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Verburgt CM, Dunn KA, Ghiboub M, Lewis JD, Wine E, Sigall Boneh R, Gerasimidis K, Shamir R, Penny S, Pinto DM, Cohen A, Bjorndahl P, Svolos V, Bielawski JP, Benninga MA, de Jonge WJ, Van Limbergen JE. Successful Dietary Therapy in Paediatric Crohn's Disease is Associated with Shifts in Bacterial Dysbiosis and Inflammatory Metabotype Towards Healthy Controls. J Crohns Colitis 2022; 17:61-72. [PMID: 36106847 PMCID: PMC9880954 DOI: 10.1093/ecco-jcc/jjac105] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 06/02/2022] [Accepted: 07/28/2022] [Indexed: 02/02/2023]
Abstract
BACKGROUND AND AIMS Nutritional therapy with the Crohn's Disease Exclusion Diet + Partial Enteral Nutrition [CDED+PEN] or Exclusive Enteral Nutrition [EEN] induces remission and reduces inflammation in mild-to-moderate paediatric Crohn's disease [CD]. We aimed to assess if reaching remission with nutritional therapy is mediated by correcting compositional or functional dysbiosis. METHODS We assessed metagenome sequences, short chain fatty acids [SCFA] and bile acids [BA] in 54 paediatric CD patients reaching remission after nutritional therapy [with CDED + PEN or EEN] [NCT01728870], compared to 26 paediatric healthy controls. RESULTS Successful dietary therapy decreased the relative abundance of Proteobacteria and increased Firmicutes towards healthy controls. CD patients possessed a mixture of two metabotypes [M1 and M2], whereas all healthy controls had metabotype M1. M1 was characterised by high Bacteroidetes and Firmicutes, low Proteobacteria, and higher SCFA synthesis pathways, and M2 was associated with high Proteobacteria and genes involved in SCFA degradation. M1 contribution increased during diet: 48%, 63%, up to 74% [Weeks 0, 6, 12, respectively.]. By Week 12, genera from Proteobacteria reached relative abundance levels of healthy controls with the exception of E. coli. Despite an increase in SCFA synthesis pathways, remission was not associated with increased SCFAs. Primary BA decreased with EEN but not with CDED+PEN, and secondary BA did not change during diet. CONCLUSION Successful dietary therapy induced correction of both compositional and functional dysbiosis. However, 12 weeks of diet was not enough to achieve complete correction of dysbiosis. Our data suggests that composition and metabotype are important and change quickly during the early clinical response to dietary intervention. Correction of dysbiosis may therefore be an important future treatment goal for CD.
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Affiliation(s)
| | | | - Mohammed Ghiboub
- Department of Paediatric Gastroenterology and Nutrition, Amsterdam University Medical Centers, University of Amsterdam, Emma Children’s Hospital, Amsterdam, The Netherlands,Tytgat Institute for Liver and Intestinal Research, Amsterdam Gastroenterology Endocrinology Metabolism, University of Amsterdam, Amsterdam, The Netherlands
| | - James D Lewis
- Centre for Clinical Epidemiology and Biostatistics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA,Division of Gastroenterology and Hepatology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Eytan Wine
- Division of Paediatric Gastroenterology, Stollery Children’s Hospital, University of Alberta, Edmonton, AB, Canada
| | - Rotem Sigall Boneh
- Wolfson Medical Centre, Holon, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Konstantinos Gerasimidis
- Department of Human Nutrition, School of Medicine, Dentistry & Nursing, University of Glasgow, Glasgow, UK
| | - Raanan Shamir
- Institute of Gastroenterology, Nutrition and Liver Diseases, Schneider Children’s Medical Centre, Petach-Tikva, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Susanne Penny
- Human Health Therapeutics, National Research Council, Halifax, NS, Canada
| | - Devanand M Pinto
- Human Health Therapeutics, National Research Council, Halifax, NS, Canada
| | - Alejandro Cohen
- Proteomics and Mass Spectrometry Core Facility, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
| | - Paul Bjorndahl
- Department of Mathematics & Statistics, Dalhousie University, Halifax, NS, Canada
| | - Vaios Svolos
- Department of Human Nutrition, School of Medicine, Dentistry & Nursing, University of Glasgow, Glasgow, UK
| | - Joseph P Bielawski
- Centre for Clinical Epidemiology and Biostatistics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA,Department of Mathematics & Statistics, Dalhousie University, Halifax, NS, Canada
| | - Marc A Benninga
- Department of Paediatric Gastroenterology and Nutrition, Amsterdam University Medical Centers, University of Amsterdam, Emma Children’s Hospital, Amsterdam, The Netherlands
| | - Wouter J de Jonge
- Tytgat Institute for Liver and Intestinal Research, Amsterdam Gastroenterology Endocrinology Metabolism, University of Amsterdam, Amsterdam, The Netherlands,Department of Mathematics & Statistics, Dalhousie University, Halifax, NS, Canada,Department of Surgery, University of Bonn, Bonn, Germany
| | - Johan E Van Limbergen
- Corresponding author: Dr Johan Van Limbergen, MD, PhD, Department of Paediatric Gastroenterology and Nutrition, Emma Children’s Hospital, Amsterdam University Medical Centers, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands. Tel.: +31-20 566 3053;
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Krell T, Gavira JA, Velando F, Fernández M, Roca A, Monteagudo-Cascales E, Matilla MA. Histamine: A Bacterial Signal Molecule. Int J Mol Sci 2021; 22:6312. [PMID: 34204625 PMCID: PMC8231116 DOI: 10.3390/ijms22126312] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 06/09/2021] [Accepted: 06/10/2021] [Indexed: 02/07/2023] Open
Abstract
Bacteria have evolved sophisticated signaling mechanisms to coordinate interactions with organisms of other domains, such as plants, animals and human hosts. Several important signal molecules have been identified that are synthesized by members of different domains and that play important roles in inter-domain communication. In this article, we review recent data supporting that histamine is a signal molecule that may play an important role in inter-domain and inter-species communication. Histamine is a key signal molecule in humans, with multiple functions, such as being a neurotransmitter or modulator of immune responses. More recent studies have shown that bacteria have evolved different mechanisms to sense histamine or histamine metabolites. Histamine sensing in the human pathogen Pseudomonas aeruginosa was found to trigger chemoattraction to histamine and to regulate the expression of many virulence-related genes. Further studies have shown that many bacteria are able to synthesize and secrete histamine. The release of histamine by bacteria in the human gut was found to modulate the host immune responses and, at higher doses, to result in host pathologies. The elucidation of the role of histamine as an inter-domain signaling molecule is an emerging field of research and future investigation is required to assess its potential general nature.
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Affiliation(s)
- Tino Krell
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Prof. Albareda 1, 18008 Granada, Spain; (F.V.); (E.M.-C.)
| | - José A. Gavira
- Laboratory of Crystallographic Studies, IACT (CSIC-UGR), Avenida de las Palmeras 4, 18100 Armilla, Spain;
| | - Félix Velando
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Prof. Albareda 1, 18008 Granada, Spain; (F.V.); (E.M.-C.)
| | - Matilde Fernández
- Department of Microbiology, Facultad de Farmacia, Campus Universitario de Cartuja, Universidad de Granada, 18071 Granada, Spain; (M.F.); (A.R.)
| | - Amalia Roca
- Department of Microbiology, Facultad de Farmacia, Campus Universitario de Cartuja, Universidad de Granada, 18071 Granada, Spain; (M.F.); (A.R.)
| | - Elizabet Monteagudo-Cascales
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Prof. Albareda 1, 18008 Granada, Spain; (F.V.); (E.M.-C.)
| | - Miguel A. Matilla
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Prof. Albareda 1, 18008 Granada, Spain; (F.V.); (E.M.-C.)
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Horsing around: Escherichia coli ST1250 of equine origin harbouring epidemic IncHI1/ST9 plasmid with bla CTX-M-1 and an operon for short-chain fructooligosaccharides metabolism. Antimicrob Agents Chemother 2021; 65:AAC.02556-20. [PMID: 33619063 PMCID: PMC8092906 DOI: 10.1128/aac.02556-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The relatedness of the equine-associated Escherichia coli ST1250 and its single- and double-locus variants (ST1250-SLV/DLV), obtained from horses in Europe, was studied by comparative genome analysis. A total of 54 isolates of E. coli ST1250 and ST1250-SLV/DLV from healthy and hospitalized horses across Europe [Czech Republic (n=23), the Netherlands (n=18), Germany (n=9), Denmark (n=3) and France (n=1)] from 2008-2017 were subjected to whole-genome sequencing. An additional 25 draft genome assemblies of E. coli ST1250 and ST1250-SLV/DLV were obtained from the public databases. The isolates were compared for genomic features, virulence genes, clade structure and plasmid content. The complete nucleotide sequences of eight IncHI1/ST9 and one IncHI1/ST2 plasmids were obtained using long-read sequencing by PacBio or MinION. In the collection of 79 isolates, only 10 were phylogenetically close (<8 SNP). The majority of isolates belonged to phylogroup B1 (73/79, 92.4%) and carried bla CTX-M-1 (58/79, 73.4%). The plasmid content of the isolates was dominated by IncHI1 of ST9 (56/62, 90.3%) and ST2 (6/62, 9.7%), while 84.5% (49/58) bla CTX-M-1 genes were associated with presence of IncHI1 replicon of ST9 and 6.9% (4/58) with IncHI1 replicon of ST2 within the corresponding isolates. The operon for the utilization of short chain fructooligosaccharides (fos operon) was present in 55 (55/79, 69.6%) isolates, and all of these carried IncHI1/ST9 plasmids. The eight complete IncHI1/ST9 plasmid sequences showed the presence of bla CTX-M-1 and the fos operon within the same molecule. Sequences of IncHI1/ST9 plasmids were highly conserved (>98% similarity) regardless of country of origin and varied only in the structure and integration site of MDR region. E. coli ST1250 and ST1250-SLV/DLV are phylogenetically-diverse strains associated with horses. A strong linkage of E. coli ST1250 with epidemic multi-drug resistance plasmid lineage IncHI1/ST9 carrying bla CTX-M-1 and the fos operon was identified.
