A Catalytic Role for Mod5 in the Formation of the Tea1 Cell Polarity Landmark

作者：Bicho Claudia C; Kelly David A; Snaith Hilary A; Goryachev Andrew B^*; Sawin Kenneth E

来源：Current Biology, 2010, 20(19): 1752-1757.

DOI：10.1016/j.cub.2010.08.035

Many systems regulating cell polarity involve stable landmarks defined by internal cues [1-5]. In the rod-shaped fission yeast Schizosaccharomyces pombe, microtubules regulate polarized vegetative growth via a landmark involving the protein Teal [6-9]. Teal is delivered to cell tips as packets of molecules associated with growing microtubule ends [10] and anchored at the plasma membrane via a mechanism involving interaction with the membrane protein Mod5 [11, 12]. Teal and Mod5 are highly concentrated in clusters at cell tips in a mutually dependent manner, but how the Tea1-Mod5 interaction contributes mechanistically to generating a stable landmark is not understood. Here, we use live-cell imaging, FRAP, and computational modeling to dissect dynamics of the Teal -Mod5 interaction. Surprisingly, we find that Teal and Mod5 exhibit distinctly different turnover rates at cell tips. Our data and modeling suggest that rather than acting simply as a Teal receptor or as a molecular "glue" to retain Teal, Mod5 functions catalytically to stimulate incorporation of Teal into a stable tip-associated cluster network. The model also suggests an emergent self-focusing property of the Teal -Mod5 cluster network, which can increase the fidelity of polarized growth.

• 出版日期2010-10-12