Limits...
Structural basis of regiospecificity of a mononuclear iron enzyme in antibiotic fosfomycin biosynthesis.

Yun D, Dey M, Higgins LJ, Yan F, Liu HW, Drennan CL - J. Am. Chem. Soc. (2011)

Bottom Line: Hydroxypropylphosphonic acid epoxidase (HppE) is an unusual mononuclear iron enzyme that uses dioxygen to catalyze the oxidative epoxidation of (S)-2-hydroxypropylphosphonic acid (S-HPP) in the biosynthesis of the antibiotic fosfomycin.Additionally, the enzyme converts the R-enantiomer of the substrate (R-HPP) to 2-oxo-propylphosphonic acid.These structures, along with previously determined structures of S-HPP-HppE, identify the dioxygen binding site on iron and elegantly illustrate how HppE is able to recognize both substrate enantiomers to catalyze two completely distinct reactions.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.

ABSTRACT
Hydroxypropylphosphonic acid epoxidase (HppE) is an unusual mononuclear iron enzyme that uses dioxygen to catalyze the oxidative epoxidation of (S)-2-hydroxypropylphosphonic acid (S-HPP) in the biosynthesis of the antibiotic fosfomycin. Additionally, the enzyme converts the R-enantiomer of the substrate (R-HPP) to 2-oxo-propylphosphonic acid. To probe the mechanism of HppE regiospecificity, we determined three X-ray structures: R-HPP with inert cobalt-containing enzyme (Co(II)-HppE) at 2.1 Å resolution; R-HPP with active iron-containing enzyme (Fe(II)-HppE) at 3.0 Å resolution; and S-HPP-Fe(II)-HppE in complex with dioxygen mimic NO at 2.9 Å resolution. These structures, along with previously determined structures of S-HPP-HppE, identify the dioxygen binding site on iron and elegantly illustrate how HppE is able to recognize both substrate enantiomers to catalyze two completely distinct reactions.

Show MeSH

Related in: MedlinePlus

Substrate binding pocket. Cantilever hairpin residues and residues interacting with the aliphatic portion of R-HPP (L144, L193, and F182) are shown as sticks. Iron is shown as a sphere (rust).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3140168&req=5

fig5: Substrate binding pocket. Cantilever hairpin residues and residues interacting with the aliphatic portion of R-HPP (L144, L193, and F182) are shown as sticks. Iron is shown as a sphere (rust).

Mentions: With experimental information from our NO data supporting the assignment of the binding site for dioxygen on iron, we can examine the proposed mechanisms for regiospecificity by comparing our S-HPP and R-HPP bound structures. Both enantiomers bind to the same general site on the metal in the active site of HppE. For S-HPP, its hydrophobic portion including the C2 methyl group is accommodated by a hydrophobic pocket on the enzyme, comprising residues Phe182, Leu193, and Leu144 (Figure 5).(15) Because the position of the C2 methyl moiety of the R-HPP molecule (bidentate binding mode) is within 1 Å of the corresponding position of the C2 methyl moiety of S-HPP (Figure 6a), the same hydrophobic binding pocket serves to accommodate the methyl moiety of the R-enantiomer (Figure 5).


Structural basis of regiospecificity of a mononuclear iron enzyme in antibiotic fosfomycin biosynthesis.

Yun D, Dey M, Higgins LJ, Yan F, Liu HW, Drennan CL - J. Am. Chem. Soc. (2011)

Substrate binding pocket. Cantilever hairpin residues and residues interacting with the aliphatic portion of R-HPP (L144, L193, and F182) are shown as sticks. Iron is shown as a sphere (rust).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3140168&req=5

fig5: Substrate binding pocket. Cantilever hairpin residues and residues interacting with the aliphatic portion of R-HPP (L144, L193, and F182) are shown as sticks. Iron is shown as a sphere (rust).
Mentions: With experimental information from our NO data supporting the assignment of the binding site for dioxygen on iron, we can examine the proposed mechanisms for regiospecificity by comparing our S-HPP and R-HPP bound structures. Both enantiomers bind to the same general site on the metal in the active site of HppE. For S-HPP, its hydrophobic portion including the C2 methyl group is accommodated by a hydrophobic pocket on the enzyme, comprising residues Phe182, Leu193, and Leu144 (Figure 5).(15) Because the position of the C2 methyl moiety of the R-HPP molecule (bidentate binding mode) is within 1 Å of the corresponding position of the C2 methyl moiety of S-HPP (Figure 6a), the same hydrophobic binding pocket serves to accommodate the methyl moiety of the R-enantiomer (Figure 5).

Bottom Line: Hydroxypropylphosphonic acid epoxidase (HppE) is an unusual mononuclear iron enzyme that uses dioxygen to catalyze the oxidative epoxidation of (S)-2-hydroxypropylphosphonic acid (S-HPP) in the biosynthesis of the antibiotic fosfomycin.Additionally, the enzyme converts the R-enantiomer of the substrate (R-HPP) to 2-oxo-propylphosphonic acid.These structures, along with previously determined structures of S-HPP-HppE, identify the dioxygen binding site on iron and elegantly illustrate how HppE is able to recognize both substrate enantiomers to catalyze two completely distinct reactions.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.

ABSTRACT
Hydroxypropylphosphonic acid epoxidase (HppE) is an unusual mononuclear iron enzyme that uses dioxygen to catalyze the oxidative epoxidation of (S)-2-hydroxypropylphosphonic acid (S-HPP) in the biosynthesis of the antibiotic fosfomycin. Additionally, the enzyme converts the R-enantiomer of the substrate (R-HPP) to 2-oxo-propylphosphonic acid. To probe the mechanism of HppE regiospecificity, we determined three X-ray structures: R-HPP with inert cobalt-containing enzyme (Co(II)-HppE) at 2.1 Å resolution; R-HPP with active iron-containing enzyme (Fe(II)-HppE) at 3.0 Å resolution; and S-HPP-Fe(II)-HppE in complex with dioxygen mimic NO at 2.9 Å resolution. These structures, along with previously determined structures of S-HPP-HppE, identify the dioxygen binding site on iron and elegantly illustrate how HppE is able to recognize both substrate enantiomers to catalyze two completely distinct reactions.

Show MeSH
Related in: MedlinePlus