ΔCHL and the ΔBCHL strain), with 44 genes showing an FC > 100; only four σL-dependent, and no σH- or σC-dependent genes showed FC >100. While σB-regulated genes identified in this study are involved in stress-associated functions and metabolic pathways, σL appears to largely regulate genes involved in a few specific metabolic pathways, including positive regulation of operons encoding phosphoenolpyruvate (PEP)-dependent phosphotransferase systems (PTSs). Overall, our data show that (i) σB and σL directly and indirectly regulate genes involved in several energy metabolism-related functions; (ii) alternative σ factors are involved in complex regulatory networks and appear to have epistatic effects in stationary phase cells; and (iii) σB regulates multiple stress response pathways, while σL and σH positively regulate a smaller number of specific pathways.
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7
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Han L, Chen Q, Lin Q, Cheng J, Zhou L, Liu Z, Guo J, Zhang L, Cui W, Zhou Z. Realization of Robust and Precise Regulation of Gene Expression by Multiple Sigma Recognizable Artificial Promoters. Front Bioeng Biotechnol 2020; 8:92. [PMID: 32140461 PMCID: PMC7042180 DOI: 10.3389/fbioe.2020.00092] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 01/31/2020] [Indexed: 01/28/2023] Open
Abstract
Precise regulation of gene expression is fundamental for tailor-made gene circuit design in synthetic biology. Current strategies for this type of development are mainly based on directed evolution beginning with a native promoter template. The performances of engineered promoters are usually limited by the growth phase because only one promoter is recognized by one type of sigma factor (σ). Here, we constructed multiple-σ recognizable artificial hybrid promoters (AHPs) composed of tandems of dual and triple natural minimal promoters (NMPs). These NMPs, which use σA, σH and σW, had stable functions in different growth phases. The functions of these NMPs resulted from an effect called transcription compensation, in which AHPs sequentially use one type of σ in the corresponding growth phase. The strength of the AHPs was influenced by the combinatorial order of each NMP and the length of the spacers between the NMPs. More importantly, the output of the precise regulation was achieved by equipping AHPs with synthetic ribosome binding sites and by redesigning them for induced systems. This strategy might offer promising applications to rationally design robust synthetic promoters in diverse chassis to spur the construction of more complex gene circuits, which will further the development of synthetic biology.
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Affiliation(s)
- Laichuang Han
- Key Laboratory of Industrial Biotechnology, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Qiaoqing Chen
- Key Laboratory of Industrial Biotechnology, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Qiao Lin
- Key Laboratory of Industrial Biotechnology, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Jintao Cheng
- Key Laboratory of Industrial Biotechnology, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Li Zhou
- Key Laboratory of Industrial Biotechnology, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Zhongmei Liu
- Key Laboratory of Industrial Biotechnology, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Junling Guo
- Key Laboratory of Industrial Biotechnology, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Linpei Zhang
- Key Laboratory of Industrial Biotechnology, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Wenjing Cui
- Key Laboratory of Industrial Biotechnology, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Zhemin Zhou
- Key Laboratory of Industrial Biotechnology, School of Biotechnology, Jiangnan University, Wuxi, China
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8
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Dormeyer M, Lentes S, Richts B, Heermann R, Ischebeck T, Commichau FM. Variants of the Bacillus subtilis LysR-Type Regulator GltC With Altered Activator and Repressor Function. Front Microbiol 2019; 10:2321. [PMID: 31649652 PMCID: PMC6794564 DOI: 10.3389/fmicb.2019.02321] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 09/23/2019] [Indexed: 11/20/2022] Open
Abstract
The Gram-positive soil bacterium Bacillus subtilis relies on the glutamine synthetase and the glutamate synthase for glutamate biosynthesis from ammonium and 2-oxoglutarate. During growth with the carbon source glucose, the LysR-type transcriptional regulator GltC activates the expression of the gltAB glutamate synthase genes. With excess of intracellular glutamate, the gltAB genes are not transcribed because the glutamate-degrading glutamate dehydrogenases (GDHs) inhibit GltC. Previous in vitro studies revealed that 2-oxoglutarate and glutamate stimulate the activator and repressor function, respectively, of GltC. Here, we have isolated GltC variants with enhanced activator or repressor function. The majority of the GltC variants with enhanced activator function differentially responded to the GDHs and to glutamate. The GltC variants with enhanced repressor function were still capable of activating the PgltA promoter in the absence of a GDH. Using PgltA promoter variants (PgltA∗) that are active independent of GltC, we show that the wild type GltC and the GltC variants with enhanced repressor function inactivate PgltA∗ promoters in the presence of the native GDHs. These findings suggest that GltC may also act as a repressor of the gltAB genes in vivo. We discuss a model combining previous models that were derived from in vivo and in vitro experiments.
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Affiliation(s)
- Miriam Dormeyer
- Department of General Microbiology, Institute of Microbiology and Genetics, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Sabine Lentes
- Department of General Microbiology, Institute of Microbiology and Genetics, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Björn Richts
- Department of General Microbiology, Institute of Microbiology and Genetics, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Ralf Heermann
- Institut für Molekulare Physiologie, Mikrobiologie und Weinforschung, Johannes Gutenberg-Universität Mainz, Mainz, Germany
| | - Till Ischebeck
- Department for Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Fabian M Commichau
- Department of General Microbiology, Institute of Microbiology and Genetics, Georg-August-Universität Göttingen, Göttingen, Germany
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9
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Shen BA, Landick R. Transcription of Bacterial Chromatin. J Mol Biol 2019; 431:4040-4066. [PMID: 31153903 PMCID: PMC7248592 DOI: 10.1016/j.jmb.2019.05.041] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 05/22/2019] [Accepted: 05/23/2019] [Indexed: 12/12/2022]
Abstract
Decades of research have probed the interplay between chromatin (genomic DNA associated with proteins and RNAs) and transcription by RNA polymerase (RNAP) in all domains of life. In bacteria, chromatin is compacted into a membrane-free region known as the nucleoid that changes shape and composition depending on the bacterial state. Transcription plays a key role in both shaping the nucleoid and organizing it into domains. At the same time, chromatin impacts transcription by at least five distinct mechanisms: (i) occlusion of RNAP binding; (ii) roadblocking RNAP progression; (iii) constraining DNA topology; (iv) RNA-mediated interactions; and (v) macromolecular demixing and heterogeneity, which may generate phase-separated condensates. These mechanisms are not mutually exclusive and, in combination, mediate gene regulation. Here, we review the current understanding of these mechanisms with a focus on gene silencing by H-NS, transcription coordination by HU, and potential phase separation by Dps. The myriad questions about transcription of bacterial chromatin are increasingly answerable due to methodological advances, enabling a needed paradigm shift in the field of bacterial transcription to focus on regulation of genes in their native state. We can anticipate answers that will define how bacterial chromatin helps coordinate and dynamically regulate gene expression in changing environments.
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Affiliation(s)
- Beth A Shen
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, United States
| | - Robert Landick
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, United States; Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, United States.
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10
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Sharma AK, Leppla SH, Pomerantsev AP, Shiloach J. Effect of over expressing protective antigen on global gene transcription in Bacillus anthracis BH500. Sci Rep 2018; 8:16108. [PMID: 30382110 PMCID: PMC6208434 DOI: 10.1038/s41598-018-34196-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 10/08/2018] [Indexed: 01/22/2023] Open
Abstract
Protective antigen (PA) of Bacillus anthracis is being considered as a vaccine candidate against anthrax and its production has been explored in several heterologous host systems. Since the systems tested introduced adverse issues such as inclusion body formation and endotoxin contamination, the production from B. anthracis is considered as a preferred method. The present study examines the effect of PA expression on the metabolism of B. anthracis producing strain, BH500, by comparing it with a control strain carrying an empty plasmid. The strains were grown in a bioreactor and RNA-seq analysis of the producing and non-producing strain was conducted. Among the observed differences, the strain expressing rPA had increased transcription of sigL, the gene encoding RNA polymerase σ54, sigB, the general stress transcription factor gene and its regulators rsbW and rsbV, as well as the global regulatory repressor ctsR. There were also decreased expression of intracellular heat stress related genes such as groL, groES, hslO, dnaJ, and dnaK and increased expression of extracellular chaperons csaA and prsA2. Also, major central metabolism genes belonging to TCA, glycolysis, PPP, and amino acids biosynthesis were up-regulated in the PA-producing strain during the lag phase and down-regulated in the log and late-log phases, which was associated with decreased specific growth rates. The information obtained from this study may guide genetic modification of B. anthracis to improve PA production.
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Affiliation(s)
- Ashish K Sharma
- Biotechnology Core Laboratory, National Institute of Diabetes and Digestives and Kidney Diseases (NIDDK) NIH, Maryland, USA
| | - Stephen H Leppla
- Microbial Pathogenesis Section, National Institute of Allergy and Infectious diseases (NIAID), NIH, Maryland, USA
| | - Andrei P Pomerantsev
- Microbial Pathogenesis Section, National Institute of Allergy and Infectious diseases (NIAID), NIH, Maryland, USA
| | - Joseph Shiloach
- Biotechnology Core Laboratory, National Institute of Diabetes and Digestives and Kidney Diseases (NIDDK) NIH, Maryland, USA.
