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Complex structures of MoeN5 with substrate analogues suggest sequential catalytic mechanism
Lilan Zhang1, Tzu-Ping Ko2, Satish R Malwal3
1University of Chinese Academy of Sciences, Beijing, 100049, China; Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China.
Biochemical and Biophysical Research Communications
|March 7, 2019
Summary
Moenomycin A antibiotic synthesis involves the enzyme MoeN5. New crystal structures reveal prenyl-containing substrates bind to the S1 site first, suggesting a sequential binding mechanism for prenyltransferases.
Area of Science:
- Biochemistry
- Enzymology
- Structural Biology
Background:
- Moenomycin A is a phosphoglycerate antibiotic with a C25-moenocinyl chain and oligosaccharide.
- The enzyme MoeN5 catalyzes C25-chain formation using geranyl pyrophosphate (GPP) and 2-Z,E-farnesyl-3-phosphoglycerate (FPG).
Purpose of the Study:
- To elucidate the substrate binding mechanism of MoeN5.
- To investigate the role of S1 and S2 sites in MoeN5 activity.
Main Methods:
- X-ray crystallography of MoeN5 complexed with GPP and FPG derivatives.
- Synthesis of novel FPG derivatives for structural studies.
Main Results:
- Complex crystal structures revealed FPG derivatives binding to the S1 site, not the previously hypothesized S2 site.
- The S1 site appears to be the preferred binding site for prenyl-containing ligands.
- S2 binding likely occurs only after S1 site occupation.
Conclusions:
- MoeN5 likely utilizes a sequential ionization-condensation-elimination mechanism, common to trans-type prenyltransferases.
- This mechanism involves a carbocation intermediate during C25-chain formation.
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