scholarly journals ThiN as a Versatile Domain of Transcriptional Repressors and Catalytic Enzymes of Thiamine Biosynthesis

2017 ◽  
Vol 199 (7) ◽  
Author(s):  
Sungmin Hwang ◽  
Bryan Cordova ◽  
Merna Abdo ◽  
Friedhelm Pfeiffer ◽  
Julie A. Maupin-Furlow
Keyword(s):  
Transcriptional Repressor ◽  
Thiamine Pyrophosphate ◽  
Thiazole Ring ◽  
Transcriptional Repressors ◽  
Thin Domains ◽  
Thin Domain ◽  
Content Type ◽  
Α Helix ◽  
Thiamine Biosynthesis ◽  
Insight Into

ABSTRACT Thiamine biosynthesis is commonly regulated by a riboswitch mechanism; however, the enzymatic steps and regulation of this pathway in archaea are poorly understood. Haloferax volcanii, one of the representative archaea, uses a eukaryote-like Thi4 (thiamine thiazole synthase) for the production of the thiazole ring and condenses this ring with a pyrimidine moiety synthesized by an apparent bacterium-like ThiC (2-methyl-4-amino-5-hydroxymethylpyrimidine [HMP] phosphate synthase) branch. Here we found that archaeal Thi4 and ThiC were encoded by leaderless transcripts, ruling out a riboswitch mechanism. Instead, a novel ThiR transcription factor that harbored an N-terminal helix-turn-helix (HTH) DNA binding domain and C-terminal ThiN (TMP synthase) domain was identified. In the presence of thiamine, ThiR was found to repress the expression of thi4 and thiC by a DNA operator sequence that was conserved across archaeal phyla. Despite having a ThiN domain, ThiR was found to be catalytically inactive in compensating for the loss of ThiE (TMP synthase) function. In contrast, bifunctional ThiDN, in which the ThiN domain is fused to an N-terminal ThiD (HMP/HMP phosphate [HMP-P] kinase) domain, was found to be interchangeable for ThiE function and, thus, active in thiamine biosynthesis. A conserved Met residue of an extended α-helix near the active-site His of the ThiN domain was found to be important for ThiDN catalytic activity, whereas the corresponding Met residue was absent and the α-helix was shorter in ThiR homologs. Thus, we provide new insight into residues that distinguish catalytic from noncatalytic ThiN domains and reveal that thiamine biosynthesis in archaea is regulated by a transcriptional repressor, ThiR, and not by a riboswitch. IMPORTANCE Thiamine pyrophosphate (TPP) is a cofactor needed for the enzymatic activity of many cellular processes, including central metabolism. In archaea, thiamine biosynthesis is an apparent chimera of eukaryote- and bacterium-type pathways that is not well defined at the level of enzymatic steps or regulatory mechanisms. Here we find that ThiN is a versatile domain of transcriptional repressors and catalytic enzymes of thiamine biosynthesis in archaea. Our study provides new insight into residues that distinguish catalytic from noncatalytic ThiN domains and reveals that archaeal thiamine biosynthesis is regulated by a ThiN domain transcriptional repressor, ThiR, and not by a riboswitch.

scholarly journals The Iron Deficiency Response of Corynebacterium glutamicum and a Link to Thiamine Biosynthesis

2020 ◽  
Vol 86 (10) ◽  
Author(s):  
Andreas Küberl ◽  
Aliye Mengus-Kaya ◽  
Tino Polen ◽  
Michael Bott
Keyword(s):  
Corynebacterium Glutamicum ◽  
Iron Homeostasis ◽  
Essential Element ◽  
Iron Limitation ◽  
Thiamine Pyrophosphate ◽  
Exponential Growth Phase ◽  
Iron Starvation ◽  
Content Type ◽  
Oxoglutarate Dehydrogenase ◽  
Thiamine Biosynthesis

