Mechanism of insertion of prosthetic groups into complex molybdo-enzymes (molybdo-iron-flavo enzymes)

• Applicant: Professor Dr. Günter Schwarz, since 12/2015
• Subject Area: Plant Biochemistry and Biophysics
• Term: from 2009 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 100799727

Complex molybdo-enzymes (Mo-enzymes) such as xanthine dehydrogenase (XDH) and aldehyde oxidase (AO) are composed of two identical subunits each binding molybdenum cofactor (Moco), two iron-sulfur clusters of the [2Fe-2S]-type, and a flavin adenine dinucleotide (FAD). Due to the diversity of these prosthetic groups AO and XDH represent suitable models for studying the sequential insertion of prosthetic groups during protein maturation. Thus, it will be one aim of this project to identify the order of insertion and to show whether the insertion of the previous group is the prerequisite for insertion of the next. For this reason we intend to establish a fully defined in vitro system for insertion of each prosthetic group, in particular FAD and Moco, by using the apo-forms of XDH and AO. Since in vivo the insertion of prosthetic groups is likely to be facilitated by specific proteins we want to identify proteins that are involved in the insertion process. As a unique feature, AO and XDH require sulfuration of the Moco for activation catalyzed by the Moco sulfurase ABA3. Preliminary data include the possibility that not only a sulfur is transferred to AO and XDH by ABA3, but an entire sulfurated Moco. It is thus another aim of this project to co-crystallize ABA3 with its target enzymes.

• DFG Programme: Research Units
• Subproject of: FOR 1220: Prosthetic Groups: Transport and Insertion - PROTRAIN
• Ehemaliger Antragsteller: Dr. Florian Bittner, until 11/2015