MrpH, a new class of metal-binding adhesin, requires zinc to mediate biofilm formation

• Published in: PLoS pathogens 2020-08, Vol.16 (8), p.e1008707
• Main Authors: Jiang, Wangshu, Ubhayasekera, Wimal, Breed, Michael C, Norsworthy, Allison N, Serr, Nina, Mobley, Harry L. T, Pearson, Melanie M, Knight, Stefan D
• Format: Article
• Language: English
• Subjects: Agglutination; Bacteria; Bacterial infections; Binding sites; Biofilms; Biology and Life Sciences; Bladder; Catheters; Cellular proteins; Chelation; Colonization; Crystal structure; E coli; Engineering and Technology; Erythrocytes; Funding; Genetic aspects; Gram-negative bacteria; Growth; Histidine; Immunology; Infectivity; Kidneys; Mannose; Medical instruments; Medical schools; Medicine and Health Sciences; Metals; Microbial mats; Molecular biology; Mutagenesis; Mutation; Observations; Physical Sciences; Pili; Properties; Protein binding; Red blood cells; Research and Analysis Methods; Site-directed mutagenesis; Transition metals; Urinary tract; Urinary tract infections; Urogenital system; Zinc
• ISSN: 1553-7374; 1553-7366; 1553-7374
• DOI: 10.1371/journal.ppat.1008707

Proteus mirabilis, a Gram-negative uropathogen, is a major causative agent in catheter-associated urinary tract infections (CAUTI). Mannose-resistant Proteus-like fimbriae (MR/P) are crucially important for P. mirabilis infectivity and are required for biofilm formation and auto-aggregation, as well as for bladder and kidney colonization. Here, the X-ray crystal structure of the MR/P tip adhesin, MrpH, is reported. The structure has a fold not previously described and contains a transition metal center with Zn.sup.2+ coordinated by three conserved histidine residues and a ligand. Using biofilm assays, chelation, metal complementation, and site-directed mutagenesis of the three histidines, we show that an intact metal binding site occupied by zinc is essential for MR/P fimbria-mediated biofilm formation, and furthermore, that P. mirabilis biofilm formation is reversible in a zinc-dependent manner. Zinc is also required for MR/P-dependent agglutination of erythrocytes, and mutation of the metal binding site renders P. mirabilis unfit in a mouse model of UTI. The studies presented here provide important clues as to the mechanism of MR/P-mediated biofilm formation and serve as a starting point for identifying the physiological MR/P fimbrial receptor.