Crystal structure of TchmY from Actinoplanes teichomyceticus

Area of Science:

• Microbiology
• Biochemistry
• Structural Biology

Background:

• Moenomycin-type antibiotics are phosphoglycolipids with unique mechanisms and applications in animal nutrition.
• Known moenomycin biosynthesis pathways include the tchm gene cluster from Actinoplanes teichomyceticus and the moe cluster from Streptomyces.
• The functions of tchmy and tchmz genes within the tchm cluster are currently unknown.

Purpose of the Study:

• To determine the function of the previously uncharacterized TchmY enzyme.
• To elucidate the structural basis for TchmY's role in moenomycin biosynthesis.
• To provide insights into the biosynthetic pathway of moenomycin antibiotics.

Main Methods:

• Sequence analysis to predict TchmY's enzymatic function.
• Recombinant expression of TchmY protein in Escherichia coli.
• Crystallography and SIRAS (Single Isomorphous Replacement with Anomalous Scattering) to solve the crystal structure of TchmY.
• Structural comparison with known prenylcyclases.

Main Results:

• Sequence analysis suggested TchmY belongs to the isoprenoid enzyme C2-like superfamily and may function as a prenylcyclase.
• The crystal structure of recombinant TchmY was determined, revealing an (α/α)₆-barrel fold.
• A potential substrate-binding pocket was identified within the enzyme's central chamber.

Conclusions:

• TchmY is identified as a prenylcyclase involved in the terminal cyclization of the moenocinyl chain.
• The structural data provides a foundation for understanding the enzymatic mechanisms in moenomycin biosynthesis.
• This study contributes significant information to the biosynthetic pathways of moenomycin antibiotics.