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Polyphosphate metabolism and profiling of myristoylation in Sulfolobus acidocaldarius
Archaea were introduced as the third domain of life in the late 1970s. Nevertheless, both chapters of this thesis illustrate that essential metabolic pathways and cellular processes are still not fully understood. An important feature of the archaeal domain is the great variance of organisms, containing some members which are able to adapt to diverse extreme habitats. Previous studies already demonstrated the function of polyP in Archaea, acting in a variety of stress responses and thus helping the cell to adapt to new environmental conditions. Likewise, this polymer was described to provide energy through high-energy phosphoanhydride bonds, as well as having many other functions such as phosphate storage, influence on motility, biofilm formation and copper tolerance in Archaea. With respect to polyP metabolism studied in chapter 3.1, it has been determined for Archaea by bioinformatic analysis that many of these organisms do not comprise a complete metabolic pathway. This includes the Crenarchaeon Sulfolobus acidocaldarius, where no enzyme responsible for polyP synthesis could be ascertained. However, the presence of polyP, as well as the presence of an exopolyphosphatase (PPX), the enzyme responsible for polyP hydrolysis, have been demonstrated in this organism. Accordingly, PPX was biochemically characterized and showed high specific activity, favoring long-chain polyP (P700) degradation. Using 31P NMR analysis, enzymatic degradation of polyP45 was demonstrated, yielding the enzymatically catalyzed formation of orthophosphate and the heat-stable by-product cyclic-P3 (non-enzymatically). In the search for the polyphosphate kinase, the examination of the genome organization revealed two thymidylate kinase (dTMPK) genes (saci_2019, saci_2020) in the gene neighborhood of the ppx gene, with dTMPKs sharing high structural similarity to PPK2 enzymes. Moreover, a third dtmpk gene (saci_0893) was examined, which is differently located in the genome and is the only one of the three dTMPKs comprising dTMPK function. ...
Polyphosphate metabolism and profiling of myristoylation in Sulfolobus acidocaldarius
Archaea were introduced as the third domain of life in the late 1970s. Nevertheless, both chapters of this thesis illustrate that essential metabolic pathways and cellular processes are still not fully understood. An important feature of the archaeal domain is the great variance of organisms, containing some members which are able to adapt to diverse extreme habitats. Previous studies already demonstrated the function of polyP in Archaea, acting in a variety of stress responses and thus helping the cell to adapt to new environmental conditions. Likewise, this polymer was described to provide energy through high-energy phosphoanhydride bonds, as well as having many other functions such as phosphate storage, influence on motility, biofilm formation and copper tolerance in Archaea. With respect to polyP metabolism studied in chapter 3.1, it has been determined for Archaea by bioinformatic analysis that many of these organisms do not comprise a complete metabolic pathway. This includes the Crenarchaeon Sulfolobus acidocaldarius, where no enzyme responsible for polyP synthesis could be ascertained. However, the presence of polyP, as well as the presence of an exopolyphosphatase (PPX), the enzyme responsible for polyP hydrolysis, have been demonstrated in this organism. Accordingly, PPX was biochemically characterized and showed high specific activity, favoring long-chain polyP (P700) degradation. Using 31P NMR analysis, enzymatic degradation of polyP45 was demonstrated, yielding the enzymatically catalyzed formation of orthophosphate and the heat-stable by-product cyclic-P3 (non-enzymatically). In the search for the polyphosphate kinase, the examination of the genome organization revealed two thymidylate kinase (dTMPK) genes (saci_2019, saci_2020) in the gene neighborhood of the ppx gene, with dTMPKs sharing high structural similarity to PPK2 enzymes. Moreover, a third dtmpk gene (saci_0893) was examined, which is differently located in the genome and is the only one of the three dTMPKs comprising dTMPK function. ...
Polyphosphate metabolism and profiling of myristoylation in Sulfolobus acidocaldarius
Höfmann, Svenja (author) / Siebers, Bettina
2023-05-15
Theses
Electronic Resource
English