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11
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Liu XX, Shen MJ, Liu WB, Ye BC. GlnR-Mediated Regulation of Short-Chain Fatty Acid Assimilation in Mycobacterium smegmatis. Front Microbiol 2018; 9:1311. [PMID: 29988377 PMCID: PMC6023979 DOI: 10.3389/fmicb.2018.01311] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 05/29/2018] [Indexed: 11/20/2022] Open
Abstract
Assimilation of short-chain fatty acids (SCFAs) plays an important role in the survival and lipid biosynthesis of Mycobacteria. However, regulation of this process has not been thoroughly described. In the present work, we demonstrate that GlnR as a well-known nitrogen-sensing regulator transcriptionally modulates the AMP-forming propionyl-CoA synthetase (MsPrpE), and acetyl-CoA synthetases (MsAcs) is associated with SCFAs assimilation in Mycobacterium smegmatis, a model Mycobacterium. GlnR can directly activate the expression of MsprpE and Msacs by binding to their promoter regions based upon sensed nitrogen starvation in the host. Moreover, GlnR can activate the expression of lysine acetyltransferase encoding Mspat, which significantly decreases the activity of MsPrpE and MsAcs through increased acylation. Next, growth curves and resazurin assay show that GlnR can further regulate the growth of M. smegmatis on different SCFAs to control the viability. These results demonstrate that GlnR-mediated regulation of SCFA assimilation in response to the change of nitrogen signal serves to control the survival of M. smegmatis. These findings provide insights into the survival and nutrient utilization mechanisms of Mycobacteria in their host, which may enable new strategies in drug discovery for the control of tuberculosis.
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Affiliation(s)
- Xin-Xin Liu
- Laboratory of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Meng-Jia Shen
- Laboratory of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Wei-Bing Liu
- Laboratory of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Bang-Ce Ye
- Laboratory of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China.,Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou, China
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12
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The Nitrogen Regulatory PII Protein (GlnB) and N-Acetylglucosamine 6-Phosphate Epimerase (NanE) Allosterically Activate Glucosamine 6-Phosphate Deaminase (NagB) in Escherichia coli. J Bacteriol 2018; 200:JB.00691-17. [PMID: 29229699 DOI: 10.1128/jb.00691-17] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 11/27/2017] [Indexed: 12/21/2022] Open
Abstract
Amino sugars are good sources of both ammonia and fructose-6-phosphate, produced by the glucosamine 6-phosphate deaminase, NagB. NagB is known to be allosterically regulated by N-acetylglucosamine 6-phosphate (GlcNAc-6P) and the phosphocarrier protein of the bacterial phosphotransferase system, HPr, in Escherichia coli We provide evidence that NanE, GlcNAc-6P epimerase, and the uridylylated PII protein (U-PII) also allosterically activate NagB by direct protein-protein interactions. NanE is essential for neuraminic acid (NANA) and N-acetylmannosamine (ManNAc) utilization, and PII is known to be a central metabolic nitrogen regulator. We demonstrate that uridylylated PII (but not underivatized PII) activates NagB >10-fold at low concentrations of substrate, whereas NanE increases NagB activity >2-fold. NanE activates NagB in the absence or presence of GlcNAc-6P, but HPr and U-PII activation requires the presence of GlcNAc-6P. Activation of NagB by HPr and uridylylated PII, as well as by NanE and HPr (but not by NanE and U-PII), is synergistic, and the modeling, which suggests specific residues involved in complex formation, provides possible explanations. Specific physiological functions for the regulation of NagB by its three protein activators are proposed. Each regulatory agent is suggested to mediate signal transduction in response to a different stimulus.IMPORTANCE The regulation of amino sugar utilization is important for the survival of bacteria in a competitive environment. NagB, a glucosamine 6-phosphate deaminase in Escherichia coli, is essential for amino sugar utilization and is known to be allosterically regulated by N-acetylglucosamine 6-phosphate (GlcNAc-6P) and the histidine-phosphorylatable phosphocarrier protein, HPr. We provide evidence here that NanE, GlcNAc-6P epimerase, and the uridylylated PII protein allosterically activate NagB by direct protein-protein interactions. NanE is essential for N-acetylneuraminic acid (NANA) and N-acetylmannosamine (ManNAc) utilization, and the PII protein is known to be a central metabolic nitrogen regulator. Regulatory links between carbon and nitrogen metabolism are important for adaptation of metabolism to different growth conditions.
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Randazzo P, Aucouturier A, Delumeau O, Auger S. Revisiting the in vivo GlnR-binding sites at the genome scale in Bacillus subtilis. BMC Res Notes 2017; 10:422. [PMID: 28835263 PMCID: PMC5569456 DOI: 10.1186/s13104-017-2703-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 07/29/2017] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND In Bacillus subtilis, two major transcriptional factors, GlnR and TnrA, are involved in a sophisticated network of adaptive responses to nitrogen availability. GlnR was reported to repress the transcription of the glnRA, tnrA and ureABC operons under conditions of excess nitrogen. As GlnR and TnrA regulators share the same DNA binding motifs, a genome-wide mapping of in vivo GlnR-binding sites was still needed to clearly define the set of GlnR/TnrA motifs directly bound by GlnR. METHODS We used chromatin immunoprecipitation coupled with hybridization to DNA tiling arrays (ChIP-on-chip) to identify the GlnR DNA-binding sites, in vivo, at the genome scale. RESULTS We provide evidence that GlnR binds reproducibly to 61 regions on the chromosome. Among those, 20 regions overlap the previously defined in vivo TnrA-binding sites. In combination with real-time in vivo transcriptional profiling using firefly luciferase, we identified the alsT gene as a new member of the GlnR regulon. Additionally, we characterized the GlnR secondary regulon, which is composed of promoter regions harboring a GlnR/TnrA box and bound by GlnR in vivo. However, the growth conditions revealing a GlnR-dependent regulation for this second category of genes are still unknown. CONCLUSIONS Our findings show an extended overlap between the GlnR and TnrA in vivo binding sites. This could allow efficient and fine tuning of gene expression in response to nitrogen availability. GlnR appears to be part of complex transcriptional regulatory networks, which involves interactions between different regulatory proteins.
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Affiliation(s)
- Paola Randazzo
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | - Anne Aucouturier
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | - Olivier Delumeau
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | - Sandrine Auger
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France.
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14
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Noda-Garcia L, Romero Romero ML, Longo LM, Kolodkin-Gal I, Tawfik DS. Bacilli glutamate dehydrogenases diverged via coevolution of transcription and enzyme regulation. EMBO Rep 2017; 18:1139-1149. [PMID: 28468957 DOI: 10.15252/embr.201743990] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 03/23/2017] [Accepted: 03/27/2017] [Indexed: 12/29/2022] Open
Abstract
The linkage between regulatory elements of transcription, such as promoters, and their protein products is central to gene function. Promoter-protein coevolution is therefore expected, but rarely observed, and the manner by which these two regulatory levels are linked remains largely unknown. We study glutamate dehydrogenase-a hub of carbon and nitrogen metabolism. In Bacillus subtilis, two paralogues exist: GudB is constitutively transcribed whereas RocG is tightly regulated. In their active, oligomeric states, both enzymes show similar enzymatic rates. However, swaps of enzymes and promoters cause severe fitness losses, thus indicating promoter-enzyme coevolution. Characterization of the proteins shows that, compared to RocG, GudB's enzymatic activity is highly dependent on glutamate and pH Promoter-enzyme swaps therefore result in excessive glutamate degradation when expressing a constitutive enzyme under a constitutive promoter, or insufficient activity when both the enzyme and its promoter are tightly regulated. Coevolution of transcriptional and enzymatic regulation therefore underlies paralogue-specific spatio-temporal control, especially under diverse growth conditions.
