One interesting aspect is the involvement and the relevance of one sole enzyme in the microbial tauropine degradation pathway: the tauropine dehydrogenase. Therefore three main questions were studied. The first was to verify the action of a tauropine dehydrogenase in microorganisms. The second step was to further characterize this enzyme by its molecular weight and its localization within bacterial cells. In addition, the degradation pathway downstream of the potential tauropine dehydrogenase should be clarified. Therefore, in this study, the metabolism of tauropine in four different model organisms was investigated. As model organisms a Ralstonia strain from fresh water was used and in addition three terrestrial bacterial strains were isolated.
The metabolism of tauropine in microorganisms is not yet clarified. Tauropine, besides other opines, has also been reported in the context of bacteria. In fact, it was found in plants, which were infected by agrobacteria with a virulent Ti plasmid. The resulting genetic modification leads to tumor formation, and the plant is triggered to produce opines. As plants cannot use opines themselves, the opines serve as nutrition for the agrobacteria and other opine-degrading bacterial strains.
But so far, compared to marine animal phyla, the intermediate steps in the degradation of tauropine in microorganisms are widely unknown. Preliminary investigation in marine bacteria like Ruegeria pomeroyi DSS-3 and Roseovarius nubinhibens ISM has shown that they can use tauropine as source of carbon and nitrogen. Sulfate thereby occurs as end product.
It is possible, that the tauropine degradation in bacteria is analogous to that in invertebrates. This would mean that a dehydrogenase is involved. If in microorganisms tauropine can be degraded into pyruvate and taurine by a tauropine dehydrogenase, it is also possible that taurine is further metabolized in the processes, which are already quite well understood. Those processes could include the taurine dehydrogenase and desulfonation by sulfoacetaldehyde acetyltransferase.
Table of Contents
1. Introduction
1.1 Opines
1.2 The degradation pathway of tauropine in marine invertebrates is well known
1.3 The metabolism of tauropine in microorganisms is not yet clarified
2. Results and Discussion
2.1 Dissimilation pathway of tauropine
2.2 Detection of the metabolites of tauropine degradation
2.3 Investigation of enzymes involved in the tauropine dissimilation pathway
2.4 Identification of the tauropine dehydrogenase in one-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis
2.5 Synthesis of tauropine4,15
2.6 Isolation and identification of potential tauropine-degrading strains
2.7 Screening for antibacterial and antifungal activity of Ralstonia solanacearum
2.8 Summary and Outlook
3. Methods
3.1 Synthesis, purification, identification, and quantification of tauropine
3.2 Isolation and cultivation of tauropine-degrading strains from soil
3.3 16S rDNA analysis of the model organisms
3.4 Screening for antibacterial and antifungal activity
3.5 Growth curves
3.6 Preparation of cell-free extract
3.7 Enzymatic activity tests for clarification of the tauropine degradation pathway
3.8 Identification of the tauropine dehydrogenase in one-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE)
Research Objectives and Topics
This study aims to elucidate the microbial degradation pathway of tauropine, an opine molecule, particularly focusing on the role of tauropine dehydrogenase in bacterial model organisms like Ralstonia solanacearum. The research investigates the enzymatic intermediate steps, validates the involvement of specific enzymes downstream in the pathway, and explores the potential for isolating new tauropine-degrading bacterial strains from environmental samples.
- Microbial metabolism of tauropine in Ralstonia solanacearum.
- Enzymatic characterization of the tauropine dissimilation pathway.
- Isolation and identification of novel environmental tauropine-degrading bacteria.
- Verification of downstream enzymes including taurine dehydrogenase and sulfoacetaldehyde acetyltransferase.
- Structural and functional analysis of tauropine-degrading enzymes via SDS-PAGE and photometric assays.
Excerpt from the Book
Introduction
Tauropine, which is a C5-amino sulfonate (Figure 1), belongs to the group of opines. Opines are molecules, that are typically formed in a reductive condensation reaction of an α-keto acid with an L-amino acid. The first opine to be isolated was D-octopine, which was found in sepia in 1927. D-octopine probably serves as functional analog of lactate for fast energy supply in cephalopods.