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Adaptation by Ancient Horizontal Acquisition of Butyrate Metabolism Genes in Aggregatibacter actinomycetemcomitans. mBio 2021; 12:mBio.03581-20. [PMID: 33758084 PMCID: PMC8092312 DOI: 10.1128/mbio.03581-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
There has been considerable interest in the impact of short-chain fatty acids (SCFAs) on inflammatory effects related to the microbiome. Here, we present evidence that SCFAs may also be important in disease by providing an energy source or disease-associated cue for colonizing pathogens. Like the bacterial residents of the human gut, it is likely that many of the species in the human oral microbiota have evolved to better occupy and persist in their niche. Aggregatibacter actinomycetemcomitans (Aa) is both a common colonizer of the oral cavity and has been implicated in the pathogenesis of periodontal disease. Here, we present a whole-genome phylogenetic analysis of Aa isolates from humans and nonhuman primates that revealed an ancient origin for this species and a long history of association with the Catarrhini, the lineage that includes Old World monkeys (OWM) and humans. Further genomic analysis showed a strong association with the presence of a short-chain fatty acid (SCFA) catabolism locus (atoRDAEB) in many human isolates that was absent in almost all nonhuman OWM isolates. We show that this locus was likely acquired through horizontal gene transfer. When grown under conditions that are similar to those at the subgingival site of periodontitis (anaerobic, SCFA replete), Aa strains with atoRDAEB formed robust biofilms and showed upregulation of genes involved in virulence, colonization, and immune evasion. Both an isogenic deletion mutant and nonhuman primate isolates lacking the ato locus failed to grow in a robust biofilm under these conditions, but grew well under the carbohydrate-rich conditions similar to those found above the gumline. We propose that the acquisition of the ato locus was a key evolutionary step allowing Aa to utilize SCFAs, adapt, and modulate subgingival disease.
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Schütze A, Benndorf D, Püttker S, Kohrs F, Bettenbrock K. The Impact of ackA, pta, and ackA-pta Mutations on Growth, Gene Expression and Protein Acetylation in Escherichia coli K-12. Front Microbiol 2020; 11:233. [PMID: 32153530 PMCID: PMC7047895 DOI: 10.3389/fmicb.2020.00233] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 01/31/2020] [Indexed: 01/06/2023] Open
Abstract
Acetate is a characteristic by-product of Escherichia coli K-12 growing in batch cultures with glucose, both under aerobic as well as anaerobic conditions. While the reason underlying aerobic acetate production is still under discussion, during anaerobic growth acetate production is important for ATP generation by substrate level phosphorylation. Under both conditions, acetate is produced by a pathway consisting of the enzyme phosphate acetyltransferase (Pta) producing acetyl-phosphate from acetyl-coenzyme A, and of the enzyme acetate kinase (AckA) producing acetate from acetyl-phosphate, a reaction that is coupled to the production of ATP. Mutants in the AckA-Pta pathway differ from each other in the potential to produce and accumulate acetyl-phosphate. In the publication at hand, we investigated different mutants in the acetate pathway, both under aerobic as well as anaerobic conditions. While under aerobic conditions only small changes in growth rate were observed, all acetate mutants showed severe reduction in growth rate and changes in the by-product pattern during anaerobic growth. The AckA- mutant showed the most severe growth defect. The glucose uptake rate and the ATP concentration were strongly reduced in this strain. This mutant exhibited also changes in gene expression. In this strain, the atoDAEB operon was significantly upregulated under anaerobic conditions hinting to the production of acetoacetate. During anaerobic growth, protein acetylation increased significantly in the ackA mutant. Acetylation of several enzymes of glycolysis and central metabolism, of aspartate carbamoyl transferase, methionine synthase, catalase and of proteins involved in translation was increased. Supplementation of methionine and uracil eliminated the additional growth defect of the ackA mutant. The data show that anaerobic, fermentative growth of mutants in the AckA-Pta pathway is reduced but still possible. Growth reduction can be explained by the lack of an important ATP generating pathway of mixed acid fermentation. An ackA deletion mutant is more severely impaired than pta or ackA-pta deletion mutants. This is most probably due to the production of acetyl-P in the ackA mutant, leading to increased protein acetylation.
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Affiliation(s)
- Andrea Schütze
- Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany
| | - Dirk Benndorf
- Bioprocess Engineering, Otto von Guericke University, Magdeburg, Germany
| | - Sebastian Püttker
- Bioprocess Engineering, Otto von Guericke University, Magdeburg, Germany
| | - Fabian Kohrs
- Bioprocess Engineering, Otto von Guericke University, Magdeburg, Germany
| | - Katja Bettenbrock
- Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany
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Krewing M, Jarzina F, Dirks T, Schubert B, Benedikt J, Lackmann JW, Bandow JE. Plasma-sensitive Escherichia coli mutants reveal plasma resistance mechanisms. J R Soc Interface 2019; 16:20180846. [PMID: 30913981 PMCID: PMC6451402 DOI: 10.1098/rsif.2018.0846] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 02/28/2019] [Indexed: 12/31/2022] Open
Abstract
Non-thermal atmospheric pressure plasmas are investigated as augmenting therapy to combat bacterial infections. The strong antibacterial effects of plasmas are attributed to the complex mixture of reactive species, (V)UV radiation and electric fields. The experience with antibiotics is that upon their introduction as medicines, resistance occurs in pathogens and spreads. To assess the possibility of bacterial resistance developing against plasma, we investigated intrinsic protective mechanisms that allow Escherichia coli to survive plasma stress. We performed a genome-wide screening of single-gene knockout mutants of E. coli and identified 87 mutants that are hypersensitive to the effluent of a microscale atmospheric pressure plasma jet. For selected genes ( cysB, mntH, rep and iscS) we showed in complementation studies that plasma resistance can be restored and increased above wild-type levels upon over-expression. To identify plasma-derived components that the 87 genes confer resistance against, mutants were tested for hypersensitivity against individual stressors (hydrogen peroxide, superoxide, hydroxyl radicals, ozone, HOCl, peroxynitrite, NO•, nitrite, nitrate, HNO3, acid stress, diamide, heat stress and detergents). k-means++ clustering revealed that most genes protect from hydrogen peroxide, superoxide and/or nitric oxide. In conclusion, individual bacterial genes confer resistance against plasma providing insights into the antibacterial mechanisms of plasma.
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Affiliation(s)
- Marco Krewing
- Applied Microbiology, Faculty of Biology and Biotechnology, Ruhr-Universität Bochum, Universitätsstraße 150, 44780 Bochum, Germany
| | - Fabian Jarzina
- Applied Microbiology, Faculty of Biology and Biotechnology, Ruhr-Universität Bochum, Universitätsstraße 150, 44780 Bochum, Germany
| | - Tim Dirks
- Applied Microbiology, Faculty of Biology and Biotechnology, Ruhr-Universität Bochum, Universitätsstraße 150, 44780 Bochum, Germany
| | - Britta Schubert
- Applied Microbiology, Faculty of Biology and Biotechnology, Ruhr-Universität Bochum, Universitätsstraße 150, 44780 Bochum, Germany
| | - Jan Benedikt
- Experimental Plasma Physics, Christian-Albrechts-Universität zu Kiel, Christian-Albrechts-Platz 4, 24118 Kiel, Germany
| | - Jan-Wilm Lackmann
- Applied Microbiology, Faculty of Biology and Biotechnology, Ruhr-Universität Bochum, Universitätsstraße 150, 44780 Bochum, Germany
| | - Julia E. Bandow
- Applied Microbiology, Faculty of Biology and Biotechnology, Ruhr-Universität Bochum, Universitätsstraße 150, 44780 Bochum, Germany
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Chu HY, Sprouffske K, Wagner A. Assessing the benefits of horizontal gene transfer by laboratory evolution and genome sequencing. BMC Evol Biol 2018; 18:54. [PMID: 29673327 PMCID: PMC5909237 DOI: 10.1186/s12862-018-1164-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 03/22/2018] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Recombination is widespread across the tree of life, because it helps purge deleterious mutations and creates novel adaptive traits. In prokaryotes, it often takes the form of horizontal gene transfer from a donor to a recipient bacterium. While such transfer is widespread in natural communities, its immediate fitness benefits are usually unknown. We asked whether any such benefits depend on the environment, and on the identity of donor and recipient strains. To this end, we adapted Escherichia coli to two novel carbon sources over several hundred generations of laboratory evolution, exposing evolving populations to various DNA donors. RESULTS At the end of these experiments, we measured fitness and sequenced the genomes of 65 clones from 34 replicate populations to study the genetic changes associated with adaptive evolution. Furthermore, we identified candidate de novo beneficial mutations. During adaptive evolution on the first carbon source, 4-Hydroxyphenylacetic acid (HPA), recombining populations adapted better, which was likely mediated by acquiring the hpa operon from the donor. In contrast, recombining populations did not adapt better to the second carbon source, butyric acid, even though they suffered fewer extinctions than non-recombining populations. The amount of DNA transferred, but not its benefit, strongly depended on the donor-recipient strain combination. CONCLUSIONS To our knowledge, our study is the first to investigate the genomic consequences of prokaryotic recombination and horizontal gene transfer during laboratory evolution. It shows that the benefits of recombination strongly depend on the environment and the foreign DNA donor.
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Affiliation(s)
- Hoi Yee Chu
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - Kathleen Sprouffske
- The Swiss Institute of Bioinformatics, Quartier Sorge – Batiment Genopode, 1015 Lausanne, Switzerland
| | - Andreas Wagner
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
- The Swiss Institute of Bioinformatics, Quartier Sorge – Batiment Genopode, 1015 Lausanne, Switzerland
- Santa Fe Institute, Santa Fe, New Mexico USA
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Badilla C, Osborne TH, Cole A, Watson C, Djordjevic S, Santini JM. A new family of periplasmic-binding proteins that sense arsenic oxyanions. Sci Rep 2018; 8:6282. [PMID: 29674678 PMCID: PMC5908839 DOI: 10.1038/s41598-018-24591-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Accepted: 04/06/2018] [Indexed: 01/21/2023] Open
Abstract
Arsenic contamination of drinking water affects more than 140 million people worldwide. While toxic to humans, inorganic forms of arsenic (arsenite and arsenate), can be used as energy sources for microbial respiration. AioX and its orthologues (ArxX and ArrX) represent the first members of a new sub-family of periplasmic-binding proteins that serve as the first component of a signal transduction system, that’s role is to positively regulate expression of arsenic metabolism enzymes. As determined by X-ray crystallography for AioX, arsenite binding only requires subtle conformational changes in protein structure, providing insights into protein-ligand interactions. The binding pocket of all orthologues is conserved but this alone is not sufficient for oxyanion selectivity, with proteins selectively binding either arsenite or arsenate. Phylogenetic evidence, clearly demonstrates that the regulatory proteins evolved together early in prokaryotic evolution and had a separate origin from the metabolic enzymes whose expression they regulate.
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Affiliation(s)
- Consuelo Badilla
- Institute of Structural & Molecular Biology, Division of Biosciences, University College London, London, WC1E 6BT, UK
| | - Thomas H Osborne
- Institute of Structural & Molecular Biology, Division of Biosciences, University College London, London, WC1E 6BT, UK
| | - Ambrose Cole
- Institute of Structural & Molecular Biology, Department of Biological Sciences, Birkbeck College, University of London, WC1E 7HX, London, UK
| | - Cameron Watson
- Institute of Structural & Molecular Biology, Division of Biosciences, University College London, London, WC1E 6BT, UK
| | - Snezana Djordjevic
- Institute of Structural & Molecular Biology, Division of Biosciences, University College London, London, WC1E 6BT, UK.
| | - Joanne M Santini
- Institute of Structural & Molecular Biology, Division of Biosciences, University College London, London, WC1E 6BT, UK.
