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Updated: Feb 3, 2026
Super-resolution Imaging of Proteus mirabilis Biofilm by Expansion Microscopy
Published on: July 18, 2025
Structures of two fimbrial adhesins, AtfE and UcaD, from the uropathogen Proteus mirabilis
Wangshu Jiang1, Wimal Ubhayasekera1, Melanie M Pearson2
1Department of Cell and Molecular Biology, Uppsala University, Biomedical Center, PO Box 596, SE-751 24 Uppsala, Sweden.
Abstract:
The important uropathogen Proteus mirabilis encodes a record number of chaperone/usher-pathway adhesive fimbriae. Such fimbriae, which are used for adhesion to cell surfaces/tissues and for biofilm formation, are typically important virulence factors in bacterial pathogenesis. Here, the structures of the receptor-binding domains of the tip-located two-domain adhesins UcaD (1.5 Å resolution) and AtfE (1.58 Å resolution) from two P. mirabilis fimbriae (UCA/NAF and ATF) are presented. The structures of UcaD and AtfE are both similar to the F17G type of tip-located fimbrial receptor-binding domains, and the structures are very similar despite having only limited sequence similarity. These structures represent an important step towards a molecular-level understanding of P. mirabilis fimbrial adhesins and their roles in the complex pathogenesis of urinary-tract infections.
Insights
Proteus mirabilis, a urinary tract pathogen, has many fimbriae. Researchers determined the structures of two adhesins, UcaD and AtfE, crucial for bacterial adhesion and infection.
Area of Science:
- Microbiology
- Structural Biology
- Pathogenesis
Background:
- Proteus mirabilis is a significant uropathogen.
- It possesses a large number of chaperone/usher-pathway fimbriae, which are key virulence factors involved in adhesion and biofilm formation.
Purpose of the Study:
- To elucidate the molecular structures of the receptor-binding domains of two P. mirabilis fimbrial adhesins, UcaD and AtfE.
- To understand the structural basis of adhesion in P. mirabilis pathogenesis.
Main Methods:
- X-ray crystallography was used to determine the structures.
- High-resolution structures of UcaD (1.5 Å) and AtfE (1.58 Å) were obtained.
Main Results:
- The structures of UcaD and AtfE were determined, revealing similarity to the F17G type of tip-located fimbrial receptor-binding domains.
- Despite limited sequence similarity, the overall structures of UcaD and AtfE are highly conserved.
Conclusions:
- These structural findings provide critical insights into the molecular mechanisms of P. mirabilis fimbrial adhesins.
- Understanding these adhesins is vital for comprehending the pathogenesis of urinary tract infections caused by P. mirabilis.
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