Opines in the past have mainly been known to play a role in marine animals, such as in slugs, shells, and worms. Under anoxic circumstances, these phylogenically lower invertebrates would exceedingly use an opine dehydrogenase system than the lactate dehydrogenase in anaerobic glycolysis. As this reaction is essential for adjustment of redox levels in cells, opines occur as end products in the anaerobic metabolism.
The product of the reaction of pyruvate and taurine has been called tauropine. Equivalent names for tauropine are D-rhodoic acid or N-(D-1-Carboxyethyl)-taurine.
For tauropine, not only its significance for the anaerobic metabolism in various marine invertebrate phyla has been clarified. Scientists also succeeded several years ago in isolating the underlying enzyme, called tauropine dehydrogenase.
Summary of Chapters
Introduction: Provides a background on opines, the established knowledge of tauropine metabolism in marine invertebrates, and the current research gap regarding microbial tauropine degradation.
Results and Discussion: Details the experimental validation of the tauropine dissimilation pathway in Ralstonia solanacearum, including metabolite detection, enzymatic assays, and the isolation of new terrestrial degrader strains.
Methods: Describes the specific experimental protocols utilized, including chemical synthesis of tauropine, cultivation techniques, PCR-based 16S rDNA analysis, and various photometric enzyme assays.
Keywords
Tauropine, Tauropine dehydrogenase, Microbial degradation, Ralstonia solanacearum, Opines, Taurine, Enzyme kinetics, Sulfoacetaldehyde acetyltransferase, 16S rDNA, Bacterial metabolism, Dissimilation pathway, SDS-PAGE, Environmental microbiology.
Frequently Asked Questions
What is the primary focus of this research?
The research focuses on the microbial degradation pathway of the opine tauropine, specifically identifying the enzymes involved in its breakdown and investigating how microorganisms like Ralstonia solanacearum metabolize it.
What are the central thematic areas?
The study covers biochemistry, microbial ecology, enzymology, and molecular identification, specifically looking at the metabolic fate of amino sulfonates.
What is the main research question?
The primary goal is to verify the existence and function of a tauropine dehydrogenase in bacteria and to characterize the downstream intermediate steps of the tauropine degradation pathway.
Which scientific methods were employed?
The researchers used photometric enzyme assays, 1D SDS-PAGE for protein identification, peptide fingerprint mass spectrometry, and 16S rDNA sequencing for taxonomic classification of bacterial strains.
What is discussed in the main body of the work?
The main body details the growth of Ralstonia solanacearum on tauropine, the measurement of metabolite concentrations (sulfate and ammonium), the activity tests for various enzymes, and the analysis of environmental soil isolates.
How can this study be characterized by keywords?
Key terms include Tauropine, Tauropine dehydrogenase, microbial degradation, Ralstonia solanacearum, opine metabolism, and downstream enzymatic pathways.
What role does Ralstonia solanacearum play in this study?
It serves as the primary model organism used to investigate and confirm the proposed tauropine degradation pathway.
What were the challenges regarding tauropine synthesis?
The synthesis resulted in a product contaminated with D-alanine, which could not be completely removed under the applied experimental conditions, potentially impacting some quantitative calculations.
Were new degrader strains discovered?
Yes, the researchers successfully isolated three new bacterial strains from forest soil, root stock, and compost, which are capable of degrading tauropine.
What did the SDS-PAGE analysis reveal about the enzymes?
The SDS-PAGE analysis allowed for the identification of potential proteins involved in the pathway, although it proved challenging to unequivocally isolate the tauropine dehydrogenase band due to overlapping molecular weights with other cellular proteins.
- Quote paper
- Manuel Langer (Author), 2015, Microbal Degradation of Tauropine. An investigation, Munich, GRIN Verlag, https://www.grin.com/document/335477
