Organohalides have been abundantly utilized as pesticides and in industrial processes for the past 100 years, with over 30 000 sites in Europe still being contaminated today. Because of their recalcitrance, large quantities have accumulated in soils, sediments, and groundwater. Many organohalides can cause multiple adverse health effects, including neurological damage, congenital malformations, and a variety of human cancers. Fortunately, bacterial genera from a diverse range of phyla are capable of detoxifying these organohalides via anaerobic respiration, i.e., by using them as their terminal electron acceptor. These metabolic pathways involve a reductive dehalogenation reaction, during which a chlorine atom dissociates and thereby either immediately reduces the toxicity of the organohalide, or enables it to be further degraded by a broader range of organisms. Thus, organohalide-respiring bacteria can be used for the bioremediation of contaminated environments. To be able to support this application, fundamental research on these reactions and the metabolism of organohalide-respiring bacteria is a prerequisite. Many aspects of the physiology of organohalide-respiring bacteria are unresolved. Organohalide-respiring bacteria harbor up to 38 reductive dehalogenase homologous genes, which putatively encode the key enzymes of reductive dehalogenation. However, the regulation, protein-coding ability, the function of these enzymes as well as their interactions with other proteins has yet to be elucidated. Organohalide-respiring bacteria are difficult to study due to their slow growth, low biomass yields, oxygen sensitivity and genetic inaccessibility. The aim of this thesis was to circumvent these obstacles by introducing new methods for studying organohalide respiration and thereby enabling the formulation of informed predictions about the functions of reductive dehalogenases and the identity of their regulators. For this, obligate and facultative organohalide-respiring bacteria were assessed. To form a basis of the current research in the field, all available genomic, transcriptomic and proteomic literature on organohalide-respiring bacteria were reviewed and compared. Through combining quantitative expression data of hundreds of orthologs and subjecting them to statistical analyses, many new aspects of the metabolism of organohalide-respiring bacteria were uncovered. Especially notable were the unclear expression patterns of reductive dehalogenases and their accessory proteins. An important conclusion from this review was that shotgun proteomics is essential to reveal how many reductive dehalogenase proteins are produced in parallel, but this approach alone cannot clarify the function of these enzymes nor their underlying regulation processes. Therefore, the next chapter of this thesis aimed to extend and refine the standard proteomics approaches. First, proteomics conducted via mass spectrometry requires optimization of sample processing and analysis. Utilizing harsher conditions for protein extraction and digestion substantially improved proteome coverage compared to previous studies, especially of membrane proteins. The combination of this approach with a highly stringent statistical filtering procedure allowed a more detailed, reliable and thus more valid view of the proteome to be obtained from the model organism Sulfurospirillum halorespirans. The quantification of the putative protein histidine kinase provided the first evidence of its involvement in controlling organohalide respiration together with the putative response regulator, forming a complete two-component regulatory system. The quantification of the putative quinol dehydrogenase membrane subunit also supported its involvement in the organohalide respiratory chain of this genus. We observed that S. halorespirans undergoes the same type of peculiar memory-effect as Sulfurospirillum multivorans, that is, continuing to produce its complete dehalogenating machinery even after prolonged cultivation on a non-halogenated electron acceptor. To reveal the underlying mechanism, protein lysine acetylation was additionally measured, which is an important post-translational modification involved in many regulatory processes