The modification and targeting of complex metal-cofactors into their apo-enzymes

• Applicant: Professorin Dr. Silke Leimkühler
• Subject Area: Biochemistry
• Term: from 2009 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 157108951

The biosynthesis of the molybdenum cofactor (Moco) in bacteria involves the initial formation of Precursor Z from 5 GTP, its conversion to molybdopterin (MPT), insertion of molybdenum into MPT (Mo-MPT), and further modification of Mo-MPT by the attachment of different nucleofides either forming the bis-molybdopterin dinucleotide cofactor (bis-MGD) or the molybdopterin cytosine dinucleotide cofactor (MCD). Mo-MPT or MCD can be further modified by the addition of a terminal sulfido ligand to the catalytic molybdenum site. After the synthesis of the Moco-variants, the specific form has to be targeted to the respective apo-enzyme. The main goal is to analyze the specificity of Moco insertion into target enzymes and to specify the protein components, e.g. Mocobinding chaperones, involved in this reacfion. In addition, the factors that determine whether Mo- MPT is modified to bis-MGD or MCD are only poorly understood. We will use two different model systems to study the modificafion and targeting of Moco in the cell: the well defined Escherichia coli system, containing enzymes that either bind Mo-MPT, bis-MGD or sulfurated MCD, and the simpler Rhodobacter capsulatus system, which contains only two forms of Moco: sulfurated Mo- MPT and bis-MGD. The main goal is to understand the regulafion and interplay of the specific compounds involved in the maturafion and specific distribution of Moco in bacteria.

• DFG Programme: Research Grants