title: The krebs cycle enzyme α-ketoglutarate decarboxylase is an essential glycosomal protein in bloodstream African trypanosomes.
abstract: α-Ketoglutarate decarboxylase (α-KDE1) is a Krebs cycle enzyme found in the mitochondrion of the procyclic form (PF) of Trypanosoma brucei. The bloodstream form (BF) of T. brucei lacks a functional Krebs cycle and relies exclusively on glycolysis for ATP production. Despite the lack of a functional Krebs cycle, α-KDE1 was expressed in BF T. brucei and RNA interference knockdown of α-KDE1 mRNA resulted in rapid growth arrest and killing. Cell death was preceded by progressive swelling of the flagellar pocket as a consequence of recruitment of both flagellar and plasma membranes into the pocket. BF T. brucei expressing an epitope-tagged copy of α-KDE1 showed localization to glycosomes and not the mitochondrion. We used a cell line transfected with a reporter construct containing the N-terminal sequence of α-KDE1 fused to green fluorescent protein to examine the requirements for glycosome targeting. We found that the N-terminal 18 amino acids of α-KDE1 contain overlapping mitochondrion- and peroxisome-targeting sequences and are sufficient to direct localization to the glycosome in BF T. brucei. These results suggest that α-KDE1 has a novel moonlighting function outside the mitochondrion in BF T. brucei.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, USA.
authors.forename: Steven
authors.initials: S
authors.lastname: Sykes
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, USA.
authors.forename: Anthony
authors.initials: A
authors.lastname: Szempruch
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, USA shajduk@bmb.uga.edu.
authors.forename: Stephen
authors.initials: S
authors.lastname: Hajduk
mesh_terms: D000595:Amino Acid Sequence; D002262:Carboxy-Lyases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008830:Microbodies / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism; D008969:Molecular Sequence Data; D021382:Protein Sorting Signals; D021381:Protein Transport; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014346:Trypanosoma brucei brucei / Q000201:enzymology* / Q000378:metabolism
chemical_list: D021382:Protein Sorting Signals; D015800:Protozoan Proteins; D012333:RNA, Messenger; D002262:Carboxy-Lyases; C021474:2-oxoglutarate decarboxylase