Hydrogenosomes and mitosomes: conservation and evolution of functions

Area of Science:

• Microbiology and Eukaryotic Cell Biology
• Organelle Biology
• Evolutionary Biology

Background:

• Historically, some microbial eukaryotes were believed to lack mitochondria.
• Genetic evidence suggested a mitochondrial ancestry even in their absence.
• Recent discoveries confirm mitochondrial presence in all studied amitochondriate protists.

Purpose of the Study:

• To investigate the characteristics and functions of unusual mitochondria in anaerobic protists.
• To determine if these organelles have converged on similar roles.
• To explore the implications for theories on eukaryotic origins.

Main Methods:

• Comparative genomics to identify mitochondrial genes.
• Cellular and biochemical analyses of organelle functions.
• Ecological niche analysis of protist hosts.

Main Results:

• Mitochondrial compartments are now recognized in all previously amitochondriate protists.
• Iron-sulfur cluster assembly is proposed as a common feature, but the key protein remains unidentified.
• Protists with unusual mitochondria inhabit diverse ecological niches.

Conclusions:

• All eukaryotes possess mitochondria, challenging previous assumptions and influencing theories of eukaryotic origin.
• The physiological roles of unusual mitochondria likely vary due to different ecological pressures.
• Further research is needed to identify the specific proteins and functions unique to these diverse organelles.