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Affiliation(s)
- Lianet Noda-Garcia
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | | | - Liam M Longo
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Ilana Kolodkin-Gal
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Dan S Tawfik
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
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15
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Padhi SK, Maiti NK. Molecular insight into the dynamic central metabolic pathways of Achromobacter xylosoxidans CF-S36 during heterotrophic nitrogen removal processes. J Biosci Bioeng 2017; 123:46-55. [DOI: 10.1016/j.jbiosc.2016.07.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 06/23/2016] [Accepted: 07/14/2016] [Indexed: 10/21/2022]
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16
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Mirouze N, Bidnenko E, Noirot P, Auger S. Genome-wide mapping of TnrA-binding sites provides new insights into the TnrA regulon in Bacillus subtilis. Microbiologyopen 2015; 4:423-35. [PMID: 25755103 PMCID: PMC4475385 DOI: 10.1002/mbo3.249] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Revised: 01/22/2015] [Accepted: 02/02/2015] [Indexed: 01/13/2023] Open
Abstract
Under nitrogen limitation conditions, Bacillus subtilis induces a sophisticated network of adaptation responses. More precisely, the B. subtilis TnrA regulator represses or activates directly or indirectly the expression of a hundred genes in response to nitrogen availability. The global TnrA regulon have already been identified among which some directly TnrA-regulated genes have been characterized. However, a genome-wide mapping of in vivo TnrA-binding sites was still needed to clearly define the set of genes directly regulated by TnrA. Using chromatin immunoprecipitation coupled with hybridization to DNA tiling arrays (ChIP-on-chip), we now provide in vivo evidence that TnrA reproducibly binds to 42 regions on the chromosome. Further analysis with real-time in vivo transcriptional profiling, combined with results from previous reports, allowed us to define the TnrA primary regulon. We identified 35 promoter regions fulfilling three criteria necessary to be part of this primary regulon: (i) TnrA binding in ChIP-on-chip experiments and/or in previous in vitro studies; (ii) the presence of a TnrA box; (iii) TnrA-dependent expression regulation. In addition, the TnrA primary regulon delimitation allowed us to improve the TnrA box consensus. Finally, our results reveal new interconnections between the nitrogen regulatory network and other cellular processes.
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Affiliation(s)
- Nicolas Mirouze
- UMR1319 Micalis, INRA, F-78352, Jouy-en-Josas, France.,UMR Micalis, AgroParisTech, F-78352, Jouy-en-Josas, France
| | - Elena Bidnenko
- UMR1319 Micalis, INRA, F-78352, Jouy-en-Josas, France.,UMR Micalis, AgroParisTech, F-78352, Jouy-en-Josas, France
| | - Philippe Noirot
- UMR1319 Micalis, INRA, F-78352, Jouy-en-Josas, France.,UMR Micalis, AgroParisTech, F-78352, Jouy-en-Josas, France
| | - Sandrine Auger
- UMR1319 Micalis, INRA, F-78352, Jouy-en-Josas, France.,UMR Micalis, AgroParisTech, F-78352, Jouy-en-Josas, France
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17
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Tanaka K, Iwasaki K, Morimoto T, Matsuse T, Hasunuma T, Takenaka S, Chumsakul O, Ishikawa S, Ogasawara N, Yoshida KI. Hyperphosphorylation of DegU cancels CcpA-dependent catabolite repression of rocG in Bacillus subtilis. BMC Microbiol 2015; 15:43. [PMID: 25880922 PMCID: PMC4348106 DOI: 10.1186/s12866-015-0373-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 02/04/2015] [Indexed: 11/18/2022] Open
Abstract
Background The two-component regulatory system, involving the histidine sensor kinase DegS and response regulator DegU, plays an important role to control various cell processes in the transition phase of Bacillus subtilis. The degU32 allele in strain 1A95 is characterized by the accumulation of phosphorylated form of DegU (DegU-P). Results Growing 1A95 cells elevated the pH of soytone-based medium more than the parental strain 168 after the onset of the transition phase. The rocG gene encodes a catabolic glutamate dehydrogenase that catalyzes one of the main ammonia-releasing reactions. Inactivation of rocG abolished 1A95-mediated increases in the pH of growth media. Thus, transcription of the rocG locus was examined, and a novel 3.7-kb transcript covering sivA, rocG, and rocA was found in 1A95 but not 168 cells. Increased intracellular fructose 1,6-bisphosphate (FBP) levels are known to activate the HPr kinase HPrK, and to induce formation of the P-Ser-HPr/CcpA complex, which binds to catabolite responsive elements (cre) and exerts CcpA-dependent catabolite repression. A putative cre found within the intergenic region between sivA and rocG, and inactivation of ccpA led to creation of the 3.7-kb transcript in 168 cells. Analyses of intermediates in central carbon metabolism revealed that intracellular FBP levels were lowered earlier in 1A95 than in 168 cells. A genome wide transcriptome analysis comparing 1A95 and 168 cells suggested similar events occurring in other catabolite repressive loci involving induction of lctE encoding lactate dehydrogenase. Conclusions Under physiological conditions the 3.7-kb rocG transcript may be tightly controlled by a roadblock mechanism involving P-Ser-HPr/CcpA in 168 cells, while in 1A95 cells abolished repression of the 3.7-kb transcript. Accumulation of DegU-P in 1A95 affects central carbon metabolism involving lctE enhanced by unknown mechanisms, downregulates FBP levels earlier, and inactivates HPrK to allow the 3.7-kb transcription, and thus similar events may occur in other catabolite repressive loci. Electronic supplementary material The online version of this article (doi:10.1186/s12866-015-0373-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kosei Tanaka
- Organization of Advanced Science and Technology, Kobe University, Kobe, Hyogo, Japan.
| | - Kana Iwasaki
- Department of Agrobioscience, Kobe University, Kobe, Hyogo, Japan.
| | - Takuya Morimoto
- Biological Science Laboratories, Kao Corporation, Haga, Tochigi, Japan. .,Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara, Japan.
| | | | - Tomohisa Hasunuma
- Organization of Advanced Science and Technology, Kobe University, Kobe, Hyogo, Japan.
| | - Shinji Takenaka
- Organization of Advanced Science and Technology, Kobe University, Kobe, Hyogo, Japan. .,Department of Agrobioscience, Kobe University, Kobe, Hyogo, Japan.
| | - Onuma Chumsakul
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara, Japan.
| | - Shu Ishikawa
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara, Japan.
| | - Naotake Ogasawara
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara, Japan.
| | - Ken-ichi Yoshida
- Organization of Advanced Science and Technology, Kobe University, Kobe, Hyogo, Japan. .,Department of Agrobioscience, Kobe University, Kobe, Hyogo, Japan.
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18
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Prestel E, Noirot P, Auger S. Genome-wide identification of Bacillus subtilis Zur-binding sites associated with a Zur box expands its known regulatory network. BMC Microbiol 2015; 15:13. [PMID: 25649915 PMCID: PMC4324032 DOI: 10.1186/s12866-015-0345-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 01/13/2015] [Indexed: 11/10/2022] Open
Abstract
Background The Bacillus subtilis Zur transcription factor recognizes a specific DNA motif, the Zur box, to repress expression of genes in response to zinc availability. Although several Zur-regulated genes are well characterized, a genome-wide mapping of Zur-binding sites is needed to define further the set of genes directly regulated by this protein. Results Using chromatin immunoprecipitation coupled with hybridization to DNA tiling arrays (ChIP-on-chip), we reported the identification of 80 inter- and intragenic chromosomal sites bound by Zur. Seven Zur-binding regions constitute the Zur primary regulon while 35 newly identified targets were associated with a predicted Zur box. Using transcriptional fusions an intragenic Zur box was showed to promote a full Zur-mediated repression when placed within a promoter region. In addition, intragenic Zur boxes appeared to mediate a transcriptional cis-repressive effect (4- to 9-fold) but the function of Zur at these sites remains unclear. Zur binding to intragenic Zur boxes could prime an intricate mechanisms of regulation of the transcription elongation, possibly with other transcriptional factors. However, the disruption of zinc homeostasis in Δzur cells likely affects many cellular processes masking direct Zur-dependent effects. Finally, most Zur-binding sites were located near or within genes responsive to disulfide stress. These findings expand the potential Zur regulon and reveal unknown interconnections between zinc and redox homeostasis regulatory networks. Conclusions Our findings considerably expand the potential Zur regulon, and reveal a new level of complexity in Zur binding to its targets via a Zur box motif and via a yet unknown mechanism that remains to be characterized. Electronic supplementary material The online version of this article (doi:10.1186/s12866-015-0345-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Eric Prestel
- INRA, UMR1319 Micalis, F-78352, Jouy-en-Josas, France. .,AgroParisTech, UMR Micalis, F-78352, Jouy-en-Josas, France.
| | - Philippe Noirot
- INRA, UMR1319 Micalis, F-78352, Jouy-en-Josas, France. .,AgroParisTech, UMR Micalis, F-78352, Jouy-en-Josas, France.
| | - Sandrine Auger
- INRA, UMR1319 Micalis, F-78352, Jouy-en-Josas, France. .,AgroParisTech, UMR Micalis, F-78352, Jouy-en-Josas, France.
