The Rice Kinesin Oskch1 is a Dynamic Cross-Linker of Actin Filaments and Microtubules

Abstract

The interaction between microtubules and actin filaments impacts many processes during plant growth and development including cell division and expansion. Despite numerous reports of co-localization between the two filament types in the past, only recently plant kinesins with a calponin-homology domain (KCH) were identified as putative dynamic cross-linkers. OsKCH1, a KCH from rice, has been described to interact with cortical microtubules and actin filaments both in vivo and in vitro. However, it remained unsolved whether this interaction is static or dynamic. Here, we show that OsKCH1 drives the active sliding of actin filaments along microtubules in vitro. We found that the sliding velocities corresponded to the velocities of microtubules propelled along OsKCH1 immobilized on glass substrates. This suggests that the motor interacts statically with actin filaments and dynamically with microtubules. We propose that kinesins with a calponin-homology domain play an essential role in the dynamic interaction between microtubules and actin filaments in plant cells.