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Lee H, Yu SH, Shim JE, Yong D. Use of a combined antibacterial synergy approach and the ANNOgesic tool to identify novel targets within the gene networks of multidrug-resistant Klebsiella pneumoniae. mSystems 2024; 9:e0087723. [PMID: 38349171 PMCID: PMC10949472 DOI: 10.1128/msystems.00877-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Accepted: 01/13/2024] [Indexed: 03/20/2024] Open
Abstract
Since the 1980s, the development of new drug classes for the treatment of multidrug-resistant Klebsiella pneumoniae has become limited, highlighting the urgent need for novel antibiotics. To address this challenge, this study aimed to explore the synergistic interactions between chemical compounds and representative antibiotics, such as carbapenem and colistin. The primary objective of this study was not only to mitigate the adverse impact of multidrug-resistant K. pneumoniae on public health but also to establish a sustainable balance among humans, animals, and the environment. Phenotypical measurements were conducted using the broth microdilution technique to determine the drug sensitivity of bacterial strains. Additionally, a genotypical approach was employed, involving traditional RNA sequencing analysis to identify differentially expressed genes and the computational ANNOgesic tool to detect noncoding RNAs. This study revealed the existence of various pathways and regulatory RNA elements that form a functional network. These pathways, characterized by the expression of specific genes, contribute to the combined treatment effect and bacterial survival strategies. The connections between pathways are facilitated by regulatory RNA elements that respond to environmental changes. These findings suggest an adaptive response of bacteria to harsh environmental conditions.IMPORTANCENoncoding RNAs were identified as key players in post-transcriptional regulation. Moreover, this study predicted the presence of novel small regulatory RNAs that interact with target genes, as well as the involvement of riboswitches and RNA thermometers in conjunction with associated genes. These findings will contribute to the discovery of potential antimicrobial therapeutic candidates. Overall, this study offers valuable insights into the synergistic effects of chemical compounds and antibiotics, highlighting the role of regulatory RNA elements in bacterial response, and survival strategies. The identification of novel noncoding RNAs and their interactions with target genes, riboswitches, and RNA thermometers holds promise for the development of antimicrobial therapies.
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Affiliation(s)
- Hyunsook Lee
- Department of Laboratory Medicine and Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Seoul, South Korea
- Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul, South Korea
| | - Sung-Huan Yu
- Institute of Precision Medicine, College of Medicine, National Sun Yat-sen University, Kaohsiung, Taiwan
- School of Medicine, College of Medicine, National Sun Yat-sen University, Kaohsiung, Taiwan
| | - Jung Eun Shim
- Bioinformatics Collaboration Unit, Yonsei Biomedical Research Institute, Yonsei University College of Medicine, Seoul, South Korea
| | - Dongeun Yong
- Department of Laboratory Medicine and Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Seoul, South Korea
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2
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Valk LC, Luttik MAH, de Ram C, Pabst M, van den Broek M, van Loosdrecht MCM, Pronk JT. A Novel D-Galacturonate Fermentation Pathway in Lactobacillus suebicus Links Initial Reactions of the Galacturonate-Isomerase Route With the Phosphoketolase Pathway. Front Microbiol 2020; 10:3027. [PMID: 32010092 PMCID: PMC6978723 DOI: 10.3389/fmicb.2019.03027] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Accepted: 12/17/2019] [Indexed: 11/13/2022] Open
Abstract
D-galacturonate, a key constituent of pectin, is a ubiquitous monomer in plant biomass. Anaerobic, fermentative conversion of D-galacturonate is therefore relevant in natural environments as well as in microbial processes for microbial conversion of pectin-containing agricultural residues. In currently known microorganisms that anaerobically ferment D-galacturonate, its catabolism occurs via the galacturonate-isomerase pathway. Redox-cofactor balancing in this pathway strongly constrains the possible range of products generated from anaerobic D-galacturonate fermentation, resulting in acetate as the predominant organic fermentation product. To explore metabolic diversity of microbial D-galacturonate fermentation, anaerobic enrichment cultures were performed at pH 4. Anaerobic batch and chemostat cultures of a dominant Lactobacillus suebicus strain isolated from these enrichment cultures produced near-equimolar amounts of lactate and acetate from D-galacturonate. A combination of whole-genome sequence analysis, quantitative proteomics, enzyme activity assays in cell extracts, and in vitro product identification demonstrated that D-galacturonate metabolism in L. suebicus occurs via a novel pathway. In this pathway, mannonate generated by the initial reactions of the canonical isomerase pathway is converted to 6-phosphogluconate by two novel biochemical reactions, catalyzed by a mannonate kinase and a 6-phosphomannonate 2-epimerase. Further catabolism of 6-phosphogluconate then proceeds via known reactions of the phosphoketolase pathway. In contrast to the classical isomerase pathway for D-galacturonate catabolism, the novel pathway enables redox-cofactor-neutral conversion of D-galacturonate to ribulose-5-phosphate. While further research is required to identify the structural genes encoding the key enzymes for the novel pathway, its redox-cofactor coupling is highly interesting for metabolic engineering of microbial cell factories for conversion of pectin-containing feedstocks into added-value fermentation products such as ethanol or lactate. This study illustrates the potential of microbial enrichment cultivation to identify novel pathways for the conversion of environmentally and industrially relevant compounds.