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19
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Jeong DE, Park SH, Pan JG, Kim EJ, Choi SK. Genome engineering using a synthetic gene circuit in Bacillus subtilis. Nucleic Acids Res 2014; 43:e42. [PMID: 25552415 PMCID: PMC4381049 DOI: 10.1093/nar/gku1380] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Accepted: 12/19/2014] [Indexed: 11/16/2022] Open
Abstract
Genome engineering without leaving foreign DNA behind requires an efficient counter-selectable marker system. Here, we developed a genome engineering method in Bacillus subtilis using a synthetic gene circuit as a counter-selectable marker system. The system contained two repressible promoters (B. subtilis xylA (Pxyl) and spac (Pspac)) and two repressor genes (lacI and xylR). Pxyl-lacI was integrated into the B. subtilis genome with a target gene containing a desired mutation. The xylR and Pspac–chloramphenicol resistant genes (cat) were located on a helper plasmid. In the presence of xylose, repression of XylR by xylose induced LacI expression, the LacIs repressed the Pspac promoter and the cells become chloramphenicol sensitive. Thus, to survive in the presence of chloramphenicol, the cell must delete Pxyl-lacI by recombination between the wild-type and mutated target genes. The recombination leads to mutation of the target gene. The remaining helper plasmid was removed easily under the chloramphenicol absent condition. In this study, we showed base insertion, deletion and point mutation of the B. subtilis genome without leaving any foreign DNA behind. Additionally, we successfully deleted a 2-kb gene (amyE) and a 38-kb operon (ppsABCDE). This method will be useful to construct designer Bacillus strains for various industrial applications.
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Affiliation(s)
- Da-Eun Jeong
- Super-Bacteria Research Center, KRIBB, 125 Gwahak-ro, Yuseong-gu, Daejeon 305-806, Republic of Korea
| | - Seung-Hwan Park
- Super-Bacteria Research Center, KRIBB, 125 Gwahak-ro, Yuseong-gu, Daejeon 305-806, Republic of Korea Biosystems and Bioengineering Program, University of Science and Technology (UST), 217 Gajung-ro, Yuseong-gu, Daejeon 305-350, Republic of Korea
| | - Jae-Gu Pan
- Super-Bacteria Research Center, KRIBB, 125 Gwahak-ro, Yuseong-gu, Daejeon 305-806, Republic of Korea
| | - Eui-Joong Kim
- Genofocus Inc., 533-1 Yongsan-dong, Yuseong-gu, Daejeon 305-500, Republic of Korea
| | - Soo-Keun Choi
- Super-Bacteria Research Center, KRIBB, 125 Gwahak-ro, Yuseong-gu, Daejeon 305-806, Republic of Korea Biosystems and Bioengineering Program, University of Science and Technology (UST), 217 Gajung-ro, Yuseong-gu, Daejeon 305-350, Republic of Korea
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20
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Voigt B, Schroeter R, Schweder T, Jürgen B, Albrecht D, van Dijl JM, Maurer KH, Hecker M. A proteomic view of cell physiology of the industrial workhorse Bacillus licheniformis. J Biotechnol 2014; 191:139-49. [DOI: 10.1016/j.jbiotec.2014.06.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Revised: 05/26/2014] [Accepted: 06/03/2014] [Indexed: 11/16/2022]
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21
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Hao N, Krishna S, Ahlgren-Berg A, Cutts EE, Shearwin KE, Dodd IB. Road rules for traffic on DNA-systematic analysis of transcriptional roadblocking in vivo. Nucleic Acids Res 2014; 42:8861-72. [PMID: 25034688 PMCID: PMC4132739 DOI: 10.1093/nar/gku627] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Genomic DNA is bound by many proteins that could potentially impede elongation of RNA polymerase (RNAP), but the factors determining the magnitude of transcriptional roadblocking in vivo are poorly understood. Through systematic experiments and modeling, we analyse how roadblocking by the lac repressor (LacI) in Escherichia coli cells is controlled by promoter firing rate, the concentration and affinity of the roadblocker protein, the transcription-coupled repair protein Mfd, and promoter–roadblock spacing. Increased readthrough of the roadblock at higher RNAP fluxes requires active dislodgement of LacI by multiple RNAPs. However, this RNAP cooperation effect occurs only for strong promoters because roadblock-paused RNAP is quickly terminated by Mfd. The results are most consistent with a single RNAP also sometimes dislodging LacI, though we cannot exclude the possibility that a single RNAP reads through by waiting for spontaneous LacI dissociation. Reducing the occupancy of the roadblock site by increasing the LacI off-rate (weakening the operator) increased dislodgement strongly, giving a stronger effect on readthrough than decreasing the LacI on-rate (decreasing LacI concentration). Thus, protein binding kinetics can be tuned to maintain site occupation while reducing detrimental roadblocking.
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Affiliation(s)
- Nan Hao
- School of Molecular and Biomedical Sciences (Biochemistry), The University of Adelaide, Adelaide, SA 5005, Australia
| | - Sandeep Krishna
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences, Bangalore 560065, India
| | - Alexandra Ahlgren-Berg
- School of Molecular and Biomedical Sciences (Biochemistry), The University of Adelaide, Adelaide, SA 5005, Australia
| | - Erin E Cutts
- School of Molecular and Biomedical Sciences (Biochemistry), The University of Adelaide, Adelaide, SA 5005, Australia
| | - Keith E Shearwin
- School of Molecular and Biomedical Sciences (Biochemistry), The University of Adelaide, Adelaide, SA 5005, Australia
| | - Ian B Dodd
- School of Molecular and Biomedical Sciences (Biochemistry), The University of Adelaide, Adelaide, SA 5005, Australia
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22
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Shasaltaneh MD, Moosavi-Nejad Z, Gharavi S, Fooladi J. Cane molasses as a source of precursors in the bioproduction of tryptophan by Bacillus subtilis. IRANIAN JOURNAL OF MICROBIOLOGY 2013; 5:285-92. [PMID: 24475338 PMCID: PMC3895569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND AND OBJECTIVES The essential amino acid L-tryptophan can be produced by a condensation reaction between indole and L-serine, catalyzed by B. subtilis with tryptophan synthase activity. Application of the tryptophan is widespread in the biotechnology domain and is sometimes added to feed products as a food fortifier. MATERIALS AND METHODS The optimum concentration of the Iranian cane molasses was determined by measuring the amount of biomass after growth in 1 to 30 g/mL of molasses. The maximum amount of biomass was obtained in 10 g/mL molasses. Chromatographic methods, TLC and HPLC, were used to assay the amount of tryptophan produced in the presence of precursors of tryptophan production (indole and serine) and/or molasses. RESULTS Our results indicate the importance of the Iranian cane molasses not only as carbon source, but also as a source of precursors for tryptophan production. CONCLUSION This report evaluates the potential of cane molasses as an economical source for tryptophan production by B. subtilis, hence eliminating the requirement for additional serine and indole as precursors.
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Affiliation(s)
| | - Zahra Moosavi-Nejad
- Department of Biology, Faculty of Basic Sciences, Alzahra University, Tehran, Iran
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23
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Regulation of internal promoters in a zinc-responsive operon is influenced by transcription from upstream promoters. J Bacteriol 2013; 195:1285-93. [PMID: 23316045 DOI: 10.1128/jb.01488-12] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In the cyanobacterium Anabaena sp. strain PCC 7120 (also known as Nostoc sp. strain PCC 7120), a zinc-responsive operon (all4725-all4721) has been described, which contains 4 distinct promoters. The two most upstream ones bind Zur with high affinity, whereas the other two do not or do so with a very low affinity. In this paper, a detailed characterization of the four promoters is presented, showing that all four were induced by metal depletion, and they were constitutively derepressed in a zur mutant, despite the two downstream promoters not being direct targets for this regulator. Crucially, induction by metal depletion of the two downstream promoters was abrogated when transcription initiated at the upstream promoters was interrupted by a polar insertion midway in the operon. In contrast, insertion of a nitrogen-responsive promoter at a roughly similar position provoked the two downstream promoters to adopt a regulatory pattern mimicking that of the inserted promoter. Thus, regulation of the two downstream promoters is apparently influenced by transcription from promoters upstream. Evidence is presented indicating that the activity of the two downstream promoters is kept basal in Anabaena by repression. A regulatory model compatible with these results is proposed, where promoters controlled by repression in bacterial operons may be subjected to a hierarchical regulation depending on their position in the operon. According to this model, internal promoters may respond to stimuli governing the activity of promoters upstream by an indirect regulation and to specific stimuli by a direct regulation.
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Reexamining transcriptional regulation of the Bacillus subtilis htpX gene and the ykrK gene, encoding a novel type of transcriptional regulator, and redefining the YkrK operator. J Bacteriol 2012; 194:6758-65. [PMID: 23042994 DOI: 10.1128/jb.01258-12] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
HtpX is an integral cytoplasmic membrane metalloprotease well conserved in numerous bacteria. A recent study showed that expression of the Bacillus subtilis htpX gene is under dual negative control by Rok and a novel type of transcriptional regulator, YkrK. Here we report that expression of the B. subtilis htpX gene is strongly heat inducible. Contrary to the previous prediction, ykrK expression has been found to be not subject to autoregulation. We have identified the htpX promoter and the authentic ykrK promoter, which is also distinct from the previously predicted one. We have redefined a conserved inverted repeat sequence to be the YkrK operator, which is somewhat different from the previously proposed one. We provide evidence that YkrK is not a substrate of HtpX and that heat induction of htpX is not YkrK mediated. We have also found that the absence of FtsH or HtpX alone did not impair B. subtilis cell viability on LB agar plates at high temperature, whereas the absence of both FtsH and HtpX caused a severe growth defect under heat stress. This finding supports the notion that FtsH and HtpX may have partially overlapping functions in heat resistance. Finally, we show that htpX expression is subject to transient negative control by sigB under heat stress in a Rok- and YkrK-independent manner. Triple negative control of htpX expression at high temperature by rok, sigB, and ykrK may help cells to prevent uncontrolled and detrimental oversynthesis of the HtpX protease.
