9T4Z

Crystal structure of PpNeuA CMP-Kdn synthetase

Summary for 9T4Z

• Entry DOI: 10.2210/pdb9t4z/pdb
• Descriptor: PpNeuA (2 entities in total)
• Functional Keywords: cmp-kdn synthetase, ligase
• Biological source: Prymnesium parvum
• Total number of polymer chains: 2
• Total formula weight: 56522.56

Authors

Levy, C.W.,Ortmayer, M.,Morley, C. (deposition date: 2025-11-03, release date: 2026-03-11)

Primary citation

Morley, C.,Munro-Clark, A.J.,Wagstaff, B.A.,Ivanova, I.,Dubinskaya, E.,Rostock, A.,Ortmayer, M.,Levy, C.W.,Field, R.A.
Structure and characterisation of CMP-Kdn synthetase from the haptophyte microalgae Prymnesium parvum.
Rsc Chem Biol, 2026

PubMed Abstract: Sialic acids - 9-carbon ulosonic acids - are implicated in many cell-cell and host-pathogen interactions due to their prevalent location at the non-reducing end of glycoconjugates. Sialic acids have recently been observed in microalgae, including the toxic bloom-forming , which produces the deaminated sialic acid, ketodeoxynonulosonic acid (Kdn), through biosynthesis. Here we report on the key CMP-sialic acid synthetase enzyme (CMAS), PpNeuA, which activates Kdn to its sugar nucleotide congener, CMP-Kdn. In the present study, the X-ray crystal structure of PpNeuA was determined to 1.8 Å resolution and shows that it adopts a similar overall fold to that of other sialic acid synthetase enzymes, with which it shares ca 30% amino acid sequence identity. PpNeuA specificity for Kdn is dependent upon Arg196, a hydrophilic residue that is only found in Kdn-specific sialic acid synthetases. R196L mutation switches the substrate preference of PpNeuA from Kdn to -acetylneuraminic acid (Neu5Ac). Kinetic analysis shows that Arg196 plays both a role in substrate binding (impact on ) and catalysis (impact on ). In the context of generating metabolic probes to identify the location and context (glycolipid vs glycoprotein) of Kdn in , we also report on the ability of PpNeuA to accept both 5Az-Kdn and 9Az-Kdn as substrates.

PubMed: 41756713
DOI: 10.1039/d5cb00285k

Experimental method

X-RAY DIFFRACTION (1.8 Å)