Related Experiment Video
Updated: Jun 23, 2026
06:08
Biophysical Characterization of Flagellar Motor Functions
Published on: January 18, 2017
The last bacterial common ancestor encoded a complex flagellum.
Biorxiv : the Preprint Server for Biology
|June 22, 2026
Summary
The last bacterial common ancestor had a complex, 52-gene flagellum, not a simpler one. This finding suggests many modern bacterial flagella evolved through gene loss, not just gene gain.
Area of Science:
- Microbiology
- Evolutionary Biology
- Genomics
Background:
- Bacterial flagella are essential rotary nanomachines for motility.
- Previously, only 24 flagellar genes were thought to be conserved across bacteria.
- This raised questions about the complexity of the ancestral bacterial flagellum.
Purpose of the Study:
- To reconstruct the ancestral complexity of bacterial flagellar systems.
- To determine if the last bacterial common ancestor had a simple or complex flagellum.
- To investigate the evolutionary history of flagellar genes.
Main Methods:
- Large-scale profile- and sequence-based searches across bacterial genomes.
- Analysis of conserved sequence signatures and gene-tree clustering.
- Examination of flagellar gene-neighborhood evidence.
Main Results:
- Identified 28 additional flagellar gene families originating before major bacterial diversification.
- Reconstructed a 52-gene ancestral flagellum, including all essential components.
- Found evidence that many extant bacterial flagella resulted from lineage-specific gene loss.
Conclusions:
- The last bacterial common ancestor possessed a highly complex flagellar system.
- The ancestral flagellum was not genetically minimal, contrary to previous notions.
- Evolutionary models of early bacterial motility require revision based on these findings.
More Related Videos
07:59Investigating Flagella-Driven Motility in Escherichia coli by Applying Three Established Techniques in a Series
Published on: May 10, 2020
09:12Applying Live Cell Imaging and Cryo-Electron Tomography to Resolve Spatiotemporal Features of the Legionella pneumophila Dot/Icm Secretion System
Published on: March 10, 2020
Related Concept Videos
01:18Flagella and Motility in Bacteria
Flagella are specialized, thread-like structures that extend from a bacteria's cell envelope. They play a crucial role in motility and chemotaxis. Their structural organization and functioning exemplify sophisticated biological engineering, enabling bacterial survival and adaptability in diverse environments.Structure of the FlagellumA bacterial flagellum consists of three key components: the filament, the hook, and basal body. The filament, a long, helical structure composed of repeating...
01:24Eukaryotic Evolution
The endosymbiont theory is the most widely accepted theory of eukaryotic evolution; however, its progression is still somewhat debated. According to the nucleus-first hypothesis, the ancestral prokaryote first evolved a membrane to enclose DNA and form the nucleus. Conversely, the mitochondria-first hypothesis suggests that the nucleus was formed after endosymbiosis of mitochondria.
Contrary to the endosymbiont theory, the eukaryote-first hypothesis proposes that the simpler prokaryotic and...
Contrary to the endosymbiont theory, the eukaryote-first hypothesis proposes that the simpler prokaryotic and...
01:24Microtubules in Cell Motility
Microtubules are thick hollow cylindrical proteins that help form the cytoskeleton. Microtubules have varied roles in the cell. These filaments help form cellular appendages like cilia and flagella, which are responsible for locomotion. The cilia arise from basal bodies, separated from the main body by a membrane-like structure forming the transition zone. This zone is the gate for the entry of lipids and proteins, creating a unique composition of lipids and proteins in the ciliary membrane and...
01:24Microtubules in Cell Motility
Microtubules are thick hollow cylindrical proteins that help form the cytoskeleton. Microtubules have varied roles in the cell. These filaments help form cellular appendages like cilia and flagella, which are responsible for locomotion. The cilia arise from basal bodies, separated from the main body by a membrane-like structure forming the transition zone. This zone is the gate for the entry of lipids and proteins, creating a unique composition of lipids and proteins in the ciliary membrane and...
01:28Fimbriae, Pili, and Axial Filaments
Fimbriae and pili are specialized bacterial surface structures that play pivotal roles in adhesion, genetic exchange, and motility. Composed primarily of pilin protein, these hairlike appendages are crucial for bacterial survival and pathogenicity in various environments.Fimbriae: Adhesion and PathogenicityFimbriae are fine, filamentous structures measuring 2–10 nanometers in diameter and are densely distributed on the bacterial cell surface. They facilitate bacterial adhesion to abiotic...
01:29Cytoskeletal Proteins in Bacteria
Bacterial cells were initially considered simple, randomly organized structures lacking a cytoskeleton. However, the discovery of cytoskeleton homologs in bacteria led to the change of this opinion. Bacterial cytoskeletal filaments regulate the cell shape, cell polarity, cell division, and partitioning of plasmids during cell division. It was later discovered that bacterial cytoskeletal proteins, mainly actin and tubulin homologs, are diverse compared to their eukaryotic counterparts. On the...