3BHF

Crystal structure of R49K mutant of Monomeric Sarcosine Oxidase crystallized in PEG as precipitant

Summary for 3BHF

• Entry DOI: 10.2210/pdb3bhf/pdb
• Related: 1L9F 3BHK
• Descriptor: Monomeric sarcosine oxidase, CHLORIDE ION, FLAVIN-ADENINE DINUCLEOTIDE, ... (4 entities in total)
• Functional Keywords: flavoprotein oxidase, cytoplasm, fad, oxidoreductase
• Biological source: Bacillus sp.
• Cellular location: Cytoplasm: P40859
• Total number of polymer chains: 2
• Total formula weight: 88051.08

Authors

Hassan-Abdallah, A.,Zhao, G.,Chen, Z.,Mathews, F.S.,Jorns, M.S. (deposition date: 2007-11-28, release date: 2008-02-26, Last modification date: 2023-08-30)

Primary citation

Hassan-Abdallah, A.,Zhao, G.,Chen, Z.W.,Mathews, F.S.,Schuman Jorns, M.
Arginine 49 is a bifunctional residue important in catalysis and biosynthesis of monomeric sarcosine oxidase: a context-sensitive model for the electrostatic impact of arginine to lysine mutations.
Biochemistry, 47:2913-2922, 2008

PubMed Abstract: Monomeric sarcosine oxidase (MSOX) contains covalently bound FAD and catalyzes the oxidative demethylation of sarcosine ( N-methylglycine). The side chain of Arg49 is in van der Waals contact with the si face of the flavin ring; sarcosine binds just above the re face. Covalent flavin attachment requires a basic residue (Arg or Lys) at position 49. Although flavinylation is scarcely affected, mutation of Arg49 to Lys causes a 40-fold decrease in k cat and a 150-fold decrease in k cat/ K m sarcosine. The overall structure of the Arg49Lys mutant is very similar to wild-type MSOX; the side chain of Lys49 in the mutant is nearly congruent to that of Arg49 in the wild-type enzyme. The Arg49Lys mutant exhibits several features consistent with a less electropositive active site: (1) Charge transfer bands observed for mutant enzyme complexes with competitive inhibitors absorb at higher energy than the corresponding wild-type complexes. (2) The p K a for ionization at N(3)H of FAD is more than two pH units higher in the mutant than in wild-type MSOX. (3) The reduction potential of the oxidized/radical couple in the mutant is 100 mV lower than in the wild-type enzyme. The lower reduction potential is likely to be a major cause of the reduced catalytic activity of the mutant. Electrostatic interactions with Arg49 play an important role in catalysis and covalent flavinylation. A context-sensitive model for the electrostatic impact of an arginine to lysine mutation can account for the dramatically different consequences of the Arg49Lys mutation on MSOX catalysis and holoenzyme biosysnthesis.

PubMed: 18251505
DOI: 10.1021/bi702351v

Experimental method

X-RAY DIFFRACTION (2.1 Å)