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Affiliation(s)
| | | | | | | | | | | | - Jack T. Pronk
- Department of Biotechnology, Delft University of Technology, Delft, Netherlands
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3
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Zhu F, Qiu N, Sun H, Meng Y, Zhou Y. Integrated Proteomic and N-Glycoproteomic Analyses of Chicken Egg during Embryonic Development. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2019; 67:11675-11683. [PMID: 31545598 DOI: 10.1021/acs.jafc.9b05133] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
To better appreciate the alterations of egg proteins and their modifications during embryonic development, a comparative and quantitative study was performed aimed at chicken egg white and yolk proteome and N-glycoproteome after 12 days of incubation using tandem mass tag (TMT)-labeling technology in conjunction with reversed-phase high-performance liquid chromatography (RP-HPLC). A total of 334 unique N-glycosite-containing peptides from 153 N-glycoproteins were identified, of which 82 N-glycosite-containing peptides showed significant changes after 12 days of incubation. The varied proteome was mainly involved with antibacterial, ionic binding, cell proliferation, and embryonic development, while the different degrading and/or absorbing priorities of egg proteins were proposed. This study provides substantial insight into the effects of N-glycoprotein variations on the utilization of egg proteins by chicken embryo during incubation.
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Affiliation(s)
- Fangli Zhu
- Key Laboratory of Environment Correlative Dietology, Ministry of Education, College of Food Science and Technology , Huazhong Agricultural University , Wuhan , Hubei 430070 , People's Republic of China
| | - Ning Qiu
- Key Laboratory of Environment Correlative Dietology, Ministry of Education, College of Food Science and Technology , Huazhong Agricultural University , Wuhan , Hubei 430070 , People's Republic of China
| | - Haohao Sun
- Key Laboratory of Environment Correlative Dietology, Ministry of Education, College of Food Science and Technology , Huazhong Agricultural University , Wuhan , Hubei 430070 , People's Republic of China
| | - Yaqi Meng
- Key Laboratory of Environment Correlative Dietology, Ministry of Education, College of Food Science and Technology , Huazhong Agricultural University , Wuhan , Hubei 430070 , People's Republic of China
| | - Yu Zhou
- Key Laboratory of Environment Correlative Dietology, Ministry of Education, College of Food Science and Technology , Huazhong Agricultural University , Wuhan , Hubei 430070 , People's Republic of China
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4
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An optogenetic toolbox of LOV-based photosensitizers for light-driven killing of bacteria. Sci Rep 2018; 8:15021. [PMID: 30301917 PMCID: PMC6177443 DOI: 10.1038/s41598-018-33291-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Accepted: 09/26/2018] [Indexed: 01/04/2023] Open
Abstract
Flavin-binding fluorescent proteins (FPs) are genetically encoded in vivo reporters, which are derived from microbial and plant LOV photoreceptors. In this study, we comparatively analyzed ROS formation and light-driven antimicrobial efficacy of eleven LOV-based FPs. In particular, we determined singlet oxygen (1O2) quantum yields and superoxide photosensitization activities via spectroscopic assays and performed cell toxicity experiments in E. coli. Besides miniSOG and SOPP, which have been engineered to generate 1O2, all of the other tested flavoproteins were able to produce singlet oxygen and/or hydrogen peroxide but exhibited remarkable differences in ROS selectivity and yield. Accordingly, most LOV-FPs are potent photosensitizers, which can be used for light-controlled killing of bacteria. Furthermore, the two variants Pp2FbFP and DsFbFP M49I, exhibiting preferential photosensitization of singlet oxygen or singlet oxygen and superoxide, respectively, were shown to be new tools for studying specific ROS-induced cell signaling processes. The tested LOV-FPs thus further expand the toolbox of optogenetic sensitizers usable for a broad spectrum of microbiological and biomedical applications.
