Cloning, expression, purification, crystallization and preliminary X-ray diffraction studies of N-acetylneuraminate lyase from methicillin-resistant Staphylococcus aureus

The enzyme N-acetylneuraminate lyase (EC 4.1.3.3) is involved in the metabolism of sialic acids. Specifically, the enzyme catalyzes the retro-aldol cleavage of N-acetylneuraminic acid to form N-acetyl-d-mannosamine and pyruvate. Sialic acids comprise a large family of nine-carbon amino sugars, all of which are derived from the parent compound N-acetylneuraminic acid. In recent years, N-acetylneuraminate lyase has received considerable attention from both mechanistic and structural viewpoints and has been recognized as a potential antimicrobial drug target. The N-acetylneuraminate lyase gene was cloned from methicillin-resistant Staphylococcus aureus genomic DNA, and recombinant protein was expressed and purified from Escherichia coli BL21(DE3). The enzyme crystallized in a number of crystal forms, predominantly from PEG precipitants, with the best crystal diffracting to beyond 1.70Å resolution in space group P21. Molecular replacement indicates the presence of eight monomers per asymmetric unit. Understanding the structural biology of N-acetylneuraminate lyase in pathogenic bacteria, such as methicillin-resistant S. aureus, will provide insights for the development of future antimicrobials.