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Titel:Studies on the rare earth elements- and calcium- dependent quinoproteins in Pseudomonas putida KT2440
Autor:Elsayed, Eslam Mohsen Ahmed Gabr
Weitere Beteiligte: Bange, Gert (Prof. Dr.)
URN: urn:nbn:de:hebis:04-z2021-04761
DDC:540 Chemie


Strukturelle und mechanistische Untersuchung der Seltenerdelemente- und Calcium-abhängigen Chinoproteine in Pseudomonas putida KT2440. Entwickelte PQ, Structural and mechanistic investigation of the rare earth elements- and calcium- dependent quinoproteins in Pseudomonas putida KT2440. Engineered PQ, Biochemie, Strukturbiologie, Mikrobiologie, Biokatalyse, Seltenerdelementen, PQQ, Chinoproteinen, Pseudomonas putida KT2440, Alkoholdehydrogen

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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