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Biermann R, Beutel S. Endospore production of Bacillus spp. for industrial use. Eng Life Sci 2023; 23:e2300013. [PMID: 37970521 PMCID: PMC10630785 DOI: 10.1002/elsc.202300013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 08/02/2023] [Accepted: 10/05/2023] [Indexed: 11/17/2023] Open
Abstract
The increased occurrence of antibiotic resistance and the harmful use of pesticides are a major problem of modern times. A ban on the use of antibiotics as growth promoters in animal breeding has put a focus on the probiotics market. Probiotic food supplements are versatile and show promising results in animal and human nutrition. Chemical pesticides can be substituted by biopesticides, which are very effective against various pests in plants due to increased research. What these fields have in common is the use of spore-forming bacteria. The endospore-forming Bacillus spp. belonging to this group offer an effective solution to the aforementioned problems. Therefore, the biotechnological production of sufficient qualities of such endospores has become an innovative and financially viable field of research. In this review, the production of different Bacillus spp. endospores will be reviewed. For this purpose, the media compositions, cultivation conditions and bioprocess optimization methods of the last 20 years are presented and reflected.
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Affiliation(s)
- Riekje Biermann
- Institute of Technical ChemistryLeibniz University HannoverHannoverGermany
| | - Sascha Beutel
- Institute of Technical ChemistryLeibniz University HannoverHannoverGermany
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2
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Akintayo SO, Hosseini B, Vahidinasab M, Messmer M, Pfannstiel J, Bertsche U, Hubel P, Henkel M, Hausmann R, Voegele RT, Lilge L. Characterization ofantifungal properties of lipopeptide-producing Bacillus velezensis strains and their proteome-based response to the phytopathogens, Diaporthe spp. Front Bioeng Biotechnol 2023; 11:1228386. [PMID: 37609113 PMCID: PMC10440741 DOI: 10.3389/fbioe.2023.1228386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Accepted: 07/28/2023] [Indexed: 08/24/2023] Open
Abstract
Introduction: B. velezensis strains are of interest in agricultural applications due to their beneficial interactions with plants, notable through their antimicrobial activity. The biocontrol ability of two new lipopeptides-producing B. velezensis strains ES1-02 and EFSO2-04, against fungal phytopathogens of Diaporthe spp., was evaluated and compared with reference strains QST713 and FZB42. All strains were found to be effective against the plant pathogens, with the new strains showing comparable antifungal activity to QST713 and slightly lower activity than FZB42. Methods: Lipopeptides and their isoforms were identified by high-performance thin-layer chromatography (HPTLC) and mass spectrometric measurements. The associated antifungal influences were determined in direct in vitro antagonistic dual culture assays, and the inhibitory growth effects on Diaporthe spp. as representatives of phytopathogenic fungi were determined. The effects on bacterial physiology of selected B. velezensis strains were analyzed by mass spectrometric proteomic analyses using nano-LC-MS/MS. Results and Discussion: Lipopeptide production analysis revealed that all strains produced surfactin, and one lipopeptide of the iturin family, including bacillomycin L by ES1-02 and EFSO2-04, while QST713 and FZB42 produced iturin A and bacillomycin D, respectively. Fengycin production was however only detected in the reference strains. As a result of co-incubation of strain ES1-02 with the antagonistic phytopathogen D. longicolla, an increase in surfactin production of up to 10-fold was observed, making stress induction due to competitors an attractive strategy for surfactin bioproduction. An associated global proteome analysis showed a more detailed overview about the adaptation and response mechanisms of B. velezensis, including an increased abundance of proteins associated with the biosynthesis of antimicrobial compounds. Furthermore, higher abundance was determined for proteins associated with oxidative, nitrosative, and general stress response. In contrast, proteins involved in phosphate uptake, amino acid transport, and translation were decreased in abundance. Altogether, this study provides new insights into the physiological adaptation of lipopeptide-producing B. velezensis strains, which show the potential for use as biocontrol agents with respect to phytopathogenic fungi.
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Affiliation(s)
- Stephen Olusanmi Akintayo
- Department of Bioprocess Engineering, Institute of Food Science and Biotechnology, University of Hohenheim, Stuttgart, Germany
| | - Behnoush Hosseini
- Department of Phytopathology, Institute of Phytomedicine, University of Hohenheim, Stuttgart, Germany
| | - Maliheh Vahidinasab
- Department of Bioprocess Engineering, Institute of Food Science and Biotechnology, University of Hohenheim, Stuttgart, Germany
| | - Marc Messmer
- Department of Bioprocess Engineering, Institute of Food Science and Biotechnology, University of Hohenheim, Stuttgart, Germany
| | - Jens Pfannstiel
- Core Facility Hohenheim, Mass Spectrometry Core Facility, University of Hohenheim, Stuttgart, Germany
| | - Ute Bertsche
- Core Facility Hohenheim, Mass Spectrometry Core Facility, University of Hohenheim, Stuttgart, Germany
| | - Philipp Hubel
- Core Facility Hohenheim, Mass Spectrometry Core Facility, University of Hohenheim, Stuttgart, Germany
| | - Marius Henkel
- Cellular Agriculture, TUM School of Life Sciences, Technical University of Munich, Freising, Germany
| | - Rudolf Hausmann
- Department of Bioprocess Engineering, Institute of Food Science and Biotechnology, University of Hohenheim, Stuttgart, Germany
| | - Ralf T. Voegele
- Department of Phytopathology, Institute of Phytomedicine, University of Hohenheim, Stuttgart, Germany
| | - Lars Lilge
- Department of Bioprocess Engineering, Institute of Food Science and Biotechnology, University of Hohenheim, Stuttgart, Germany
- Department of Molecular Genetics, University of Groningen, Groningen, Netherlands
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Rajpurohit H, Eiteman MA. Nutrient-Limited Operational Strategies for the Microbial Production of Biochemicals. Microorganisms 2022; 10:2226. [PMID: 36363817 PMCID: PMC9695796 DOI: 10.3390/microorganisms10112226] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 10/31/2022] [Accepted: 11/07/2022] [Indexed: 08/24/2023] Open
Abstract
Limiting an essential nutrient has a profound impact on microbial growth. The notion of growth under limited conditions was first described using simple Monod kinetics proposed in the 1940s. Different operational modes (chemostat, fed-batch processes) were soon developed to address questions related to microbial physiology and cell maintenance and to enhance product formation. With more recent developments of metabolic engineering and systems biology, as well as high-throughput approaches, the focus of current engineers and applied microbiologists has shifted from these fundamental biochemical processes. This review draws attention again to nutrient-limited processes. Indeed, the sophisticated gene editing tools not available to pioneers offer the prospect of metabolic engineering strategies which leverage nutrient limited processes. Thus, nutrient- limited processes continue to be very relevant to generate microbially derived biochemicals.
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Affiliation(s)
| | - Mark A. Eiteman
- School of Chemical, Materials and Biomedical Engineering, University of Georgia, Athens, GA 30602, USA
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Complete Genome Sequence of Lactobacillus hilgardii LMG 7934, Carrying the Gene Encoding for the Novel PII-Like Protein PotN. Curr Microbiol 2020; 77:3538-3545. [PMID: 32803419 DOI: 10.1007/s00284-020-02161-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 08/07/2020] [Indexed: 02/02/2023]
Abstract
Lactic acid bacteria are widespread in various ecological niches with the excess of nutrients and have reduced capabilities to adapt to starvation. Among more than 280 Lactobacillus species known to the date, only five, including Lactobacillus hilgardii, carry in their genome the gene encoding for PII-like protein, one of the central regulators of cellular metabolism generally responding to energy- and carbon-nitrogen status in many free-living Bacteria, Archaea and in plant chloroplasts. In contrast to the classical PII encoding genes, in L. hilgardii genome the gene for PII homologue is located within the potABCD operon, encoding the ABC transporter for polyamines. Based on the unique genetic context and low sequence identity with genes of any other so-far characterized PII subfamilies, we termed this gene potN (Pot-protein, Nucleotide-binding). The second specific feature of L. hilgardii genome is that many genes encoding the proteins with similar function are present in two copies, while with low mutual identity. Thus, L. hilgardii LMG 7934 genome carries two genes of glutamine synthetase with 55% identity. One gene is located within classical glnRA operon with the gene of GlnR-like transcriptional regulator, while the second is monocistronic. Together with the relative large genome of L. hilgardii as compared to other Lactobacilli (2.771.862 bp vs ~ 2.2 Mbp in median), these data suggest significant re-arrangements of the genome and a wider range of adaptive capabilities of L. hilgardii in comparison to other bacteria of the genus Lactobacillus.
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Ranganathan S, Cheung J, Cassidy M, Ginter C, Pata JD, McDonough KA. Novel structural features drive DNA binding properties of Cmr, a CRP family protein in TB complex mycobacteria. Nucleic Acids Res 2019; 46:403-420. [PMID: 29165665 PMCID: PMC5758884 DOI: 10.1093/nar/gkx1148] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Accepted: 11/13/2017] [Indexed: 11/16/2022] Open
Abstract
Mycobacterium tuberculosis (Mtb) encodes two CRP/FNR family transcription factors (TF) that contribute to virulence, Cmr (Rv1675c) and CRPMt (Rv3676). Prior studies identified distinct chromosomal binding profiles for each TF despite their recognizing overlapping DNA motifs. The present study shows that Cmr binding specificity is determined by discriminator nucleotides at motif positions 4 and 13. X-ray crystallography and targeted mutational analyses identified an arginine-rich loop that expands Cmr’s DNA interactions beyond the classical helix-turn-helix contacts common to all CRP/FNR family members and facilitates binding to imperfect DNA sequences. Cmr binding to DNA results in a pronounced asymmetric bending of the DNA and its high level of cooperativity is consistent with DNA-facilitated dimerization. A unique N-terminal extension inserts between the DNA binding and dimerization domains, partially occluding the site where the canonical cAMP binding pocket is found. However, an unstructured region of this N-terminus may help modulate Cmr activity in response to cellular signals. Cmr’s multiple levels of DNA interaction likely enhance its ability to integrate diverse gene regulatory signals, while its novel structural features establish Cmr as an atypical CRP/FNR family member.
