[Perspective] Pathogen to powerhouse
Mitochondria and plastids are essential for harnessing energy in eukaryotic cells. They are believed to have formed through primary endosymbioses, in which bacterial symbionts were converted into energy-producing organelles. Primary endosymbiosis is extremely rare: Only one other case is known, in the amoeba Paulinella (1). This rarity is usually attributed to the many innovations that are required for organelles to be integrated into the cellular machinery (2). However, the first challenges for an endosymbiont are to avoid being digested by the host and to replicate in its novel environment. Recent studies provide clues to how the precursors to mitochondria and the plastid overcame these challenges. Authors: Steven G. Ball, Debashish Bhattacharya, Andreas P. M. Weber