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25
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Marciniak BC, Pabijaniak M, de Jong A, Dűhring R, Seidel G, Hillen W, Kuipers OP. High- and low-affinity cre boxes for CcpA binding in Bacillus subtilis revealed by genome-wide analysis. BMC Genomics 2012; 13:401. [PMID: 22900538 PMCID: PMC3463425 DOI: 10.1186/1471-2164-13-401] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 08/09/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In Bacillus subtilis and its relatives carbon catabolite control, a mechanism enabling to reach maximal efficiency of carbon and energy sources metabolism, is achieved by the global regulator CcpA (carbon catabolite protein A). CcpA in a complex with HPr-Ser-P (seryl-phosphorylated form of histidine-containing protein, HPr) binds to operator sites called catabolite responsive elements, cre. Depending on the cre box position relative to the promoter, the CcpA/HPr-Ser-P complex can either act as a positive or a negative regulator. The cre boxes are highly degenerate semi-palindromes with a lowly conserved consensus sequence. So far, studies aimed at revealing how CcpA can bind such diverse sites were focused on the analysis of single cre boxes. In this study, a genome-wide analysis of cre sites was performed in order to identify differences in cre sequence and position, which determine their binding affinity. RESULTS The transcriptomes of B. subtilis cultures with three different CcpA expression levels were compared. The higher the amount of CcpA in the cells, the more operons possessing cre sites were differentially regulated. The cre boxes that mediated regulation at low CcpA levels were designated as strong (high affinity) and those which responded only to high amounts of CcpA, as weak (low affinity). Differences in the sequence and position in relation to the transcription start site between strong and weak cre boxes were revealed. CONCLUSIONS Certain residues at specific positions in the cre box as well as, to a certain extent, a more palindromic nature of cre sequences and the location of cre in close vicinity to the transcription start site contribute to the strength of CcpA-dependent regulation. The main factors contributing to cre regulatory efficiencies, enabling subtle differential control of various subregulons of the CcpA regulon, are identified.
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Affiliation(s)
- Bogumiła C Marciniak
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, Centrum voor Levenswetenschappen, University of Groningen, Groningen, The Netherlands
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Gunka K, Commichau FM. Control of glutamate homeostasis in Bacillus subtilis: a complex interplay between ammonium assimilation, glutamate biosynthesis and degradation. Mol Microbiol 2012; 85:213-24. [DOI: 10.1111/j.1365-2958.2012.08105.x] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Delumeau O, Lecointe F, Muntel J, Guillot A, Guédon E, Monnet V, Hecker M, Becher D, Polard P, Noirot P. The dynamic protein partnership of RNA polymerase in Bacillus subtilis. Proteomics 2011; 11:2992-3001. [PMID: 21710567 DOI: 10.1002/pmic.201000790] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Revised: 03/11/2011] [Accepted: 04/13/2011] [Indexed: 11/10/2022]
Abstract
In prokaryotes, transcription results from the activity of a 400 kDa RNA polymerase (RNAP) protein complex composed of at least five subunits (2α, β, β', ω). To ensure adequate responses to changing environmental cues, RNAP activity is tightly controlled by means of interacting regulatory proteins. Here, we report the affinity-purification of the Bacillus subtilis RNAP complexes from cells in different growth states and stress conditions, and the quantitative assessment by mass spectrometry of the dynamic changes in the composition of the RNAP complex. The stoichiometry of RNA polymerase was determined by a comparison of two mass spectrometry-based quantification methods: a label-based and a label-free method. The validated label-free method was then used to quantify the proteins associated with RNAP. The levels of sigma factors bound to RNAP varied during growth and exposure to stress. Elongation factors, helicases such as HelD and PcrA, and novel unknown proteins were also associated with RNAP complexes. The content in 6S RNAs of purified RNAP complexes increased at the onset of the stationary phase. These quantitative variations in the protein and RNA composition of the RNAP complexes well correlate with the known physiology of B. subtilis cells under different conditions.
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Schumacher MA, Sprehe M, Bartholomae M, Hillen W, Brennan RG. Structures of carbon catabolite protein A-(HPr-Ser46-P) bound to diverse catabolite response element sites reveal the basis for high-affinity binding to degenerate DNA operators. Nucleic Acids Res 2010; 39:2931-42. [PMID: 21106498 PMCID: PMC3074128 DOI: 10.1093/nar/gkq1177] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
In Gram-positive bacteria, carbon catabolite protein A (CcpA) is the master regulator of carbon catabolite control, which ensures optimal energy usage under diverse conditions. Unlike other LacI-GalR proteins, CcpA is activated for DNA binding by first forming a complex with the phosphoprotein HPr-Ser46-P. Bacillus subtilis CcpA functions as both a transcription repressor and activator and binds to more than 50 operators called catabolite response elements (cres). These sites are highly degenerate with the consensus, WTGNNARCGNWWWCAW. How CcpA–(HPr-Ser46-P) binds such diverse sequences is unclear. To gain insight into this question, we solved the structures of the CcpA–(HPr-Ser46-P) complex bound to three different operators, the synthetic (syn) cre, ackA2 cre and gntR-down cre. Strikingly, the structures show that the CcpA-bound operators display different bend angles, ranging from 31° to 56°. These differences are accommodated by a flexible linkage between the CcpA helix-turn-helix-loop-helix motif and hinge helices, which allows independent docking of these DNA-binding modules. This flexibility coupled with an abundance of non-polar residues capable of non-specific nucleobase interactions permits CcpA–(HPr-Ser46-P) to bind diverse operators. Indeed, biochemical data show that CcpA–(HPr-Ser46-P) binds the three cre sites with similar affinities. Thus, the data reveal properties that license this protein to function as a global transcription regulator.
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Affiliation(s)
- Maria A Schumacher
- Department of Biochemistry and Molecular Biology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
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Regulation of acetoin and 2,3-butanediol utilization in Bacillus licheniformis. Appl Microbiol Biotechnol 2010; 87:2227-35. [DOI: 10.1007/s00253-010-2681-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Revised: 05/11/2010] [Accepted: 05/11/2010] [Indexed: 10/19/2022]
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Transcriptional Regulation of the rsbV Promoter Controlling Stress Responses to Ethanol, Carbon Limitation, and Phosphorous Limitation in Bacillus subtilis. Int J Microbiol 2010; 2010:263410. [PMID: 20454630 PMCID: PMC2862951 DOI: 10.1155/2010/263410] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2009] [Accepted: 02/02/2010] [Indexed: 11/17/2022] Open
Abstract
The σB-dependent promoter in front of the rsbV gene of Bacillus subtilis is induced ∼5-fold in response to (1) the addition of 4% ethanol, (2) carbon starvation, and (3) phosphorous starvation. Binding sites for the global carbon and nitrogen regulators, CcpA and TnrA, were mutated, and the consequences of their loss and that of CcpA or TnrA were studied using rsbV-lacZ fusions. These responses proved to be dependent on CcpA, TnrA, and their putative binding sites upstream of the promoter. Induction in response to glucose limitation was largely abolished by loss of CcpA or the upstream region, while induction in response to phosphorous limitation was largely abolished only by the upstream mutations. The results suggest that CcpA directly influences the carbon starvation response and that both proteins exert indirect effects on all three stress responses. The integrity of the DNA sequence is important for all three responses.
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Regulation of mannose phosphotransferase system permease and virulence gene expression in Listeria monocytogenes by the EII(t)Man transporter. Appl Environ Microbiol 2009; 75:6671-8. [PMID: 19734332 DOI: 10.1128/aem.01104-09] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The EII(t)(Man) phosphotransferase system (PTS) permease encoded by the mpt operon is the principal glucose transporter in Listeria monocytogenes. EII(t)(Man) participates in glucose-mediated carbon catabolite repression (CCR) and downregulation of virulence gene expression, and it is the receptor for class IIa bacteriocins. The regulation of this important protein and its roles in gene control were examined using derivatives of strain EGD-e in which the mpt operon or its regulatory genes, manR and lmo0095, were deleted. Real-time reverse transcription-PCR analysis showed that the mpt mRNA level was 10- and 100-fold lower in the lmo0095 and manR deletion strains, respectively. The manR mRNA level was higher in the mpt deletion mutant in medium lacking glucose, possibly due to disruption of a regulatory process that normally downregulates manR transcription in the absence of this sugar. Analysis of the mpt deletion mutant also showed that EII(t)(Man) participates to various degrees in glucose-mediated CCR of PTS operons. CCR of the lmo0027 gene, which encodes a beta-glucoside PTS transporter, required expression of EII(t)(Man). In contrast, genes in two mannose PTS operons (lmo0024, lmo1997, and lmo2002) were repressed by glucose even when EII(t)(Man) was not synthesized. A third mannose PTS operon, mpo, was not regulated by glucose or by the level of EII(t)(Man). Finally, the mRNA levels for five genes in the prfA virulence gene cluster were two- to fourfold higher in the mpt deletion mutant. The results show that EII(t)(Man) participates to various extents in glucose-mediated CCR of PTS operons and makes a small, albeit significant, contribution to downregulation of virulence gene transcription by glucose in strain EGD-e.
