Single-Cell Biophysics: Measurement, Modulation, and Modeling

Single-Cell Biophysics: Measurement, Modulation, and Modeling

Poster Abstracts

43-POS Board 22 Post-Translational Modifications Regulate Function and Self-Assembly of Axonemal Tubulin Yin-wei Kuo 1 , Ron Orbach 2 , Jonathon Howard 2 . 2 Yale University, New Haven, CT, USA. 1 Yale University, New Haven, CT, USA, Microtubules, cytoskeletal polymers assembled from building blocks comprising α- and β- tubulin heterodimers, are involved in many important intracellular functions including the maintenance of cell structure, the formation of the mitotic spindle, the transport of organelles, the sensation of force and the motility of cells. The diverse functions of microtubules require delicate control over the dynamics of assembly and disassembly, and the interactions with microtubule-associated proteins (MAPs). A long standing question is how do the evolutionally highly conserved tubulin building blocks differentially regulate microtubule dynamics and functions in different cellular processes. Highly versatile post-translational modifications (PTMs) are present on tubulin, contributing to the so-called “tubulin code” and are suggested to be crucial for regulating the diverse functions of cellular microtubules. However, our current knowledge about microtubule dynamics is predominantly based on the highly heterogeneous mammalian brain tubulin system, whose complex isotypes and PTM combinations make it challenging to elucidate the effect and function of the individual modifications. To reduce the complication of tubulin isotype, we selected biflagellated green algae Chlamydomonas reinhardtii as our model system. We recently developed a novel method to purify axonemal tubulin from various strains of C. reinhardtii , including a polyglutamylation- deficient mutant tpg1 , to study the self-assembly dynamics of axonemal tubulin and how tubulin post-translational modifications (PTMs) contribute to the distinct properties of axonemal tubulin. We will do this using total-internal-reflection-fluorescence (TIRF) and other microscope techniques to determine the effects of PTMs on dynamics at the single-microtubule level.

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