From The Origin of Species to the origin of bacterial flagella

  title={From The Origin of Species to the origin of bacterial flagella},
  author={Mark J. Pallen and Nicholas J. Matzke},
  journal={Nature Reviews Microbiology},
In the recent Dover trial, and elsewhere, the 'Intelligent Design' movement has championed the bacterial flagellum as an irreducibly complex system that, it is claimed, could not have evolved through natural selection. Here we explore the arguments in favour of viewing bacterial flagella as evolved, rather than designed, entities. We dismiss the need for any great conceptual leaps in creating a model of flagellar evolution and speculate as to how an experimental programme focused on this topic… 
Evolution of the Bacterial Flagellum
Proponents of the intelligent design (ID) explanation for how organisms developed claim that the bacterial flagellum (BF) is irreducibly complex. They argue that this structure is so complicated that
Evolution of the Bacterial Flagellum Cumulative evidence indicates that flagella developed as modular systems, with many components deriving from other systems
Evidence is summarized from hundreds of laboratories showing that assumptions that the bacterial flagellum is irreducibly complex are false and that it developed as modular systems, with components deriving from many different sources.
Bacterial flagella and Type III secretion: case studies in the evolution of complexity.
In conclusion, rather than providing evidence of intelligent design, flagellar and non-flagllar Type III secretion systems provide excellent case studies in the evolution of complex systems from simpler components.
Stepwise formation of the bacterial flagellar system
These results show that core components of the bacterial flagellum originated through the successive duplication and modification of a few, or perhaps even a single, precursor gene.
Spontaneous adaptation of ion selectivity in a bacterial flagellar motor
Overall, transplanted Na+-powered stator genes can spontaneously incorporate novel mutations that allow H+-motility when environmental Na+ is lacking, and both flagellar- and non-flagella-associated genes that are involved in longer-term adaptation to new power sources are indicated.
Arriving at a correlation between the flagellar arrangement and multicellularity
A working hypothesis is offered for this pattern and the gradual shift in the flagellar arrangement from polar, peritrichous, sub-apical, and apical to lateral throughout evolution.
An evolutionary link between capsular biogenesis and surface motility in bacteria
This Opinion article argues that the available data suggest that the motility machinery evolved from this capsule assembly system following a gene duplication event, a change in carbohydrate polymer specificity and the acquisition of additional proteins by the Motility complex, all of which are key features that distinguish the surface motility and sporulation systems.
Structural differences in the bacterial flagellar motor among bacterial species
The current findings on the divergent structures of the bacterial flagellar motor suggest that the flageLLar motors have adapted to function in various environments where bacteria live and survive.
Origins of Flagellar Gene Operons and Secondary Flagellar Systems
The results demonstrate that the genetic basis of this ancient and structurally conserved organelle has been subject to many lineage-specific modifications.


Prokaryotic motility structures.
Research on the bacterial flagellum has greatly aided the authors' understanding of not only motility but also protein secretion and genetic regulation systems, and continued study and understanding of all prokaryotic motility structures will provide a wealth of knowledge that is sure to extend beyond the bounds of proKaryotic movement.
Spirochete periplasmic flagella and motility.
To better understand spirochete motility on a more molecular level, the proteins and genes involved in motility are being analyzed and unique aspects have already become evident.
Flagellar glycosylation - a new component of the motility repertoire?
This review focuses on the structural diversity in flagellar glycosylation systems and demonstrates that as a consequence of the unique assembly processes, the type of glycosidic linkage found on archaeal and bacterialflagellins is distinctive.
Characterization of the fliL gene in the flagellar regulon of Escherichia coli and Salmonella typhimurium
FliL does not appear to have a major role in flagellar structure or function and is therefore unlikely to be a component of the motor or switch; the effect on motility caused by truncation of the gene is probably an indirect one.
Diversity in Chemotaxis Mechanisms among the Bacteria and Archaea
The Bacillus subtilis chemotaxis system is considerably more complex and appears to be similar to the one that existed when the bacteria and archaea separated during evolution, so that understanding this mechanism should provide insight into the variety of mechanisms used today by the broad sweep of chemotactic bacteria and Archaea.
Regulation of flagella.