A Distinct Type of Pilus from the Human Microbiome
Qingping Xu1, Mikio Shoji2, Satoshi Shibata2
1Joint Center for Structural Genomics, http://www.jcsg.org; SLAC National Accelerator Laboratory, Stanford Synchrotron Radiation Lightsource, Menlo Park, CA 94025, USA.
Cell
|April 12, 2016
Summary
Researchers uncovered the unique structure and assembly of Bacteroidia pili from the human microbiome. These bacterial pili utilize a novel strand-exchange mechanism for biogenesis, distinct from previously known types.
Area of Science:
- Microbiology and Structural Biology
- Bacterial Adherence and Virulence Factors
Background:
- Pili are essential bacterial surface appendages involved in adhesion and virulence.
- The structure and assembly of pili from Bacteroidia species in the human microbiome were previously uncharacterized.
Purpose of the Study:
- To elucidate the molecular structures of 20 Bacteroidia pilins.
- To determine the mechanism by which these pilins assemble into functional pili.
Main Methods:
- X-ray crystallography was employed to determine the three-dimensional structures of the pilins.
- Biochemical assays were performed to investigate the polymerization and assembly processes.
- Comparative analysis with known pilus systems was conducted.
Main Results:
- A common Greek-key β sandwich fold with two transthyretin-like repeats was identified across the pilin superfamily.
- Pilus assembly occurs via a strand-exchange mechanism, involving proteinase-assisted N-terminal β-strand removal and hydrophobic groove binding.
- Accessory pilins at the tip and base exhibit specialized structures for assembly initiation and termination.
Conclusions:
- Bacteroidia pili possess a distinct biogenesis mechanism, differing from other characterized bacterial pili.
- This discovery reveals a novel type of bacterial pilus with unique assembly strategies.
- Understanding these mechanisms can provide insights into bacterial interactions within the human microbiome.
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