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Appl. Environ. Microbiol., 07 1996, 2405-2410, Vol 62, No. 7
Y Nishiya and T Imanaka
Sarcosine oxidase from Arthrobacter sp. TE1826 (SoxA) tightly binds with
the coenzyme flavin adenine dinucleotide (FAD). The amino-terminal region
of this enzyme was recognized as a part of the FAD-binding domain by
homology search analysis. Comparison with other structurally well-known
flavoproteins suggested that the aspartate residue at position 35 (D-35)
and the motif sequence (six residues at positions 12 to 17) were important
for the interaction with FAD. Site-directed mutagenesis of each position
was performed, and mutant SoxAs were purified and characterized. When D-35
was substituted with glutamate, asparagine, and alanine, it was indicated
that the carboxyl group of the side chain interacted with FAD. Changes in
the enzyme-bound FAD were also observed from the altered spectral profiles.
Thirteen mutant SoxAs were obtained by replacing amino acids in the motif
sequence. Most of them showed inhibited or remarkably decreased sarcosine
oxidase activity, and their spectral profiles were altered. However, some
of them were reactivated by chloride ion. Their spectral profiles also
became close to that of wild type in the presence of chloride ion. These
results strongly suggest that the inhibition of interaction of enzyme with
FAD was caused by the substitution in the motif and that it could be
recovered under different conditions.
Copyright © 1996, American Society for Microbiology
Analysis of interaction between the Arthrobacter sarcosine oxidase and the coenzyme flavin adenine dinucleotide by site-directed mutagenesis
Tsuruga Institute of Biotechnology, Toyobo Co., Ltd., Fukui Prefecture, Japan.
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