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9
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Sitkiewicz I, Musser JM. Deletion of from Streptococcus pyogenes. Results in Hypervirulence in a Mouse Model of Sepsis and is LuxS Independent. Pol J Microbiol 2018; 66:17-24. [PMID: 29359701 DOI: 10.5604/17331331.1234989] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Group A Streptococcus (GAS) is a Gram-positive human pathogen that causes a variety of diseases ranging from pharyngitis to life-threatening streptococcal toxic shock syndrome. Recently, several global gene expression analyses have yielded extensive new information regarding the regulation of genes encoding known and putative virulence factors in GAS. A microarray analysis found that transcription of the GAS gene M5005_Spy_1343 was significantly increased in response to interaction with human polymorphonuclear leukocytes. M5005_Spy_1343 is predicted to encode a member of the LysR family of transcriptional regulators and is located upstream of a putative operon containing six genes. Five of these genes have sequence similarity to genes involved in short-chain fatty acid metabolism, whereas the sixth gene (luxS) is found in many bacterial species and is involved in quorum sensing. Unexpectedly, inactivation of the M5005_Spy_1343 gene resulted in hypervirulence in an intraperitoneal mouse model of infection. Increased virulence was not due to changes in luxS gene expression. We postulate that short-chain fatty acid metabolism is involved in GAS pathogenesis.
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Affiliation(s)
- Izabela Sitkiewicz
- Department of Molecular Microbiology, National Medicines Institute, Warsaw, Poland
| | - James M Musser
- Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, and Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, Texas, USA
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Rand JM, Pisithkul T, Clark RL, Thiede JM, Mehrer CR, Agnew DE, Campbell CE, Markley AL, Price MN, Ray J, Wetmore KM, Suh Y, Arkin AP, Deutschbauer AM, Amador-Noguez D, Pfleger BF. A metabolic pathway for catabolizing levulinic acid in bacteria. Nat Microbiol 2017; 2:1624-1634. [PMID: 28947739 PMCID: PMC5705400 DOI: 10.1038/s41564-017-0028-z] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 08/16/2017] [Indexed: 12/21/2022]
Abstract
Microorganisms can catabolize a wide range of organic compounds and therefore have the potential to perform many industrially relevant bioconversions. One barrier to realizing the potential of biorefining strategies lies in our incomplete knowledge of metabolic pathways, including those that can be used to assimilate naturally abundant or easily generated feedstocks. For instance, levulinic acid (LA) is a carbon source that is readily obtainable as a dehydration product of lignocellulosic biomass and can serve as the sole carbon source for some bacteria. Yet, the genetics and structure of LA catabolism have remained unknown. Here, we report the identification and characterization of a seven-gene operon that enables LA catabolism in Pseudomonas putida KT2440. When the pathway was reconstituted with purified proteins, we observed the formation of four acyl-CoA intermediates, including a unique 4-phosphovaleryl-CoA and the previously observed 3-hydroxyvaleryl-CoA product. Using adaptive evolution, we obtained a mutant of Escherichia coli LS5218 with functional deletions of fadE and atoC that was capable of robust growth on LA when it expressed the five enzymes from the P. putida operon. This discovery will enable more efficient use of biomass hydrolysates and metabolic engineering to develop bioconversions using LA as a feedstock.
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Affiliation(s)
- Jacqueline M Rand
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Tippapha Pisithkul
- Graduate Program in Cellular and Molecular Biology, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Ryan L Clark
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Joshua M Thiede
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Christopher R Mehrer
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Daniel E Agnew
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Candace E Campbell
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Andrew L Markley
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Morgan N Price
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Jayashree Ray
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Kelly M Wetmore
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Yumi Suh
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Adam P Arkin
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.,Department of Bioengineering, University of California, Berkeley, CA, 94720, USA
| | - Adam M Deutschbauer
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Daniel Amador-Noguez
- Graduate Program in Cellular and Molecular Biology, University of Wisconsin-Madison, Madison, WI, 53706, USA.,Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Brian F Pfleger
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA.
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Effect of acetate as a co-feedstock on the production of poly(lactate-co-3-hydroxyalkanoate) by pflA-deficient Escherichia coli RSC10. J Biosci Bioeng 2017; 123:547-554. [DOI: 10.1016/j.jbiosc.2016.12.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 12/14/2016] [Indexed: 11/23/2022]
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12
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Lundgren BR, Connolly MP, Choudhary P, Brookins-Little TS, Chatterjee S, Raina R, Nomura CT. Defining the Metabolic Functions and Roles in Virulence of the rpoN1 and rpoN2 Genes in Ralstonia solanacearum GMI1000. PLoS One 2015; 10:e0144852. [PMID: 26659655 PMCID: PMC4676750 DOI: 10.1371/journal.pone.0144852] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 11/24/2015] [Indexed: 11/18/2022] Open
Abstract
The alternative sigma factor RpoN is a unique regulator found among bacteria. It controls numerous processes that range from basic metabolism to more complex functions such as motility and nitrogen fixation. Our current understanding of RpoN function is largely derived from studies on prototypical bacteria such as Escherichia coli. Bacillus subtilis and Pseudomonas putida. Although the extent and necessity of RpoN-dependent functions differ radically between these model organisms, each bacterium depends on a single chromosomal rpoN gene to meet the cellular demands of RpoN regulation. The bacterium Ralstonia solanacearum is often recognized for being the causative agent of wilt disease in crops, including banana, peanut and potato. However, this plant pathogen is also one of the few bacterial species whose genome possesses dual rpoN genes. To determine if the rpoN genes in this bacterium are genetically redundant and interchangeable, we constructed and characterized ΔrpoN1, ΔrpoN2 and ΔrpoN1 ΔrpoN2 mutants of R. solanacearum GMI1000. It was found that growth on a small range of metabolites, including dicarboxylates, ethanol, nitrate, ornithine, proline and xanthine, were dependent on only the rpoN1 gene. Furthermore, the rpoN1 gene was required for wilt disease on tomato whereas rpoN2 had no observable role in virulence or metabolism in R. solanacearum GMI1000. Interestingly, plasmid-based expression of rpoN2 did not fully rescue the metabolic deficiencies of the ΔrpoN1 mutants; full recovery was specific to rpoN1. In comparison, only rpoN2 was able to genetically complement a ΔrpoN E. coli mutant. These results demonstrate that the RpoN1 and RpoN2 proteins are not functionally equivalent or interchangeable in R. solanacearum GMI1000.
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Affiliation(s)
- Benjamin R. Lundgren
- Department of Chemistry, State University of New York–College of Environmental Science and Forestry, Syracuse, New York, United States of America
| | - Morgan P. Connolly
- Department of Chemistry, State University of New York–College of Environmental Science and Forestry, Syracuse, New York, United States of America
| | - Pratibha Choudhary
- Department of Biology, Syracuse University, Syracuse, New York, United States of America
| | - Tiffany S. Brookins-Little
- Department of Chemistry, State University of New York–College of Environmental Science and Forestry, Syracuse, New York, United States of America
| | - Snigdha Chatterjee
- Department of Biology, Syracuse University, Syracuse, New York, United States of America
| | - Ramesh Raina
- Department of Biology, Syracuse University, Syracuse, New York, United States of America
| | - Christopher T. Nomura
- Department of Chemistry, State University of New York–College of Environmental Science and Forestry, Syracuse, New York, United States of America
- Center for Applied Microbiology, State University of New York–College of Environmental Science and Forestry, Syracuse, New York, United States of America
- * E-mail:
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13
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Abstract
Early investigations on arginine biosynthesis brought to light basic features of metabolic regulation. The most significant advances of the last 10 to 15 years concern the arginine repressor, its structure and mode of action in both E. coli and Salmonella typhimurium, the sequence analysis of all arg structural genes in E. coli and Salmonella typhimurium, the resulting evolutionary inferences, and the dual regulation of the carAB operon. This review provides an overall picture of the pathways, their interconnections, the regulatory circuits involved, and the resulting interferences between arginine and polyamine biosynthesis. Carbamoylphosphate is a precursor common to arginine and the pyrimidines. In both Escherichia coli and Salmonella enterica serovar Typhimurium, it is produced by a single synthetase, carbamoylphosphate synthetase (CPSase), with glutamine as the physiological amino group donor. This situation contrasts with the existence of separate enzymes specific for arginine and pyrimidine biosynthesis in Bacillus subtilis and fungi. Polyamine biosynthesis has been particularly well studied in E. coli, and the cognate genes have been identified in the Salmonella genome as well, including those involved in transport functions. The review summarizes what is known about the enzymes involved in the arginine pathway of E. coli and S. enterica serovar Typhimurium; homologous genes were identified in both organisms, except argF (encoding a supplementary OTCase), which is lacking in Salmonella. Several examples of putative enzyme recruitment (homologous enzymes performing analogous functions) are also presented.
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14
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Contribution of the distal pocket residue to the acyl-chain-length specificity of (R)-specific enoyl-coenzyme A hydratases from Pseudomonas spp. Appl Environ Microbiol 2015; 81:8076-83. [PMID: 26386053 DOI: 10.1128/aem.02412-15] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 09/09/2015] [Indexed: 11/20/2022] Open
Abstract
(R)-Specific enoyl-coenzyme A (enoyl-CoA) hydratases (PhaJs) are capable of supplying monomers from fatty acid β-oxidation to polyhydroxyalkanoate (PHA) biosynthesis. PhaJ1Pp from Pseudomonas putida showed broader substrate specificity than did PhaJ1Pa from Pseudomonas aeruginosa, despite sharing 67% amino acid sequence identity. In this study, the substrate specificity characteristics of two Pseudomonas PhaJ1 enzymes were investigated by site-directed mutagenesis, chimeragenesis, X-ray crystallographic analysis, and homology modeling. In PhaJ1Pp, the replacement of valine with isoleucine at position 72 resulted in an increased preference for enoyl-coenzyme A (CoA) elements with shorter chain lengths. Conversely, at the same position in PhaJ1Pa, the replacement of isoleucine with valine resulted in an increased preference for enoyl-CoAs with longer chain lengths. These changes suggest a narrowing and broadening in the substrate specificity range of the PhaJ1Pp and PhaJ1Pa mutants, respectively. However, the substrate specificity remains broader in PhaJ1Pp than in PhaJ1Pa. Additionally, three chimeric PhaJ1 enzymes, composed from PhaJ1Pp and PhaJ1Pa, all showed significant hydratase activity, and their substrate preferences were within the range exhibited by the parental PhaJ1 enzymes. The crystal structure of PhaJ1Pa was determined at a resolution of 1.7 Å, and subsequent homology modeling of PhaJ1Pp revealed that in the acyl-chain binding pocket, the amino acid at position 72 was the only difference between the two structures. These results indicate that the chain-length specificity of PhaJ1 is determined mainly by the bulkiness of the amino acid residue at position 72, but that other factors, such as structural fluctuations, also affect specificity.
