Crystal Structure of LAAO from Calloselasma rhodostoma with an l-Phenylalanine Substrate

Insights into Structure and Mechanism

Ibrahim Moustafa, Scott Foster, Artem Y. Lyubimov, Alice Vrielink

Research output: Contribution to journalArticle

94 Citations (Scopus)

Abstract

l-Amino acid oxidase is a dimeric glycosylated flavoenzyme, a major constituent of the venom-from the snake Calloselasma rhodostoma. The enzyme exhibits apoptosis inducing effects as well as antibacterial and anti-HIV activities. The structure of l-amino acid oxidase with its substrate (l-phenylalanine) has been refined to a resolution of 1.8 Å. The complex structure reveals the substrate bound to the reduced flavin (FADred). Alternative conformations for the key residues His223 and Arg322 are evident, suggesting a dynamic active site. Furthermore, conformational changes are apparent for the isoalloxazine ring; the three-ring system exhibits more bending around the N5-N10 axis compared to the oxidized flavin. The implications of the observed dynamics on the mechanism of catalysis are discussed. Inspection of buried surfaces in the enzyme reveals a Y-shaped channel system extending from the external surface of the protein to the active site. One portion of this channel may serve as the entry path for O2 during the oxidative half-reaction. The second region, separated from the proposed O2 channel by the N terminus (residues 8-16) of the protein, may play a role in H2O2 release. Interestingly, the latter portion of the channel would direct the H2O2 product to the exterior surface of the protein, near the glycan moiety, thought to anchor the enzyme to the host cell. This channel location may explain the ability of the enzyme to localize H2O2 to the targeted cell and thus induce the apoptotic effect.

Original languageEnglish (US)
Pages (from-to)991-1002
Number of pages12
JournalJournal of Molecular Biology
Volume364
Issue number5
DOIs
StatePublished - Dec 15 2006

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Phenylalanine
Enzymes
Catalytic Domain
Oxidoreductases
Membrane Proteins
Amino Acids
Snake Venoms
Catalysis
Polysaccharides
HIV
Apoptosis
Proteins
4,6-dinitro-o-cresol

All Science Journal Classification (ASJC) codes

  • Structural Biology
  • Molecular Biology

Cite this

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title = "Crystal Structure of LAAO from Calloselasma rhodostoma with an l-Phenylalanine Substrate: Insights into Structure and Mechanism",
abstract = "l-Amino acid oxidase is a dimeric glycosylated flavoenzyme, a major constituent of the venom-from the snake Calloselasma rhodostoma. The enzyme exhibits apoptosis inducing effects as well as antibacterial and anti-HIV activities. The structure of l-amino acid oxidase with its substrate (l-phenylalanine) has been refined to a resolution of 1.8 {\AA}. The complex structure reveals the substrate bound to the reduced flavin (FADred). Alternative conformations for the key residues His223 and Arg322 are evident, suggesting a dynamic active site. Furthermore, conformational changes are apparent for the isoalloxazine ring; the three-ring system exhibits more bending around the N5-N10 axis compared to the oxidized flavin. The implications of the observed dynamics on the mechanism of catalysis are discussed. Inspection of buried surfaces in the enzyme reveals a Y-shaped channel system extending from the external surface of the protein to the active site. One portion of this channel may serve as the entry path for O2 during the oxidative half-reaction. The second region, separated from the proposed O2 channel by the N terminus (residues 8-16) of the protein, may play a role in H2O2 release. Interestingly, the latter portion of the channel would direct the H2O2 product to the exterior surface of the protein, near the glycan moiety, thought to anchor the enzyme to the host cell. This channel location may explain the ability of the enzyme to localize H2O2 to the targeted cell and thus induce the apoptotic effect.",
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Crystal Structure of LAAO from Calloselasma rhodostoma with an l-Phenylalanine Substrate : Insights into Structure and Mechanism. / Moustafa, Ibrahim; Foster, Scott; Lyubimov, Artem Y.; Vrielink, Alice.

In: Journal of Molecular Biology, Vol. 364, No. 5, 15.12.2006, p. 991-1002.

Research output: Contribution to journalArticle

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T1 - Crystal Structure of LAAO from Calloselasma rhodostoma with an l-Phenylalanine Substrate

T2 - Insights into Structure and Mechanism

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AU - Foster, Scott

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AU - Vrielink, Alice

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