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The regulatory role of the transcription factor Crz1 in stress tolerance, pathogenicity, and its target gene expression in Metarhizium acridum. Appl Microbiol Biotechnol 2017; 101:5033-5043. [DOI: 10.1007/s00253-017-8290-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 03/24/2017] [Accepted: 03/27/2017] [Indexed: 12/29/2022]
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Roy S, Patra T, Golder T, Chatterjee S, Koley H, Nandy RK. Characterization of the gluconate utilization system ofVibrio choleraewith special reference to virulence modulation. Pathog Dis 2016; 74:ftw085. [DOI: 10.1093/femspd/ftw085] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/05/2016] [Indexed: 11/13/2022] Open
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7
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Abstract
Following elucidation of the regulation of the lactose operon in Escherichia coli, studies on the metabolism of many sugars were initiated in the early 1960s. The catabolic pathways of D-gluconate and of the two hexuronates, D-glucuronate and D-galacturonate, were investigated. The post genomic era has renewed interest in the study of these sugar acids and allowed the complete characterization of the D-gluconate pathway and the discovery of the catabolic pathways for L-idonate, D-glucarate, galactarate, and ketogluconates. Among the various sugar acids that are utilized as sole carbon and energy sources to support growth of E. coli, galacturonate, glucuronate, and gluconate were shown to play an important role in the colonization of the mammalian large intestine. In the case of sugar acid degradation, the regulators often mediate negative control and are inactivated by interaction with a specific inducer, which is either the substrate or an intermediate of the catabolism. These regulators coordinate the synthesis of all the proteins involved in the same pathway and, in some cases, exert crosspathway control between related catabolic pathways. This is particularly well illustrated in the case of hexuronide and hexuronate catabolism. The structural genes encoding the different steps of hexuronate catabolism were identified by analysis of numerous mutants affected for growth with galacturonate or glucuronate. E. coli is able to use the diacid sugars D-glucarate and galactarate (an achiral compound) as sole carbon source for growth. Pyruvate and 2-phosphoglycerate are the final products of the D-glucarate/galactarate catabolism.
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Cao Y, Du M, Luo S, Xia Y. Calcineurin modulates growth, stress tolerance, and virulence in Metarhizium acridum and its regulatory network. Appl Microbiol Biotechnol 2014; 98:8253-65. [DOI: 10.1007/s00253-014-5876-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2014] [Revised: 05/23/2014] [Accepted: 05/29/2014] [Indexed: 10/25/2022]
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9
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Rohatgi N, Nielsen TK, Bjørn SP, Axelsson I, Paglia G, Voldborg BG, Palsson BO, Rolfsson Ó. Biochemical characterization of human gluconokinase and the proposed metabolic impact of gluconic acid as determined by constraint based metabolic network analysis. PLoS One 2014; 9:e98760. [PMID: 24896608 PMCID: PMC4045858 DOI: 10.1371/journal.pone.0098760] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 05/06/2014] [Indexed: 11/19/2022] Open
Abstract
The metabolism of gluconate is well characterized in prokaryotes where it is known to be degraded following phosphorylation by gluconokinase. Less is known of gluconate metabolism in humans. Human gluconokinase activity was recently identified proposing questions about the metabolic role of gluconate in humans. Here we report the recombinant expression, purification and biochemical characterization of isoform I of human gluconokinase alongside substrate specificity and kinetic assays of the enzyme catalyzed reaction. The enzyme, shown to be a dimer, had ATP dependent phosphorylation activity and strict specificity towards gluconate out of 122 substrates tested. In order to evaluate the metabolic impact of gluconate in humans we modeled gluconate metabolism using steady state metabolic network analysis. The results indicate that significant metabolic flux changes in anabolic pathways linked to the hexose monophosphate shunt (HMS) are induced through a small increase in gluconate concentration. We argue that the enzyme takes part in a context specific carbon flux route into the HMS that, in humans, remains incompletely explored. Apart from the biochemical description of human gluconokinase, the results highlight that little is known of the mechanism of gluconate metabolism in humans despite its widespread use in medicine and consumer products.