ABSTRACT The response to iron limitation of the Gram-positive soil bacterium Corynebacterium glutamicum was analyzed with respect to secreted metabolites, the transcriptome, and the proteome. During growth in glucose minimal medium, iron limitation caused a shift from lactate to pyruvate as the major secreted organic acid complemented by l-alanine and 2-oxoglutarate. Transcriptome and proteome analyses revealed that a pronounced iron starvation response governed by the transcriptional regulators DtxR and RipA was detectable in the late, but not in the early, exponential-growth phase. A link between iron starvation and thiamine pyrophosphate (TPP) biosynthesis was uncovered by the strong upregulation of thiC. As phosphomethylpyrimidine synthase (ThiC) contains an iron-sulfur cluster, limiting activities of the TPP-dependent pyruvate–2-oxoglutarate dehydrogenase supercomplex probably cause the excretion of pyruvate and 2-oxoglutarate. In line with this explanation, thiamine supplementation could strongly diminish the secretion of these acids. The upregulation of thiC and other genes involved in thiamine biosynthesis and transport is presumably due to TPP riboswitches present at the 5′ end of the corresponding operons. The results obtained in this study provide new insights into iron homeostasis in C. glutamicum and demonstrate that the metabolic consequences of iron limitation can be due to the iron dependency of coenzyme biosynthesis. IMPORTANCE Iron is an essential element for most organisms but causes problems due to poor solubility under oxic conditions and due to toxicity by catalyzing the formation of reactive oxygen species (ROS). Therefore, bacteria have evolved complex regulatory networks for iron homeostasis aiming at a sufficient iron supply while minimizing ROS formation. In our study, the responses of the actinobacterium Corynebacterium glutamicum to iron limitation were analyzed, resulting in a detailed view on the processes involved in iron homeostasis in this model organism. In particular, we provide evidence that iron limitation causes TPP deficiency, presumably due to insufficient activity of the iron-dependent phosphomethylpyrimidine synthase (ThiC). TPP deficiency was deduced from the upregulation of genes controlled by a TPP riboswitch and secretion of metabolites caused by insufficient activity of the TPP-dependent enzymes pyruvate dehydrogenase and 2-oxoglutarate dehydrogenase. To our knowledge, the link between iron starvation and thiamine synthesis has not been elaborated previously.

scholarly journals A Novel Transcriptional Regulator Related to Thiamine Phosphate Synthase Controls Thiamine Metabolism Genes in Archaea

2016 ◽  
Vol 199 (4) ◽  
Author(s):  
Dmitry A. Rodionov ◽  
Semen A. Leyn ◽  
Xiaoqing Li ◽  
Irina A. Rodionova
Keyword(s):  
Comparative Genomics ◽  
Dna Binding ◽  
Transcriptional Control ◽  
Binding Domain ◽  
Thiamine Pyrophosphate ◽  
Vitamin B ◽  
Binding Assays ◽  
Content Type ◽  
Thiamine Metabolism ◽  
Thiamine Biosynthesis

ABSTRACT Thiamine (vitamin B1) is a precursor of thiamine pyrophosphate (TPP), an essential coenzyme in the central metabolism of all living organisms. Bacterial thiamine biosynthesis and salvage genes are controlled at the RNA level by TPP-responsive riboswitches. In Archaea, TPP riboswitches are restricted to the Thermoplasmatales order. Mechanisms of transcriptional control of thiamine genes in other archaeal lineages remain unknown. Using the comparative genomics approach, we identified a novel family of transcriptional regulators (named ThiR) controlling thiamine biosynthesis and transport genes in diverse lineages in the Crenarchaeota phylum as well as in the Halobacteria and Thermococci classes of the Euryarchaeota. ThiR regulators are composed of an N-terminal DNA-binding domain and a C-terminal ligand-binding domain, which is similar to the archaeal thiamine phosphate synthase ThiN. By using comparative genomics, we predicted ThiR-binding DNA motifs and reconstructed ThiR regulons in 67 genomes representing all above-mentioned lineages. The predicted ThiR-binding motifs are characterized by palindromic symmetry with several distinct lineage-specific consensus sequences. In addition to thiamine biosynthesis genes, the reconstructed ThiR regulons include various transporters for thiamine and its precursors. Bioinformatics predictions were experimentally validated by in vitro DNA-binding assays with the recombinant ThiR protein from the hyperthermophilic archaeon Metallosphaera yellowstonensis MK1. Thiamine phosphate and, to some extent, TPP and hydroxyethylthiazole phosphate were required for the binding of ThiR to its DNA targets, suggesting that ThiR is derepressed by limitation of thiamine phosphates. The thiamine phosphate-binding residues previously identified in ThiN are highly conserved in ThiR regulators, suggesting a conserved mechanism for effector recognition. IMPORTANCE Thiamine pyrophosphate is a cofactor for many essential enzymes for glucose and energy metabolism. Thiamine or vitamin B1 biosynthesis and its transcriptional regulation in Archaea are poorly understood. We applied the comparative genomics approach to identify a novel family of regulators for the transcriptional control of thiamine metabolism genes in Archaea and reconstructed the respective regulons. The predicted ThiR regulons in archaeal genomes control the majority of thiamine biosynthesis genes. The reconstructed regulon content suggests that numerous uptake transporters for thiamine and/or its precursors are encoded in archaeal genomes. The ThiR regulon was experimentally validated by DNA-binding assays with Metallosphaera spp. These discoveries contribute to our understanding of metabolic and regulatory networks involved in vitamin homeostasis in diverse lineages of Archaea.

