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Studies on the rare earth elements- and calcium- dependent quinoproteins in Pseudomonas putida KT2440
Rare-earth elements (REEs) have long been believed to play a crucial role in a wide variety of several modern technologies, but insignificant roles for biological processes. In recent days, a growing body of evidence shows a variety of enzymes with REEs-dependent activities. For example, the soil-dw...
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| Formato: | Dissertation |
| Lenguaje: | inglés |
| Publicado: |
Philipps-Universität Marburg
2021
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| Materias: | |
| Acceso en línea: | Texto Completo PDF |
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| Sumario: | Rare-earth elements (REEs) have long been believed to play a crucial role in a wide variety of several modern technologies, but insignificant roles for biological processes. In recent days, a growing body of evidence shows a variety of enzymes with REEs-dependent activities. For example, the soil-dwelling bacterium Pseudomonas putida KT2440 employs the REEs-dependent alcohol dehydrogenase (ADH), PedH (PP_2679), in order to degrade plant-, fungal-, and bacteria-derived volatiles. Mechanistically, PedH resides in the periplasm of P. putida and exhibits activity on a similar set of substrates as its strictly calcium-dependent counterpart PedE (PP_2674). As members of quinoproteins family, both enzymes strictly rely on the redox cofactor pyrroloquinoline quinone (PQQ), which plays an essential role in direct electron transfer towards a c-type cytochrome in the electron transport chain for bacterial ATP synthesis during the periplasmic oxidation process.
There is no clear evidence till now why PedH could be REEs-dependent in its ADH activity while its counterpart PedE utilizes calcium to perform the same function. In the first part of this work, I have tried to get in-depth insights into the structural and mechanistic characterization of PedE and PedH. Structure analysis clearly showed that an aspartate amino acid residue (D325PedH) plays a significant role in the optimization of PedH towards the REEs-dependence. The functional analysis of both ADHs revealed that both enzymes use a cognate c-type cytochrome (PedF) in their periplasmic oxidation process where the REEs-dependent PedH has more catalytical efficiency compared to the calcium-dependent PedE.
On the other hand, understanding the structure and mechanistic background of PedH enables me in collaboration with 2 research groups to engineer PedH as a novel tool for biocatalysis in the second part of this work. In our publication, PedH has been established for a biosynthetic pathway of 2,5-furandicarboxylic acid (FDCA), one of the top 12 value-added renewable chemicals that provides a promising alternative to the petroleum-based terephthalic acid to produce polymers, to reach the goal of net-zero greenhouse gas emissions. |
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| Descripción Física: | 161 Seiten |
| DOI: | 10.17192/z2021.0476 |