across all living organisms. Lysine acetylations are, e.g., known to alter the binding properties of DNA-interacting proteins like transcription factors or response regulators but have a range of other regulatory effects. In the first ‘acetylome’ study of an organohalide-respiring bacterium and an Epsilonproteobacterium, one-third of all S. halorespirans proteins were found to be acetylated at one point over the course of a long-term cultivation experiment. Interestingly, the putative response regulator of the two-component regulatory system described earlier was acetylated during the metabolic transition phase, after short-term adaptation to a non-halogenated electron acceptor. Another advancement of shotgun proteomics was its combination with thermal proteome profiling to elucidate substrate specificities of reductive dehalogenases and their regulators. The underlying principle behind thermal proteome profiling is to identify the interaction of a protein with a binding ligand through its impact on the thermal stability of the protein. The thermal stability of hundreds of proteins can be measured in parallel by a proteomics approach. Aliquots of protein extract are first incubated at different temperatures, and the non-denatured fraction of each protein is then quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS), thus allowing the composition of melting curves of each protein to be determined. With this unbiased approach, unknown protein-ligand interactions can also be identified. In a proof-of-concept study on S. multivorans, we adapted the method to anaerobic conditions and showed that this technique is suitable for the detection of interactions between enzymes and their specific substrates. For example, a melting curve shift was detected when the tetrachloroethene reductive dehalogenase, PceA, bound to its known substrate, trichloroethene. Furthermore, the melting curve shift of the putative response regulator in the two-component regulatory system indicated at least an indirect interaction between it and trichloroethene, providing the first biochemical evidence of its role in organohalide respiration besides mere expression data. In conclusion, this work not only includes the first systematic analysis of all omics-based studies conducted to date but substantially advanced the methods for assessing organohalide-respiring bacteria by providing a more detailed picture of their physiology. Besides methodological advances, it was demonstrated that the two-component regulatory system interacts with halogenated compounds and that its post-translational modification might impact long-term downregulation of the organohalide respiratory apparatus in Sulfurospirillum spp. The insights into the involvement of the two-component regulatory system in the organohalide respiration of Sulfurospirillum spp. would not have been uncovered by using less complex standard shotgun proteomics measurements. In the future, our findings will help to further elucidate regulators and functioning of reductive dehalogenases also in other organohalide-respiring bacteria.:Summary 7 Zusammenfassung 10 1 Introduction 14 1.1 Halogenated compounds and the environment……………………...……….……. 14 1.2 Transformation of organohalides……………………..……………….…………….. 15 1.3 Reductive dehalogenation………………………..……………………………….…... 16 1.3.1 Dehalococcoides mccartyi……………………………………………….……… 18 1.3.2 Sulfurospirillum spp. …………………..………………………………..……... 20 1.4 Proteomics……………………..………………..…………………………………...….. 22 1.4.1 The principle of shotgun proteomics..………………..………………....……. 22 1.4.2 Protein lysine acetylations–an important post-translational modification…………………………………………………………...………… 24 1.4.3 Thermal proteome profiling..………………..………..……..………………... 28 1.5 Objectives..………………..……..………..………..………………..…………………. 29 2 Publications 31 2.1 Overview of publications..………..………………..………….………..…………….. 31 2.1.1 Publication 1..………..………….………..…….………..………………………. 31 2.1.2 Publication 2..………..…………..………..…….………..……………………… 31 2.1.3 Publication 3..………..…………….………..…..………..……………………… 32 2.1.4 Publication 4..………..…………..……….…..………..……………….……….. 32 2.2 Published articles..………..……………....…………..………..………………..……. 33 3 Discussion 88 3.1 The application of ‘omics’ to organohalide-respiring bacteria..