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Affiliation(s)
- Sridevi Ranganathan
- Department of Biomedical Sciences, School of Public Health, University at Albany, SUNY, Albany, NY 12201, USA
| | - Jonah Cheung
- New York Structural Biology Center, New York, NY 10027, USA
| | | | | | - Janice D Pata
- Department of Biomedical Sciences, School of Public Health, University at Albany, SUNY, Albany, NY 12201, USA.,Wadsworth Center, New York State Department of Health, 120 New Scotland Avenue, PO Box 22002, Albany, NY 12201-2002, USA
| | - Kathleen A McDonough
- Department of Biomedical Sciences, School of Public Health, University at Albany, SUNY, Albany, NY 12201, USA.,Wadsworth Center, New York State Department of Health, 120 New Scotland Avenue, PO Box 22002, Albany, NY 12201-2002, USA
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6
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glnA Truncation in Salmonella enterica Results in a Small Colony Variant Phenotype, Attenuated Host Cell Entry, and Reduced Expression of Flagellin and SPI-1-Associated Effector Genes. Appl Environ Microbiol 2018; 84:AEM.01838-17. [PMID: 29150501 DOI: 10.1128/aem.01838-17] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 10/25/2017] [Indexed: 11/20/2022] Open
Abstract
Many pathogenic bacteria use sophisticated survival strategies to overcome harsh environmental conditions. One strategy is the formation of slow-growing subpopulations termed small colony variants (SCVs). Here we characterize an SCV that spontaneously emerged from an axenic Salmonella enterica serovar Typhimurium water culture. We found that the SCV harbored a frameshift mutation in the glutamine synthetase gene glnA, leading to an ∼90% truncation of the corresponding protein. Glutamine synthetase, a central enzyme in nitrogen assimilation, converts glutamate and ammonia to glutamine. Glutamine is an important nitrogen donor that is required for the synthesis of cellular compounds. The internal glutamine pool serves as an indicator of nitrogen availability in Salmonella In our study, the SCV and a constructed glnA knockout mutant showed reduced growth rates, compared to the wild type. Moreover, the SCV and the glnA mutant displayed attenuated entry into host cells and severely reduced levels of exoproteins, including flagellin and several Salmonella pathogenicity island 1 (SPI-1)-dependent secreted virulence factors. We found that these proteins were also depleted in cell lysates, indicating their diminished synthesis. Accordingly, the SCV and the glnA mutant had severely decreased expression of flagellin genes, several SPI-1 effector genes, and a class 2 motility gene (flgB). However, the expression of a class 1 motility gene (flhD) was not affected. Supplementation with glutamine or genetic reversion of the glnA truncation restored growth, cell entry, gene expression, and protein abundance. In summary, our data show that glnA is essential for the growth of S. enterica and controls important motility- and virulence-related traits in response to glutamine availability.IMPORTANCE Salmonella enterica serovar Typhimurium is a significant pathogen causing foodborne infections. Here we describe an S Typhimurium small colony variant (SCV) that spontaneously emerged from a long-term starvation experiment in water. It is important to study SCVs because (i) SCVs may arise spontaneously upon exposure to stresses, including environmental and host defense stresses, (ii) SCVs are slow growing and difficult to eradicate, and (iii) only a few descriptions of S. enterica SCVs are available. We clarify the genetic basis of the SCV described here as a frameshift mutation in the glutamine synthetase gene glnA, leading to glutamine auxotrophy. In Salmonella, internal glutamine limitation serves as a sign of external nitrogen deficiency and is thought to regulate cell growth. In addition to exhibiting impaired growth, the SCV showed reduced host cell entry and reduced expression of SPI-1 virulence and flagellin genes.
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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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8
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de Jong L, de Koning EA, Roseboom W, Buncherd H, Wanner MJ, Dapic I, Jansen PJ, van Maarseveen JH, Corthals GL, Lewis PJ, Hamoen LW, de Koster CG. In-Culture Cross-Linking of Bacterial Cells Reveals Large-Scale Dynamic Protein-Protein Interactions at the Peptide Level. J Proteome Res 2017; 16:2457-2471. [PMID: 28516784 PMCID: PMC5504490 DOI: 10.1021/acs.jproteome.7b00068] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
![]()
Identification of
dynamic protein–protein interactions at
the peptide level on a proteomic scale is a challenging approach that
is still in its infancy. We have developed a system to cross-link
cells directly in culture with the special lysine cross-linker bis(succinimidyl)-3-azidomethyl-glutarate
(BAMG). We used the Gram-positive model bacterium Bacillus
subtilis as an exemplar system. Within 5 min extensive intracellular
cross-linking was detected, while intracellular cross-linking in a
Gram-negative species, Escherichia coli, was still
undetectable after 30 min, in agreement with the low permeability
in this organism for lipophilic compounds like BAMG. We were able
to identify 82 unique interprotein cross-linked peptides with <1%
false discovery rate by mass spectrometry and genome-wide database
searching. Nearly 60% of the interprotein cross-links occur in assemblies
involved in transcription and translation. Several of these interactions
are new, and we identified a binding site between the δ and
β′ subunit of RNA polymerase close to the downstream
DNA channel, providing a clue into how δ might regulate promoter
selectivity and promote RNA polymerase recycling. Our methodology
opens new avenues to investigate the functional dynamic organization
of complex protein assemblies involved in bacterial growth. Data are
available via ProteomeXchange with identifier PXD006287.
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Affiliation(s)
| | | | | | - Hansuk Buncherd
- Faculty of Medical Technology, Prince of Songkla University , Hatyai, Songkhla 90110, Thailand
| | | | | | | | | | | | - Peter J Lewis
- School of Environmental and Life Sciences, University of Newcastle , Callaghan, New South Wales 2308, Australia
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Calcium regulates glutamate dehydrogenase and poly-γ-glutamic acid synthesis in Bacillus natto. Biotechnol Lett 2015; 38:673-9. [PMID: 26712367 DOI: 10.1007/s10529-015-2023-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 12/14/2015] [Indexed: 10/22/2022]
Abstract
OBJECTIVE To study the effect of Ca(2+) on glutamate dehydrogenase (GDH) and its role in poly-γ-glutamic acid (γ-PGA) synthesis in Bacillus natto HSF 1410. RESULTS When the concentration of Ca(2+) varied from 0 to 0.1 g/l in the growth medium of B. natto HSF 1410, γ-PGA production increased from 6.8 to 9.7 g/l, while GDH specific activity and NH4Cl consumption improved from 183 to 295 U/mg and from 0.65 to 0.77 g/l, respectively. GDH with α-ketoglutarate as substrate primarily used NADPH as coenzyme with a K m of 0.08 mM. GDH was responsible for the synthesis of endogenous glutamate. The specific activity of GDH remained essentially unchanged in the presence of CaCl2 (0.05-0.2 g/l) in vitro. However, the specific activity of GDH and its expression was significantly increased by CaCl2 in vivo. Therefore, the regulation of GDH and PGA synthesis by Ca(2+) is an intracellular process. CONCLUSION Calcium regulation may be an effective approach for producing γ-PGA on an industrial scale.
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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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11
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Ren Y, Huang B, Meng Y, Wei L, Zhang C. Metabolic and phylogenetic analyses based on nitrogen in a new poly-γ-glutamic acid-producing strain of Bacillus subtilis. Biotechnol Lett 2015; 37:1221-6. [DOI: 10.1007/s10529-015-1776-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Accepted: 01/22/2015] [Indexed: 10/24/2022]
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12
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Ter Beek A, Wijman JG, Zakrzewska A, Orij R, Smits GJ, Brul S. Comparative physiological and transcriptional analysis of weak organic acid stress in Bacillus subtilis. Food Microbiol 2015; 45:71-82. [DOI: 10.1016/j.fm.2014.02.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2013] [Revised: 02/16/2014] [Accepted: 02/17/2014] [Indexed: 10/25/2022]
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13
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Ardin AC, Fujita K, Nagayama K, Takashima Y, Nomura R, Nakano K, Ooshima T, Matsumoto-Nakano M. Identification and functional analysis of an ammonium transporter in Streptococcus mutans. PLoS One 2014; 9:e107569. [PMID: 25229891 PMCID: PMC4167856 DOI: 10.1371/journal.pone.0107569] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 08/13/2014] [Indexed: 12/26/2022] Open
Abstract
Streptococcus mutans, a Gram-positive bacterium, is considered to be a major etiologic agent of human dental caries and reported to form biofilms known as dental plaque on tooth surfaces. This organism is also known to possess a large number of transport proteins in the cell membrane for export and import of molecules. Nitrogen is an essential nutrient for Gram-positive bacteria, though alternative sources such as ammonium can also be utilized. In order to obtain nitrogen for macromolecular synthesis, nitrogen-containing compounds must be transported into the cell. However, the ammonium transporter in S. mutans remains to be characterized. The present study focused on characterizing the ammonium transporter gene of S. mutans and its operon, while related regulatory genes were also analyzed. The SMU.1658 gene corresponding to nrgA in S. mutans is homologous to the ammonium transporter gene in Bacillus subtilis and SMU.1657, located upstream of the nrgA gene and predicted to be glnB, is a member of the PII protein family. Using a nrgA-deficient mutant strain (NRGD), we examined bacterial growth in the presence of ammonium, calcium chloride, and manganese sulfate. Fluorescent efflux assays were also performed to reveal export molecules associated with the ammonium transporter. The growth rate of NRGD was lower, while its fluorescent intensity was much higher as compared to the parental strain. In addition, confocal laser scanning microscopy revealed that the structure of biofilms formed by NRGD was drastically different than that of the parental strain. Furthermore, transcriptional analysis showed that the nrgA gene was co-transcribed with the glnB gene. These results suggest that the nrgA gene in S. mutans is essential for export of molecules and biofilm formation.
