Magnetosomes: how do they stay in shape?

Biology textbooks taught us that eukaryotes could be easily distinguished from the far less complex bacteria. One criterion is that eukaryotes can segregate their DNA into a lipid-bounded compartment called a nucleus which isolates DNA replication and transcription from the rest of the cytoplasmic content. The second criterion is that eukaryotes can compartmentalize their cytoplasm so as to isolate specific pathways, enzymes and chemical reactions in membrane-bounded subcellular compartments called organelles. Time and high resolution imaging taught us that the story is a little more complicated. In fact, bacteria too can isolate cell components in subcellular compartments, including, in rare cases, their DNA. Clearly, some bacteria also have the capacity to isolate reactions that require a specific chemistry or that generate toxic byproducts within specialized organelles. Despite the significant advances made in the field of bacterial cell biology in the past 15 years, little is known about the mechanisms employed by bacteria to shape, position and segregate organelles, or how the cells can discriminate and address specific proteins to these compartments. Then, if eukaryotes did not invent organelles or the nucleus, who did? Are bacteria with a complex cell plan providing us with an unexpected opportunity to investigate how organelles came to exist? Is it possible that the mechanisms leading to cell compartmentalization in eukaryotes were invented by bacteria? Or, by studying how bacterial organelles are formed, will we discover new ways to control membrane curvature, target proteins, organize and segregate organelles?