MAP6-F is a temperature sensor that directly binds to and protects microtubules from cold-induced depolymerization

J Biol Chem. 2012 Oct 12;287(42):35127-35138. doi: 10.1074/jbc.M112.398339. Epub 2012 Aug 17.

Abstract

Microtubules are dynamic structures that present the peculiar characteristic to be ice-cold labile in vitro. In vivo, microtubules are protected from ice-cold induced depolymerization by the widely expressed MAP6/STOP family of proteins. However, the mechanism by which MAP6 stabilizes microtubules at 4 °C has not been identified. Moreover, the microtubule cold sensitivity and therefore the needs for microtubule stabilization in the wide range of temperatures between 4 and 37 °C are unknown. This is of importance as body temperatures of animals can drop during hibernation or torpor covering a large range of temperatures. Here, we show that in the absence of MAP6, microtubules in cells below 20 °C rapidly depolymerize in a temperature-dependent manner whereas they are stabilized in the presence of MAP6. We further show that in cells, MAP6-F binding to and stabilization of microtubules is temperature- dependent and very dynamic, suggesting a direct effect of the temperature on the formation of microtubule/MAP6 complex. We also demonstrate using purified proteins that MAP6-F binds directly to microtubules through its Mc domain. This binding is temperature-dependent and coincides with progressive conformational changes of the Mc domain as revealed by circular dichroism. Thus, MAP6 might serve as a temperature sensor adapting its conformation according to the temperature to maintain the cellular microtubule network in organisms exposed to temperature decrease.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cold Temperature*
  • HeLa Cells
  • Humans
  • Mice
  • Microtubule-Associated Proteins / genetics
  • Microtubule-Associated Proteins / metabolism*
  • Microtubules / genetics
  • Microtubules / metabolism*
  • NIH 3T3 Cells
  • Protein Structure, Tertiary

Substances

  • MAP6 protein, human
  • Microtubule-Associated Proteins