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Affiliation(s)
- Arifah Chieko Ardin
- Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan
| | - Kazuyo Fujita
- Department of Pediatric Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Kayoko Nagayama
- Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan
| | - Yukiko Takashima
- Department of Pediatric Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Ryota Nomura
- Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan
| | - Kazuhiko Nakano
- Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan
| | - Takashi Ooshima
- Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan
| | - Michiyo Matsumoto-Nakano
- Department of Pediatric Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
- * E-mail:
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Kaspar D, Auer F, Schardt J, Schindele F, Ospina A, Held C, Ehrenreich A, Scherer S, Müller-Herbst S. Temperature- and nitrogen source-dependent regulation of GlnR target genes in Listeria monocytogenes. FEMS Microbiol Lett 2014; 355:131-41. [PMID: 24801548 DOI: 10.1111/1574-6968.12458] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 04/30/2014] [Indexed: 11/28/2022] Open
Abstract
The ubiquitous pathogen Listeria monocytogenes lives either saprophytically in the environment or within cells in a vertebrate host, thus adapting its lifestyle to its ecological niche. Growth experiments at 24 and 37 °C (environmental and host temperature) with ammonium or glutamine as nitrogen sources revealed that ammonium is the preferred nitrogen source of L. monocytogenes. Reduced growth on glutamine is more obvious at 24 °C. Global transcriptional microarray analyses showed that the most striking difference in temperature-dependent transcription was observed for central nitrogen metabolism genes, glnR (glutamine synthetase repressor GlnR), glnA (glutamine synthetase GlnA), amtB (ammonium transporter AmtB), glnK (PII regulatory protein GlnK), and gdh (glutamate dehydrogenase) when cells were grown on glutamine. When grown on ammonium, both at 24 and 37 °C, the transcriptional level of these genes resembles that of cells grown with glutamine at 37 °C. Electrophoretic mobility shift assay studies and qPCR analyses in the wild-type L. monocytogenes and the deletion mutant L. monocytogenes ∆glnR revealed that the transcriptional regulator GlnR is directly involved in temperature- and nitrogen source-dependent regulation of the respective genes. Glutamine, a metabolite known to influence GlnR activity, seems unlikely to be the (sole) intracellular signal mediating this temperature-and nitrogen source-dependent metabolic adaptation.
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Affiliation(s)
- Daniela Kaspar
- Lehrstuhl für Mikrobielle Ökologie, Technische Universität München, Wissenschaftszentrum Weihenstephan, Freising, Germany; Abteilung Mikrobiologie, Zentralinstitut für Ernährungs- und Lebensmittelforschung, Technische Universität München, Freising, Germany
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15
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Gao T, Ho KP. l-Lactic acid production by Bacillus subtilis MUR1 in continuous culture. J Biotechnol 2013; 168:646-51. [DOI: 10.1016/j.jbiotec.2013.09.023] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 09/03/2013] [Accepted: 09/27/2013] [Indexed: 11/25/2022]
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16
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Gunka K, Stannek L, Care RA, Commichau FM. Selection-driven accumulation of suppressor mutants in bacillus subtilis: the apparent high mutation frequency of the cryptic gudB gene and the rapid clonal expansion of gudB(+) suppressors are due to growth under selection. PLoS One 2013; 8:e66120. [PMID: 23785476 PMCID: PMC3681913 DOI: 10.1371/journal.pone.0066120] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 05/01/2013] [Indexed: 11/25/2022] Open
Abstract
Soil bacteria like Bacillus subtilis can cope with many growth conditions by adjusting gene expression and metabolic pathways. Alternatively, bacteria can spontaneously accumulate beneficial mutations or shape their genomes in response to stress. Recently, it has been observed that a B. subtilis mutant lacking the catabolically active glutamate dehydrogenase (GDH), RocG, mutates the cryptic gudBCR gene at a high frequency. The suppressor mutants express the active GDH GudB, which can fully replace the function of RocG. Interestingly, the cryptic gudBCR allele is stably inherited as long as the bacteria synthesize the functional GDH RocG. Competition experiments revealed that the presence of the cryptic gudBCR allele provides the bacteria with a selective growth advantage when glutamate is scarce. Moreover, the lack of exogenous glutamate is the driving force for the selection of mutants that have inactivated the active gudB gene. In contrast, two functional GDHs are beneficial for the cells when glutamate was available. Thus, the amount of GDH activity strongly affects fitness of the bacteria depending on the availability of exogenous glutamate. At a first glance the high mutation frequency of the cryptic gudBCR allele might be attributed to stress-induced adaptive mutagenesis. However, other loci on the chromosome that could be potentially mutated during growth under the selective pressure that is exerted on a GDH-deficient mutant remained unaffected. Moreover, we show that a GDH-proficient B. subtilis strain has a strong selective growth advantage in a glutamate-dependent manner. Thus, the emergence and rapid clonal expansion of the active gudB allele can be in fact explained by spontaneous mutation and growth under selection without an increase of the mutation rate. Moreover, this study shows that the selective pressure that is exerted on a maladapted bacterium strongly affects the apparent mutation frequency of mutational hot spots.
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Affiliation(s)
- Katrin Gunka
- Department of General Microbiology, Georg-August-University Göttingen, Göttingen, Germany
| | - Lorena Stannek
- Department of General Microbiology, Georg-August-University Göttingen, Göttingen, Germany
| | - Rachel A. Care
- Department of General Microbiology, Georg-August-University Göttingen, Göttingen, Germany
| | - Fabian M. Commichau
- Department of General Microbiology, Georg-August-University Göttingen, Göttingen, Germany
- * E-mail:
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Vasco-Cárdenas MF, Baños S, Ramos A, Martín JF, Barreiro C. Proteome response of Corynebacterium glutamicum to high concentration of industrially relevant C₄ and C₅ dicarboxylic acids. J Proteomics 2013; 85:65-88. [PMID: 23624027 DOI: 10.1016/j.jprot.2013.04.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2012] [Revised: 03/05/2013] [Accepted: 04/09/2013] [Indexed: 12/11/2022]
Abstract
UNLABELLED More than fifty years of industrial and scientific developments on the amino acid-producer strain Corynebacterium glutamicum has generated an extremely huge knowledge highly applicable to the development of new products. Despite the production of dicarboxylic acids has already been engineered in C. glutamicum, the effect caused by these acids at competitive industrial levels has not yet been described. Thus, aspartic, fumaric, itaconic, malic and succinic acids have been tested on the growth of C. glutamicum to obtain their minimal inhibitory concentrations and their intracellular effects analyzed by 2D-DIGE. This analysis showed the modification of the central metabolism of C. glutamicum, the cross-regulation between malic acid and glucose as well as the aspartic acid utilization as nitrogen source. The analysis of the transcriptional regulators involved in the control of the detected proteins pointed to the ramB gene as a candidate for strain improvement. The analysis of the ΔramB mutant demonstrated its function as an enhancer of the growth speed or resistance level against aspartic, fumaric, itaconic and malic acids in C. glutamicum. BIOLOGICAL SIGNIFICANCE The effect of dicarboxylic acids addition to the C. glutamicum culture broth has been described. This proteome response is detailed and the deletion of a global regulator (ramB) has been described as a possible improving method for industrial strains. In addition, the consumption of aspartic acid as nitrogen source has been described for the first time in C. glutamicum, as well as, the cross-regulation between malic acid and glucose through the F0F1 respiratory system.
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Affiliation(s)
- María F Vasco-Cárdenas
- Área de Microbiología, Departamento de Biología Molecular, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain
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18
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Pandey R, Ter Beek A, Vischer NOE, Smelt JPPM, Brul S, Manders EMM. Live cell imaging of germination and outgrowth of individual bacillus subtilis spores; the effect of heat stress quantitatively analyzed with SporeTracker. PLoS One 2013; 8:e58972. [PMID: 23536843 PMCID: PMC3607599 DOI: 10.1371/journal.pone.0058972] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Accepted: 02/08/2013] [Indexed: 11/25/2022] Open
Abstract
Spore-forming bacteria are a special problem for the food industry as some of them are able to survive preservation processes. Bacillus spp. spores can remain in a dormant, stress resistant state for a long period of time. Vegetative cells are formed by germination of spores followed by a more extended outgrowth phase. Spore germination and outgrowth progression are often very heterogeneous and therefore, predictions of microbial stability of food products are exceedingly difficult. Mechanistic details of the cause of this heterogeneity are necessary. In order to examine spore heterogeneity we made a novel closed air-containing chamber for live imaging. This chamber was used to analyze Bacillus subtilis spore germination, outgrowth, as well as subsequent vegetative growth. Typically, we examined around 90 starting spores/cells for ≥4 hours per experiment. Image analysis with the purposely built program “SporeTracker” allows for automated data processing from germination to outgrowth and vegetative doubling. In order to check the efficiency of the chamber, growth and division of B. subtilis vegetative cells were monitored. The observed generation times of vegetative cells were comparable to those obtained in well-aerated shake flask cultures. The influence of a heat stress of 85°C for 10 min on germination, outgrowth, and subsequent vegetative growth was investigated in detail. Compared to control samples fewer spores germinated (41.1% less) and fewer grew out (48.4% less) after the treatment. The heat treatment had a significant influence on the average time to the start of germination (increased) and the distribution and average of the duration of germination itself (increased). However, the distribution and the mean outgrowth time and the generation time of vegetative cells, emerging from untreated and thermally injured spores, were similar.