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15
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Mann MS, Lütke-Eversloh T. Thiolase engineering for enhanced butanol production in Clostridium acetobutylicum. Biotechnol Bioeng 2012; 110:887-97. [PMID: 23096577 DOI: 10.1002/bit.24758] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Revised: 10/01/2012] [Accepted: 10/12/2012] [Indexed: 12/20/2022]
Abstract
Biosynthetic thiolases catalyze the condensation of two molecules acetyl-CoA to acetoacetyl-CoA and represent key enzymes for carbon-carbon bond forming metabolic pathways. An important biotechnological example of such a pathway is the clostridial n-butanol production, comprising various natural constraints that limit titer, yield, and productivity. In this study, the thiolase of Clostridium acetobutylicum, the model organism for solventogenic clostridia, was specifically engineered for reduced sensitivity towards its physiological inhibitor coenzyme A (CoA-SH). A high-throughput screening assay in 96-well microtiter plates was developed employing Escherichia coli as host cells for expression of a mutant thiolase gene library. Screening of this library resulted in the identification of a thiolase derivative with significantly increased activity in the presence of free CoA-SH. This optimized thiolase comprised three amino acid substitutions (R133G, H156N, G222V) and its gene was expressed in C. acetobutylicum ATCC 824 to assess the effect of reduced CoA-SH sensitivity on solvent production. In addition to a clearly delayed ethanol and acetone formation, the ethanol and butanol titers were increased by 46% and 18%, respectively, while the final acetone concentrations were similar to the vector control strain. These results demonstrate that thiolase engineering constitutes a suitable methodology applicable to improve clostridial butanol production, but other biosynthetic pathways involving thiolase-mediated carbon flux limitations might also be subjected to this new metabolic engineering approach.
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Affiliation(s)
- Miriam S Mann
- Abteilung Mikrobiologie, Institut für Biowissenschaften, Universität Rostock, Rostock, Germany
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16
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Shozui F, Matsumoto K, Motohashi R, Sun J, Satoh T, Kakuchi T, Taguchi S. Biosynthesis of a lactate (LA)-based polyester with a 96mol% LA fraction and its application to stereocomplex formation. Polym Degrad Stab 2011. [DOI: 10.1016/j.polymdegradstab.2011.01.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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17
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Boghigian BA, Zhang H, Pfeifer BA. Multi-factorial engineering of heterologous polyketide production in Escherichia coli reveals complex pathway interactions. Biotechnol Bioeng 2011; 108:1360-71. [PMID: 21337322 DOI: 10.1002/bit.23069] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Revised: 12/13/2010] [Accepted: 01/18/2011] [Indexed: 11/05/2022]
Abstract
Polyketides represent a significant fraction of all natural products. Many possess pharmacological activity which makes them attractive drug candidates. The production of the parent macrocyclic aglycones is catalyzed by multi-modular polyketide synthases utilizing short-chain acyl-CoA monomers. When producing polyketides through heterologous hosts, one must not only functionally express the synthase itself, but activate the machinery used to generate the required substrate acyl-CoA's. As a result, metabolic engineering of these pathways is necessary for high-level production of heterologous polyketides. In this study, we over-express three different pathways for provision of the two substrates (propionyl-CoA and (2S)-methylmalonyl-CoA) utilized for the biosynthesis of 6-deoxyerythronolide B (6-dEB; the macrolactone precursor of erythromycin): (1) a propionate → propionyl-CoA → (2S)-methylmalonyl-CoA pathway, (2) a methylmalonate → methylmalonyl-CoA → propionyl-CoA pathway, and (3) a succinate → succinyl-CoA → (2R)-methylmalonyl-CoA → (2S)-methylmalonyl-CoA → propionyl-CoA pathway. The current study revealed that propionate is a necessary component for greater than 5 mg L(-1) titers. Deletion of the propionyl-CoA:succinate CoA transferase (ygfH) or over-expression of the transcriptional activator of short chain fatty acid uptake improved titer to over 100 mg L(-1), while the combination of the two improved titer to over 130 mg L(-1). The addition of exogenous methylmalonate could also improve titer to over 100 mg L(-1). Expression of a Streptomyces coelicolor A3(2) methylmalonyl-CoA epimerase, in conjunction with over-expression of Escherichia coli's native methylmalonyl-CoA mutase, allowed for the incorporation of exogenously fed succinate into the 6-dEB core.
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Affiliation(s)
- Brett A Boghigian
- Department of Chemical and Biological Engineering, Science and Technology Center, Tufts University, 4 Colby Street, Medford, Massachusetts 02155, USA
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18
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Metabolism of select amino acids in bacteria from the pig small intestine. Amino Acids 2011; 42:1597-608. [PMID: 21344175 DOI: 10.1007/s00726-011-0846-x] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Accepted: 02/08/2011] [Indexed: 12/14/2022]
Abstract
This study investigated the metabolism of select amino acids (AA) in bacterial strains (Streptococcus sp., Escherichia coli and Klebsiella sp.) and mixed bacterial cultures derived from the jejunum and ileum of pigs. Cells were incubated at 37°C for 3 h in anaerobic media containing 0.5-5 mM select AA plus [U-14C]-labeled tracers to determine their decarboxylation and incorporation into bacterial protein. Results showed that all types of bacteria rapidly utilized glutamine, lysine, arginine and threonine. However, rates of the utilization of AA by pure cultures of E. coli and Klebsiella sp. were greater than those for mixed bacterial cultures or Streptococcus sp. The oxidation of lysine, threonine and arginine accounted for 10% of their utilization in these pure bacterial cultures, but values were either higher or lower in mixed bacterial cultures depending on AA, bacterial species and the gut segment (e.g., 15% for lysine in jejunal and ileal mixed bacteria; 5.5 and 0.3% for threonine in jejunal mixed bacteria and ileal mixed bacteria, respectively; and 20% for arginine in ileal mixed bacteria). Percentages of AA used for bacterial protein synthesis were 50-70% for leucine, 25% for threonine, proline and methionine, 15% for lysine and arginine and 10% for glutamine. These results indicate diverse metabolism of AA in small-intestinal bacteria in a species- and gut compartment-dependent manner. This diversity may contribute to AA homeostasis in the gut. The findings have important implications for both animal and human nutrition, as well as their health and well-beings.
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19
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Sato S, Kanazawa H, Tsuge T. Expression and characterization of (R)-specific enoyl coenzyme A hydratases making a channeling route to polyhydroxyalkanoate biosynthesis in Pseudomonas putida. Appl Microbiol Biotechnol 2011; 90:951-9. [DOI: 10.1007/s00253-011-3150-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Revised: 01/20/2011] [Accepted: 01/20/2011] [Indexed: 11/29/2022]
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20
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Papadopoulos G, Grigoroudis AI, Kyriakidis DA. Dimerization of the AtoC response regulator and modelling of its binding to DNA. J Mol Graph Model 2010; 29:565-72. [PMID: 21115262 DOI: 10.1016/j.jmgm.2010.10.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Revised: 10/12/2010] [Accepted: 10/18/2010] [Indexed: 11/28/2022]
Abstract
Bacterial signal transduction systems can be viewed as an entity of multi-sensory and output domains, whereas the functions of response regulators play a pivotal role in the complex network interactions. One crucial property among response regulators functions is their oligomerization and subsequent binding to DNA. The AtoS-AtoC two component system, functionally modulated by various agents, influences fundamental cellular processes such as short-chain fatty acid catabolism and poly-(R)-3-hydroxybutyrate biosynthesis in Escherichia coli. Among the already reported characteristic properties, AtoC binds to a specific site, a palindromic repeat of 20 nucleotides within the atoDAEB promoter. Since experimental structures of AtoC or its complex with DNA are not yet available, an almost complete homology model of AtoC and of its putative entity as a dimer is constructed for this study, as well as a model of its binding to its target DNA sequence. The latter is associated with large conformational changes, as shown by molecular dynamics simulations. Subsequent biochemical study, including cross-linking via chemical agents, revealed the ability of AtoC to form oligomers in vitro.
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Affiliation(s)
- G Papadopoulos
- Department of Biochemistry & Biotechnology, University of Thessaly Ploutonos 26 & Aeolou, Larisa GR-41221, Greece
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21
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Abstract
Several recombinant Escherichia coli strains, including XL1-Blue, JM109, HB101, and DH5alpha harboring a stable high-copynumber plasmid pSYL105 containing the Alcaligenes eutrophus polyhydroxyalkanoate (PHA) biosynthesis genes were constructed. These recombinant strains were examined for their ability to synthesize and accumulate poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] copolymer from glucose and either propionate or valerate. All recombinant E. coli strains could synthesize the P(3HB-co-3HV) copolymer in the medium containing glucose and propionate. However, only the homopolymer poly-(3-hydroxybutyrate) [P(3HB)] was synthesized from glucose and valerate. The PHA concentration and the 3HV fraction could be increased by inducing with acetate and/or oleate. When supplemented with oleate, the 3HV fraction increased by fourfold compared with that obtained without induction. Induction with propionate resulted in lower PHA concentration due to the inhibitory effect, but an 3HV fraction of as high as 33.0% could be obtained. These results suggest that P(3HB-co-3HV) can be efficiently produced from propionate by recombinant E. coli by inducing with acetate, propionate, or oleate.
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Affiliation(s)
- K S Yim
- Department of Chemical Engineering and BioProcess Engineering Research Center, Korea Advanced Institute of Science and Technology, 373-1 Kusong-dong, Yusong-gu, Taejon 305-701, Korea
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22
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Mills TY, Sandoval NR, Gill RT. Cellulosic hydrolysate toxicity and tolerance mechanisms in Escherichia coli. BIOTECHNOLOGY FOR BIOFUELS 2009; 2:26. [PMID: 19832972 PMCID: PMC2770041 DOI: 10.1186/1754-6834-2-26] [Citation(s) in RCA: 203] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2009] [Accepted: 10/15/2009] [Indexed: 05/03/2023]
Abstract
The sustainable production of biofuels will require the efficient utilization of lignocellulosic biomass. A key barrier involves the creation of growth-inhibitory compounds by chemical pretreatment steps, which ultimately reduce the efficiency of fermentative microbial biocatalysts. The primary toxins include organic acids, furan derivatives, and phenolic compounds. Weak acids enter the cell and dissociate, resulting in a drop in intracellular pH as well as various anion-specific effects on metabolism. Furan derivatives, dehydration products of hexose and pentose sugars, have been shown to hinder fermentative enzyme function. Phenolic compounds, formed from lignin, can disrupt membranes and are hypothesized to interfere with the function of intracellular hydrophobic targets. This review covers mechanisms of toxicity and tolerance for these compounds with a specific focus on the important industrial organism Escherichia coli. Recent efforts to engineer E. coli for improved tolerance to these toxins are also discussed.
