Int. J. Mol. Sci. 2012, 13(11), 14492-14517; doi:10.3390/ijms131114492
Article

Role of Key Residues at the Flavin Mononucleotide (FMN):Adenylyltransferase Catalytic Site of the Bifunctional Riboflavin Kinase/Flavin Adenine Dinucleotide (FAD) Synthetase from Corynebacterium ammoniagenes

1email, 1email, 1,2 and 1,* email
Received: 24 September 2012; in revised form: 1 November 2012 / Accepted: 2 November 2012 / Published: 8 November 2012
(This article belongs to the Special Issue Flavins)
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: In mammals and in yeast the conversion of Riboflavin (RF) into flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) is catalysed by the sequential action of two enzymes: an ATP:riboflavin kinase (RFK) and an ATP:FMN adenylyltransferase (FMNAT). However, most prokaryotes depend on a single bifunctional enzyme, FAD synthetase (FADS), which folds into two modules: the C-terminal associated with RFK activity and the N-terminal associated with FMNAT activity. Sequence and structural analysis suggest that the 28-HxGH-31, 123-Gx(D/N)-125 and 161-xxSSTxxR-168 motifs from FADS must be involved in ATP stabilisation for the adenylylation of FMN, as well as in FAD stabilisation for FAD phyrophosphorolysis. Mutants were produced at these motifs in the Corynebacterium ammoniagenes FADS (CaFADS). Their effects on the kinetic parameters of CaFADS activities (RFK, FMNAT and FAD pyrophosphorilase), and on substrates and product binding properties indicate that H28, H31, N125 and S164 contribute to the geometry of the catalytically competent complexes at the FMNAT-module of CaFADS.
Keywords: FAD synthetase; ATP:riboflavin kinase; ATP:FMN adenylyltransferase; FAD pyrophosphorylase; site-directed mutagenesis; catalytic activity; substrate binding
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MDPI and ACS Style

Serrano, A.; Frago, S.; Velázquez-Campoy, A.; Medina, M. Role of Key Residues at the Flavin Mononucleotide (FMN):Adenylyltransferase Catalytic Site of the Bifunctional Riboflavin Kinase/Flavin Adenine Dinucleotide (FAD) Synthetase from Corynebacterium ammoniagenes. Int. J. Mol. Sci. 2012, 13, 14492-14517.

AMA Style

Serrano A, Frago S, Velázquez-Campoy A, Medina M. Role of Key Residues at the Flavin Mononucleotide (FMN):Adenylyltransferase Catalytic Site of the Bifunctional Riboflavin Kinase/Flavin Adenine Dinucleotide (FAD) Synthetase from Corynebacterium ammoniagenes. International Journal of Molecular Sciences. 2012; 13(11):14492-14517.

Chicago/Turabian Style

Serrano, Ana; Frago, Susana; Velázquez-Campoy, Adrián; Medina, Milagros. 2012. "Role of Key Residues at the Flavin Mononucleotide (FMN):Adenylyltransferase Catalytic Site of the Bifunctional Riboflavin Kinase/Flavin Adenine Dinucleotide (FAD) Synthetase from Corynebacterium ammoniagenes." Int. J. Mol. Sci. 13, no. 11: 14492-14517.

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