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Affiliation(s)
- Rachna Pandey
- Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Alex Ter Beek
- Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
- * E-mail:
| | - Norbert O. E. Vischer
- Van Leeuwenhoek Centre for Advanced Microscopy Section of Molecular Cytology, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Jan P. P. M. Smelt
- Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Stanley Brul
- Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Erik M. M. Manders
- Van Leeuwenhoek Centre for Advanced Microscopy Section of Molecular Cytology, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
- Department of Molecular Biotechnology, Faculty of Bioscience Engineering, University of Ghent, Ghent, Belgium
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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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20
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Comparison of dynamic responses of cellular metabolites in Escherichia coli to pulse addition of substrates. Biologia (Bratisl) 2011. [DOI: 10.2478/s11756-011-0136-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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21
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McCown PJ, Roth A, Breaker RR. An expanded collection and refined consensus model of glmS ribozymes. RNA (NEW YORK, N.Y.) 2011; 17:728-36. [PMID: 21367971 PMCID: PMC3062183 DOI: 10.1261/rna.2590811] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2010] [Accepted: 01/17/2011] [Indexed: 05/21/2023]
Abstract
Self-cleaving glmS ribozymes selectively bind glucosamine-6-phosphate (GlcN6P) and use this metabolite as a cofactor to promote self-cleavage by internal phosphoester transfer. Representatives of the glmS ribozyme class are found in Gram-positive bacteria where they reside in the 5' untranslated regions (UTRs) of glmS messenger RNAs that code for the essential enzyme L-glutamine:D-fructose-6-phosphate aminotransferase. By using comparative sequence analyses, we have expanded the number of glmS ribozyme representatives from 160 to 463. All but two glmS ribozymes are present in glmS mRNAs and most exhibit striking uniformity in sequence and structure, which are features that make representatives attractive targets for antibacterial drug development. However, our discovery of rare variants broadens the consensus sequence and structure model. For example, in the Deinococcus-Thermus phylum, several structural variants exist that carry additional stems within the catalytic core and changes to the architecture of core-supporting substructures. These findings reveal that glmS ribozymes have a broader phylogenetic distribution than previously known and suggest that additional rare structural variants may remain to be discovered.
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Affiliation(s)
- Phillip J McCown
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8103, USA
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Rehm N, Georgi T, Hiery E, Degner U, Schmiedl A, Burkovski A, Bott M. l-Glutamine as a nitrogen source for Corynebacterium glutamicum: derepression of the AmtR regulon and implications for nitrogen sensing. Microbiology (Reading) 2010; 156:3180-3193. [DOI: 10.1099/mic.0.040667-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Corynebacterium glutamicum, a Gram-positive soil bacterium employed in the industrial production of various amino acids, is able to use a number of different nitrogen sources, such as ammonium, urea or creatinine. This study shows that l-glutamine serves as an excellent nitrogen source for C. glutamicum and allows similar growth rates in glucose minimal medium to those in ammonium. A transcriptome comparison revealed that the nitrogen starvation response was elicited when glutamine served as the sole nitrogen source, meaning that the target genes of the global nitrogen regulator AmtR were derepressed. Subsequent growth experiments with a variety of mutants defective in nitrogen metabolism showed that glutamate synthase is crucial for glutamine utilization, while a putative glutaminase is dispensable under the experimental conditions used. The gltBD operon encoding the glutamate synthase is a member of the AmtR regulon. The observation that the nitrogen starvation response was elicited at high intracellular l-glutamine levels has implications for nitrogen sensing. In contrast with other Gram-positive and Gram-negative bacteria such as Bacillus subtilis, Salmonella enterica serovar Typhimurium and Klebsiella pneumoniae, a drop in glutamine concentration obviously does not serve as a nitrogen starvation signal in C. glutamicum.
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Affiliation(s)
- Nadine Rehm
- Lehrstuhl für Mikrobiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany
| | - Tobias Georgi
- Institut für Biotechnologie 1, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Eva Hiery
- Lehrstuhl für Mikrobiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany
| | - Ursula Degner
- Institut für Biotechnologie 1, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Alfred Schmiedl
- Lehrstuhl für Biochemie, Friedrich-Alexander-Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany
| | - Andreas Burkovski
- Lehrstuhl für Mikrobiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany
| | - Michael Bott
- Institut für Biotechnologie 1, Forschungszentrum Jülich, D-52425 Jülich, Germany
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Challenges and advances in systems biology analysis of Bacillus spore physiology; molecular differences between an extreme heat resistant spore forming Bacillus subtilis food isolate and a laboratory strain. Food Microbiol 2010; 28:221-7. [PMID: 21315977 DOI: 10.1016/j.fm.2010.06.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Revised: 06/02/2010] [Accepted: 06/24/2010] [Indexed: 01/13/2023]
Abstract
Bacterial spore formers are prime organisms of concern in the food industry. Spores from the genus Bacillus are extremely stress resistant, most notably exemplified by high thermotolerance. This sometimes allows surviving spores to germinate and grow out to vegetative cells causing food spoilage and possible intoxication. Similar issues though more pending toward spore toxigenicity are observed for the anaerobic Clostridia. The paper indicates the nature of stress resistance and highlights contemporary molecular approaches to analyze the mechanistic basis of it in Bacilli. A molecular comparison between a laboratory strain and a food borne isolate, very similar at the genomic level to the laboratory strain but generating extremely heat resistant spores, is discussed. The approaches cover genome-wide genotyping, proteomics and genome-wide expression analyses studies. The analyses aim at gathering sufficient molecular information to be able to put together an initial framework for dynamic modelling of spore germination and outgrowth behaviour. Such emerging models should be developed both at the population and at the single spore level. Tools and challenges in achieving the latter are succinctly discussed.
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Amon J, Titgemeyer F, Burkovski A. Common patterns - unique features: nitrogen metabolism and regulation in Gram-positive bacteria. FEMS Microbiol Rev 2010; 34:588-605. [PMID: 20337720 DOI: 10.1111/j.1574-6976.2010.00216.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Gram-positive bacteria have developed elaborate mechanisms to control ammonium assimilation, at the levels of both transcription and enzyme activity. In this review, the common and specific mechanisms of nitrogen assimilation and regulation in Gram-positive bacteria are summarized and compared for the genera Bacillus, Clostridium, Streptomyces, Mycobacterium and Corynebacterium, with emphasis on the high G+C genera. Furthermore, the importance of nitrogen metabolism and control for the pathogenic lifestyle and virulence is discussed. In summary, the regulation of nitrogen metabolism in prokaryotes shows an impressive diversity. Virtually every phylum of bacteria evolved its own strategy to react to the changing conditions of nitrogen supply. Not only do the transcription factors differ between the phyla and sometimes even between families, but the genetic targets of a given regulon can also differ between closely related species.
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Affiliation(s)
- Johannes Amon
- Lehrstuhl für Mikrobiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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25
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The effect of calcium on the transcriptome of sporulating B. subtilis cells. Int J Food Microbiol 2009; 133:234-42. [PMID: 19552981 DOI: 10.1016/j.ijfoodmicro.2009.05.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2008] [Revised: 05/08/2009] [Accepted: 05/11/2009] [Indexed: 11/21/2022]
Abstract
Bacterial spores formed in the presence of high concentrations of minerals are a major problem in the food industry because of their extreme heat resistance. In order to enhance our insight in the molecular mechanisms underlying this phenomenon we have performed a detailed time-resolved analysis of the genome-wide transcriptome pattern of Bacillus subtilis sporulated both in the absence and presence of high calcium concentrations. The data was analysed in two ways. First, we determined the influence of the presence of high calcium levels during sporulation on the expression of gene groups as defined in Subtilist and KEGG pathways database. Second, we assessed the differential expression at the level of individual genes. When analysing groups and pathways, we found that those annotated as being involved in sporulation were significantly affected. Also, groups and pathways involved in flagella formation and biofilm matrix production were affected by the presence of calcium in the sporulation medium. When we analysed the behaviour of individual genes we found 305 genes influenced by calcium, including all known spore coat polysaccharide biosynthesis genes (10 induced and 1 repressed). A number of the calcium affected genes were also involved in biofilm formation. Minimal overlap with other stress outputs like sigma B activation and weak acid stress response was noted. Those genes that did overlap were unique to that combination which corroborates the notion that the cells sense these conditions differently.
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26
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Novel trans-Acting Bacillus subtilis glnA mutations that derepress glnRA expression. J Bacteriol 2009; 191:2485-92. [PMID: 19233925 DOI: 10.1128/jb.01734-08] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacillus subtilis contains two nitrogen transcription factors, GlnR and TnrA. The activities of GlnR and TnrA are regulated by direct protein-protein interactions with the feedback-inhibited form of glutamine synthetase (GS). To look for other factors involved in regulating GlnR activity, we isolated mutants with constitutive glnRA expression (Gln(C)). The twenty-seven Gln(C) mutants isolated in this mutant screen all contained mutations tightly linked to the glnRA operon which encodes GlnR (glnR) and GS (glnA). Four Gln(C) mutants contained mutations in the glnR gene that most likely impair the ability of GlnR to bind DNA. Three other Gln(C) mutants contained novel glnA mutations (S55F, V173I, and L174F). GlnR regulation was completely relieved in the three glnA mutants, while only modest defects in TnrA regulation were observed. In vitro enzymatic assays showed that the purified S55F mutant enzyme was catalytically defective while the V173I and L174F enzymes were highly resistant to feedback inhibition. The V173I and L174F GS proteins were found to require higher glutamine concentrations than the wild-type GS to regulate the DNA-binding activities of GlnR and TnrA in vitro. These results are consistent with a model where feedback-inhibited GS is the only cellular factor involved in regulating the activity of GlnR in B. subtilis.
