N-acetylmannosamine kinase (NanK)

N-acetylmannosamine kinase (NanK) is an enzyme that catalyzes the phosphorylation of N-acetylmannosamine to N-acetylmannosamine-6-phosphate, a critical step in the biosynthesis of sialic acids, which are negatively charged terminal sugars on glycoproteins and glycolipids. In humans, this kinase activity is part of a bifunctional protein encoded by the GNE gene, which is also responsible for the preceding epimerase reaction converting UDP-N-acetylglucosamine to N-acetylmannosamine. Proper function of this kinase is essential for normal sialylation of cell surfaces, affecting cell adhesion, signaling, and recognition processes in both health and disease. In bacteria, NanK is involved in sialic acid catabolism, important for nutrient acquisition and pathogenesis. Experimental inhibitors of NanK can disrupt sialic acid biosynthesis and serve as potential research tools. Deficiency or mutation of the human enzyme can lead to inborn errors of metabolism such as sialuria, and abnormal sialylation patterns are implicated in cancer and infection.

Other names

Acylmannosamine kinaseAcetylamidodeoxymannokinaseAcetylmannosamine kinaseAcylaminodeoxymannokinaseAcylmannosamine kinase (phosphorylating)N-acyl-D-mannosamine kinaseATP:N-acetylmannosamine 6-phosphotransferaseUDP-N-acetylglucosamine-2-epimerase/N-acetylmannosamine kinase (for the human bifunctional enzyme)

Inhibition of N-acetylmannosamine kinase decreases sialic acid biosynthesis, reducing cell surface sialylation. This can affect cell-cell interactions and susceptibility to pathogens, or in bacteria can disrupt catabolism of sialic acids.