scholarly journals Draft Genome Sequences of 12 Mycolicibacterium smegmatis Strains Resistant to Imidazo[1,2-b][1,2,4,5]Tetrazines

2019 ◽  
Vol 8 (16) ◽  
Author(s):  
Aleksey A. Vatlin ◽  
Kirill V. Shur ◽  
Valery N. Danilenko ◽  
Dmitry A. Maslov
Keyword(s):  
Draft Genome ◽  
Transcriptional Repressor ◽  
Antituberculosis Drug ◽  
Genome Sequences ◽  
Content Type ◽  
Drug Candidates

Here, we report 12 draft genome sequences of mutant Mycolicibacterium smegmatis strains resistant to imidazo[1,2-b][1,2,4,5]tetrazines, which are antituberculosis drug candidates. We have identified 7 different mutations in the MSMEG_1380 gene, which encodes the AcrR/TetR_N transcriptional repressor, which may activate efflux-mediated resistance.

Rethinking bibliographic utilities for library consortia

2020 ◽  
Vol 37 (8) ◽  
pp. 7-9
Author(s):  
Israel Odede
Keyword(s):  
Literature Review ◽  
Paradigm Shift ◽  
Design Methodology ◽  
Distributed Network ◽  
Network Resources ◽  
Content Type ◽  
Library Consortia ◽  
Individual Ownership ◽  
Insight Into

Purpose The paper aims to critically examine the bibliographic utility as a roadmap to increase library consortia and provide an insight into a new library consortia strategy that integrates librarians into a system of sharing both resources and knowledge. Design/methodology/approach This study adopted a literature review approach with a focus on bibliographic utility as a necessary prerequisite for effective library consortia, which is a paradigm shift from the concept of individual ownership to a collective access of distributed network resources and knowledge. Findings The reviewed literature indicated that significant bibliographic utilities and integrated library systems are factors that shaped and developed consortia activities in libraries. Originality/value The bibliographic utility has limited literature, and a few published scholarly studies have combined bibliographic utility and library consortia as strategies to share resources and knowledge

Formation of contracts for the international sale of goods under Korean law and the CISG

2017 ◽  
Vol 21 (3) ◽  
pp. 208-223
Author(s):  
Byung Mun Lee
Keyword(s):  
Comparative Study ◽  
Design Methodology ◽  
Case Law ◽  
The Other ◽  
Basic Question ◽  
Content Type ◽  
International Sale Of Goods ◽  
The Comparative Study ◽  
International Sales ◽  
Insight Into

Purpose The purpose of this paper is to describe and analyze the rules on the formation of contracts under Korean law and the Contracts for the International Sale of Goods (CISG) in a comparative way and introduce the relevant proposed rules under the Amendment Draft of the Korean Civil Code (KCC). In addition, it attempts to compare and evaluate them in light of the discipline of comparative law. Design/methodology/approach In order to achieve the purposes of the study, it executes a comparative study of the rules as to the formation of contracts of the CISG, Korean law and the Amendment Draft of the KCC. The basic question for this comparative study is placed on whether a solution from one jurisdiction is more logical than the others and to what extent each jurisdiction has responded to protect the reasonable expectations of the parties in the rules as to the formation of contracts. Findings The comparative study finds that most of the rules under the CISG are quite plausible and logical and they are more or less well reflected in the proposals advanced by the KCC amendment committee. On the other hand, the other rules under the CISG which have brought criticisms in terms of their complexity and inconsistent case law invite us their revision or consistent interpretation. The drawbacks of the CISG have also been well responded in the Amendment Draft of the KCC. Nevertheless, it is quite unfortunate that the Amendment Draft of the KCC still has a rule that regards any purported performance with non-material alteration of the terms of an offer as an acceptance. Originality/value This study may provide legal and practical advice to both the seller and the buyer when they enter into a contract for international sales of goods. In addition, it may render us an insight into newly developed or developing rules in this area and show us how they interact with each other. Furthermore, it may be particularly useful in Korea where there is an ongoing discussion for revision of the KCC.