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Affiliation(s)
- Neha Rohatgi
- Center for Systems Biology, University of Iceland, Reykjavik, Iceland
- University of Iceland Biomedical Center, Reykjavik, Iceland
| | - Tine Kragh Nielsen
- Center for Protein Research, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Sara Petersen Bjørn
- Center for Protein Research, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ivar Axelsson
- Center for Systems Biology, University of Iceland, Reykjavik, Iceland
| | - Giuseppe Paglia
- Center for Systems Biology, University of Iceland, Reykjavik, Iceland
| | - Bjørn Gunnar Voldborg
- Center for Protein Research, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Óttar Rolfsson
- Center for Systems Biology, University of Iceland, Reykjavik, Iceland
- University of Iceland Biomedical Center, Reykjavik, Iceland
- * E-mail:
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10
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Cetó X, Céspedes F, Capdevila J, del Valle M. A new amperometric bienzymatic biosensor based on biocomposites for the determination of gluconic acid in wines. Talanta 2011; 85:1207-12. [PMID: 21726760 DOI: 10.1016/j.talanta.2011.05.047] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Revised: 05/16/2011] [Accepted: 05/24/2011] [Indexed: 11/18/2022]
Abstract
A new amperometric bienzymatic biosensor for gluconic acid based on the coimmobilization of gluconokinase (EC 2.7.1.12) and phosphogluconate dehydrogenase (EC 1.1.1.44) by polysulfone membrane entrapment onto the surface of a graphite-epoxy composite is reported. This biosensor represents an alternative to gluconate dehydrogenase (EC 1.1.99.3) based methods, which is no longer commercially available. Measurements were done at an applied potential of +0.800 V, room temperature and phosphate buffer pH 7.50; obtaining a linear response range for gluconic acid extended from 7.0 × 10(-6) to 2.5 × 10(-4)M. Constructed biosensors showed good reproducibility for calibrations using different electrodes (RSD of 1.74%). Finally, biosensor was applied to real wine samples, and the results obtained were validated by comparison with those provided by a reference laboratory. Good correlation was found when the biosensor results were plotted vs. the reference values (slope=1.03 ± 0.04, intercept=0.01 ± 0.02, r(2)=0.995).