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Affiliation(s)
- Tirzah Y Mills
- Department of Chemical and Biological Engineering, UCB424/ECCH120, University of Colorado, Boulder, CO 80309, USA
| | - Nicholas R Sandoval
- Department of Chemical and Biological Engineering, UCB424/ECCH120, University of Colorado, Boulder, CO 80309, USA
| | - Ryan T Gill
- Department of Chemical and Biological Engineering, UCB424/ECCH120, University of Colorado, Boulder, CO 80309, USA
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23
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Kyriakidis DA, Tiligada E. Signal transduction and adaptive regulation through bacterial two-component systems: the Escherichia coli AtoSC paradigm. Amino Acids 2009; 37:443-58. [PMID: 19198978 DOI: 10.1007/s00726-009-0241-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2008] [Accepted: 01/12/2009] [Indexed: 02/07/2023]
Abstract
Adaptive signal transduction within microbial cells involves a multi-faceted regulated phosphotransfer mechanism that comprises structural rearrangements of sensor histidine kinases upon ligand-binding and phosphorylation-induced conformational changes in response regulators of versatile two-component systems (TCS), arisen early in bacterial evolution. In Escherichia coli, cross-talk between the AtoS histidine kinase and the AtoC response regulator, forming the AtoSC TCS, through His --> Asp phosphotransfer, activates AtoC directly to induce atoDAEB operon expression, thus modulating diverse fundamental cellular processes such as short-chain fatty acid catabolism, poly-(R)-3-hydroxybutyrate biosynthesis and chemotaxis. Among the inducers hitherto identified, acetoacetate is the classical activator. The AtoSC TCS functional modulation by polyamines, histamine and Ca(2+), as well as the role of AtoC as transcriptional regulator, add new promising perspectives in the physiological significance and potential pharmacological exploitation of this TCS in cell proliferation, bacteria-host interactions, chemotaxis, and adaptation.
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24
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Effect of histamine on the signal transduction of the AtoS-AtoC two component system and involvement in poly-(R)-3-hydroxybutyrate biosynthesis in Escherichia coli. Amino Acids 2008; 35:45-52. [PMID: 18235991 DOI: 10.1007/s00726-007-0635-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2007] [Accepted: 10/31/2007] [Indexed: 01/25/2023]
Abstract
AtoS-AtoC two-component system acts directly on the atoDAEB operon transcription to regulate the biosynthesis of short-chain poly-(R)-3-hydroxybutyrate. This study sought to investigate the effect of histamine and compound 48/80 on the regulation of AtoS-AtoC two-component system in Escherichia coli K-12 MA255 (speC(-), speB(-)) and the isogenic E. coli strains BW25113 (atoSC(+)) and BW28878 (DeltaatoSC) transformed with plasmids carrying related genes. Histamine or compound 48/80 induced or tended to reduce atoC transcription, respectively, while neither compound showed any effect on atoDAEB operon transcription. Moreover, histamine down-regulated poly-(R)-3-hydroxybutyrate biosynthesis, whereas compound 48/80 up-regulated its biosynthesis, maximal induction being obtained in the presence of multiple copies of AtoS-AtoC. Interestingly, co-administration of histamine counteracted this inductive effect of compound 48/80. The reported data provide the first evidence for a differential modulator role of histamine and compound 48/80 on the AtoS-AtoC two-component system signaling in potentially pathogenic bacteria, leading to a new perspective on their symbiotic behavior.
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Expression of Clostridium acetobutylicum butanol synthetic genes in Escherichia coli. Appl Microbiol Biotechnol 2007; 77:1305-16. [PMID: 18060402 DOI: 10.1007/s00253-007-1257-5] [Citation(s) in RCA: 237] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2007] [Revised: 10/24/2007] [Accepted: 10/25/2007] [Indexed: 10/22/2022]
Abstract
A recombinant butanol pathway composed of Clostridium acetobutylicum ATCC 824 genes, thiL, hbd, crt, bcd-etfB-etfA, and adhe1 (or adhe) coding for acetyl-CoA acetyltransferase (THL), beta-hydroxybutyryl-CoA dehydrogenase (HBD), 3-hydroxybutyryl-CoA dehydratase (CRT), butyryl-CoA dehydrogenase (BCD), butyraldehyde dehydrogenase (BYDH), and butanol dehydrogenase (BDH), under the tac promoter control was constructed and was introduced into Escherichia coli. The functional expression of these six enzymes was proved by demonstrating the corresponding enzyme activities using spectrophotometric, high performance liquid chromatography and gas chromatography analyses. The BCD activity, which was not detected in E. coli previously, was shown in the present study by performing the procedure from cell extract preparation to activity measurement under anaerobic condition. Moreover, the etfA and etfB co-expression was found to be essential for the BCD activity. In the case of BYDH activity, the adhe gene product was shown to have higher specificity towards butyryl-CoA compared to the adhe1 product. Butanol production from glucose was achieved by the highly concentrated cells of the butanologenic E. coli strains, BUT1 with adhe1 and BUT2 with adhe, under anaerobic condition, and the BUT1 and BUT2 strains were shown to produce 4 and 16-mM butanol with 6- and 1-mM butyrate as a byproduct, respectively. This study reports the novel butanol production by an aerobically pregrown microorganism possessing the genes of a strict anaerobe, Clostridium acetobutylicum.
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Theodorou MC, Theodorou EC, Panagiotidis CA, Kyriakidis DA. Spermidine triggering effect to the signal transduction through the AtoS–AtoC/Az two-component system in Escherichia coli. Biochim Biophys Acta Gen Subj 2007; 1770:1104-14. [PMID: 17475408 DOI: 10.1016/j.bbagen.2007.03.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2006] [Revised: 03/06/2007] [Accepted: 03/16/2007] [Indexed: 11/16/2022]
Abstract
Recent analysis revealed that, in Escherichia coli the AtoS-AtoC/Az two-component system (TCS) and its target atoDAEB operon regulate the biosynthesis of short-chain poly-(R)-3-hydroxybutyrate (cPHB) biosynthesis, a biopolymer with many physiological roles, upon acetoacetate-mediated induction. We report here that spermidine further enhanced this effect, in E. coli that overproduces both components of the AtoS-AtoC/Az TCS, without altering their protein levels. However, bacteria that overproduce either AtoS or AtoC did not display this phenotype. The extrachromosomal introduction of AtoS-AtoC/Az in an E. coli DeltaatoSC strain restored cPHB biosynthesis to the level of the atoSC(+) cells, in the presence of the polyamine. Lack of enhanced cPHB production was observed in cells overproducing the TCS that did not have the atoDAEB operon. Spermidine attained the cPHB enhancement through the AtoC/Az response regulator phosphorylation, since atoC phosphorylation site mutants, which overproduce AtoS, accumulated less amounts of cPHB, compared to their wild-type counterparts. Exogenous addition of N(8)-acetyl-spermidine resulted in elevated amounts of cPHB but at lower levels than those attained upon spermidine addition. Furthermore, AtoS-AtoC/Az altered the intracellular distribution of cPHB according to the inducer recognized by the TCS. Overall, AtoS-AtoC/Az TCS was induced by spermidine to regulate both the biosynthesis and the intracellular distribution of cPHB in E. coli.
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Affiliation(s)
- Marina C Theodorou
- Laboratory of Biochemistry, Department of Chemistry, Aristotle University of Thessaloniki, Thessaloniki, 54124, Greece
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27
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Grigoroudis AI, Panagiotidis CA, Lioliou EE, Vlassi M, Kyriakidis DA. Molecular modeling and functional analysis of the AtoS–AtoC two-component signal transduction system of Escherichia coli. Biochim Biophys Acta Gen Subj 2007; 1770:1248-58. [PMID: 17537579 DOI: 10.1016/j.bbagen.2007.04.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2007] [Revised: 04/02/2007] [Accepted: 04/06/2007] [Indexed: 12/01/2022]
Abstract
The AtoS-AtoC two-component signal transduction system positively regulates the expression of the atoDAEB operon in Escherichia coli. Upon acetoacetate induction, AtoS sensor kinase autophosphorylates and subsequently phosphorylates, thereby activating, the response regulator AtoC. In a previous work we have shown that AtoC is phosphorylated at both aspartate 55 and histidine73. In this study, based on known three-dimensional structures of other two component regulatory systems, we modeled the 3D-structure of the receiver domain of AtoC in complex with the putative dimerization/autophosphorylation domain of the AtoS sensor kinase. The produced structural model indicated that aspartate 55, but not histidine 73, of AtoC is in close proximity to the conserved, putative phosphate-donor, histidine (H398) of AtoS suggesting that aspartate 55 may be directly involved in the AtoS-AtoC phosphate transfer. Subsequent biochemical studies with purified recombinant proteins showed that AtoC mutants with alterations of aspartate 55, but not histidine 73, were unable to participate in the AtoS-AtoC phosphate transfer in support of the modeling prediction. In addition, these AtoC mutants displayed reduced DNA-dependent ATPase activity, although their ability to bind their target DNA sequences in a sequence-specific manner was found to be unaltered.
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Affiliation(s)
- A I Grigoroudis
- Laboratory of Biochemistry, Department of Chemistry, Aristotle University of Thessaloniki, Thessaloniki, 54124, Greece
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28
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Matta MK, Lioliou EE, Panagiotidis CH, Kyriakidis DA, Panagiotidis CA. Interactions of the antizyme AtoC with regulatory elements of the Escherichia coli atoDAEB operon. J Bacteriol 2007; 189:6324-32. [PMID: 17616594 PMCID: PMC1951910 DOI: 10.1128/jb.00214-07] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
AtoC has a dual function as both an antizyme, the posttranslational inhibitor of polyamine biosynthetic enzymes, and the transcriptional regulator of genes involved in short-chain fatty acid catabolism (the atoDAEB operon). We have previously shown that AtoC is the response regulator of the AtoS-AtoC two-component signal transduction system that activates atoDAEB when Escherichia coli is exposed to acetoacetate. Here, we show that the same cis elements control both promoter inducibility and AtoC binding. Chromatin immunoprecipitation experiments confirmed the acetoacetate-inducible binding of AtoC to the predicted DNA region in vivo. DNase I protection footprinting analysis revealed that AtoC binds two 20-bp stretches, constituting an inverted palindrome, that are located at -146 to -107 relative to the transcription initiation site. Analyses of promoter mutants obtained by in vitro chemical mutagenesis of the atoDAEB promoter verified both the importance of AtoC binding for the inducibility of the promoter by acetoacetate and the sigma54 dependence of atoDAEB expression. The integration host factor was also identified as a critical component of the AtoC-mediated induction of atoDAEB.
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Affiliation(s)
- Meropi K Matta
- Department of Pharmaceutical Sciences, Laboratory of Biochemistry, Aristotle University, Thessaloniki 54124, Greece
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Sato S, Nomura CT, Abe H, Doi Y, Tsuge T. Poly[(R)-3-hydroxybutyrate] formation in Escherichia coli from glucose through an enoyl-CoA hydratase-mediated pathway. J Biosci Bioeng 2007; 103:38-44. [PMID: 17298899 DOI: 10.1263/jbb.103.38] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2006] [Accepted: 10/11/2006] [Indexed: 11/17/2022]
Abstract
In this study, a new metabolic pathway for the synthesis of poly[(R)-3-hydroxybutyrate] [P(3HB)] was constructed in a recombinant Escherichia coli strain that utilized forward and reverse reactions catalyzed by two substrate-specific enoyl-CoA hydratases, R-hydratase (PhaJ) and S-hydratase (FadB), to epimerize (S)-3HB-CoA to (R)-3HB-CoA via a crotonyl-CoA intermediate. The R-hydratase gene (phaJ(Ac)) from Aeromonas caviae was coexpressed with the PHA synthase gene (phaC(Re)) and 3-ketothiolase gene (phaA(Re)) from Ralstonia eutropha in fadR mutant E. coli strains (CAG18497 and LS5218), which had constitutive levels of the beta-oxidation multienzyme FadB(Ec). When grown on glucose as the sole carbon source, the cells accumulated P(3HB) up to an amount 6.5 wt% of the dry cell weight, whereas the control cells without phaJ(Ac) or fadR mutation accumulated significantly smaller amounts of P(3HB). These results suggest that PhaJ(Ac) and FadB(Ec) played an important role in supplying monomers for P(3HB) synthesis in the pathway. Furthermore, by using this pathway, a P(3HB)-concentration-dependent fluorescent staining screening technique was developed to rapidly identify cells that possess active R-hydratase.
