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Publication Abstract from PubMed

Mutants of flavin mononucleotide-binding protein (FMN-bp) were made by site-directed mutagenesis to investigate the role of carboxyl-terminal Leu122 of the pairing subunit in controlling redox potentials, binding the prosthetic group, and forming the tertiary and quaternary structure. We compared the oxidation-reduction potentials, FMN-binding properties, and higher structures of wild-type FMN-bp and four mutant proteins (L122Y, L122E, L122K and L122-deleted). We found that the redox potentials were affected by mutations. Also, the affinities of L122E, L122K and L122 deletion mutant apoproteins for FMN were lower than for the wild-type apoprotein, whereas the affinity of L122Y for FMN was increased. Analytical ultracentrifugation showed that the dissociation constants for dimerization of L122E and L122K were larger than for wild-type FMN-bp, whereas the dissociation constants for L122Y and the deletion mutant were lower than for the wild type. Finally, we determined the higher structures of L122Y, L122E and L122K mutants by X-ray crystallography. Our results show that the mutation of Leu122 in FMN-bp changes midpoint potentials, dissociation constants for FMN, and dimer formation, indicating that this residue is important in the pairing subunit.

Determination of the role of the Carboxyl-terminal leucine-122 in FMN-binding protein by mutational and structural analysis.,Kitamura M, Terakawa K, Inoue H, Hayashida T, Suto K, Morimoto Y, Yasuoka N, Shibata N, Higuchi Y J Biochem. 2007 Apr;141(4):459-68. Epub 2007 Jan 29. PMID:17261542^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.