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Acid and base stress and transcriptomic responses in Bacillus subtilis. Appl Environ Microbiol 2008; 75:981-90. [PMID: 19114526 DOI: 10.1128/aem.01652-08] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Acid and base environmental stress responses were investigated in Bacillus subtilis. B. subtilis AG174 cultures in buffered potassium-modified Luria broth were switched from pH 8.5 to pH 6.0 and recovered growth rapidly, whereas cultures switched from pH 6.0 to pH 8.5 showed a long lag time. Log-phase cultures at pH 6.0 survived 60 to 100% at pH 4.5, whereas cells grown at pH 7.0 survived <15%. Cells grown at pH 9.0 survived 40 to 100% at pH 10, whereas cells grown at pH 7.0 survived <5%. Thus, growth in a moderate acid or base induced adaptation to a more extreme acid or base, respectively. Expression indices from Affymetrix chip hybridization were obtained for 4,095 protein-encoding open reading frames of B. subtilis grown at external pH 6, pH 7, and pH 9. Growth at pH 6 upregulated acetoin production (alsDS), dehydrogenases (adhA, ald, fdhD, and gabD), and decarboxylases (psd and speA). Acid upregulated malate metabolism (maeN), metal export (czcDO and cadA), oxidative stress (catalase katA; OYE family namA), and the SigX extracytoplasmic stress regulon. Growth at pH 9 upregulated arginine catabolism (roc), which generates organic acids, glutamate synthase (gltAB), polyamine acetylation and transport (blt), the K(+)/H(+) antiporter (yhaTU), and cytochrome oxidoreductases (cyd, ctaACE, and qcrC). The SigH, SigL, and SigW regulons were upregulated at high pH. Overall, greater genetic adaptation was seen at pH 9 than at pH 6, which may explain the lag time required for growth shift to high pH. Low external pH favored dehydrogenases and decarboxylases that may consume acids and generate basic amines, whereas high external pH favored catabolism-generating acids.
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Karlsson S, Burman LG, Åkerlund T. Induction of toxins in Clostridium difficile is associated with dramatic changes of its metabolism. MICROBIOLOGY-SGM 2008; 154:3430-3436. [PMID: 18957596 DOI: 10.1099/mic.0.2008/019778-0] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Certain amino acids, and cysteine in particular, promptly blocked toxin expression in Clostridium difficile strain VPI 10463 when added to late-exponential-phase peptone-yeast cultures, i.e. prior to normal induction of toxins A and B. Glucose reduced toxin yields by 80-fold, but only when supplemented at inoculation. Forty upregulated C. difficile proteins were identified during maximum toxin expression, and most of these were enzymes involved in energy exchange, e.g. succinate, CO/folate and butyrate metabolism. Transcription of tcdA (toxin operon) and folD (CO/folate operon) was induced by 20- and 10-fold, respectively, and with strikingly similar kinetics between OD 0.8 and 1.2. The sigma factors tcdR and sigH were upregulated simultaneously with tcdA and folD (3.5-fold increase of mRNA level), whereas transcription of tcdC, codY, sigB and sigL showed little or no correlation with that of tcdA and folD. The results suggest a connection between toxin expression, alternative energy metabolism and initial sporulation events in C. difficile.
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Affiliation(s)
- Sture Karlsson
- Karolinska Institute, Microbiology and Tumor Biology Center, S-171 77 Stockholm, Sweden.,Swedish Institute for Infectious Disease Control, Department of Bacteriology, S-171 82 Solna, Sweden
| | - Lars G Burman
- Swedish Institute for Infectious Disease Control, Department of Bacteriology, S-171 82 Solna, Sweden
| | - Thomas Åkerlund
- Swedish Institute for Infectious Disease Control, Department of Bacteriology, S-171 82 Solna, Sweden
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Görke B, Stülke J. Carbon catabolite repression in bacteria: many ways to make the most out of nutrients. Nat Rev Microbiol 2008; 6:613-24. [PMID: 18628769 DOI: 10.1038/nrmicro1932] [Citation(s) in RCA: 1089] [Impact Index Per Article: 68.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Most bacteria can selectively use substrates from a mixture of different carbon sources. The presence of preferred carbon sources prevents the expression, and often also the activity, of catabolic systems that enable the use of secondary substrates. This regulation, called carbon catabolite repression (CCR), can be achieved by different regulatory mechanisms, including transcription activation and repression and control of translation by an RNA-binding protein, in different bacteria. Moreover, CCR regulates the expression of virulence factors in many pathogenic bacteria. In this Review, we discuss the most recent findings on the different mechanisms that have evolved to allow bacteria to use carbon sources in a hierarchical manner.
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Affiliation(s)
- Boris Görke
- Department of General Microbiology, Institute of Microbiology and Genetics, Georg-August University Göttingen, Grisebachstr 8, D-37077 Göttingen, Germany
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Folli C, Mangiarotti L, Folloni S, Alfieri B, Gobbo M, Berni R, Rivetti C. Specificity of the TraA-DNA interaction in the regulation of the pPD1-encoded sex pheromone response in Enterococcus faecalis. J Mol Biol 2008; 380:932-45. [PMID: 18579153 DOI: 10.1016/j.jmb.2008.05.058] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Revised: 05/20/2008] [Accepted: 05/23/2008] [Indexed: 10/22/2022]
Abstract
The Enterococcus faecalis conjugative plasmid pPD1 encodes proteins responsible for the mating response to the sex pheromone cPD1 secreted by a recipient cell. This response involves the respectively negative and positive determinants traA and traE, the pheromone-inhibitor determinant ipd and structural genes participating in the conjugation process. TraA is capable of binding to key sites within the regulatory gene cluster. The binding of TraA to cognate sites is modulated by the pheromone (cPD1) and the pheromone-inhibitor (iPD1) peptides. Using atomic force microscopy and classic biochemical techniques, we mapped and characterized the TraA-DNA interactions within the pPD1 regulatory gene cluster and the role of TraA in the transcription regulation of the sex pheromone response. A previous report showed that TraA binds to three adjacent sites (tab1, tab2 and tab3) located upstream of the ipd promoter region. Here, we provide direct evidence for such interactions and show that TraA alone or in the presence of iPD1 inhibits ipd transcription by preferentially binding to tab1, whereas in the presence of saturating cPD1, the overall binding to the tab sites decreases, TraA preferentially binds to tab3 and the ipd repression is relieved. Moreover, TraA alone or in the presence of iPD1 binds to two non-adjacent sites within the ipd terminators T1 and T2, an interaction that is also relieved in the presence of cPD1. The binding of TraA to the termination region of ipd may play an important role in controlling traE and traF expression via a transcriptional read-through mechanism already postulated for the pAD1 plasmid. TraA may also regulate its own expression by binding to a site in the proximity of the traA promoter, which has been relocated 200 bp downstream of the ipd gene. A model for the TraA-mediated regulation of the pPD1-encoded sex pheromone response is presented.
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Affiliation(s)
- Claudia Folli
- Department of Biochemistry and Molecular Biology, University of Parma, Viale G.P. Usberti 23/A, 43100 Parma, Italy
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Goelzer A, Bekkal Brikci F, Martin-Verstraete I, Noirot P, Bessières P, Aymerich S, Fromion V. Reconstruction and analysis of the genetic and metabolic regulatory networks of the central metabolism of Bacillus subtilis. BMC SYSTEMS BIOLOGY 2008; 2:20. [PMID: 18302748 PMCID: PMC2311275 DOI: 10.1186/1752-0509-2-20] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2007] [Accepted: 02/26/2008] [Indexed: 12/15/2022]
Abstract
Background Few genome-scale models of organisms focus on the regulatory networks and none of them integrates all known levels of regulation. In particular, the regulations involving metabolite pools are often neglected. However, metabolite pools link the metabolic to the genetic network through genetic regulations, including those involving effectors of transcription factors or riboswitches. Consequently, they play pivotal roles in the global organization of the genetic and metabolic regulatory networks. Results We report the manually curated reconstruction of the genetic and metabolic regulatory networks of the central metabolism of Bacillus subtilis (transcriptional, translational and post-translational regulations and modulation of enzymatic activities). We provide a systematic graphic representation of regulations of each metabolic pathway based on the central role of metabolites in regulation. We show that the complex regulatory network of B. subtilis can be decomposed as sets of locally regulated modules, which are coordinated by global regulators. Conclusion This work reveals the strong involvement of metabolite pools in the general regulation of the metabolic network. Breaking the metabolic network down into modules based on the control of metabolite pools reveals the functional organization of the genetic and metabolic regulatory networks of B. subtilis.
