Procyclic forms of Trypanosoma brucei brucei remain and propagate in the midgut of tsetse fly where iron is rich. Additional iron is also required for their growth in in vitro culture. However, little is known about the genes involved in iron metabolism and the mechanism of iron utilization in procyclic-form cells. Therefore, we surveyed the genes involved in iron metabolism in the T. b. brucei genome sequence database. We found a potential homologue of vacuole protein sorting 41 (VPS41), a gene that is required for high-affinity iron transport in Saccharomyces cerevisiae and cloned the full-length gene (TbVPS41). Complementation analysis of TbVPS41 in DeltaScvps41 yeast cells showed that TbVPS41 could partially suppress the inability of DeltaScvps41 yeast cells to grow on low-iron medium, but it could not suppress the fragmented vacuole phenotype. Further RNA interference (RNAi)-mediated gene knock-down in procyclic-form cells resulted in a significant reduction of growth in low-iron medium; however, no change in growth was observed in normal culture medium. Transmission electron microscopy showed that RNAi caused T. b. brucei cells to have larger numbers of small intracellular vesicles, similar to the fragmented vacuoles observed in DeltaScvps41 yeast cells. The present study demonstrates that TbVPS41 plays an important role in the intracellular iron utilization system as well as in the maintenance of normal cellular morphology.

• PMID: 17577424
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Journal Article | Research Support, Non-U.S. Gov't

Authors

Lu S, Suzuki T, Iizuka N, Ohshima S, Yabu Y, Suzuki M, Wen L, Ohta N

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