………..………... 88 3.2 Parallel proteome and acetylome analysis..………..………………..…………….. 91 3.2.1 Specific challenges for the analysis of protein lysine acetylations………. 92 3.2.2 Insights into the metabolism of S. halorespirans..………..………………... 93 3.3 Protein interaction analysis by thermal proteome profiling..………..……......... 97 3.3.1 Other potential approaches to study protein-ligand-interactions..…….... 98 3.3.2 Potential of using thermal proteome profiling for organohalide- respiring bacteria..………..……….………..………….………..……………… 99 3.4 Conclusions and future perspectives..………..……………..………..…..………… 101 4 References 104 5 Appendix 118 5.1 Declaration of authorship..………..……………..………..……………………..…… 118 5.2 Author contribution of published articles..………..……………..……………….... 118 5.3 Curriculum vitae..………..………………..…………….………..…………………… 124 5.4 List of publications and conference contributions..………..……………...………. 124 5.5 Acknowledgements..………..………… ………..…………………..…………..…….. 127 5.6 Supplementary material..…………………..………..………………………….……. 128 5.6.1 Supplementary material for Publication 3..………..……..………..……….. 128 / Während der letzten einhundert Jahre wurden halogenierte organische Verbindungen großflächig in Industrie und Landwirtschaft eingesetzt, wodurch heute mehr als 30 000 Flächen in Europa kontaminiert sind. Aufgrund ihrer eingeschränkten Abbaubarkeit konnten sich riesige Mengen in Böden, Sedimenten und Grundwasser ausbreiten. Viele halogenierte organische Verbindungen können erhebliche nachteilige Auswirkungen auf die Gesundheit des Menschen haben, u.a. neurologische Schäden, Fehlbildungen und eine Vielzahl von Krebserkrankungen. Glücklicherweise sind bestimmte Bakterientypen unterschiedlicher Phyla in der Lage, diese Stoffe mittels anaerober Atmung, d.h. über deren Nutzung als terminalen Elektronenakzeptor, umzuwandeln. Diese reduktive Dehalogenierung, bei der ein Chlor-Rest abgespalten wird, vermindert die Toxizität der meisten Organohalide bzw. macht sie zugänglich für den Abbau durch ein breiteres Organismenspektrum. Demgemäß können Organohalid-atmende Bakterien für die Bioremediation kontaminierter Flächen genutzt werden. Voraussetzung für deren Einsatz ist jedoch das Verständnis der zugrundeliegenden biochemischen Reaktionen und des Metabolismus der Organohalid-Atmer. Viele Aspekte der Physiologie Organohalid-atmender Bakterien sind noch ungeklärt. Die Organismen besitzen bis zu 38 unterschiedliche Gene, die reduktive Dehalogenasen, die Schlüsselenzyme der Organohalid-Atmung, kodieren. Allerdings sind deren Regulation, Proteinkodierung, die Funktion der einzelnen Enzyme sowie deren Interaktionen mit anderen Proteinen noch unbekannt. Die Forschung an Organohalid-atmenden Bakterien wird durch deren langsames Wachstum, die geringen Zelldichten, die hohe Sensitivität gegenüber Sauerstoff und fehlende gentechnische Methoden erschwert. Ziel dieser Arbeit war es, die genannten Hindernisse mittels neuartiger Methoden an Organohalid-Atmern zu umgehen und damit Regulatoren und Funktionsweise der reduktiven Dehalogenasen zu bestimmen. Hierfür wurden sowohl obligate als auch fakultative Organohalid-atmende Bakterien herangezogen. Als Grundlage führte ich zunächst alle bisher durchgeführten Genomik-, Transkriptomik- und Proteomikstudien zu Organohalid-atmenden Bakterien zusammen. Hunderte zu Orthologen kombinierte und statistisch analysierte quantitative Expressionsdaten lieferten dabei ein umfassendes Bild vom Metabolismus der Organohalid-Atmer. Insbesondere die unklaren Expressionsmuster der reduktiven Dehalogenasen und ihrer akzessorischen Proteine wurden offenbar. Eine wichtige Erkenntnis des Review-Prozesses war, dass Standard-Proteomikansätze zwar unerlässlich sind, um beispielsweise die gleichzeitige Produktion mehrerer reduktiver Dehalogenasen offenzulegen, aber weder deren Funktionen noch Regulation aufklären können. Aus diesem Grund sollten im weiteren Verlauf dieser Arbeit die bisher genutzten Shotgun-Proteomikmethoden weiterentwickelt werden. Für eine umfassende Proteinanalyse mittels Massenspektrometrie müssen zunächst Probenaufarbeitung und Analyse optimiert werden. Durch die Verwendung harscherer Bedingungen bei Proteinextraktion und -verdau konnten wir die