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Human leukotriene C(4) synthase at 4.5 A resolution in projection
Ingeborg Schmidt-Krey1, Yoshihide Kanaoka, Deryck J Mills
1Department of Structural Biology, Max-Planck-Institute of Biophysics, Marie-Curie-Strasse 15, 60439 Frankfurt am Main, Germany. ingeborg.schmidt-krey@mpibp-frankfurt.mpg.de
Structure (London, England : 1993)
|November 9, 2004
Summary
Researchers determined the structure of leukotriene C4 synthase, an enzyme crucial for asthma, revealing it forms a trimer with transmembrane alpha helices. This structure offers insights into eicosanoid and glutathione metabolism.
Area of Science:
- Biochemistry
- Structural Biology
- Membrane Protein Research
Background:
- Leukotriene C4 (LTC4) synthase is an 18 kDa integral membrane enzyme.
- It conjugates LTA4 with glutathione to form LTC4, a key mediator in asthma pathobiology.
- Understanding its structure is vital for eicosanoid and glutathione metabolism research.
Purpose of the Study:
- To determine the three-dimensional structure of recombinant human LTC4 synthase.
- To elucidate the structural basis for its function in leukotriene synthesis.
- To compare its structure with related enzymes like microsomal glutathione S-transferase 1.
Main Methods:
- Electron crystallography was used to generate a projection map of human LTC4 synthase.
- The map was calculated at a resolution of 4.5 Å.
- Further analysis involved truncating the map to 7.5 Å to visualize transmembrane alpha helices.
Main Results:
- The electron crystallography data revealed that LTC4 synthase exists as a trimer.
- The structure shows four transmembrane alpha helices per monomer.
- Most alpha helices are oriented nearly perpendicular to the membrane plane.
- LTC4 synthase exhibits structural similarity to microsomal glutathione S-transferase 1 despite low sequence identity.
Conclusions:
- The determined structure provides new insights into the organization of LTC4 synthase.
- The findings highlight structural similarities between functionally distinct enzymes in the same gene family.
- This research advances the understanding of membrane proteins involved in eicosanoid and glutathione metabolism.