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Affiliation(s)
- Shun Sato
- Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502, Japan
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Van Immerseel F, Russell JB, Flythe MD, Gantois I, Timbermont L, Pasmans F, Haesebrouck F, Ducatelle R. The use of organic acids to combatSalmonellain poultry: a mechanistic explanation of the efficacy. Avian Pathol 2007; 35:182-8. [PMID: 16753609 DOI: 10.1080/03079450600711045] [Citation(s) in RCA: 250] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Salmonella is a human pathogen that is commonly found in poultry products. It is possible to decrease chicken carcass and egg contaminations by adding organic acids to the feed or drinking water at appropriate times. Medium-chain fatty acids are more antibacterial against Salmonella than short-chain fatty acids. The antibacterial effect of these acids is species specific. Bacteria that are unable to decrease intracellular pH accumulate organic acid anions in accordance with the pH gradient across their cell membranes. The short-chain fatty acid butyrate specifically down-regulates expression of invasion genes in Salmonella spp. at low doses. Also medium-chain fatty acids and propionate decrease the ability of Salmonella spp. to invade epithelial cells, in contrast to acetic acid. Because not all bacteria are affected in a similar fashion by organic acids, it may be possible to use probiotic and prebiotic bacteria to achieve beneficial effects. If diets can be designed to stimulate organic acid production in the caecum, it may be possible to control Salmonella spp. via even easier and more cost-effective measures, compared with addition of acids to feed or drinking water.
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Affiliation(s)
- F Van Immerseel
- Ghent University, Faculty of Veterinary Medicine, Research Group Veterinary Public Health and Zoonoses, Department of Pathology, Bacteriology and Avian Diseases, Salisburylaan 133, B-9820, Merelbeke, Belgium.
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Effect of polyamines and synthetic polyamine-analogues on the expression of antizyme (AtoC) and its regulatory genes. BMC BIOCHEMISTRY 2007; 8:1. [PMID: 17224065 PMCID: PMC1784093 DOI: 10.1186/1471-2091-8-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2006] [Accepted: 01/15/2007] [Indexed: 02/05/2023]
Abstract
Background In bacteria, the biosynthesis of polyamines is modulated at the level of transcription as well as post-translationally. Antizyme (Az) has long been identified as a non-competitive protein inhibitor of polyamine biosynthesis in E. coli. Az was also revealed to be the product of the atoC gene. AtoC is the response regulator of the AtoS-AtoC two-component system and it functions as the positive transcriptional regulator of the atoDAEB operon genes, encoding enzymes involved in short chain fatty acid metabolism. The antizyme is referred to as AtoC/Az, to indicate its dual function as both a transcriptional and post-translational regulator. Results The roles of polyamines on the transcription of atoS and atoC genes as well as that of atoDAEB(ato) operon were studied. Polyamine-mediated induction was tested both in atoSC positive and negative E. coli backgrounds by using β-galactosidase reporter constructs carrying the appropriate promoters patoDAEB, patoS, patoC. In addition, a selection of synthetic polyamine analogues have been synthesized and tested for their effectiveness in inducing the expression of atoC/Az, the product of which plays a pivotal role in the feedback inhibition of putrescine biosynthesis and the transcriptional regulation of the ato operon. The effects of these compounds were also determined on the ato operon expression. The polyamine analogues were also tested for their effect on the activity of ornithine decarboxylase (ODC), the key enzyme of polyamine biosynthesis and on the growth of polyamine-deficient E. coli. Conclusion Polyamines, which have been reported to induce the protein levels of AtoC/Az in E. coli, act at the transcriptional level, since they cause activation of the atoC transcription. In addition, a series of polyamine analogues were studied on the transcription of atoC gene and ODC activity.
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Reva ON, Weinel C, Weinel M, Böhm K, Stjepandic D, Hoheisel JD, Tümmler B. Functional genomics of stress response in Pseudomonas putida KT2440. J Bacteriol 2006; 188:4079-92. [PMID: 16707699 PMCID: PMC1482902 DOI: 10.1128/jb.00101-06] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2006] [Accepted: 03/15/2006] [Indexed: 11/20/2022] Open
Abstract
The metabolically versatile soil bacterium Pseudomonas putida has to cope with numerous abiotic stresses in its habitats. The stress responses of P. putida KT2440 to 4 degrees C, pH 4.5, 0.8 M urea, and 45 mM sodium benzoate were analyzed by determining the global mRNA expression profiles and screening for stress-intolerant nonauxotrophic Tn5 transposon mutants. In 392 regulated genes or operons, 36 gene regions were differentially expressed by more than 2.5-fold, and 32 genes in 23 operons were found to be indispensable for growth during exposure to one of the abiotic stresses. The transcriptomes of the responses to urea, benzoate, and 4 degrees C correlated positively with each other but negatively with the transcriptome of the mineral acid response. The CbrAB sensor kinase, the cysteine synthase CysM, PcnB and VacB, which control mRNA stability, and BipA, which exerts transcript-specific translational control, were essential to cope with cold stress. The cyo operon was required to cope with acid stress. A functional PhoP, PtsP, RelA/SpoT modulon, and adhesion protein LapA were necessary for growth in the presence of urea, and the outer membrane proteins OmlA and FepA and the phosphate transporter PstBACS were indispensable for growth in the presence of benzoate. A lipid A acyltransferase (PP0063) was a mandatory component of the stress responses to cold, mineral acid, and benzoate. Adaptation of the membrane barrier, uptake of phosphate, maintenance of the intracellular pH and redox status, and translational control of metabolism are key mechanisms of the response of P. putida to abiotic stresses.
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Affiliation(s)
- Oleg N Reva
- Klinische Forschergruppe, OE 6710, Medizinische Hochschule Hannover, Carl-Neuberg-Strasse 1, D-30623 Hannover, Germany
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Clark DP, Cronan JE. Two-Carbon Compounds and Fatty Acids as Carbon Sources. EcoSal Plus 2005; 1. [PMID: 26443509 DOI: 10.1128/ecosalplus.3.4.4] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2004] [Indexed: 06/05/2023]
Abstract
This review concerns the uptake and degradation of those molecules that are wholly or largely converted to acetyl-coenzyme A (CoA) in the first stage of metabolism in Escherichia coli and Salmonella enterica. These include acetate, acetoacetate, butyrate and longer fatty acids in wild type cells plus ethanol and some longer alcohols in certain mutant strains. Entering metabolism as acetyl-CoA has two important general consequences. First, generation of energy from acetyl-CoA requires operation of both the citric acid cycle and the respiratory chain to oxidize the NADH produced. Hence, acetyl-CoA serves as an energy source only during aerobic growth or during anaerobic respiration with such alternative electron acceptors as nitrate or trimethylamine oxide. In the absence of a suitable oxidant, acetyl-CoA is converted to a mixture of acetic acid and ethanol by the pathways of anaerobic fermentation. Catabolism of acetyl-CoA via the citric acid cycle releases both carbon atoms of the acetyl moiety as carbon dioxide and growth on these substrates as sole carbon source therefore requires the operation of the glyoxylate bypass to generate cell material. The pair of related two-carbon compounds, glycolate and glyoxylate are also discussed. However, despite having two carbons, these are metabolized via malate and glycerate, not via acetyl-CoA. In addition, mutants of E. coli capable of growth on ethylene glycol metabolize it via the glycolate pathway, rather than via acetyl- CoA. Propionate metabolism is also discussed because in many respects its pathway is analogous to that of acetate. The transcriptional regulation of these pathways is discussed in detail.
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Affiliation(s)
- David P Clark
- Department of Microbiology, Southern Illinois University, Carbondale, Illinois 62901
| | - John E Cronan
- Departments of Microbiology and Biochemistry, University of Illinois, B103 CLSL, 601 S. Goodwin Avenue, Urbana, Illinois 61801
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Lioliou EE, Mimitou EP, Grigoroudis AI, Panagiotidis CH, Panagiotidis CA, Kyriakidis DA. Phosphorylation activity of the response regulator of the two-component signal transduction system AtoS–AtoC in E. coli. Biochim Biophys Acta Gen Subj 2005; 1725:257-68. [PMID: 16153782 DOI: 10.1016/j.bbagen.2005.06.019] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2004] [Revised: 06/30/2005] [Accepted: 06/30/2005] [Indexed: 10/25/2022]
Abstract
Antizyme, long known to be a non-competitive inhibitor of ornithine decarboxylase, is encoded by the atoC gene in Escherichia coli. The present study reveals another role for AtoC, that of a response regulator of the AtoS-AtoC two component system regulating the expression of the atoDAEB operon upon acetoacetate induction. This operon encodes enzymes involved in short-chain fatty acid catabolism in E. coli. Evidence is presented to show that AtoS is a sensor kinase that together with AtoC constitutes a two-component signal transduction system. AtoS is a membrane protein which can autophosphorylate and then transfer that phosphoryl group to AtoC. This process can also be reproduced in vitro. AtoC contains in its amino acid sequence a conserved aspartic acid (D55), which is the putative phosphorylation site, as well as an unexpected "H box" consensus sequence (SHETRTPV), common to histidine kinases, with the histidine contained therein (H73) being a second potential target for phosphorylation. Substitution of either D55 or H73 in His10-AtoC diminished but did not abrogate AtoC phosphorylation suggesting that either both residues can be phosphorylated independently or that the phosphate group can be transferred between them. However, the D55 mutation in comparison to H73 had a more pronounced effect in vivo, on the activation of atoDAEB promoter after acetoacetate induction, although it was the presence of both mutations that rendered AtoC totally unresponsive to induction. These data provide evidence that the gene products of atoS and atoC constitute a two-component signal transduction system, with some unusual properties, involved in the regulation of the atoDAEB operon.