Proteomabdeckung, insbesondere unter Membranproteinen, im Vergleich zu früheren Studien erheblich verbessern. In Kombination mit einem sehr stringenten statistischen Filterprozess erlaubte dies einen detaillierten und validen Blick auf das Proteom des Modellorganismus Sulfurospirillum halorespirans. Die Quantifizierung der mutmaßlichen Protein-Histidinkinase ist der erste Beleg dafür, dass diese zusammen mit dem Regulationsprotein im Zweikomponentensystem an der Kontrolle der Organohalid-Atmung in Sulfurospirillum spp. beteiligt ist. Die quantifizierte Membranuntereinheit der Quinoldehydrogenase stützt die Annahme zu deren Beteiligung an der Atmungskette dieses Organismus. Wir konnten weiterhin zeigen, dass in S. halorespirans die gleiche außergewöhnliche Langzeitregulation wie in Sulfurospirillum multivorans wirksam ist, sodass auch nach langanhaltender Kultivierung auf nicht-halogenierten Substraten der komplette Organohalid-Atmungsapparat synthetisiert wird. Zur Aufklärung der zugrundeliegenden Regulation erweiterten wir unsere Analyse um Protein-Lysin-Acetylierungen, wichtige posttranslationale Modifikationen, die an verschiedensten regulatorischen Prozessen in allen Lebewesen beteiligt sind. Protein-Lysin-Acetylierungen beeinflussen z.B. die Wechselwirkungen zwischen Transkriptionsfaktoren oder Regulationsproteinen und der DNA, aber haben noch viele weitere regulatorische Effekte. In dieser ersten „Acetylom“-Studie an einem Organohalid-atmenden Bakterium bzw. einem Epsilonproteobacterium, konnten wir zeigen, dass ein Drittel aller S. halorespirans-Proteine im Verlauf der Langzeitkultivierung mindestens einmal acetyliert wurden. Interessanterweise war auch das mutmaßliche Regulatorprotein des oben erwähnten Zweikomponentensystems während der metabolischen Umstellungsphase, d.h. nach Kurzzeitanpassung an den nicht-halogenierten Elektronenakzeptor, acetyliert. Eine zusätzliche Weiterentwicklung der klassischen proteomischen Messungen war deren Kombination mit Thermal Proteome Profiling, um Substratspezifitäten und Regulatoren von reduktiven Dehalogenasen zu bestimmen. Zugrundeliegendes Prinzip des Thermal Proteome Profiling ist die Identifikation eines Proteinbindungspartners über dessen Einfluss auf die Thermostabilität der Faltung eines Proteins. Die Thermostabilität tausender Proteine kann mit Hilfe eines Proteomikansatzes bestimmt werden. Hierfür werden extrahierte Proteine zunächst aufgeteilt und unterschiedlichen Temperaturen ausgesetzt. Die nicht-denaturierte Fraktion jedes Proteins kann mittels Flüssigchromatographie mit Tandemmassenspektrometrie-Kopplung (LC-MS/MS) quantifiziert und zu Schmelzkurven zusammengesetzt werden. Mit dieser Methode können auch unbekannte Protein-Liganden-Interaktionen identifiziert werden. In unserer Machbarkeitsstudie an S. multivorans konnten wir zeigen, dass die von uns modifizierte Technik auch zur Aufklärung von Enzym-Substrat-Interaktionen und sogar unter anaeroben Bedigungen eingesetzt werden kann. So konnte nachgewiesen werden, dass die Schmelzkurve der reduktiven Tetrachlorethen-Dehalogenase PceA durch Bindung ihres bekannten Substrates Trichlorethen signifikant verschoben wurde. Außerdem deutet die Verschiebung der Schmelzkurve des mutmaßlichen Regulatorproteins des Zweikomponentensystems zumindest auf eine indirekte Interaktion mit Trichlorethen hin und ist damit, abgesehen von bloßen Expressionsdaten, der erste biochemische Beleg für dessen Rolle bei der Organohalid-Atmung. Zusammenfassend beinhaltet diese Arbeit nicht nur die erste systematische Analyse und Kombination aller bisher verfügbaren „Omics“-Studien, sondern auch deren Weiterenwiclung für die Untersuchung organohalid-atmender Bakterien, wodurch ein detailliertes Bild von deren Physiologie geschaffen werden konnte. Neben den technischen Neuerungen konnte gezeigt werden, dass das Zweikomponentensystem von Sulfurospirillum sp. mit halogenierten organischen Verbindungen interagiert und dass dessen posttranslationale Modifikation die Langzeitreulation des Organohalid-Atmungsapparates beeinflussen könnte. Die Einblicke in die Beteiligung des Zweikomponentensystems an der Organohalidatmung in Sulfurospirillum sp. wären durch Nutzung von weniger komplexen Standard-Proteomikmethoden unentdeckt geblieben. In Zukunft können uns diese neu entwickelten Methoden dabei unterstützen, Funktionalität und Regulation von reduktiven Dehalogenasen in anderen Organohalid-Atmern aufzuklären.:Summary 7 Zusammenfassung 10 1 Introduction 14 1.1 Halogenated compounds and the environment……………………...