Professionals freaking out: the case of accreditation in Dutch higher education

2009 ◽  
Vol 21 (5) ◽  
pp. 473-485 ◽  
Author(s):  
Everard van Kemenade ◽  
Teun W. Hardjono
Keyword(s):  
The Netherlands ◽  
Design Methodology ◽  
Iso 9000 ◽  
Preliminary Survey ◽  
External Evaluation ◽  
Content Type ◽  
Evaluation Systems ◽  
System A ◽  
Engineering And Technology ◽  
Insight Into

PurposeThe purpose of this paper is to define what factors cause willingness and/or resistance among lecturers in universities towards external evaluation systems, especially accreditation.Design/methodology/approachA model has been designed to describe possible factors of willingness and/or resistance towards accreditation based on Ajzen and Metselaar. A literature review has been undertaken on the effects of external evaluation like ISO 9000 as well as accreditation systems such as Accreditation Board for Engineering and Technology and European Quality Improvement System. A questionnaire has been administered to a group of 63 lecturers from three departments at Fontys University in The Netherlands. The results of this preliminary survey have been presented to 1,500 academics in The Netherlands and Flanders to collect empirical data.FindingsResistance to accreditation can be found in the consequences of accreditation for the work of the lecturer (workload), negative emotions (stress and insecurity); the lack of knowledge and experience (help from specialists is needed); and lack of acceptance (other paradigm).Originality/valueThe paper provides more insight into the difficulties that organizations, especially universities, have to commit their employees to external evaluation. It might be possible to generalize the findings to other professionals in other organizations. Little research in this field has been undertaken so far.

scholarly journals The future of financial markets and regulation: what strategy for Europe?

foresight ◽  
2014 ◽  
Vol 16 (2) ◽  
pp. 95-108 ◽  
Author(s):  
Jean-Baptiste Gossé ◽  
Dominique Plihon
Keyword(s):  
Financial Markets ◽  
Capital Market ◽  
Financial Stability ◽  
Design Methodology ◽  
Financial Integration ◽  
Content Type ◽  
Realistic Option ◽  
The Future ◽  
Unstable Environment ◽  
Insight Into

Purpose – This article aims to provide insight into the future of financial markets and regulation in order to define what would be the best strategy for Europe. Design/methodology/approach – First the authors define the potential changes in financial markets and then the tools available for the regulator to tame them. Finally, they build five scenarios according to the main evolutions observed on the financial markets and on the tools used by the regulator to modify these trends. Findings – Among the five scenarios defined, two present highly unstable features since the regulator refuses to choose between financial opening and independently determining how to regulate finance in order to preserve financial stability. Three of them achieve financial stability. However, they are more or less efficient or feasible. In terms of market efficiency, the multi-polar scenario is the best and the fragmentation scenario is the worst, since gains of integration depend on the size of the new capital market. Regarding sovereignty of regulation, fragmentation is the best scenario and the multi-polar scenario is the worst, because it necessitates coordination at the global level which implies moving further away from respective national preferences. However, the more realistic option seems to be the regionalisation scenario: this level of coordination seems much more realistic than the global one; the market should be of sufficient size to enjoy substantial benefits of integration. Nevertheless, the “European government” might gradually increase the degree of financial integration outside Europe in line with the degree of cooperation with the rest of the world. Originality/value – Foresight studies on financial markets and regulation are quite rare. This may be explained by the difficulty to forecast what will be their evolution in the coming decades, not least because finance is fundamentally unstable. This paper provides a framework to consider what could be the best strategy of regulators in such an unstable environment.

Correlation between sustainability education and engineering students’ attitudes towards sustainability

2018 ◽  
Vol 19 (3) ◽  
pp. 459-472 ◽  
Author(s):  
Kuok Ho Daniel Tang
Keyword(s):  
Sustainable Development ◽  
Design Methodology ◽  
Engineering Students ◽  
Sustainability Education ◽  
Content Type ◽  
Fundamental Knowledge ◽  
Students Attitudes ◽  
Development Course ◽  
Beliefs And Attitudes ◽  
Insight Into

