The Function of Phosphatidylinositol 4-Kinase III-Beta in Trypanosoma Brucei

Show full item record

Title: The Function of Phosphatidylinositol 4-Kinase III-Beta in Trypanosoma Brucei
Author: Rodgers, Melissa Jeane
Abstract: Phosphatidylinositol 4 -kinase phosphorylates phosphatidylinositol at the D4 position resulting in phosphatidylinositol 4 -monophosphate . Subsequent phosphorylation events result in a group of molecules known as phosphoinositides . These molecules are important in signal transduction , endocytosis , exocytosis , and protein trafficking . Two phosphatidylinositol 4 -kinases are found in Trypanosoma Brucei . We have cloned the gene encoding the Type III phosphatidylinositol 4 -kinase Beta (TbPI4KIII ) in Trypanosoma Brucei . The protein was exogenously expressed in COS -7 cells and assayed for phosphatidylinositol kinase activity . The expressed protein migrated on SDS -PAGE near the predicted molecular weight of 66 kDa and phosphorylates phosphatidylinositol . Depletion of TbPI4KIII -ß in procyclic T . brucei by RNAi results in inhibition of cell growth and a distorted cellular morphology . Immunofluorescence studies revealed a distorted Golgi apparatus and mislocalization of lysosomal and flagellar pocket proteins . Ultrastructural analysis reveals internal accumulation of a heterogeneous population of vesicles , abnormal positioning of organelles and a loss of cell polarity . Scanning EM reveals a twisted morphology most likely due to an alteration in the microtubule cytoskeleton . Dividing TbPI4KIII -ß RNAi trypanosomes often exhibited a detached daughter flagellum and lacked a cleavage furrow , suggesting a defect in cell division and /or cytokinesis . Cell cycle analysis confirmed that cells depleted of TbPI4KIII -ß have a post -mitotic cytokinesis block . In summary , TbPI4KIII -ß is an essential protein in procyclic T . brucei , required for maintenance of Golgi structure , protein trafficking , normal cellular shape and cytokinesis .
URI: http : / /hdl .handle .net /2152 .5 /616
Date: 2006-12-20


The Function of Phosphatidylinositol 4-Kinase III-Beta in Trypanosoma Brucei. Graduate School of Biomedical Sciences. Available electronically from http : / /hdl .handle .net /2152 .5 /616 .

Files in this item

Files Size Format View
rodgersmelissa.pdf 3.255Mb application/pdf View/Open

This item appears in the following Collection(s)

Show full item record

Search DSpace

Advanced Search