……….……. 14 1.2 Transformation of organohalides……………………..……………….…………….. 15 1.3 Reductive dehalogenation………………………..……………………………….…... 16 1.3.1 Dehalococcoides mccartyi……………………………………………….……… 18 1.3.2 Sulfurospirillum spp. …………………..………………………………..……... 20 1.4 Proteomics……………………..………………..…………………………………...….. 22 1.4.1 The principle of shotgun proteomics..………………..………………....……. 22 1.4.2 Protein lysine acetylations–an important post-translational modification…………………………………………………………...………… 24 1.4.3 Thermal proteome profiling..………………..………..……..………………... 28 1.5 Objectives..………………..……..………..………..………………..…………………. 29 2 Publications 31 2.1 Overview of publications..………..………………..………….………..…………….. 31 2.1.1 Publication 1..………..………….………..…….………..………………………. 31 2.1.2 Publication 2..………..…………..………..…….………..……………………… 31 2.1.3 Publication 3..………..…………….………..…..………..……………………… 32 2.1.4 Publication 4..………..…………..……….…..………..……………….……….. 32 2.2 Published articles..………..……………....…………..………..………………..……. 33 3 Discussion 88 3.1 The application of ‘omics’ to organohalide-respiring bacteria..………..………... 88 3.2 Parallel proteome and acetylome analysis..………..………………..…………….. 91 3.2.1 Specific challenges for the analysis of protein lysine acetylations………. 92 3.2.2 Insights into the metabolism of S. halorespirans..………..………………... 93 3.3 Protein interaction analysis by thermal proteome profiling..………..……......... 97 3.3.1 Other potential approaches to study protein-ligand-interactions..…….... 98 3.3.2 Potential of using thermal proteome profiling for organohalide- respiring bacteria..………..……….………..………….………..……………… 99 3.4 Conclusions and future perspectives..………..……………..………..…..………… 101 4 References 104 5 Appendix 118 5.1 Declaration of authorship..………..……………..………..……………………..…… 118 5.2 Author contribution of published articles..………..……………..……………….... 118 5.3 Curriculum vitae..………..………………..…………….………..…………………… 124 5.4 List of publications and conference contributions..………..……………...………. 124 5.5 Acknowledgements..………..………… ………..…………………..…………..…….. 127 5.6 Supplementary material..…………………..………..………………………….……. 128 5.6.1 Supplementary material for Publication 3..………..……..………..……….. 128

Indiana University-Purdue University Indianapolis (IUPUI) / Thousands of missense mutations have been found to be associated with human diseases, ~60% of which have been predicted to affect protein stability and/or protein-protein interactions (PPIs). Current proteomic methods for studying the effects of mutations on the cell focus on measures of protein abundance or post-translational modifications (PTMs), which cannot directly be used for PPI analysis. High-throughput methodology to evaluate how mutations in a single protein affect PPI networks would help streamline the characterization of global effects caused by mutant proteins and aid in the prediction of phenotypic outcomes resulting from genomic mutations. Temperature sensitive Mutant Proteome Profiling (TeMPP) is a novel application of a mass spectrometry (MS) based thermal proteome profiling (TPP) approach that measures changes in missense mutant containing proteomes without the requirement for large amounts of starting material, specific antibodies against proteins of interest, and/or genetic manipulation of the biological system. This study measures the impact of temperature sensitivity-inducing missense mutations of proteins in the ubiquitin proteasome system and the transcription termination machinery on the thermal stability of the proteome at large. Results reveal distinct mechanistic details that were not obtained using only steady-state transcriptome and proteome analyses. Furthermore, my data suggests that TeMPP is highly specific to proteins functionally related to the mutated protein of interest and capable of differentiating effects between two proteins in the same complex. Overall, TeMPP provides unique mechanistic insights into missense mutation dysfunction and connection of genotype to phenotype in a rapid, non-biased fashion. Use of this method along with other complementary -omics approaches will help to characterize how missense mutations affect cellular protein homeostasis and thus enable deeper insight into disease phenotypes. / 2022-08-10

