Alliin is a suicide substrate of Citrobacter freundii methionine [gamma]-lyase: structural bases of inactivation of the enzyme

• Published in: Acta crystallographica. Section D, Biological crystallography. Vol. 70; no. 11; p. 3034
• Main Authors: Morozova, Elena A, Revtovich, Svetlana V, Anufrieva, Natalya V, Kulikova, Vitalia V, Nikulin, Alexey D, Demidkina, Tatyana V
• Format: Journal Article
• Language: English
• Published: Chester Wiley Subscription Services, Inc 01.11.2014
• ISSN: 0907-4449; 1399-0047
• DOI: 10.1107/S1399004714020938

The interaction of Citrobacter freundii methionine [gamma]-lyase (MGL) and the mutant form in which Cys115 is replaced by Ala (MGL C115A) with the nonprotein amino acid (2R)-2-amino-3-[(S)-prop-2-enylsulfinyl]propanoic acid (alliin) was investigated. It was found that MGL catalyzes the [beta]-elimination reaction of alliin to form 2-propenethiosulfinate (allicin), pyruvate and ammonia. The [beta]-elimination reaction of alliin is followed by the inactivation and modification of SH groups of the wild-type and mutant enzymes. Three-dimensional structures of inactivated wild-type MGL (iMGL wild type) and a C115A mutant form (iMGL C115A) were determined at 1.85 and 1.45Å resolution and allowed the identification of the SH groups that were oxidized by allicin. On this basis, the mechanism of the inactivation of MGL by alliin, a new suicide substrate of MGL, is proposed.