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Title
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Structural analysis of the L-methionine gamma-lyase gene from Pseudomonas putida.
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Authors
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H.Inoue,
K.Inagaki,
M.Sugimoto,
N.Esaki,
K.Soda,
H.Tanaka.
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Ref.
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J Biochem (tokyo), 1995,
117,
1120-1125.
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PubMed id
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Abstract
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The gene encoding L-methionine gamma-lyase from Pseudomonas putida was cloned
and the primary structure of the enzyme was deduced from its nucleotide
sequence. The L-methionine gamma-lyase gene was expressed in Escherichia coli.
The amino acid sequences of BrCN-digested peptides agreed with the corresponding
parts of the L-methionine gamma-lyase sequence determined from the gene
structure. The polypeptide is composed of 398 amino acid residues with a
calculated molecular weight of 42,626, corresponding to the subunit of the
homotetrameric enzyme. The deduced amino acid sequence of L-methionine
gamma-lyase only showed extensive homology with other well known
alpha,gamma-elimination and/or gamma-replacement pyridoxal
5'-phosphate-dependent enzymes, such as cystathionine gamma-lyase, cystathionine
gamma-synthase, and O-acetylhomoserine O-acetylserine sulfhydrylase, that
participate in the biosynthesis of sulfur amino acids. However, the deduced
essential cysteine residue of L-methionine gamma-lyase was not conserved in
these enzymes. We confirmed the presence of a part of an open reading frame in
the 3'-flanking region of the L-methionine gamma-lyase gene, which showed high
homology with the N-terminal region of pyruvate dehydrogenase (lipoamide) from
E. coli, suggesting that it participates in the degradative pathway for
L-methionine together with L-methionine gamma-lyase.
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