Cryo-electron microscopy reveals two distinct type IV pili assembled by the same bacterium
Alexander Neuhaus1,2, Muniyandi Selvaraj3,4, Ralf Salzer5,6
1Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK.
Nature Communications
|May 8, 2020
Summary
Thermus thermophilus bacteria possess two types of type IV pili, wide and narrow. These pili, made of different pilin proteins, play distinct roles in bacterial functions like motility and DNA uptake.
Area of Science:
- Microbiology
- Structural Biology
- Biochemistry
Background:
- Type IV pili are essential bacterial surface appendages involved in motility, adhesion, and genetic exchange.
- Understanding the structural diversity and functional specialization of type IV pili is crucial for deciphering bacterial behavior.
Purpose of the Study:
- To investigate the structural and compositional differences of type IV pili in the bacterium Thermus thermophilus.
- To elucidate the distinct functional roles of different type IV pilus structures in bacterial processes.
Main Methods:
- Cryo-electron microscopy (cryo-EM) was employed to determine the high-resolution structures of the pili.
- Mass spectrometry was used to analyze the protein composition of the different pilus forms.
Main Results:
- Two distinct forms of type IV pili, termed 'wide' and 'narrow', were identified in Thermus thermophilus.
- Wide pili are primarily composed of PilA4 and are essential for natural transformation.
- Narrow pili are composed of a novel pilin, PilA5, and are critical for twitching motility.
Conclusions:
- Thermus thermophilus exhibits structural and functional heterogeneity in its type IV pilus system.
- The distinct pilin compositions of wide and narrow pili underlie their specialized roles in bacterial natural transformation and twitching motility, respectively.
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