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Publisher DOI: 10.3390/microorganisms9112318
Title: Biochemical characterization of recombinant isocitrate dehydrogenase and its putative role in the physiology of an acidophilic micrarchaeon
Language: English
Authors: Winkler, Dennis 
Gfrerer, Sabrina 
Gescher, Johannes 
Keywords: acidophiles;archaea;Micrarchaeota;isocitrate dehydrogenase
Issue Date: 9-Nov-2021
Publisher: Multidisciplinary Digital Publishing Institute
Source: Microorganisms 9 (11): 2318 (2021)
Journal: Microorganisms 
Abstract (english): 
Despite several discoveries in recent years, the physiology of acidophilic Micrarchaeota, such as “Candidatus Micrarchaeum harzensis A_DKE”, remains largely enigmatic, as they highly express numerous genes encoding hypothetical proteins. Due to a lacking genetic system, it is difficult to elucidate the biological function of the corresponding proteins and heterologous expression is required. In order to prove the viability of this approach, A_DKE’s isocitrate dehydrogenase (MhIDH) was recombinantly produced in Escherichia coli and purified to electrophoretic homogeneity for biochemical characterization. MhIDH showed optimal activity around pH 8 and appeared to be specific for NADP+ yet promiscuous regarding divalent cations as cofactors. Kinetic studies showed KM-values of 53.03 _ 5.63 _Mand 1.94 _ 0.12mMand kcat-values of 38.48 _ 1.62 and 43.99 _ 1.46 s1 resulting in kcat/KM-values of 725 _ 107.62 and 22.69 _ 2.15 mM1 s1 for DL-isocitrate and NADP+, respectively. MhIDH’s exceptionally low affinity for NADP+, potentially limiting its reaction rate, can likely be attributed to the presence of a proline residue in the NADP+ binding pocket, which might cause a decrease in hydrogen bonding of the cofactor and a distortion of local secondary structure.
DOI: 10.15480/882.3909
ISSN: 2076-2607
Other Identifiers: doi: 10.3390/microorganisms9112318
Institute: Technische Mikrobiologie V-7 
Document Type: Article
License: CC BY 4.0 (Attribution) CC BY 4.0 (Attribution)
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