Characterization of ammonium transporters in the dinoflagellate Alexandrium catenella (Group I).

Ammonium transporter AlcAMT with K450 residue enables ammonium uptake in A. catenella, as shown by yeast expression experiments.

• Why it matters: Understanding ammonium transport mechanisms in A. catenella is crucial because nitrogen influences its growth and toxin production, impacting shellfish poisoning risks.
• What they did: Researchers cloned multiple AMT cDNAs from A. catenella, inserted three into yeast expression vectors, and tested their ammonium transport ability in an amt-deficient yeast strain.
• The result: Only the AMT variant with K450 supported yeast growth on ammonium medium, and mutation analysis confirmed K450's essential role in AlcAMT function.