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Affiliation(s)
- Xavier Cetó
- Sensors and Biosensors Group, Department of Chemistry, Universitat Autònoma de Barcelona, Edifici Cn, 08193 Bellaterra, Barcelona, Spain
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11
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Leipe DD, Koonin EV, Aravind L. Evolution and classification of P-loop kinases and related proteins. J Mol Biol 2003; 333:781-815. [PMID: 14568537 DOI: 10.1016/j.jmb.2003.08.040] [Citation(s) in RCA: 224] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Sequences and structures of all P-loop-fold proteins were compared with the aim of reconstructing the principal events in the evolution of P-loop-containing kinases. It is shown that kinases and some related proteins comprise a monophyletic assemblage within the P-loop NTPase fold. An evolutionary classification of these proteins was developed using standard phylogenetic methods, analysis of shared sequence and structural signatures, and similarity-based clustering. This analysis resulted in the identification of approximately 40 distinct protein families within the P-loop kinase class. Most of these enzymes phosphorylate nucleosides and nucleotides, as well as sugars, coenzyme precursors, adenosine 5'-phosphosulfate and polynucleotides. In addition, the class includes sulfotransferases, amide bond ligases, pyrimidine and dihydrofolate reductases, and several other families of enzymes that have acquired new catalytic capabilities distinct from the ancestral kinase reaction. Our reconstruction of the early history of the P-loop NTPase fold includes the initial split into the common ancestor of the kinase and the GTPase classes, and the common ancestor of ATPases. This was followed by the divergence of the kinases, which primarily phosphorylated nucleoside monophosphates (NMP), but could have had broader specificity. We provide evidence for the presence of at least two to four distinct P-loop kinases, including distinct forms specific for dNMP and rNMP, and related enzymes in the last universal common ancestor of all extant life forms. Subsequent evolution of kinases seems to have been dominated by the emergence of new bacterial and, to a lesser extent, archaeal families. Some of these enzymes retained their kinase activity but evolved new substrate specificities, whereas others acquired new activities, such as sulfate transfer and reduction. Eukaryotes appear to have acquired most of their kinases via horizontal gene transfer from Bacteria, partly from the mitochondrial and chloroplast endosymbionts and partly at later stages of evolution. A distinct superfamily of kinases, which we designated DxTN after its sequence signature, appears to have evolved in selfish replicons, such as bacteriophages, and was subsequently widely recruited by eukaryotes for multiple functions related to nucleic acid processing and general metabolism. In the course of this analysis, several previously undetected groups of predicted kinases were identified, including widespread archaeo-eukaryotic and archaeal families. The results could serve as a framework for systematic experimental characterization of new biochemical and biological functions of kinases.
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Affiliation(s)
- Detlef D Leipe
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
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Tsunedomi R, Izu H, Kawai T, Matsushita K, Ferenci T, Yamada M. The activator of GntII genes for gluconate metabolism, GntH, exerts negative control of GntR-regulated GntI genes in Escherichia coli. J Bacteriol 2003; 185:1783-95. [PMID: 12618441 PMCID: PMC150117 DOI: 10.1128/jb.185.6.1783-1795.2003] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Gluconate is one of the preferred carbon sources of Escherichia coli, and two sets of gnt genes (encoding the GntI and GntII systems) are involved in its transport and metabolism. GntR represses the GntI genes gntKU and gntT, whereas GntH was previously suggested to be an activator for the GntII genes gntV and idnDO-gntWH. The helix-turn-helix residues of the two regulators GntR and GntH exhibit extensive homologies. The similarity between the two regulators prompted analysis of the cross-regulation of the GntI genes by GntH. Repression of gntKU and gntT by GntH, as well as GntR, was indeed observed using transcriptional fusions and RNA analysis. High GntH expression, from cloned gntH or induced through 5-ketogluconate, was required to observe repression of GntI genes. Two GntR-binding elements were identified in the promoter-operator region of gntKU and were also shown to be the target sites of GntH by mutational analysis. However, the GntI genes were not induced by gluconate in the presence of enhanced amounts of GntH, whereas repression by GntR was relieved by gluconate. The repression of GntI genes by GntH is thus unusual in that it is not relieved by the availability of substrate. These results led us to propose that GntH activates GntII and represses the GntI genes in the presence of metabolites derived from gluconate, allowing the organism to switch from the GntI to the GntII system. This cross-regulation may explain the progressive changes in gnt gene expression along with phases of cell growth in the presence of gluconate.
