TY  - JOUR
A1  - Neumann, Meina
A1  - Seduk, Farida
A1  - Iobbi-Nivol, Chantal
A1  - Leimkühler, Silke
T1  - Molybdopterin Dinucleotide Biosynthesis in Escherichia coli identification of amino acid residues of molybdopterin dinucleotide transferases that determine specificity for binding of guanine or  cytosine nucleotides
T2  - The journal of biological chemistry
N2  - The molybdenum cofactor is modified by the addition of GMP or CMP to the C4' phosphate of molybdopterin forming the molybdopterin guanine dinucleotide or molybdopterin cytosine dinucleotide cofactor, respectively. The two reactions are catalyzed by specific enzymes as follows: the GTP: molybdopterin guanylyltransferase MobA and the CTP: molybdopterin cytidylyltransferase MocA. Both enzymes show 22% amino acid sequence identity and are specific for their respective nucleotides. Crystal structure analysis of MobA revealed two conserved motifs in the N-terminal domain of the protein involved in binding of the guanine base. Based on these motifs, we performed site-directed mutagenesis studies to exchange the amino acids to the sequence found in the paralogue MocA. Using a fully defined in vitro system, we showed that the exchange of five amino acids was enough to obtain activity with both GTP and CTP in either MocA or MobA. Exchange of the complete N-terminal domain of each protein resulted in the total inversion of nucleotide specificity activity, showing that the N-terminal domain determines nucleotide recognition and binding. Analysis of protein-protein interactions showed that the C-terminal domain of either MocA or MobA determines the specific binding to the respective acceptor protein.
Y1  - 2011
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/37077
SN  - 0021-9258
VL  - 286
IS  - 2
SP  - 1400
EP  - 1408
PB  - American Society for Biochemistry and Molecular Biology
CY  - Bethesda
ER  -