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Proteins from the calpain super-family are involved in developmentally- and environmentally-regulated re-modelling of the eukaryotic cytoskeleton and the dynamic organisation of signal transduction cascades. In trypanosomatid parasites, calpain-related gene families are unusually large, but we have little insight into the functional roles played by these molecules during trypanosomatid lifecycles. Here we report that CAP5.5, a cytoskeletal calpain-related protein subject to strict stage-specific expression in the sleeping sickness parasite Trypanosoma brucei, is essential and required for correct cell morphogenesis of procyclic (tsetse mid-gut stage) T. brucei. Striking consequences of CAP5.5 RNA interference are the loss of protein from the posterior cell-end, organelle mis-positioning giving rise to aberrant cytokinesis, and disorganisation of the sub-pellicular microtubules that define trypanosome cell shape. We further report that the stage-specificity of CAP5.5 expression can be explained by the presence of a paralogue, CAP5.5V, which is required for cell morphogenesis in bloodstream T. brucei; RNAi against this paralogous protein results in a qualitatively similar phenotype to that described for procyclic CAP5.5 RNAi mutants. By comparison to recently described phenotypes for other procyclic trypanosome RNAi mutants, likely functions for CAP5.5 and CAP5.5V are discussed.

Original publication

DOI

10.1016/j.protis.2009.05.003

Type

Journal article

Journal

Protist

Publication Date

11/2009

Volume

160

Pages

576 - 590

Keywords

Amino Acid Sequence, Animals, Calpain, Cytokinesis, Cytoskeletal Proteins, Cytoskeleton, Gene Expression Profiling, Gene Knockdown Techniques, Genes, Essential, Genes, Protozoan, Microbial Viability, Microscopy, Microscopy, Electron, Scanning, Microscopy, Electron, Transmission, Molecular Sequence Data, Protozoan Proteins, RNA Interference, Sequence Alignment, Trypanosoma brucei brucei