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Affiliation(s)
- Anne Goelzer
- Unité Mathématique, Informatique et Génomes, Institut National Recherche Agronomique, UR1077, F-78350 Jouy-en-Josas, France.
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Abstract
Acetoin is an important physiological metabolite excreted by many microorganisms. The excretion of acetoin, which can be diagnosed by the Voges Proskauer test and serves as a microbial classification marker, has its vital physiological meanings to these microbes mainly including avoiding acification, participating in the regulation of NAD/NADH ratio, and storaging carbon. The well-known anabolism of acetoin involves alpha-acetolactat synthase and alpha-acetolactate decarboxylase; yet its catabolism still contains some differing views, although much attention has been focused on it and great advances have been achieved. Current findings in catabolite control protein A (CcpA) mediated carbon catabolite repression may provide a fuller understanding of the control mechanism in bacteria. In this review, we first examine the acetoin synthesis pathways and its physiological meanings and relevancies; then we discuss the relationship between the two conflicting acetoin cleavage pathways, the enzymes of the acetoin dehydrogenase enzyme system, major genes involved in acetoin degradation, and the CcpA mediated acetoin catabolite repression pathway; in the end we discuss the genetic engineering progresses concerning applications. To date, this is the first integrated review on acetoin metabolism in bacteria, especially with regard to catabolic aspects. The apperception of the generation and dissimilation of acetoin in bacteria will help provide a better understanding of microbial strategies in the struggle for resources, which will consequently better serve the utilization of these microbes.
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Affiliation(s)
- Zijun Xiao
- State Key Laboratory of Microbial Technology, Shandong University, People's Republic of China
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Lulko AT, Buist G, Kok J, Kuipers OP. Transcriptome analysis of temporal regulation of carbon metabolism by CcpA in Bacillus subtilis reveals additional target genes. J Mol Microbiol Biotechnol 2007; 12:82-95. [PMID: 17183215 DOI: 10.1159/000096463] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The pleiotropic regulator of carbon metabolism in Gram-positive bacteria, CcpA, regulates gene expression by binding to so-called cre elements, which are located either upstream or in promoter regions, or in open-reading frames. In this study we compared the transcriptomes of Bacillus subtilis 168 and its ccpA deletion mutant during growth in glucose-containing rich medium. Although growth was similar, glucose was completely consumed by the wild-type strain in the stationary phase, while it was still present in the culture of the mutant. At that stage, direct and indirect effects on gene expression were observed. During exponential growth, CcpA mainly influences the carbohydrate and energy metabolism, whereas from transition phase onwards its function expands on a broader range of physiological processes including nucleotide metabolism, cell motility and protein synthesis. A genome wide search revealednew putative cre sites, which could function in vivo according to our transcriptome data. Comparison of our data with published transcriptome data of ccpA mutant analysis in the exponential growth phase confirmed earlier identified CcpA regulon members. It also allowed identification of potential new CcpA-repressed genes, amongst others ycgN and the ydh operon. Novel activated members include opuE andthe opuAABC, yhb and man operons, which all have a putative cre site that appears to be dependent on helical topology. A comparative analysis of these genes with the known activated genes i.e.ackA and pta revealed the presence of a possible upstream activating region (UAR) as has been shown to be functional for the activation of ackA. The data suggest that at later growth phases CcpA may regulate gene expression by itself or complexed with other, yet unknown cofactors.
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Affiliation(s)
- Andrzej T Lulko
- Molecular Genetics Group, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren, The Netherlands
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Deutscher J, Francke C, Postma PW. How phosphotransferase system-related protein phosphorylation regulates carbohydrate metabolism in bacteria. Microbiol Mol Biol Rev 2007; 70:939-1031. [PMID: 17158705 PMCID: PMC1698508 DOI: 10.1128/mmbr.00024-06] [Citation(s) in RCA: 989] [Impact Index Per Article: 58.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The phosphoenolpyruvate(PEP):carbohydrate phosphotransferase system (PTS) is found only in bacteria, where it catalyzes the transport and phosphorylation of numerous monosaccharides, disaccharides, amino sugars, polyols, and other sugar derivatives. To carry out its catalytic function in sugar transport and phosphorylation, the PTS uses PEP as an energy source and phosphoryl donor. The phosphoryl group of PEP is usually transferred via four distinct proteins (domains) to the transported sugar bound to the respective membrane component(s) (EIIC and EIID) of the PTS. The organization of the PTS as a four-step phosphoryl transfer system, in which all P derivatives exhibit similar energy (phosphorylation occurs at histidyl or cysteyl residues), is surprising, as a single protein (or domain) coupling energy transfer and sugar phosphorylation would be sufficient for PTS function. A possible explanation for the complexity of the PTS was provided by the discovery that the PTS also carries out numerous regulatory functions. Depending on their phosphorylation state, the four proteins (domains) forming the PTS phosphorylation cascade (EI, HPr, EIIA, and EIIB) can phosphorylate or interact with numerous non-PTS proteins and thereby regulate their activity. In addition, in certain bacteria, one of the PTS components (HPr) is phosphorylated by ATP at a seryl residue, which increases the complexity of PTS-mediated regulation. In this review, we try to summarize the known protein phosphorylation-related regulatory functions of the PTS. As we shall see, the PTS regulation network not only controls carbohydrate uptake and metabolism but also interferes with the utilization of nitrogen and phosphorus and the virulence of certain pathogens.
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Affiliation(s)
- Josef Deutscher
- Microbiologie et Génétique Moléculaire, INRA-CNRS-INA PG UMR 2585, Thiverval-Grignon, France.
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Ganesan B, Stuart MR, Weimer BC. Carbohydrate starvation causes a metabolically active but nonculturable state in Lactococcus lactis. Appl Environ Microbiol 2007; 73:2498-512. [PMID: 17293521 PMCID: PMC1855592 DOI: 10.1128/aem.01832-06] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
This study characterized the ability of lactococci to become nonculturable under carbohydrate starvation while maintaining metabolic activity. We determined the changes in physiological parameters and extracellular substrate levels of multiple lactococcal strains under a number of environmental conditions along with whole-genome expression profiles. Three distinct phases were observed, logarithmic growth, sugar exhaustion, and nonculturability. Shortly after carbohydrate starvation, each lactococcal strain lost the ability to form colonies on solid media but maintained an intact cell membrane and metabolic activity for over 3.5 years. ML3, a strain that metabolized lactose rapidly, reached nonculturability within 1 week. Strains that metabolized lactose slowly (SK11) or not at all (IL1403) required 1 to 3 months to become nonculturable. In all cases, the cells contained at least 100 pM of intracellular ATP after 6 months of starvation and remained at that level for the remainder of the study. Aminopeptidase and lipase/esterase activities decreased below detection limits during the nonculturable phase. During sugar exhaustion and entry into nonculturability, serine and methionine were produced, while glutamine and arginine were depleted from the medium. The cells retained the ability to transport amino acids via proton motive force and peptides via ATP-driven translocation. The addition of branched-chain amino acids to the culture medium resulted in increased intracellular ATP levels and new metabolic products, indicating that branched-chain amino acid catabolism resulted in energy and metabolic products to support survival during starvation. Gene expression analysis showed that the genes responsible for sugar metabolism were repressed as the cells entered nonculturability. The genes responsible for cell division were repressed, while autolysis and cell wall metabolism genes were induced neither at starvation nor during nonculturability. Taken together, these observations verify that carbohydrate-starved lactococci attain a nonculturable state wherein sugar metabolism, cell division, and autolysis are repressed, allowing the cells to maintain transcription, metabolic activity, and energy production during a state that produces new metabolites not associated with logarithmic growth.
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Voigt B, Hoi LT, Jürgen B, Albrecht D, Ehrenreich A, Veith B, Evers S, Maurer KH, Hecker M, Schweder T. The glucose and nitrogen starvation response ofBacillus licheniformis. Proteomics 2007; 7:413-23. [PMID: 17274076 DOI: 10.1002/pmic.200600556] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The glucose and nitrogen starvation stimulons of Bacillus licheniformis were determined by transcriptome and proteome analyses. Under both starvation conditions, the main response of B. licheniformis was a switch to the usage of alternative nutrient sources. This was indicated by an induction of genes involved in the metabolism of C-2 substrates during glucose limitation. In addition, B. licheniformis seems to be using other organic substances like amino acids and lipids as carbon sources when subjected to glucose starvation. This observation is supported by the induction of a high number of genes coding for proteins involved in amino acid and lipid degradation. During nitrogen starvation, genes for several proteases and peptidases involved in nitrate and nitrite assimilation were induced, which enables this bacterium to recruit nitrogen from alternative sources. Both starvation conditions led to a down-regulation of transcription of most vegetative genes, which was subsequently reflected by a reduced synthesis of the corresponding proteins. A selected set of genes was induced by both starvation conditions. Among them were yvyD, citA and the putative methylcitrate shunt genes mmgD, mmgE and yqiQ. However, both starvation conditions did not induce a general SigmaB-dependent stress response.