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Brown G, Singer A, Proudfoot M, Skarina T, Kim Y, Chang C, Dementieva I, Kuznetsova E, Gonzalez CF, Joachimiak A, Savchenko A, Yakunin AF. Functional and structural characterization of four glutaminases from Escherichia coli and Bacillus subtilis. Biochemistry 2008; 47:5724-35. [PMID: 18459799 DOI: 10.1021/bi800097h] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Glutaminases belong to the large superfamily of serine-dependent beta-lactamases and penicillin-binding proteins, and they catalyze the hydrolytic deamidation of L-glutamine to L-glutamate. In this work, we purified and biochemically characterized four predicted glutaminases from Escherichia coli (YbaS and YneH) and Bacillus subtilis (YlaM and YbgJ). The proteins demonstrated strict specificity to L-glutamine and did not hydrolyze D-glutamine or L-asparagine. In each organism, one glutaminase showed higher affinity to glutamine ( E. coli YbaS and B. subtilis YlaM; K m 7.3 and 7.6 mM, respectively) than the second glutaminase ( E. coli YneH and B. subtilis YbgJ; K m 27.6 and 30.6 mM, respectively). The crystal structures of the E. coli YbaS and the B. subtilis YbgJ revealed the presence of a classical beta-lactamase-like fold and conservation of several key catalytic residues of beta-lactamases (Ser74, Lys77, Asn126, Lys268, and Ser269 in YbgJ). Alanine replacement mutagenesis demonstrated that most of the conserved residues located in the putative glutaminase catalytic site are essential for activity. The crystal structure of the YbgJ complex with the glutaminase inhibitor 6-diazo-5-oxo- l-norleucine revealed the presence of a covalent bond between the inhibitor and the hydroxyl oxygen of Ser74, providing evidence that Ser74 is the primary catalytic nucleophile and that the glutaminase reaction proceeds through formation of an enzyme-glutamyl intermediate. Growth experiments with the E. coli glutaminase deletion strains revealed that YneH is involved in the assimilation of l-glutamine as a sole source of carbon and nitrogen and suggested that both glutaminases (YbaS and YneH) also contribute to acid resistance in E. coli.
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Affiliation(s)
- Greg Brown
- Banting and Best Department of Medical Research, Ontario Centre for Structural Proteomics, University of Toronto, Toronto, Ontario M5G 1L6, Canada
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Glutamate metabolism in Bacillus subtilis: gene expression and enzyme activities evolved to avoid futile cycles and to allow rapid responses to perturbations of the system. J Bacteriol 2008; 190:3557-64. [PMID: 18326565 DOI: 10.1128/jb.00099-08] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Glutamate is a central metabolite in all organisms since it provides the link between carbon and nitrogen metabolism. In Bacillus subtilis, glutamate is synthesized exclusively by the glutamate synthase, and it can be degraded by the glutamate dehydrogenase. In B. subtilis, the major glutamate dehydrogenase RocG is expressed only in the presence of arginine, and the bacteria are unable to utilize glutamate as the only carbon source. In addition to rocG, a second cryptic gene (gudB) encodes an inactive glutamate dehydrogenase. Mutations in rocG result in the rapid accumulation of gudB1 suppressor mutations that code for an active enzyme. In this work, we analyzed the physiological significance of this constellation of genes and enzymes involved in glutamate metabolism. We found that the weak expression of rocG in the absence of the inducer arginine is limiting for glutamate utilization. Moreover, we addressed the potential ability of the active glutamate dehydrogenases of B. subtilis to synthesize glutamate. Both RocG and GudB1 were unable to catalyze the anabolic reaction, most probably because of their very high K(m) values for ammonium. In contrast, the Escherichia coli glutamate dehydrogenase is able to produce glutamate even in the background of a B. subtilis cell. B. subtilis responds to any mutation that interferes with glutamate metabolism with the rapid accumulation of extragenic or intragenic suppressor mutations, bringing the glutamate supply into balance. Similarly, with the presence of a cryptic gene, the system can flexibly respond to changes in the external glutamate supply by the selection of mutations.
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Ter Beek A, Keijser BJF, Boorsma A, Zakrzewska A, Orij R, Smits GJ, Brul S. Transcriptome analysis of sorbic acid-stressed Bacillus subtilis reveals a nutrient limitation response and indicates plasma membrane remodeling. J Bacteriol 2008; 190:1751-61. [PMID: 18156260 PMCID: PMC2258692 DOI: 10.1128/jb.01516-07] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2007] [Accepted: 12/13/2007] [Indexed: 11/20/2022] Open
Abstract
The weak organic acid sorbic acid is a commonly used food preservative, as it inhibits the growth of bacteria, yeasts, and molds. We have used genome-wide transcriptional profiling of Bacillus subtilis cells during mild sorbic acid stress to reveal the growth-inhibitory activity of this preservative and to identify potential resistance mechanisms. Our analysis demonstrated that sorbic acid-stressed cells induce responses normally seen upon nutrient limitation. This is indicated by the strong derepression of the CcpA, CodY, and Fur regulon and the induction of tricarboxylic acid cycle genes, SigL- and SigH-mediated genes, and the stringent response. Intriguingly, these conditions did not lead to the activation of sporulation, competence, or the general stress response. The fatty acid biosynthesis (fab) genes and BkdR-regulated genes are upregulated, which may indicate plasma membrane remodeling. This was further supported by the reduced sensitivity toward the fab inhibitor cerulenin upon sorbic acid stress. We are the first to present a comprehensive analysis of the transcriptional response of B. subtilis to sorbic acid stress.
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Affiliation(s)
- Alex Ter Beek
- Laboratory for Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, Nieuwe Achtergracht 166, 1018 WV Amsterdam, The Netherlands.
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Bacillus subtilis glutamine synthetase regulates its own synthesis by acting as a chaperone to stabilize GlnR-DNA complexes. Proc Natl Acad Sci U S A 2008; 105:1014-9. [PMID: 18195355 DOI: 10.1073/pnas.0709949105] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The Bacillus subtilis GlnR repressor controls gene expression in response to nitrogen availability. Because all GlnR-regulated genes are expressed constitutively in mutants lacking glutamine synthetase (GS), GS is required for repression by GlnR. Feedback-inhibited GS (FBI-GS) was shown to activate GlnR DNA binding with an in vitro electophoretic mobility shift assay (EMSA). The activation of GlnR DNA binding by GS in these experiments depended on the feedback inhibitor glutamine and did not occur with mutant GS proteins defective in regulating GlnR activity in vivo. Although stable GS-GlnR-DNA ternary complexes were not observed in the EMSA experiments, cross-linking experiments showed that a protein-protein interaction occurs between GlnR and FBI-GS. This interaction was reduced in the absence of the feedback inhibitor glutamine and with mutant GS proteins. Because FBI-GS significantly reduced the dissociation rate of the GlnR-DNA complexes, the stability of these complexes is enhanced by FBI-GS. These results argue that FBI-GS acts as a chaperone that activates GlnR DNA binding through a transient protein-protein interaction that stabilizes GlnR-DNA complexes. GS was shown to control the activity of the B. subtilis nitrogen transcription factor TnrA by forming a stable complex between FBI-GS and TnrA that inhibits TnrA DNA binding. Thus, B. subtilis GS is an enzyme with dual catalytic and regulatory functions that uses distinct mechanisms to control the activity of two different transcription factors.
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Oomes SJCM, van Zuijlen ACM, Hehenkamp JO, Witsenboer H, van der Vossen JMBM, Brul S. The characterisation of Bacillus spores occurring in the manufacturing of (low acid) canned products. Int J Food Microbiol 2007; 120:85-94. [PMID: 17644202 DOI: 10.1016/j.ijfoodmicro.2007.06.013] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2006] [Revised: 02/11/2007] [Indexed: 10/23/2022]
Abstract
Spore-forming bacteria can be a problem in the food industry, especially in the canning industry. Spores present in ingredients or present in the processing environment severely challenge the preservation process since their thermal resistance may be very high. We therefore asked the question which bacterial spore formers are found in a typical soup manufacturing plant, where they originate from and what the thermal resistance of their spores is. To answer these questions molecular techniques for bacterial species and strain identification were used as well as a protocol for the assessment of spore heat stress resistance based on the Kooiman method. The data indicate the existence and physiological cause of the high thermal resistance of spores of many of the occurring species. In particular it shows that ingredients used in soup manufacturing are a rich source of high thermal resistant spores and that sporulation in the presence of ingredients rich in divalent metal ions exerts a strong influence on spore heat resistance. It was also indicated that Bacillus spores may well be able to germinate and resporulate during manufacturing i.e. through growth and sporulation in line. Both these spores and those originating from the ingredients were able to survive certain thermal processing settings. Species identity was confirmed using fatty acid analysis, 16SrRNA gene sequencing and DNA-DNA hybridisation. Finally, molecular typing experiments using Ribotyping and AFLP analysis show that strains within the various Bacillus species can be clustered according to the thermal resistance properties of their spores. AFLP performed slightly better than Ribotyping. The data proofed to be useful for the generation of strain specific probes. Protocols to validate these probes in routine identification and innovation aimed at tailor made heat processing in soup manufacturing have been formulated.
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Affiliation(s)
- S J C M Oomes
- Unilever Food and Health Reseach Institute, Department of Advanced Food Microbiology, Unilever Research and Development Vlaardingen, Olivier van Noortlaan 120, 3133AT Vlaardingen, The Netherlands
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Abstract
Escherichia coli is among the simplest and best-understood free-living organisms. It has served as a valuable model for numerous biological processes, including cellular metabolism. Just as E. coli stood at the front of the genomic revolution, it is playing a leading role in the development of cellular metabolomics: the study of the complete metabolic contents of cells, including their dynamic concentration changes and fluxes. This review briefly describes the essentials of cellular metabolomics and its fundamental differentiation from biomarker metabolomics and lipidomics. Key technologies for metabolite quantitation from E. coli are described, with a focus on those involving mass spectrometry. In particular emphasis is given to the cell handling and sample preparation steps required for collecting data of high biological reliability, such as fast metabolome quenching. Future challenges, both in terms of data collection and application of the data to obtain a comprehensive understanding of metabolic dynamics, are discussed.
