The structure of microtubule plus end binding proteins and their influence of microtubule dynamics.

Summary

Microtubules (MTs) are long filamentous structures that are present in almost all eukaryotic cells. They are involved in the structure and support of the cell, in the spatial organization of cellular organelles and intracellular transport of proteins. A typical and important feature of MTs is that they are dynamically instable structures that can quickly assemble and disassemble by polymerization and depolymerization of tubulin. MT dynamics are important because they plays a major role in several diseases and major anti-tumor drug molecules act by modulating MT dynamics. Therefore the dynamic instability of MTs is highly regulated. +TIPs (plus-end tracking proteins) specifically bind to the growing plus ends of MTs and thereby directly regulate the dynamics of MTs.
The probable mechanism that +TIPs employ to stay constantly and specifically associated with the plus ends of growing MTs is called treadmilling, in which +TIPs associate with growing MT plus ends and dissociate when the plus end has grown. However, fundamental questions remain: how do +TIPs specifically recognize MT plus ends, how does treadmilling occur, how do +TIPs influence the stability of MTs and how are MT plus ends coupled to cellular structures.
Here I propose to elucidate how +TIPs regulate MT dynamics by determining the structure of +TIPs bound to MTs, by localizing +TIPs on the MT plus ends and by investigating their influence on the structure of MT plus ends. In this endeavor I propose using a combination of cryo-electron microscopy, object reconstruction and (immuno-) gold labeling. Docking known high resolution X-ray structures of (fragments of) these components in these low-resolution reconstructions will allow me to build models with aspects of atomic resolution. Thus I hope to make an important contribution to our understanding one of the quintessential functions within a living cell: the dynamic regulation of its MT cytoskeleton.

Output

Scientific article

  • J. van Duin, H.J. Warmenhoven, H.K. Koerten, S.H.E. van den Worm, R.I. Koning(2006): Cryo Electron Microscopy Reconstructions of the Leviviridae Unveil the Densest Icosahedral RNA Packing Possible Journal of Molecular Biology pp. 858 - 865
  • H.K. Koerten, N. Ban, J.P. Abrahams, C. Schaffitzel, R.I. Koning, T. Ishikawa, M Oswald(2006): Structure of the E. coli signal recognition particle bound to a translating ribosome Nature pp. 503 - 506

Details

Project number

700.54.408

Main applicant

Dr. R.I. Koning

Affiliated with

Universiteit Leiden, Leids Universitair Medisch Centrum, Moleculaire Celbiologie

Team members

Dr. R.I. Koning

Duration

01/09/2004 to 12/12/2007