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Affiliation(s)
- Efthimia E Lioliou
- Laboratory of Biochemistry, Department of Chemistry, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
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Lioliou EE, Kyriakidis DA. The role of bacterial antizyme: From an inhibitory protein to AtoC transcriptional regulator. Microb Cell Fact 2004; 3:8. [PMID: 15200682 PMCID: PMC441398 DOI: 10.1186/1475-2859-3-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2004] [Accepted: 06/16/2004] [Indexed: 11/10/2022] Open
Abstract
This review considers the role of bacterial antizyme in the regulation of polyamine biosynthesis and gives new perspectives on the involvement of antizyme in other significant cellular mechanisms. Antizyme is a protein molecule induced by the end product of the enzymic reaction that it inhibits, in a non-competitive manner. The bacterial ornithine decarboxylase is regulated by nucleotides, phosphorylation and antizyme. The inhibition of ornithine decarboxylase by antizyme can be relieved to different degrees by DNA or by a variety of synthetic nucleic acid polymers, attributed to a specific interaction between nucleic acid and antizyme. Recently, this interplay between bacterial antizyme and nucleic acid was determined by discerning an additional function to antizyme that proved to be the atoC gene product, encoding the response regulator of the bacterial two-component system AtoS-AtoC. The gene located just upstream of atoC encodes the sensor kinase, named AtoS, that modulates AtoC activity. AtoC regulates expression of atoDAEB operon which is involved in short-chain fatty acid metabolism. Antizyme is thus referred to as AtoC, functioning both as a post-translational and transcriptional regulator. Also, the AtoS-AtoC signal transduction system in E. coli has a positive regulatory role on poly-(R)-3-hydroxybutyrate biosynthesis. The properties and gene structural similarities of antizymes from different organisms were compared. It was revealed that conserved domains are present mostly in the C-domain of all antizymes. BLAST analysis of the E. coli antizyme protein (AtoC) showed similarities around 69-58% among proteobacteria, g-proteobacteria, enterobacteria and the thermophilic bacterium Thermus thermophilus. A working hypothesis is proposed for the metabolic role of antizyme (AtoC) describing the significant biological implications of this protein molecule. Whether antizymes exist to other enzymes in different tissues, meeting the criteria discussed in the text remains to be elucidated.
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Affiliation(s)
- Efthimia E Lioliou
- Laboratory of Biochemistry, Department of Chemistry, Aristotle University of Thessaloniki, Thessaloniki, 54124, Greece
| | - Dimitrios A Kyriakidis
- Laboratory of Biochemistry, Department of Chemistry, Aristotle University of Thessaloniki, Thessaloniki, 54124, Greece
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Lioliou EE, Pantazaki AA, Kyriakidis DA. Thermus thermophilus genome analysis: benefits and implications. Microb Cell Fact 2004; 3:5. [PMID: 15134584 PMCID: PMC419709 DOI: 10.1186/1475-2859-3-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2004] [Accepted: 05/10/2004] [Indexed: 11/24/2022] Open
Abstract
The genome sequence analysis of Thermus thermophilus HB27, a microorganism with high biotechnological potential, has recently been published. In that report, the chromosomal and the megaplasmid sequence were compared to those of other organisms and discussed on the basis of their physiological and metabolic features. Out of the 2,218 putative genes identified through the large genome sequencing project, a significant number has potential interest for biotechnology. The present communication will discuss the accumulating information on molecules participating in fundamental biological processes or having potential biotechnological importance.
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Affiliation(s)
- Efthimia E Lioliou
- Laboratory of Biochemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Anastasia A Pantazaki
- Laboratory of Biochemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Dimitrios A Kyriakidis
- Laboratory of Biochemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
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Tsuge T, Hisano T, Taguchi S, Doi Y. Alteration of chain length substrate specificity of Aeromonas caviae R-enantiomer-specific enoyl-coenzyme A hydratase through site-directed mutagenesis. Appl Environ Microbiol 2003; 69:4830-6. [PMID: 12902277 PMCID: PMC169158 DOI: 10.1128/aem.69.8.4830-4836.2003] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Aeromonas caviae R-specific enoyl-coenzyme A (enoyl-CoA) hydratase (PhaJ(Ac)) is capable of providing (R)-3-hydroxyacyl-CoA with a chain length of four to six carbon atoms from the fatty acid beta-oxidation pathway for polyhydroxyalkanoate (PHA) synthesis. In this study, amino acid substitutions were introduced into PhaJ(Ac) by site-directed mutagenesis to investigate the feasibility of altering the specificity for the acyl chain length of the substrate. A crystallographic structure analysis of PhaJ(Ac) revealed that Ser-62, Leu-65, and Val-130 define the width and depth of the acyl-chain-binding pocket. Accordingly, we targeted these three residues for amino acid substitution. Nine single-mutation enzymes and two double-mutation enzymes were generated, and their hydratase activities were assayed in vitro by using trans-2-octenoyl-CoA (C(8)) as a substrate. Three of these mutant enzymes, L65A, L65G, and V130G, exhibited significantly high activities toward octenoyl-CoA than the wild-type enzyme exhibited. PHA formation from dodecanoate (C(12)) was examined by using the mutated PhaJ(Ac) as a monomer supplier in recombinant Escherichia coli LS5218 harboring a PHA synthase gene from Pseudomonas sp. strain 61-3 (phaC1(Ps)). When L65A, L65G, or V130G was used individually, increased molar fractions of 3-hydroxyoctanoate (C(8)) and 3-hydroxydecanoate (C(10)) units were incorporated into PHA. These results revealed that Leu-65 and Val-130 affect the acyl chain length substrate specificity. Furthermore, comparative kinetic analyses of the wild-type enzyme and the L65A and V130G mutants were performed, and the mechanisms underlying changes in substrate specificity are discussed.
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Affiliation(s)
- Takeharu Tsuge
- Department of Innovative and Engineered Materials, Tokyo Institute of Technology, Midori-ku, Yokohama 226-8502, Japan.
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Ellington MJK, Bhakoo KK, Sawers G, Richardson DJ, Ferguson SJ. Hierarchy of carbon source selection in Paracoccus pantotrophus: strict correlation between reduction state of the carbon substrate and aerobic expression of the nap operon. J Bacteriol 2002; 184:4767-74. [PMID: 12169601 PMCID: PMC135276 DOI: 10.1128/jb.184.17.4767-4774.2002] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2002] [Accepted: 05/28/2002] [Indexed: 11/20/2022] Open
Abstract
Paracoccus pantotrophus can express a periplasmic nitrate reductase (Nap) during aerobic growth. A proposed role for this enzyme is the dissipation of excess redox energy during oxidative metabolism of reduced carbon substrates. To investigate the regulation of nap expression, a transcriptional fusion between the nap promoter region of P. pantotrophus and the lacZ gene was constructed. When this fusion was used, analyses showed that transcription from the nap promoter increases as the average reduction state of the carbon atoms increases. Thus, beta-galactosidase activities increase as the carbon source changes in the order succinate-acetate-butyrate. This result was obtained regardless of which of the three carbon sources was used for culture of the inoculum. If two carbon sources were presented together, the beta-galactosidase activity was always the same as it was when the least-reduced carbon source was added alone. This suggests that the regulation is dependent upon metabolism of the more-reduced carbon sources rather than just their presence in the medium. Analysis of culture medium by (1)H nuclear magnetic resonance showed that for aerobic growth P. pantotrophus strictly selected its carbon source in the order succinate-acetate-butyrate. This was reflected by diauxic growth kinetics on medium containing mixed carbon substrates. The regulatory mechanism underpinning such a selection is unknown but is likely to be related to the mechanism which controls the transcription of the nap operon.
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Affiliation(s)
- M J K Ellington
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, UK
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Serres MH, Riley M. MultiFun, a multifunctional classification scheme for Escherichia coli K-12 gene products. MICROBIAL & COMPARATIVE GENOMICS 2001; 5:205-22. [PMID: 11471834 DOI: 10.1089/omi.1.2000.5.205] [Citation(s) in RCA: 111] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
An enriched classification system for cellular functions of gene products of Escherichia coli K-12 was developed based on the initial classification by Riley. In the new classification scheme, MultiFun, cellular functions are divided into 10 major categories: Metabolism, Information Transfer, Regulation, Transport, Cell Processes, Cell Structure, Location, Extra-chromosomal Origin, DNA Site, and Cryptic Gene. These major categories are further sub-divided into a hierarchical scheme. Two thousand nine hundred twenty-two gene products of E. coli K-12 were assigned to one or more functions depending on the role they play in the cell. Functional assignments were made to 66% of E. coli gene products, ranging from 1 to 16 assignments per gene product. The expansion of cellular function categories and the assignment to more than one category (multifunction) provides a more complete description of the gene products and their roles and hence better reflects the functional complexity of organisms. We believe this classification system will be useful in the field of genome analysis, both for annotation purposes and for comparative studies. The functional classification scheme and the cellular function assignments made to E. coli gene products can be accessed from the web at the databases GenProtEC (http://genprotec.mbl.edu) and EcoCyc (http://www.ecocyc.org).
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Affiliation(s)
- M H Serres
- The Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, Massachusetts 02543, USA
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Reitzer L, Schneider BL. Metabolic context and possible physiological themes of sigma(54)-dependent genes in Escherichia coli. Microbiol Mol Biol Rev 2001; 65:422-44, table of contents. [PMID: 11528004 PMCID: PMC99035 DOI: 10.1128/mmbr.65.3.422-444.2001] [Citation(s) in RCA: 214] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Sigma(54) has several features that distinguish it from other sigma factors in Escherichia coli: it is not homologous to other sigma subunits, sigma(54)-dependent expression absolutely requires an activator, and the activator binding sites can be far from the transcription start site. A rationale for these properties has not been readily apparent, in part because of an inability to assign a common physiological function for sigma(54)-dependent genes. Surveys of sigma(54)-dependent genes from a variety of organisms suggest that the products of these genes are often involved in nitrogen assimilation; however, many are not. Such broad surveys inevitably remove the sigma(54)-dependent genes from a potentially coherent metabolic context. To address this concern, we consider the function and metabolic context of sigma(54)-dependent genes primarily from a single organism, Escherichia coli, in which a reasonably complete list of sigma(54)-dependent genes has been identified by computer analysis combined with a DNA microarray analysis of nitrogen limitation-induced genes. E. coli appears to have approximately 30 sigma(54)-dependent operons, and about half are involved in nitrogen assimilation and metabolism. A possible physiological relationship between sigma(54)-dependent genes may be based on the fact that nitrogen assimilation consumes energy and intermediates of central metabolism. The products of the sigma(54)-dependent genes that are not involved in nitrogen metabolism may prevent depletion of metabolites and energy resources in certain environments or partially neutralize adverse conditions. Such a relationship may limit the number of physiological themes of sigma(54)-dependent genes within a single organism and may partially account for the unique features of sigma(54) and sigma(54)-dependent gene expression.
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Affiliation(s)
- L Reitzer
- Department of Molecular and Cell Biology, The University of Texas at Dallas, Richardson, TX 75083-0688, USA.
