Choline transport in Fusarium graminearum A 3 5



Abstract Fusarium graminearum A 35 possesses a high affinity system (Km/32 ± 8 μ M; mean ± SE) for uptake of choline, which was shown to be energy-dependent and constitutive. The maximum rate of choline uptake by this system was repressed by ammonia and glucose, showing a three-fold increase in maximum activity after nitrogen (2 h) or carbon (4 h) starvation. The system was highly specific for choline with only dimethylethanolamine (Ki= 198 ± 29 μ M), betaine aldehyde (Ki= 95 ± 14 μ M) and chlorocholine (Ki= 352 ± 40 μ M) acting as competitive inhibitors. Hemicholinium-3 acted as a mixed (non-competitive) inhibitor (KIES= 1.9 ± 0.6 μ M; KIE= 3.6 ± 1.9 μ M).