화학공학소재연구정보센터
Biochemical and Biophysical Research Communications, Vol.353, No.1, 109-114, 2007
Concerning the dynamic instability of actin homolog ParM
Using in vitro TIRF- and electron-microscopy, we reinvestigated the dynamics of native Parts, a prokaryotic DNA segregation protein and actin homolog. In contrast to a previous study, which used a cysteine Parts mutant, we find that the polymerization process of wild type ATP-ParM filaments consists of a polymerization phase and a subsequent steady state phase, which is dynamically unstable, like that of microtubules. We find that the apparent bidirectional polymerization of Parts, is not due to the intrinsic nature of this filament, but results from Parts forming randomly oriented bundles in the presence of crowding agents. Our results imply, that in the bacterium, Parts filaments spontaneously form bipolar bundles. Due to their intrinsic dynamic instability, Parts bundles can efficiently "search" the cytoplasmic lumen for DNA, bind it equally well at the bipolar ends and segregate it approximately symmetrically, by the insertion of Parts subunits at either end. (c) 2006 Elsevier Inc. All rights reserved.