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Affiliation(s)
- Ryouichi Tsunedomi
- Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Yamaguchi 753-8515, Japan
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Kraft L, Sprenger GA, Lindqvist Y. Conformational changes during the catalytic cycle of gluconate kinase as revealed by X-ray crystallography. J Mol Biol 2002; 318:1057-69. [PMID: 12054802 DOI: 10.1016/s0022-2836(02)00215-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The crystal structure of gluconate kinase from Escherichia coli has been determined to 2.0 A resolution by X-ray crystallography. The three-dimensional structure was solved by multi-wavelength anomalous dispersion, using a crystal of selenomethionine-substituted enzyme. Gluconate kinase is an alpha/beta structure consisting of a twisted parallel beta-sheet surrounded by alpha-helices with overall topology similar to nucleoside monophosphate (NMP) kinases, such as adenylate kinase. In order to identify residues involved in substrate binding and catalysis, structures of binary complexes with ATP, the ATP analogue adenosine 5'-(beta,gamma-methylene) triphosphate and the product, gluconate-6-phosphate have been determined. Significant conformational changes are induced upon binding of ATP to the enzyme. The largest changes involve a hinge-bending motion of the NMP(bind) part and a motion of the LID with adjacent helices, which opens the cavity to the second substrate, gluconate. Opening of the active site cleft upon ATP binding is the opposite of what has been observed in the NMP kinase family so far, which usually close their active site to prevent fortuitous hydrolysis of ATP. The conformational change positions the side-chain of Arg120 to stack with the purine ring of ATP and the side-chain of Arg124 is shifted to interact with the alpha-phosphate in ATP, at the same time protecting ATP from solvent water. The beta and gamma-phosphate groups of ATP bind in the predicted P-loop. A conserved lysine side-chain interacts with the gamma-phosphate group, and might promote phosphoryl transfer. Gluconate-6-phosphate binds with its phosphate group in a similar position as the gamma-phosphate of ATP, consistent with inline phosphoryl transfer. The gluconate binding-pocket in GntK is located in a different position than the nucleoside binding-site usually found in NMP kinases.
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Affiliation(s)
- Louise Kraft
- Molecular Structural Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17177 Stockholm, Sweden
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14
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Abstract
We present a summary of recent progress in understanding Escherichia coli K-12 gene and protein functions. New information has come both from classical biological experimentation and from using the analytical tools of functional genomics. The content of the E. coli genome can clearly be seen to contain elements acquired by horizontal transfer. Nevertheless, there is probably a large, stable core of >3500 genes that are shared among all E. coli strains. The gene-enzyme relationship is examined, and, in many cases, it exhibits complexity beyond a simple one-to-one relationship. Also, the E. coli genome can now be seen to contain many multiple enzymes that carry out the same or closely similar reactions. Some are similar in sequence and may share common ancestry; some are not. We discuss the concept of a minimal genome as being variable among organisms and obligatorily linked to their life styles and defined environmental conditions. We also address classification of functions of gene products and avenues of insight into the history of protein evolution.
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Affiliation(s)
- M Riley
- The Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, Massachusetts 02543, USA. ,
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15
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Izu H, Kawai T, Yamada Y, Aoshima H, Adachi O, Yamada M. Characterization of the gntT gene encoding a high-affinity gluconate permease in Escherichia coli. Gene 1997; 199:203-10. [PMID: 9358057 DOI: 10.1016/s0378-1119(97)00368-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We characterized the gntT gene encoding a high-affinity gluconate permease of Escherichia coli K-12. Primer extension and lacZ-operon fusion analyses revealed that gntT has one strong and two weak promoters, all of which are regulated positively by cAMP-CRP and negatively by GntR. The weak promoters became constitutive when separated from the upstream region including the strong promoter that overlaps a putative GntR-binding sequence. Gluconate-specific uptake activity was observed with cells harboring the gntT plasmid clone, which was enhanced by the presence of gntK encoding gluconate kinase.
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Affiliation(s)
- H Izu
- Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Japan
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16
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Izu H, Adachi O, Yamada M. Gene organization and transcriptional regulation of the gntRKU operon involved in gluconate uptake and catabolism of Escherichia coli. J Mol Biol 1997; 267:778-93. [PMID: 9135111 DOI: 10.1006/jmbi.1996.0913] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We cloned and characterized the gntRKU operon encoding part of the GntI system involved in gluconate uptake and catabolism by Escherichia coli. The operon was shown to encode its repressor, a thermoresistant gluconate kinase, and a low affinity gluconate permease. CAT fusion analysis revealed that the operon has a promoter for gntR and another for gntKU, and that the gntR gene is constitutively expressed, while that of gntKU is regulated positively by the cAMP-CRP complex and negatively by GntR. Read-through transcription from the gntR promoter into gntK was decreased in the presence of GntR, although GntR did not repress its own promoter. In addition, transcriptional attenuation was observed after the gntK gene, so gntU expression is reduced presumably to modulate the production of the low affinity gluconate permease according to the available concentration of gluconate.
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Affiliation(s)
- H Izu
- Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Japan
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