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Affiliation(s)
- Birgit Voigt
- Institut für Mikrobiologie, Ernst-Moritz-Arndt-Universität, Greifswald, Germany
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Commichau FM, Wacker I, Schleider J, Blencke HM, Reif I, Tripal P, Stülke J. Characterization of Bacillus subtilis Mutants with Carbon Source-Independent Glutamate Biosynthesis. J Mol Microbiol Biotechnol 2006; 12:106-13. [PMID: 17183217 DOI: 10.1159/000096465] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Bacillus subtilis synthesizes glutamate from 2-oxoglutarate and glutamine using the glutamate synthase, encoded by the gltAB operon. Glutamate degradation involves the catabolic glutamate dehydrogenase (GDH) RocG. Expression of both gltAB and rocG is controlled by the carbon and nitrogen sources. In the absence of glucose or other well-metabolizable carbon sources, B. subtilis is unable to grow unless provided with external glutamate. In this work, we isolated mutations that suppressed this growth defect of B. subtilis on minimal media (sgd mutants). All mutations enabled the cells to express the gltAB operon even in the absence of glucose. The mutations were all identified in the rocG gene suggesting that the catabolic GDH is essential for controlling gltAB expression in response to the availability of sugars.
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Affiliation(s)
- Fabian M Commichau
- Abteilung für Allgemeine Mikrobiologie, Georg-August-Universität Göttingen, Göttingen, Germany
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Silbersack J, Jürgen B, Hecker M, Schneidinger B, Schmuck R, Schweder T. An acetoin-regulated expression system of Bacillussubtilis. Appl Microbiol Biotechnol 2006; 73:895-903. [PMID: 16944132 DOI: 10.1007/s00253-006-0549-5] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2006] [Revised: 06/17/2006] [Accepted: 06/19/2006] [Indexed: 11/29/2022]
Abstract
An expression system, which is based on the promoter of the acoABCL operon of Bacillus subtilis was developed and characterized. The acoABCL operon codes for the acetoin dehydrogenase complex, which is the major enzyme system responsible for the catabolism of acetoin in B. subtilis. Besides weak organic acids, the neutral overflow metabolite acetoin is metabolized by the cells in the early stationary phase. Transcription of reporter gene fusions with the acoA promoter of this operon is strongly repressed by glucose but induced by acetoin as soon as the preferred carbon source glucose is exhausted. The co-expression of an additional copy of the regulator gene acoR led to more than twofold higher activity of the acoA promoter. It is demonstrated that the induction of this promoter in growing cells with acetoin is possible with non-phosphotransferase system sugars as carbon and energy source and in a ccpA mutant background. Moreover, it could be shown that the activity of the acoA-directed expression system correlates with the level of acetoin in the medium. During glucose limitation, the utilization of the alternative energy source acetoin keeps the protein synthesis machinery of B. subtilis cells active and thus allows for a long lasting acoA-controlled expression of recombinant genes.
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Affiliation(s)
- Jörg Silbersack
- Department of Pharmaceutical Biotechnology, Institute of Pharmacy, Ernst-Moritz-Arndt University, 17487 Greifswald, Germany.
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Choi SK, Saier MH. Mechanism of CcpA-mediated glucose repression of the resABCDE operon of Bacillus subtilis. J Mol Microbiol Biotechnol 2006; 11:104-10. [PMID: 16825793 DOI: 10.1159/000092822] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The resABCDE operon of Bacillus subtilis encodes a three-protein complex involved in cytochrome c biogenesis as well as the ResE sensor kinase and the ResD response regulator that control electron transfer and other functions in response to oxygen availability. We have investigated the mechanism of CcpA-mediated control of res operon expression which occurs maximally in the stationary phase of growth. Two CcpA-binding (CRE) sites were found in the res operon, one (CRE1) in the control region in front of the resA promoter, the other (CRE2) in the resB structural gene. Both CRE sites proved to be essential for full CcpA-mediated glucose repression of res operon expression. We propose that both looping and road block mechanisms are involved in res operon control by CcpA.
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Affiliation(s)
- Soo-Keun Choi
- Division of Biological Sciences, University of California at San Diego, La Jolla, Calif., USA
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Zomer AL, Buist G, Larsen R, Kok J, Kuipers OP. Time-resolved determination of the CcpA regulon of Lactococcus lactis subsp. cremoris MG1363. J Bacteriol 2006; 189:1366-81. [PMID: 17028270 PMCID: PMC1797362 DOI: 10.1128/jb.01013-06] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Carbon catabolite control protein A (CcpA) is the main regulator involved in carbon catabolite repression in gram-positive bacteria. Time series gene expression analyses of Lactococcus lactis MG1363 and L. lactis MG1363DeltaccpA using DNA microarrays were used to define the CcpA regulon of L. lactis. Based on a comparison of the transcriptome data with putative CcpA binding motifs (cre sites) in promoter sequences in the genome of L. lactis, 82 direct targets of CcpA were predicted. The main differences in time-dependent expression of CcpA-regulated genes were differences between the exponential and transition growth phases. Large effects were observed for carbon and nitrogen metabolic genes in the exponential growth phase. Effects on nucleotide metabolism genes were observed primarily in the transition phase. Analysis of the positions of putative cre sites revealed that there is a link between either repression or activation and the location of the cre site within the promoter region. Activation was observed when putative cre sites were located upstream of the hexameric -35 sequence at an average position of -56.5 or further upstream with decrements of 10.5 bp. Repression was observed when the cre site was located in or downstream of putative -35 and -10 sequences. The highest level of repression was observed when the cre site was present at a defined side of the DNA helix relative to the canonical -10 sequence. Gel retardation experiments, Northern blotting, and enzyme assays showed that CcpA represses its own expression and activates the expression of the divergently oriented prolidase-encoding pepQ gene, which constitutes a link between regulation of carbon metabolism and regulation of nitrogen metabolism.
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Affiliation(s)
- Aldert L Zomer
- Department of Molecular Genetics, University of Groningen, Groningen Biomolecular Sciences and Biotechnology Institute, 9750 AA Haren, The Netherlands
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Choi SK, Saier MH. Regulation of pho regulon gene expression by the carbon control protein A, CcpA, in Bacillus subtilis. J Mol Microbiol Biotechnol 2006; 10:40-50. [PMID: 16491025 DOI: 10.1159/000090347] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Bacterial regulons involved in carbon, nitrogen and phosphorus metabolism must interact for purposes of coordination, but the mechanisms involved are not understood. We here report that the carbon control pro-tein-A (CcpA) of Bacillus subtilis, primarily concerned with carbon metabolism, influences expression of various phosphorus (pho) regulon genes including the two alkaline phosphatase structural genes, phoA and phoB. The directions and magnitudes of the effects of glucose and the loss of CcpA on these two genes depend on growth conditions, but they always correlate inversely. Absolute expression levels of phoA and phoB depend on a rich nitrogen source, and gene activation by a fermentable substrate such as glucose depends on the presence of a respiratory substrate such as succinate. We show that these CcpA-dependent glucose effects can be explained by the effects of glucose and CcpA acting on the phoPR operon. Although a good CcpA-binding site (CRE) is found in the control region of the phoPR operon, direct regulation of phoPR gene expression by CcpA via this CRE could not account for the effects of glucose and CcpA on phoA and phoB gene expression. We conclude that CcpA exerts indirect control over the pho regulon by a mechanism that involves CcpA and PhoRP but does not involve the phoPR operon CRE.
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Affiliation(s)
- Soo-Keun Choi
- Korea Research Institute of Bioscience and Biotechnology (KRIBB), Yusong, Taejon, Korea
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Commichau FM, Forchhammer K, Stülke J. Regulatory links between carbon and nitrogen metabolism. Curr Opin Microbiol 2006; 9:167-72. [PMID: 16458044 DOI: 10.1016/j.mib.2006.01.001] [Citation(s) in RCA: 132] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2005] [Accepted: 01/20/2006] [Indexed: 10/25/2022]
Abstract
The metabolism of carbon- and nitrogen-containing compounds is fundamental to all forms of life. To cope with changing environmental conditions, bacteria have to sense the nutrient supply and adapt their metabolism accordingly. In addition to nutrient- and pathway-specific responses, they integrate information from the different branches of metabolism to coordinate the control of the expression of many metabolic genes. Two major players interconnecting carbon and nitrogen regulation are the PII proteins and the phosphotransferase system. Moreover, several DNA-binding transcription regulators sense signals are derived from both carbon and nitrogen metabolism. The regulatory networks enable the bacteria to make the appropriate metabolic responses to changing nutrient availabilities in the environment.
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Affiliation(s)
- Fabian M Commichau
- Department of General Microbiology, Institute of Microbiology and Genetics, Georg-August University Göttingen, Grisebachstr. 8, D-37077 Göttingen, Germany
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