Beyond the bacterium: planctomycetes challenge our concepts of microbial structure and function

Area of Science:

• Microbiology
• Cell Biology
• Evolutionary Biology

Background:

• Planctomycetes are a bacterial phylum with unique cellular features, including internal membrane-bound compartments.
• Some Planctomycetes, like Gemmata, possess a membrane-bound nucleoid, resembling eukaryotic nuclei.
• Anammox planctomycetes utilize a unique metabolism involving the anammoxosome, a potential analogue to mitochondria.

Purpose of the Study:

• To highlight the unusual cellular compartmentalization in Planctomycetes.
• To discuss the implications of these features for understanding the origin of eukaryotic organelles.
• To emphasize the phylum's significance for research into eukaryotic cell evolution.

Main Methods:

• Comparative genomics and cell biology analyses were implicitly used to describe these features.
• Literature review of existing studies on Planctomycetes' cellular structure and metabolism.
• Highlighting recent discoveries of endocytosis-like abilities and clathrin homologues.

Main Results:

• Planctomycetes exhibit extensive intracellular compartmentalization, challenging traditional bacterial cell models.
• The presence of a membrane-bound nucleoid and the anammoxosome suggests functional parallels with eukaryotic organelles.
• Discovery of endocytosis-like mechanisms and clathrin proteins in Planctomycetes.

Conclusions:

• Planctomycetes' unique biology provides critical insights into the evolution of cellular complexity.
• The phylum serves as a model for studying the origins of eukaryotic cellular structures and functions.
• Further research on Planctomycetes is crucial for understanding the transition from prokaryotic to eukaryotic life.