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Affiliation(s)
- Joshua D Rabinowitz
- Princeton University, Department of Chemistry & Lewis-Sigler Institute for Integrative Genomics, Princeton, NJ 08544, USA.
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Abstract
The central nitrogen metabolic circuit in enteric bacteria consists of three enzymes: glutamine synthetase, glutamate synthase (GOGAT), and glutamate dehydrogenase (GDH). With the carbon skeleton provided by 2-oxoglutarate, ammonia/ammonium (NH(4)(+)) is assimilated into two central nitrogen intermediates, glutamate and glutamine. Although both serve as nitrogen donors for all biosynthetic needs, glutamate and glutamine play different roles. Internal glutamine serves as a sensor of external nitrogen availability, and its pool concentration decreases upon nitrogen limitation. A high glutamate pool concentration is required to maintain the internal K(+) pool. The configuration of high glutamate and low glutamine pools was disrupted in GOGAT(-) mutants under low NH(4)(+) conditions: the glutamate pool was low, the difference between glutamate and glutamine was diminished, and growth was defective. When a GOGAT(-) mutant was cultured in an NH(4)(+)-limited chemostat, two sequential spontaneous mutations occurred. Each resulted in a suppressor mutant that outgrew its predecessor in the chemostat. The first suppressor overexpressed GDH, and the second also had a partially impaired glutamine synthetase. The result was a triple mutant in which NH(4)(+) was assimilated by two enzymes instead of the normal three and yet glutamate and glutamine pools and growth were essentially normal. The results indicate preference for the usual ratio of glutamate and glutamine and the resilient and compensatory nature of the circuit on pool control. Analysis of other suppressor mutants selected on solid medium suggests that increased GDH expression is the key for rescue of the growth defect of GOGAT(-) mutants under low NH(4)(+) conditions.
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Affiliation(s)
- Dalai Yan
- Department of Microbiology and Immunology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN 46202-5120, USA.
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35
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Keijser BJF, Ter Beek A, Rauwerda H, Schuren F, Montijn R, van der Spek H, Brul S. Analysis of temporal gene expression during Bacillus subtilis spore germination and outgrowth. J Bacteriol 2007; 189:3624-34. [PMID: 17322312 PMCID: PMC1855883 DOI: 10.1128/jb.01736-06] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacillus subtilis forms dormant spores upon nutrient depletion. Under favorable environmental conditions, the spore breaks its dormancy and resumes growth in a process called spore germination and outgrowth. To elucidate the physiological processes that occur during the transition of the dormant spore to an actively growing vegetative cell, we studied this process in a time-dependent manner by a combination of microscopy, analysis of extracellular metabolites, and a genome-wide analysis of transcription. The results indicate the presence of abundant levels of late sporulation transcripts in dormant spores. In addition, the results suggest the existence of a complex and well-regulated spore outgrowth program, involving the temporal expression of at least 30% of the B. subtilis genome.
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Affiliation(s)
- Bart J F Keijser
- Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands.
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Brauer MJ, Yuan J, Bennett BD, Lu W, Kimball E, Botstein D, Rabinowitz JD. Conservation of the metabolomic response to starvation across two divergent microbes. Proc Natl Acad Sci U S A 2006; 103:19302-7. [PMID: 17159141 PMCID: PMC1697828 DOI: 10.1073/pnas.0609508103] [Citation(s) in RCA: 216] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We followed 68 cellular metabolites after carbon or nitrogen starvation of Escherichia coli and Saccharomyces cerevisiae, using a filter-culture methodology that allows exponential growth, nondisruptive nutrient removal, and fast quenching of metabolism. Dynamic concentration changes were measured by liquid chromatography-tandem mass spectrometry and viewed in clustered heat-map format. The major metabolic responses anticipated from metabolite-specific experiments in the literature were observed as well as a number of novel responses. When the data were analyzed by singular value decomposition, two dominant characteristic vectors were found, one corresponding to a generic starvation response and another to a nutrient-specific starvation response that is similar in both organisms. Together these captured a remarkable 72% of the metabolite concentration changes in the full data set. The responses described by the generic starvation response vector (42%) included, for example, depletion of most biosynthetic intermediates. The nutrient-specific vector (30%) included key responses such as increased phosphoenolpyruvate signaling glucose deprivation and increased alpha-ketoglutarate signaling ammonia deprivation. Metabolic similarity across organisms extends from the covalent reaction network of metabolism to include many elements of metabolome response to nutrient deprivation as well.
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Affiliation(s)
- Matthew J. Brauer
- *Lewis Sigler Institute for Integrative Genomics and
- Departments of Molecular Biology and
| | - Jie Yuan
- *Lewis Sigler Institute for Integrative Genomics and
- Chemistry, Princeton University, Princeton, NJ 08544
| | - Bryson D. Bennett
- *Lewis Sigler Institute for Integrative Genomics and
- Chemistry, Princeton University, Princeton, NJ 08544
| | - Wenyun Lu
- *Lewis Sigler Institute for Integrative Genomics and
- Chemistry, Princeton University, Princeton, NJ 08544
| | - Elizabeth Kimball
- *Lewis Sigler Institute for Integrative Genomics and
- Chemistry, Princeton University, Princeton, NJ 08544
| | - David Botstein
- *Lewis Sigler Institute for Integrative Genomics and
- Departments of Molecular Biology and
- To whom correspondence may be addressed. E-mail:
or
| | - Joshua D. Rabinowitz
- *Lewis Sigler Institute for Integrative Genomics and
- Chemistry, Princeton University, Princeton, NJ 08544
- To whom correspondence may be addressed. E-mail:
or
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Picossi S, Belitsky BR, Sonenshein AL. Molecular mechanism of the regulation of Bacillus subtilis gltAB expression by GltC. J Mol Biol 2006; 365:1298-313. [PMID: 17134717 PMCID: PMC1794623 DOI: 10.1016/j.jmb.2006.10.100] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2006] [Revised: 10/25/2006] [Accepted: 10/27/2006] [Indexed: 11/18/2022]
Abstract
In Bacillus subilis, glutamate synthase, a major enzyme of nitrogen metabolism, is encoded by the gltAB operon. Significant expression of this operon requires the activity of GltC, a LysR-family protein, encoded by the divergently transcribed gene. We purified a soluble, active form of GltC and found that it requires alpha-ketoglutarate, a substrate of glutamate synthase, to fully activate gltA transcription in vitro, and that its activity is inhibited by glutamate, the product of glutamate synthase. GltC regulated gltAB transcription through binding to three dyad-symmetry elements, Box I, Box II and Box III, located in the intergenic region of gltC and gltA. Free GltC bound almost exclusively to Box I and activated gltAB transcription only marginally. Glutamate-bound GltC bound to Box I and Box III, and repressed gltAB transcription. In the presence of alpha-ketoglutarate, GltC bound to Box I and Box II, stabilized binding of RNA polymerase to the gltA promoter, and activated gltAB transcription. The binding of GltC to Box II, which partially overlaps the -35 region of the gltA promoter, seems to be essential for activation of the gltAB operon. Due to the high concentration of glutamate in B. subtilis cells grown under most conditions, alterations of the concentration of alpha-ketoglutarate seem to be crucial for modulation of GltC activity and gltAB expression.
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Affiliation(s)
- Silvia Picossi
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111, USA
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38
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Sasaki H, Nonaka J, Sasaki T, Nakai Y. Ammonia removal from livestock wastewater by ammonia-assimilating microorganisms immobilized in polyvinyl alcohol. J Ind Microbiol Biotechnol 2006; 34:105-10. [PMID: 16967264 DOI: 10.1007/s10295-006-0172-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2006] [Accepted: 08/07/2006] [Indexed: 10/24/2022]
Abstract
We isolated ammonia-assimilating microorganisms from the livestock manure treatment systems and evaluated their ammonia-assimilating ability. Many isolates utilized ammonia at high rates when they were purely cultivated in a nitrogen-limited medium to which sterilized lagoon extract had been added. Some isolates that were immobilized in polyvinyl alcohol (PVA) utilized ammonia present in the media containing viable lagoon microorganisms. Staining with 4',6'-diamidino-2-phenylindole (DAPI) indicated that the immobilized high ammonia-assimilating isolates grew dominantly within the PVA beads. High ammonia-assimilating isolates in the mixed culture containing viable lagoon microorganisms were identified as Pseudomonas spp. and member of Rhizobiaceae species by partial sequencing of the 16S ribosomal DNA.
