On page 945, Kiessling et al. observe that FtsZ protein from the moss Physcomitrella patens can form a cytoskeleton-like network in chloroplasts. As McFadden discusses on page F19, FtsZ is well known in bacteria as a protein that transiently polymerizes into a ring at the division site. It has also been implicated in chloroplast division, but this is the first time that any protein has been linked to such a permanent plastoskeleton. Physcomitrella was recently chosen as a model organism, thanks to properties such as homologous recombination rates of up to 90% and tissues that are a single cell in thickness. The latter characteristic made it easier for Kiessling et al. to detect fusions between FtsZ and green fluorescent protein, and may explain why the plastoskeleton has been characterized first in this moss.
Chloroplasts are thought to be...
