An essential GDP-Fuc: β- D -Gal α-1,2-fucosyltransferase is located in the mitochondrion of Trypanosoma brucei

The biosynthesis of guanosine 5′-diphospho-β--fucose (GDP-Fuc), the activated donor for fucose, has been shown to be essential in the parasite . Fucose is a common constituent of eukaryotic glycan structures, but it has been rarely found in trypanosomatid glycoconjugates. A single putative fucosyltransferase () gene was identified in the trypanosome genome. The encoded TbFUT1 protein was enzymatically active when expressed in . Structural characterization of its reaction products identified it as a GDP-Fuc: β-D-galactose α-1,2-fucosyltransferase, with a preference for a Galβ1,3GlcNAcβ1-O-R acceptor motif among the substrates tested. Conditional null mutants of the gene demonstrated that it is essential for growth of the mammalian-infective bloodstream form and insect vector dwelling procyclic form of the parasite. Unexpectedly, TbFUT1 was localized in the mitochondrion of and found to be essential for mitochondrial function in bloodstream form trypanosomes, suggesting this kinetoplastid parasite possesses an unprecedented and essential mitochondrial fucosyltransferase activity.