title: Extra-glycosomal localisation of Trypanosoma brucei hexokinase 2.
abstract: The majority of the glycolytic enzymes in the African trypanosome are compartmentalised within peroxisome-like organelles, the glycosomes. Polypeptides harbouring peroxisomal targeting sequences (PTS type 1 or 2) are targeted to these organelles. This targeting is essential to parasite viability, as compartmentalisation of glycolytic enzymes prevents unregulated ATP-dependent phosphorylation of intermediate metabolites. Here, we report the surprising extra-glycosomal localisation of a PTS-2 bearing trypanosomal hexokinase, TbHK2. In bloodstream form parasites, the protein localises to both glycosomes and to the flagellum. Evidence for this includes fractionation and immunofluorescence studies using antisera generated against the authentic protein as well as detection of epitope-tagged recombinant versions of the protein. In the insect stage parasite, distribution is different, with the polypeptide localised to glycosomes and proximal to the basal bodies. The function of the extra-glycosomal protein remains unclear. While its association with the basal body suggests that it may have a role in locomotion in the insect stage parasite, no detectable defect in directional motility or velocity of cell movement were observed for TbHK2-deficient cells, suggesting that the protein may have a different function in the cell.
authors.affiliation: Department of Genetics and Biochemistry, Clemson University, Clemson, SC 39634, USA.
authors.forename: April C
authors.initials: AC
authors.lastname: Joice
authors.forename: Todd L
authors.initials: TL
authors.lastname: Lyda
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Sayce
authors.forename: Emilie
authors.initials: E
authors.lastname: Verplaetse
authors.forename: Meredith T
authors.initials: MT
authors.lastname: Morris
authors.forename: Paul A M
authors.initials: PA
authors.lastname: Michels
authors.forename: Derrick R
authors.initials: DR
authors.lastname: Robinson
authors.forename: James C
authors.initials: JC
authors.lastname: Morris
mesh_terms: D005407:Flagella / Q000737:chemistry / Q000201:enzymology; D017353:Gene Deletion; D006593:Hexokinase / Q000032:analysis* / Q000235:genetics; D008124:Locomotion; D008830:Microbodies / Q000737:chemistry* / Q000201:enzymology*; D014346:Trypanosoma brucei brucei / Q000737:chemistry* / Q000201:enzymology* / Q000235:genetics / Q000502:physiology
chemical_list: D006593:Hexokinase