Trypanosoma brucei AMP-activated kinase subunit homologs influence surface molecule expression

The African trypanosome, Trypanosoma brucei, can gauge its environment by sensing nutrient availability. For example, procyclic form (PF) trypanosomes monitor changes in glucose levels to regulate surface molecule expression, which is important for survival in the tsetse fly vector. The molecular connection between glycolysis and surface molecule expression is unknown. Here we partially characterize T. brucei homologs of the beta and gamma subunits of the AMP-activated protein kinase (AMPK), and determine their roles in regulating surface molecule expression. Using flow cytometry and mass spectrometry, we found that TbAMPK beta or TbAMPK gamma-deficient parasites express both of the major surface molecules, EP- and GPEET-procyclin, with the latter being a form that is expressed when glucose is low such as in the tsetse fly. Last, we have found that the putative scaffold component of the complex, TbAMPK beta, fractionates with organellar components and colocalizes in part with a glycosomal marker as well as the flagellum of PF parasites. (C) 2009 Elsevier Inc. All rights reserved.