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Affiliation(s)
- Hiraku Sasaki
- Laboratory of Animal Health and Management, Graduate School of Agricultural Science, Tohoku University, Naruko, Miyagi, 989-6711, Japan
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Lahmi R, Sendersky E, Perelman A, Hagemann M, Forchhammer K, Schwarz R. Alanine dehydrogenase activity is required for adequate progression of phycobilisome degradation during nitrogen starvation in Synechococcus elongatus PCC 7942. J Bacteriol 2006; 188:5258-65. [PMID: 16816198 PMCID: PMC1539948 DOI: 10.1128/jb.00209-06] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Degradation of the cyanobacterial light-harvesting antenna, the phycobilisome, is a general acclimation response that is observed under various stress conditions. In this study we identified a novel mutant of Synechococcus elongatus PCC 7942 that exhibits impaired phycobilisome degradation specifically during nitrogen starvation, unlike previously described mutants, which exhibit aberrant degradation under nitrogen, sulfur, and phosphorus starvation conditions. The phenotype of the new mutant, AldOmega, results from inactivation of ald (encoding alanine dehydrogenase). AldOmega is deficient in transcription induction of a number of genes during nitrogen starvation. These genes include the "general nutrient stress-related" genes, nblA and nblC, the products of which are essential for phycobilisome degradation. Furthermore, transcripts of several specific nitrogen-responsive genes accumulate at lower levels in AldOmega than in the wild-type strain. In contrast, ald inactivation did not decrease the accumulation of transcripts during sulfur starvation. Transcription of ald is induced upon nitrogen starvation, which is consistent with the ability of wild-type cells to maintain a low cellular content of alanine under these conditions. Unlike wild-type cells, AldOmega accumulates alanine upon nitrogen starvation. Our analyses suggest that alanine dehydrogenase activity is necessary for an adequate cellular response to nitrogen starvation. Decomposition of alanine may be required to provide a sufficient amount of ammonia. Furthermore, the accumulated alanine, or a related metabolite, may interfere with the cues that modulate acclimation during nitrogen starvation. Taken together, our results provide novel information regarding cellular responses to nitrogen starvation and suggest that mechanisms related to nitrogen-specific responses are involved in modulation of a general acclimation process.
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Affiliation(s)
- Roxane Lahmi
- Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, 52900, Israel
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40
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Hoque MA, Ushiyama H, Tomita M, Shimizu K. Dynamic responses of the intracellular metabolite concentrations of the wild type and pykA mutant Escherichia coli against pulse addition of glucose or NH3 under those limiting continuous cultures. Biochem Eng J 2005. [DOI: 10.1016/j.bej.2005.05.012] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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41
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Kort R, O'Brien AC, van Stokkum IHM, Oomes SJCM, Crielaard W, Hellingwerf KJ, Brul S. Assessment of heat resistance of bacterial spores from food product isolates by fluorescence monitoring of dipicolinic acid release. Appl Environ Microbiol 2005; 71:3556-64. [PMID: 16000762 PMCID: PMC1169001 DOI: 10.1128/aem.71.7.3556-3564.2005] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
This study is aimed at the development and application of a convenient and rapid optical assay to monitor the wet-heat resistance of bacterial endospores occurring in food samples. We tested the feasibility of measuring the release of the abundant spore component dipicolinic acid (DPA) as a probe for heat inactivation. Spores were isolated from the laboratory type strain Bacillus subtilis 168 and from two food product isolates, Bacillus subtilis A163 and Bacillus sporothermodurans IC4. Spores from the lab strain appeared much less heat resistant than those from the two food product isolates. The decimal reduction times (D values) for spores from strains 168, A163, and IC4 recovered on Trypticase soy agar were 1.4, 0.7, and 0.3 min at 105 degrees C, 120 degrees C, and 131 degrees C, respectively. The estimated Z values were 6.3 degrees C, 6.1 degrees C, and 9.7 degrees C, respectively. The extent of DPA release from the three spore crops was monitored as a function of incubation time and temperature. DPA concentrations were determined by measuring the emission at 545 nm of the fluorescent terbium-DPA complex in a microtiter plate fluorometer. We defined spore heat resistance as the critical DPA release temperature (Tc), the temperature at which half the DPA content has been released within a fixed incubation time. We found Tc values for spores from Bacillus strains 168, A163, and IC4 of 108 degrees C, 121 degrees C, and 131 degrees C, respectively. On the basis of these observations, we developed a quantitative model that describes the time and temperature dependence of the experimentally determined extent of DPA release and spore inactivation. The model predicts a DPA release rate profile for each inactivated spore. In addition, it uncovers remarkable differences in the values for the temperature dependence parameters for the rate of spore inactivation, DPA release duration, and DPA release delay.
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Affiliation(s)
- Remco Kort
- Laboratory for Microbiology, Room C-809, Swammerdam Institute for Life Sciences, University of Amsterdam, Nieuwe Achtergracht 166, 1018WV Amsterdam, The Netherlands.
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42
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Wray LV, Fisher SH. A feedback-resistant mutant of Bacillus subtilis glutamine synthetase with pleiotropic defects in nitrogen-regulated gene expression. J Biol Chem 2005; 280:33298-304. [PMID: 16055443 DOI: 10.1074/jbc.m504957200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Bacillus subtilis TnrA transcription factor regulates gene expression during nitrogen-limited growth. When cells are grown with excess nitrogen, feedback-inhibited glutamine synthetase forms a protein-protein complex with TnrA and prevents TnrA from binding to DNA. A mutation in glutamine synthetase with a phenylalanine replacement at the Ser-186 residue (S186F) was isolated by screening for B. subtilis mutants with constitutive TnrA activity. Although S186F glutamine synthetase has kinetic properties that are similar to the wild-type protein, the S186F enzyme is resistant to feedback inhibition by glutamine and AMP. Ligand binding experiments revealed that the S186F protein had a lower affinity for glutamine and AMP than the wild-type enzyme. S186F glutamine synthetase was defective in its ability to block DNA binding by TnrA in vitro. The properties of the feedback-resistant S186F mutant support the model in which the feedback-inhibited form of glutamine synthetase regulates TnrA activity in vivo.
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Affiliation(s)
- Lewis V Wray
- Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts 02118-2526, USA
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43
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Ehlers C, Weidenbach K, Veit K, Forchhammer K, Schmitz RA. Unique mechanistic features of post-translational regulation of glutamine synthetase activity inMethanosarcina mazeistrain Gö1 in response to nitrogen availability. Mol Microbiol 2005; 55:1841-54. [PMID: 15752204 DOI: 10.1111/j.1365-2958.2005.04511.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PII-like signal transduction proteins are found in all three domains of life and have been shown to play key roles in the control of bacterial nitrogen assimilation. This communication reports the first target protein of an archaeal PII-like protein, representing a novel PII receptor. The GlnK(1) protein of the methanogenic archaeon Methanosarcina mazei strain Go1 interacts and forms stable complexes with glutamine synthetase (GlnA(1)). Complex formation with GlnK(1) in the absence of metabolites inhibits the activity of GlnA(1). On the other hand, the activity of this enzyme is directly stimulated by the effector molecule 2-oxoglutarate. Moreover, 2-oxoglutarate antagonized the inhibitory effects of GlnK(1) on GlnA(1) activity but did not prevent GlnK(1)/GlnA(1) complex formation. On the basis of these findings, we hypothesize that besides the dominant effector molecule 2-oxoglutarate, the nitrogen sensor GlnK(1) allows finetuning control of the glutamine synthetase activity under changing nitrogen availabilities and propose the following model. (i) Under nitrogen limitation, increasing concentrations of 2-oxoglutarate stimulate maximal GlnA(1) activity and transform GlnA(1) into an activated conformation, which prevents inhibition by GlnK(1). (ii) Upon a shift to nitrogen sufficiency after a period of nitrogen limitation, GlnA(1) activity is reduced by decreasing internal 2-oxoglutarate concentrations through diminished direct activation and by GlnK(1) inhibition.
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Affiliation(s)
- Claudia Ehlers
- Institut für Mikrobiologie und Genetik, Universität Göttingen, Grisebachstr 8, 37077 Göttingen, Germany
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44
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Muro-Pastor MI, Reyes JC, Florencio FJ. Ammonium assimilation in cyanobacteria. PHOTOSYNTHESIS RESEARCH 2005; 83:135-50. [PMID: 16143848 DOI: 10.1007/s11120-004-2082-7] [Citation(s) in RCA: 169] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2004] [Accepted: 07/17/2004] [Indexed: 05/04/2023]
Abstract
In cyanobacteria, after transport by specific permeases, ammonium is incorporated into carbon skeletons by the sequential action of glutamine synthetase (GS) and glutamate synthase (GOGAT). Two types of GS (GSI and GSIII) and two types of GOGAT (ferredoxin-GOGAT and NADH-GOGAT) have been characterized in cyanobacteria. The carbon skeleton substrate of the GS-GOGAT pathway is 2-oxoglutarate that is synthesized by the isocitrate dehydrogenase (IDH). In order to maintain the C-N balance and the amino acid pools homeostasis, ammonium assimilation is tightly regulated. The key regulatory point is the GS, which is controlled at transcriptional and posttranscriptional levels. The transcription factor NtcA plays a critical role regulating the expression of the GS and the IDH encoding genes. In the unicellular cyanobacterium Synechocystis sp. PCC 6803, NtcA controls also the expression of two small proteins (IF7 and IF17) that inhibit the activity of GS by direct protein-protein interaction. Cyanobacteria perceive nitrogen status by sensing the intracellular concentration of 2-oxoglutarate, a signaling metabolite that is able to modulate allosterically the function of NtcA, in vitro. In vivo, a functional dependence between NtcA and the signal transduction protein PII in controlling NtcA-dependent genes has been also shown.
