Probing the Roles that Intraflagellar Transport B Protiens Play on Stability, Assembly, and Localization of Complex B in Chlamydomonas ReinhardtII
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Intraflagellar transport (IFT), the key mechanism for ciliogenesis, involves large protein particles moving bi-directionally along the entire ciliary length. IFT particles contain two large protein complexes, A and B, which are constructed with proteins in a core and several peripheral proteins. Prior studies have shown that in Chlamydomonas reinhardtii, IFT46, IFT52, and IFT88 directly interact with each other and are in a subcomplex of the IFT B core. However, ift46, bld1, and ift88 mutants differ in phenotype as ift46 mutants are able to form short flagella, while the other two lack flagella completely. In this study, we investigated the functional differences of these individual IFT proteins contributing to complex B assembly, stability, and basal body localization. We found that complex B is completely disrupted in bld1 mutant, indicating an essential role of IFT52 for complex B core assembly. Ift46 mutant cells are capable of assembling a relatively intact but highly unstable complex B. In contrast, in ift88 mutant cells the complex B core still assembles and remains stable, but the peripheral proteins no longer attach to the B core. Moreover, while complex A and the anterograde IFT motor FLA10 are localized normally to the transition fibers, complex B proteins instead are accumulated at the proximal ends of the basal bodies in ift88. Taken together, these results revealed a step-wise assembly process for complex B, and showed that the complex first localizes to the proximal end of the centrioles and then translocates onto the transition fibers via an IFT88-dependent mechanism. Protein interaction analyses such as the yeast two-hybrid assay in addition to identification and characterization of novel IFT complex B mutants will reveal a more complete picture of the architecture and function of IFT complex B.
Richey, Elizabeth (2012). Probing the Roles that Intraflagellar Transport B Protiens Play on Stability, Assembly, and Localization of Complex B in Chlamydomonas ReinhardtII. Master's thesis, Texas A&M University. Available electronically from