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McClelland M, Florea L, Sanderson K, Clifton SW, Parkhill J, Churcher C, Dougan G, Wilson RK, Miller W. Comparison of the Escherichia coli K-12 genome with sampled genomes of a Klebsiella pneumoniae and three salmonella enterica serovars, Typhimurium, Typhi and Paratyphi. Nucleic Acids Res 2000; 28:4974-86. [PMID: 11121489 PMCID: PMC115240 DOI: 10.1093/nar/28.24.4974] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The Escherichia coli K-12 genome (ECO) was compared with the sampled genomes of the sibling species Salmonella enterica serovars Typhimurium, Typhi and Paratyphi A (collectively referred to as SAL) and the genome of the close outgroup Klebsiella pneumoniae (KPN). There are at least 160 locations where sequences of >400 bp are absent from ECO but present in the genomes of all three SAL and 394 locations where sequences are present in ECO but close homologs are absent in all SAL genomes. The 394 sequences in ECO that do not occur in SAL contain 1350 (30.6%) of the 4405 ECO genes. Of these, 1165 are missing from both SAL and KPN. Most of the 1165 genes are concentrated within 28 regions of 10-40 kb, which consist almost exclusively of such genes. Among these regions were six that included previously identified cryptic phage. A hypothetical ancestral state of genomic regions that differ between ECO and SAL can be inferred in some cases by reference to the genome structure in KPN and the more distant relative Yersinia pestis. However, many changes between ECO and SAL are concentrated in regions where all four genera have a different structure. The rate of gene insertion and deletion is sufficiently high in these regions that the ancestral state of the ECO/SAL lineage cannot be inferred from the present data. The sequencing of other closely related genomes, such as S.bongori or Citrobacter, may help in this regard.
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Affiliation(s)
- M McClelland
- Sidney Kimmel Cancer Center, 10835 Altman Row, San Diego, CA 92121, USA
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Abstract
Two-component signal transduction (TCST) systems are the principal means for coordinating responses to environmental changes in bacteria as well as some plants, fungi, protozoa, and archaea. These systems typically consist of a receptor histidine kinase, which reacts to an extracellular signal by phosphorylating a cytoplasmic response regulator, causing a change in cellular behavior. Although several model systems, including sporulation and chemotaxis, have been extensively studied, the evolutionary relationships between specific TCST systems are not well understood, and the ancestry of the signal transduction components is unclear. Phylogenetic trees of TCST components from 14 complete and 6 partial genomes, containing 183 histidine kinases and 220 response regulators, were constructed using distance methods. The trees showed extensive congruence in the positions of 11 recognizable phylogenetic clusters. Eukaryotic sequences were found almost exclusively in one cluster, which also showed the greatest extent of domain variability in its component proteins, and archaeal sequences mainly formed species-specific clusters. Three clusters in different parts of the kinase tree contained proteins with serine-phosphorylating activity. All kinases were found to be monophyletic with respect to other members of their superfamily, such as type II topoisomerases and Hsp90. Structural analysis further revealed significant similarity to the ATP-binding domain of eukaryotic protein kinases. TCST systems are of bacterial origin and radiated into archaea and eukaryotes by lateral gene transfer. Their components show extensive coevolution, suggesting that recombination has not been a major factor in their differentiation. Although histidine kinase activity is prevalent, serine kinases have evolved multiple times independently within this family, accompanied by a loss of the cognate response regulator(s). The structural and functional similarity between TCST kinases and eukaryotic protein kinases raises the possibility of a distant evolutionary relationship.
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Affiliation(s)
- K K Koretke
- SmithKline Beecham Pharmaceuticals, Collegeville, Pennsylvania 19426-0989, USA
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Palacios S, Escalante-Semerena JC. prpR, ntrA, and ihf functions are required for expression of the prpBCDE operon, encoding enzymes that catabolize propionate in Salmonella enterica serovar typhimurium LT2. J Bacteriol 2000; 182:905-10. [PMID: 10648513 PMCID: PMC94363 DOI: 10.1128/jb.182.4.905-910.2000] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The genes required for the catabolism of propionate in Salmonella enterica serovar Typhimurium are organized as two transcriptional units (prpR and prpBCDE) that are divergently transcribed from one another. Sequence homology to genes encoding members of the sigma-54 family of transcriptional activators and the identification of a consensus sigma-54 promoter 5' to the prpBCDE operon suggested that PrpR was required to activate expression of this operon. We isolated insertions in prpR and showed that prpR function was needed for growth on propionate as a carbon and energy source. A medium-copy-number plasmid carrying the lacZ gene under the control of the native sigma-54 promoter of prpBCDE was used to study prpBCDE operon expression. Transcription of the lacZ reporter in prpR, ntrA, and ihfB mutants was 85-, 83-, and 15-fold lower than the level of transcription measured in strains carrying the wild-type allele of the gene tested. These data indicated that PrpR, IHF, and transcription sigma factor RpoN were required for the expression of the prpBCDE operon. Further analysis of the involvement of the integration host factor (IHF) protein in the expression of this operon is required due to the well-documented pleiotropic effect the lack of this global regulator has on gene expression. Deletion of the 5' 615-bp portion of the prpR gene resulted in a PrpR(c) mutant protein that activated prpBCDE transcription regardless of the ability of the strain to synthesize 2-methylcitrate, the putative coactivator of PrpR. These results indicate that the N terminus of PrpR is the coactivator-sensing domain of the protein. When placed under the control of the arabinose-inducible promoter P(araBAD), expression of prpR(c) allele by arabinose had a strong negative effect on growth of the cell. It is proposed that this deleterious effect of PrpR(c) may be due to an uncontrolled ATPase activity of PrpR or to cross-activation of genes whose functions negatively affect cell growth under the conditions tested.
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Affiliation(s)
- S Palacios
- Department of Bacteriology, University of Wisconsin-Madison, 53706-1567, USA
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MultiFun, a Multifunctional Classification Scheme forEscherichia coliK-12 Gene Products. ACTA ACUST UNITED AC 2000. [DOI: 10.1089/mcg.2000.5.205] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Marais A, Mendz GL, Hazell SL, Mégraud F. Metabolism and genetics of Helicobacter pylori: the genome era. Microbiol Mol Biol Rev 1999; 63:642-74. [PMID: 10477311 PMCID: PMC103749 DOI: 10.1128/mmbr.63.3.642-674.1999] [Citation(s) in RCA: 157] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The publication of the complete sequence of Helicobacter pylori 26695 in 1997 and more recently that of strain J99 has provided new insight into the biology of this organism. In this review, we attempt to analyze and interpret the information provided by sequence annotations and to compare these data with those provided by experimental analyses. After a brief description of the general features of the genomes of the two sequenced strains, the principal metabolic pathways are analyzed. In particular, the enzymes encoded by H. pylori involved in fermentative and oxidative metabolism, lipopolysaccharide biosynthesis, nucleotide biosynthesis, aerobic and anaerobic respiration, and iron and nitrogen assimilation are described, and the areas of controversy between the experimental data and those provided by the sequence annotation are discussed. The role of urease, particularly in pH homeostasis, and other specialized mechanisms developed by the bacterium to maintain its internal pH are also considered. The replicational, transcriptional, and translational apparatuses are reviewed, as is the regulatory network. The numerous findings on the metabolism of the bacteria and the paucity of gene expression regulation systems are indicative of the high level of adaptation to the human gastric environment. Arguments in favor of the diversity of H. pylori and molecular data reflecting possible mechanisms involved in this diversity are presented. Finally, we compare the numerous experimental data on the colonization factors and those provided from the genome sequence annotation, in particular for genes involved in motility and adherence of the bacterium to the gastric tissue.
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Affiliation(s)
- A Marais
- Laboratoire de Bactériologie, Université Victor Segalen Bordeaux 2, 33076 Bordeaux Cedex, France
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46
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Abstract
This map is an update of the edition 9 map by Berlyn et al. (M. K. B. Berlyn, K. B. Low, and K. E. Rudd, p. 1715-1902, in F. C. Neidhardt et al., ed., Escherichia coli and Salmonella: cellular and molecular biology, 2nd ed., vol. 2, 1996). It uses coordinates established by the completed sequence, expressed as 100 minutes for the entire circular map, and adds new genes discovered and established since 1996 and eliminates those shown to correspond to other known genes. The latter are included as synonyms. An alphabetical list of genes showing map location, synonyms, the protein or RNA product of the gene, phenotypes of mutants, and reference citations is provided. In addition to genes known to correspond to gene sequences, other genes, often older, that are described by phenotype and older mapping techniques and that have not been correlated with sequences are included.
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Affiliation(s)
- M K Berlyn
- Department of Biology and School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06520-8104, USA.
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Black PN, DiRusso CC. Molecular and biochemical analyses of fatty acid transport, metabolism, and gene regulation in Escherichia coli. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1210:123-45. [PMID: 8280762 DOI: 10.1016/0005-2760(94)90113-9] [Citation(s) in RCA: 128] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- P N Black
- Department of Biochemistry, College of Medicine, University of Tennessee, Memphis 38163
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Abstract
A list of currently identified gene products of Escherichia coli is given, together with a bibliography that provides pointers to the literature on each gene product. A scheme to categorize cellular functions is used to classify the gene products of E. coli so far identified. A count shows that the numbers of genes concerned with small-molecule metabolism are on the same order as the numbers concerned with macromolecule biosynthesis and degradation. One large category is the category of tRNAs and their synthetases. Another is the category of transport elements. The categories of cell structure and cellular processes other than metabolism are smaller. Other subjects discussed are the occurrence in the E. coli genome of redundant pairs and groups of genes of identical or closely similar function, as well as variation in the degree of density of genetic information in different parts of the genome.
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Affiliation(s)
- M Riley
- Marine Biological Laboratory, Woods Hole, Massachusetts 02543
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Houng HS, Noon KF, Ou JT, Baron LS. Expression of Vi antigen in Escherichia coli K-12: characterization of ViaB from Citrobacter freundii and identity of ViaA with RcsB. J Bacteriol 1992; 174:5910-5. [PMID: 1522067 PMCID: PMC207128 DOI: 10.1128/jb.174.18.5910-5915.1992] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The Vi antigen in Salmonella typhi is stably expressed and may act to protect the strain against the defensive system of the host. Citrobacter freundii, not usually a common human pathogen, also expresses the Vi antigen but expresses it unstably, exhibiting a reversible transition between the Vi+ and Vi- states. Two widely separated chromosomal regions, ViaA and ViaB, are needed for Vi synthesis. Escherichia coli K-12 harboring a functional ViaB plasmid can also express Vi antigen, but the cloned ViaB sequence can only be stably maintained and expressed in recA hosts. Vi- derivatives arise either through IS1-like insertional events occurring in ViaB sequences or by chromosomal mutations at the ViaA region. P1vir mapping indicates that the ViaA mutations are located at min 47.75 on the E. coli chromosome. All the spontaneous viaA mutants isolated from E. coli and S. typhi were identified as rcsB mutants by complementation tests using plasmid pJB100. Introduction of rcsA::Tn10 into E. coli harboring functional ViaB sequences eliminates the expression of Vi antigen. These results indicate that Vi antigen synthesis is regulated by the same regulatory proteins involved in colanic acid synthesis in E. coli.
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Affiliation(s)
- H S Houng
- Department of Bacterial Immunology, Walter Reed Army Institute of Research, Washington, D.C. 20307
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