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Affiliation(s)
- M Isabel Muro-Pastor
- Instituto de Bioquímica Vegetal y Fotosíntesis, Centro de Investigaciones Isla de la Cartuja, Universidad de Sevilla-CSIC, Av. Américo Vespucio s/n, Seville 41092, Spain. imuro@ ibvf.csic.es
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45
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Detsch C, Stülke J. Ammonium utilization in Bacillus subtilis: transport and regulatory functions of NrgA and NrgB. MICROBIOLOGY-SGM 2004; 149:3289-3297. [PMID: 14600241 DOI: 10.1099/mic.0.26512-0] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Bacillus subtilis uses glutamine as the best source of nitrogen. In the absence of glutamine, alternative nitrogen sources such as ammonium can be used. Ammonium utilization involves the uptake of the gas or the ammonium ion, the synthesis of glutamine by the glutamine synthetase and the recycling of the glutamate by the glutamate synthase. In this work, ammonium transport in B. subtilis was studied. At high ammonium concentrations, a large fraction of the ammonium is present as ammonia, which may enter the cell via diffusion. In contrast, the ammonium transporter NrgA is required for ammonium utilization at low concentrations or at low pH values when the equilibrium between uncharged ammonia and the ammonium ion is shifted towards ammonium. Moreover, a functional NrgA is essential for the transport of the ammonium analogue methylammonium. NrgA is encoded in the nrgAB operon. The product of the second gene, NrgB, is a member of the PII family of regulatory proteins. In contrast to PII proteins from other organisms, there is no indication for a covalent modification of NrgB in response to the nitrogen supply of the cell. It is demonstrated here that NrgB is localized at the membrane, most likely in association with the ammonium transporter NrgA. The presence of a functional NrgB is required for full-level expression of the nrgAB operon in response to nitrogen limitation, suggesting that NrgB might relay the information on ammonium availability to downstream regulatory factors and thus fine-tune their activity.
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Affiliation(s)
- Christian Detsch
- Lehrstuhl für Mikrobiologie, Institut für Mikrobiologie, Biochemie und Genetik der Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 5, D-91058 Erlangen, Germany
| | - Jörg Stülke
- Lehrstuhl für Mikrobiologie, Institut für Mikrobiologie, Biochemie und Genetik der Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 5, D-91058 Erlangen, Germany
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46
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Burkovski A. Ammonium assimilation and nitrogen control in Corynebacterium glutamicum and its relatives: an example for new regulatory mechanisms in actinomycetes. FEMS Microbiol Rev 2004; 27:617-28. [PMID: 14638415 DOI: 10.1016/s0168-6445(03)00067-6] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Nitrogen is an essential component of nearly all complex macromolecules in a bacterial cell, such as proteins, nucleic acids and cell wall components. Accordingly, most prokaryotes have developed elaborate control mechanisms to provide an optimal supply of nitrogen for cellular metabolism and to cope with situations of nitrogen limitation. In this review, recent advances in our knowledge of ammonium uptake, its assimilation, and related regulatory systems in Corynebacterium glutamicum, a Gram-positive soil bacterium used for the industrial production of amino acids, are summarized and discussed with respect to the situation in the bacterial model organisms, Escherichia coli and Bacillus subtilis, and in comparison to the situation in other actinomycetes, namely in mycobacteria and streptomycetes. The regulatory network of nitrogen control in C. glutamicum seems to be a patchwork of different elements. It includes proteins similar to the UTase/GlnK pathway of E. coli and expression regulation by a repressor protein as in B. subtilis, but it lacks an NtrB/NtrC two-component signal transduction system. Furthermore, the C. glutamicum regulation network has unique features, such as a new sensing mechanism. Based on its extremely well-investigated central metabolism, well-established molecular biology tools, a public genome sequence and a newly-established proteome project, C. glutamicum seems to be a suitable model organism for other corynebacteria, such as Corynebacterium diphtheriae and Corynebacterium efficiens.
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Affiliation(s)
- Andreas Burkovski
- Institut für Biochemie der Universität zu Köln, Zülpicher-Strasse 47, 50674 Cologne, Germany.
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47
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Körner H, Sofia HJ, Zumft WG. Phylogeny of the bacterial superfamily of Crp-Fnr transcription regulators: exploiting the metabolic spectrum by controlling alternative gene programs. FEMS Microbiol Rev 2003; 27:559-92. [PMID: 14638413 DOI: 10.1016/s0168-6445(03)00066-4] [Citation(s) in RCA: 325] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The Crp-Fnr regulators, named after the first two identified members, are DNA-binding proteins which predominantly function as positive transcription factors, though roles of repressors are also important. Among over 1200 proteins with an N-terminally located nucleotide-binding domain similar to the cyclic adenosine monophosphate (cAMP) receptor protein, the distinctive additional trait of the Crp-Fnr superfamily is a C-terminally located helix-turn-helix motif for DNA binding. From a curated database of 369 family members exhibiting both features, we provide a protein tree of Crp-Fnr proteins according to their phylogenetic relationships. This results in the assembly of the regulators ArcR, CooA, CprK, Crp, Dnr, FixK, Flp, Fnr, FnrN, MalR, NnrR, NtcA, PrfA, and YeiL and their homologs in distinct clusters. Lead members and representatives of these groups are described, placing emphasis on the less well-known regulators and target processes. Several more groups consist of sequence-derived proteins of unknown physiological roles; some of them are tight clusters of highly similar members. The Crp-Fnr regulators stand out in responding to a broad spectrum of intracellular and exogenous signals such as cAMP, anoxia, the redox state, oxidative and nitrosative stress, nitric oxide, carbon monoxide, 2-oxoglutarate, or temperature. To accomplish their roles, Crp-Fnr members have intrinsic sensory modules allowing the binding of allosteric effector molecules, or have prosthetic groups for the interaction with the signal. The regulatory adaptability and structural flexibility represented in the Crp-Fnr scaffold has led to the evolution of an important group of physiologically versatile transcription factors.
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Affiliation(s)
- Heinz Körner
- Lehrstuhl für Mikrobiologie, Universität Karlsruhe, PF 6980, D-76128 Karlsruhe, Germany
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Muro-Pastor MI, Barrera FN, Reyes JC, Florencio FJ, Neira JL. The inactivating factor of glutamine synthetase, IF7, is a "natively unfolded" protein. Protein Sci 2003; 12:1443-54. [PMID: 12824490 PMCID: PMC2323932 DOI: 10.1110/ps.0303203] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2003] [Revised: 03/24/2003] [Accepted: 03/28/2003] [Indexed: 10/27/2022]
Abstract
Glutamine synthetase (GS) is the key enzyme responsible for the primary assimilation of ammonium in all living organisms, and it catalyses the synthesis of glutamine from glutamic acid, ATP, and ammonium. One of the recently discovered mechanisms of GS regulation involves protein-protein interactions with a small 65-residue-long protein named IF7. Here, we study the structure and stability of IF7 and its binding properties to GS, by using several biophysical techniques (fluorescence, circular dichroism, Fourier transform infrared and nuclear magnetic resonance spectroscopies, and gel filtration chromatography) which provide complementary structural information. The findings show that IF7 has a small amount of residual secondary structure, but lacks a well defined tertiary structure, and is not compact. Thus, all of the studies indicate that IF7 is a "natively unfolded" protein. The binding of IF7 to GS, its natural binding partner, occurs with an apparent dissociation constant of K(D) = 0.3 +/- 0.1 microM, as measured by fluorescence. We discuss the implications for the GS regulation mechanisms of IF7 being unfolded.
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Affiliation(s)
- M. Isabel Muro-Pastor
- Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla-Consejo Superior de Investigaciones Científicas, 41092 Sevilla, Spain
| | - Francisco N. Barrera
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, 03202 Elche (Alicante), Spain
| | - José C. Reyes
- Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla-Consejo Superior de Investigaciones Científicas, 41092 Sevilla, Spain
| | - Francisco J. Florencio
- Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla-Consejo Superior de Investigaciones Científicas, 41092 Sevilla, Spain
| | - José L. Neira
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, 03202 Elche (Alicante), Spain
- Instituto de Biocomputación y Física de los sistemas complejos, Zaragoza, Spain
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Burkovski A. I do it my way: Regulation of ammonium uptake and ammonium assimilation in Corynebacterium glutamicum. Arch Microbiol 2003; 179:83-8. [PMID: 12560985 DOI: 10.1007/s00203-002-0505-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2002] [Revised: 11/11/2002] [Accepted: 11/16/2002] [Indexed: 02/28/2023]
Abstract
In order to utilize different nitrogen sources and to survive situations of nitrogen limitation, microorganisms have developed several mechanisms to adapt their metabolism to changes in the nitrogen supply. In this communication, recent advances in our knowledge of ammonium uptake, its assimilation, and connected regulatory systems in Corynebacterium glutamicum are discussed with respect to the situation in the bacterial model organisms Escherichia coli and Bacillus subtilis. The regulatory network of nitrogen control in C. glutamicum differs substantially from that in these bacteria, for example, by the presence of AmtR, the unique "master regulator" of nitrogen control, the absence of a NtrB/NtrC two-component signal transduction system, and a different sensing mechanism in C. glutamicum.
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Affiliation(s)
- Andreas Burkovski
- Institut für Biochemie der Universität zu Köln, Zülpicher-Strasse 47, 50674, Köln, Germany.
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Fisher SH, Brandenburg JL, Wray LV. Mutations in Bacillus subtilis glutamine synthetase that block its interaction with transcription factor TnrA. Mol Microbiol 2002; 45:627-35. [PMID: 12139611 DOI: 10.1046/j.1365-2958.2002.03054.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In Bacillus subtilis, the activity of the nitrogen regulatory factor TnrA is regulated through a protein- protein interaction with glutamine synthetase. During growth with excess nitrogen, the feedback-inhibited form of glutamine synthetase binds to TnrA and blocks DNA binding by TnrA. Missense mutations in glutamine synthetase that constitutively express the TnrA-regulated amtB gene were characterized. Four mutant proteins were purified and shown to be defective in their ability to inhibit the in vitro DNA-binding activity of TnrA. Two of the mutant proteins exhibited enzymatic properties similar to those of wild-type glutamine synthetase. A model of B. subtilis glutamine synthetase was derived from a crystal structure of the Salmonella typhimurium enzyme. Using this model, all the mutated amino acid residues were found to be located close to the glutamate entrance of the active site. These results are consistent with the glutamine synthetase protein playing a direct role in regulating TnrA activity.
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Affiliation(s)
- Susan H Fisher
- Department of Microbiology, Boston University School of Medicine, MA 02118, USA.
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