biostudies-literatureUnknownMorley CSialic 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 <i>Prymnesium parvum</i>, which produces the deaminated sialic acid, ketodeoxynonulosonic acid (Kdn), through <i>de novo</i> 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. PRSC chemical biologyhttps://www.ebi.ac.uk/biostudies/studies/S-EPMC12934254biostudies-literatureStructure and characterisation of CMP-Kdn synthetase from the haptophyte microalgae &lt;i&gt;Prymnesium parvum&lt;/i&gt;.PMC12934254Levy CWMunro-Clark AJDubinskaya EIvanova IMorley CField RAWagstaff BARostock AOrtmayer MfalseStructure and characterisation of CMP-Kdn synthetase from the haptophyte microalgae &lt;i&gt;Prymnesium parvum&lt;/i&gt;.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 <i>Prymnesium parvum</i>, which produces the deaminated sialic acid, ketodeoxynonulosonic acid (Kdn), through <i>de novo</i> 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. P2026-01-01T00:00:00Z2026 Feb2026-07-16T22:11:37.599Z2026-07-14T03:03:53.703ZS-EPMC129342544175671310.1039/d5cb00285k