Trypanosoma brucei, the causative agent of African trypanosomiasis, and its relatives Trypanosoma cruzi and several Leishmania species belong to a class of protozoa called kinetoplastids that cause a significant health burden in tropical and semitropical countries across the world. While an improved therapy was recently approved for African trypanosomiasis, the therapies available to treat infections caused by T. cruzi and Leishmania spp. remain relatively poor. Improving our understanding of T. brucei metabolism can inform on metabolism of its relatives. The purpose of the research presented in this dissertation was to develop novel tools and methods to study metabolism in T. brucei with the ultimate aim to improve treatments of all kinetoplastid diseases. We developed a novel tool to study glycosomal pH in the bloodstream form of T. brucei. Using this tool, we discovered that this life stage regulates glycosomal pH differently than the procyclic form, or insect-dwelling stage, and only uses sodium/proton transporters to regulate glycosomal pH. I pioneered a thermal proteome profiling method in this parasite to discover drug targets and their effects on cell pathways. Using this method, I found that other proteins may be involved in glycosomal pH regulation, including PEX11 and a vacuolar ATPase. This method also illuminated several important pathways influenced by glycosomal pH regulation, including glycosome proliferation, vesicle trafficking, protein glycosylation, and amino acid transport. Metabolic studies in kinetoplastid parasites are currently hampered by the lack of available chemical probes. We developed a novel flow cytometry-based high-throughput drug screening assay to discover chemical probes of T. brucei glycolysis. This method combines the advantages of phenotypic (or cell-based) screens with the advantage of targeted (purified protein) screens by multiplexing biosensors that measure multiple glycolytic metabolites simultaneously, such as glucose, ATP, and glycosomal pH. The complementary information gained is then used to distinguish the part of glycolysis identified inhibitors target. We validated the method using the well characterized glycolytic and alternative oxidase inhibitors 2-deoxyglucose and salicylhydroxamic acid respectively. We demonstrated the screening assay with a pilot screen of 14,976 compounds with decent hit rates for each sensor (0.2-0.4%). About 64% of rescreened hits repeated activity in at least one sensor. We demonstrated one compound with micromolar activity against two biosensors. In summary, we developed and demonstrated a novel screening method that can discover glycolytic chemical probes to better study metabolism in this and related parasites. There are few methods to study enzyme kinetics in the live-cell environment. I developed a kinetic flow cytometry assay that can measure enzyme and transporter activity using fluorescent biosensors. I demonstrated this by measuring glucose transport kinetics and alternative oxidase inhibition kinetics, with the measured kinetic parameters similar to those previously reported. We plan to expand on this method to measure transport kinetics in the glycosome and other organelles which has not been done before. We previously performed a drug screen to identify inhibitors that decrease intracellular glucose in T. brucei. I have performed preliminary work identifying the glucose transporter THT1 as one of the targets of optimized glucose inhibitors using the previously mentioned thermal proteome profiling method. We expect this finding will improve our ability to move these compounds from hit to lead in the drug discovery pipeline. Together, I have developed several flow cytometry and proteomics methods to better study metabolism in T. brucei. These tools are beginning to be used in related parasites. We expect the discoveries made using these tools will improve our ability to treat these neglected tropical diseases.