Purpose The purpose of this study is to investigate the impacts of a sustainable development course on the beliefs, attitudes and intentions of a cohort of engineering students in a university in Miri, Malaysia, towards sustainability. Design/methodology/approach Questionnaire survey was conducted among the cohort of students encompassing the three facets mentioned. Findings The respondents expressed low to medium agreement towards all the survey items related to beliefs, attitudes and intentions. A sense of moral obligation towards sustainability is linked to higher sustainability awareness, willingness to safeguard sustainability and a sense of responsibility towards sustainable development. The respondents were generally perceived to have fundamental knowledge of sustainable development. Research limitations/implications This study shows that a sustainable development course called Engineering Sustainable Development offered in a university in Miri, produced positive impacts on the beliefs, attitudes and intentions of the engineering students towards sustainable development. Sustainable development courses are generally instrumental to impart the value and practices of sustainability among university students. Originality/value As limited correlational studies on whether sustainable development courses effectively shape the beliefs and attitudes of students have been previously conducted, this study provides insight into the effectiveness of one of such courses and how the course can be further improved to enhance its effectiveness.

The carmine dilemma: does the natural colourant preference outweigh nausea?

2018 ◽  
Vol 120 (8) ◽  
pp. 1915-1928
Author(s):  
Judith Müller-Maatsch ◽  
Johannes Jasny ◽  
Katharina Henn ◽  
Claudia Gras ◽  
Reinhold Carle
Keyword(s):  
Design Methodology ◽  
Consumer Perception ◽  
Natural Food ◽  
German Population ◽  
Misleading Information ◽  
Content Type ◽  
Broad Cross Section ◽  
First Time ◽  
Self Administered Questionnaire ◽  
Insight Into

Purpose The purpose of this paper is to provide insight into the consumers’ perception of natural and artificial food colourants. Furthermore, attitudes towards the application of carmine, being technically important and ubiquitously used to impart red shades, are assessed and analysed. Originating from insects, carmine is considered as natural but may arouse disgust. Design/methodology/approach In total, 625 individuals were surveyed using an online, self-administered questionnaire to represent a broad cross-section of the German population. Findings Independent of their origin, the application of colourants was rejected by 57.0 per cent of the interviewees. In total, 31.8 per cent of the participants stated a neutral attitude, while only 11.2 per cent expressed a positive notion. Most respondents preferred colourants from natural sources to artificial ones. While consumers perceive natural food colourants composed of genuine plant pigments positively, 61.6 per cent of respondents disliked the application of animal-derived colourants, 24.8 per cent of them did neither reject nor like it, and only 13.6 per cent of the interviewees stated a positive attitude towards them. The findings of this paper further indicate consumers’ preference for colourants to be either artificial or plant-derived rather than carmine. Food colourants are being rejected, possibly due to misleading information and confusing labelling. Consequently, information about carmine, including its origin and production, did not increase the aversion to products that are dyed with it, but increased their acceptance. Originality/value This study outlines consumer perception and attitudes towards food colourants. For the first time, the findings of this paper report the effect of revealing information about an additive, which initially aroused disgust, and its influence on consumer perception.

scholarly journals A Cronobacter turicensis O1 Antigen-Specific Monoclonal Antibody Inhibits Bacterial Motility and Entry into Epithelial Cells

2014 ◽  
Vol 83 (3) ◽  
pp. 876-887 ◽  
Author(s):  
Kristina Schauer ◽  
Angelika Lehner ◽  
Richard Dietrich ◽  
Ina Kleinsteuber ◽  
Rocío Canals ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Epithelial Cells ◽  
Foodborne Pathogen ◽  
Antimicrobial Effect ◽  
Infection Model ◽  
Cell Agglutination ◽  
Content Type ◽  
O Antigen ◽  
Lethal Infection ◽  
Insight Into

Cronobacter turicensisis an opportunistic foodborne pathogen that can cause a rare but sometimes lethal infection in neonates. Little is known about the virulence mechanisms and intracellular lifestyle of this pathogen. In this study, we developed an IgG monoclonal antibody (MAb; MAb 2G4) that specifically recognizes the O1 antigen ofC. turicensiscells. The antilipopolysaccharide antibody bound predominantly monovalently to the O antigen and reduced bacterial growth without causing cell agglutination. Furthermore, binding of the antibody to the O1 antigen ofC. turicensiscells caused a significant reduction of the membrane potential which is required to energize flagellar rotation, accompanied by a decreased flagellum-based motility. These results indicate that binding of IgG to the O antigen ofC. turicensiscauses a direct antimicrobial effect. In addition, this feature of the antibody enabled new insight into the pathogenicity ofC. turicensis. In a tissue culture infection model, pretreatment ofC. turicensiswith MAb 2G4 showed no difference in adhesion to human epithelial cells, whereas invasion of bacteria into Caco-2 cells was significantly inhibited.

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