Methionine γ-lyase: Mechanistic deductions from the kinetic pH-effects

Faleev, N. G.; Alferov, Kirill V.; Tsvetikova, Marina A.; Morozova, Elena A.; Revtovich, Svetlana V.; Khurs, Elena N.; Vorob’ev, Mikhail M.; Phillips, Robert S.; Demidkina, Tatyana V.; Khomutov, R. M.

doi:10.1016/j.bbapap.2009.06.002

Cited by 16 publications

(1 citation statement)

References 22 publications

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“…The replacement of Tyr114 of P. putida MGL by Phe provided evidence that this residue is a general acid catalyst (Inoue et al, 2000). The data on the pH dependence of the kinetic parameters of the -elimination reaction of l-methionine catalyzed by C. freundii MGL (Faleev et al, 2009) suggested that the Tyr113 hydroxyl group is a base that accepts a proton from the amino group of l-methionine, which is necessary for the transaldimination stage to proceed.…”

Section: Figurementioning

confidence: 99%

Alliin is a suicide substrate ofCitrobacter freundiimethionine γ-lyase: structural bases of inactivation of the enzyme

Morozova¹,

Revtovich²,

Anufrieva³

et al. 2014

Acta Cryst D Biol Crystallogr

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The interaction of Citrobacter freundii methionine γ-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 β-elimination reaction of alliin to form 2-propenethiosulfinate (allicin), pyruvate and ammonia. The β-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 1.45 Å 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.

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Section: Figurementioning

confidence: 99%

Alliin is a suicide substrate ofCitrobacter freundiimethionine γ-lyase: structural bases of inactivation of the enzyme

Morozova¹,

Revtovich²,

Anufrieva³

et al. 2014

Acta Cryst D Biol Crystallogr

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Structural and mechanistic insights into homocysteine degradation by a mutant of methionine γ‐lyase based on substrate‐assisted catalysis

et al. 2017

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Methionine γ-lyse (MGL) catalyzes the α, γ-elimination of l-methionine and its derivatives as well as the α, β-elimination of l-cysteine and its derivatives to produce α-keto acids, volatile thiols, and ammonia. The reaction mechanism of MGL has been characterized by enzymological studies using several site-directed mutants. The Pseudomonas putida MGL C116H mutant showed drastically reduced degradation activity toward methionine while retaining activity toward homocysteine. To understand the underlying mechanism and to discern the subtle differences between these substrates, we analyzed the crystal structures of the reaction intermediates. The complex formed between the C116H mutant and methionine demonstrated that a loop structure (Ala51-Asn64) in the adjacent subunit of the catalytic dimer cannot approach the cofactor pyridoxal 5'-phosphate (PLP) because His116 disrupts the interaction of Asp241 with Lys240, and the liberated side chain of Lys240 causes steric hindrance with this loop. Conversely, in the complex formed between C116H mutant and homocysteine, the thiol moiety of the substrate conjugated with PLP offsets the imidazole ring of His116 via a water molecule, disrupting the interaction of His116 and Asp241 and restoring the interaction of Asp241 with Lys240. These structural data suggest that the Cys116 to His mutation renders the enzyme inactive toward the original substrate, but activity is restored when the substrate is homocysteine due to substrate-assisted catalysis.

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Crystal structure of mutant form Cys115His of Citrobacter freundii methionine γ-lyase complexed with l -norleucine

Revtovich

Morozova

Kulikova

et al. 2017

Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics

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Methionine γ-lyase: Mechanistic deductions from the kinetic pH-effects

Cited by 16 publications

References 22 publications

Alliin is a suicide substrate ofCitrobacter freundiimethionine γ-lyase: structural bases of inactivation of the enzyme

Alliin is a suicide substrate ofCitrobacter freundiimethionine γ-lyase: structural bases of inactivation of the enzyme

Structural and mechanistic insights into homocysteine degradation by a mutant of methionine γ‐lyase based on substrate‐assisted catalysis

Crystal structure of mutant form Cys115His of Citrobacter freundii methionine γ-lyase complexed with l -norleucine

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