Chaitra Moolaveesala
Pronouns: She/Her
Research Mentor(s): Harry Mobley
Research Mentor School/College/Department: Microbiology and Immunology / Medicine
Program: CG
Session: Session 5 (2:40pm – 3:30pm)
Authors: Chaitra Moolaveesala, Madison Fitzgerald, Harry Mobley
Abstract
The most common hospital-acquired infections are catheter-associated urinary tract infections (CAUTIs)4. In 2021, general acute care hospitals in the United States reported 24,710 CAUTIs to the CDC5. A major causative agent of CAUTIs is urease-producer Proteus mirabilis. Urease hydrolyzes urea to form ammonia and carbon dioxide1. These products increase the local pH, causing polyvalent cations to fall out of solution. The metals crystallize and form urinary stones that P. mirabilis can colonize1. Additionally, urease-derived ammonia provides a nitrogen source during infection2. The urease production operon (ureDABCEFG) encodes urease subunits and accessory proteins3. This operon is regulated by ureR, a transcriptional regulator directly upstream of ureD. Expression of ureR and ureDABCEFG is driven by a bi-directional promoter with two UreR binding sites. When urea is present, UreR binds at these sites to activate expression in both directions. The resulting ure transcript features an unusually long 5’ untranslated region (5’UTR) encoding a small open reading frame (ORF) and a putative sRNA. High sequence conservation of the 5’UTR could indicate these elements are functional. This promoter was characterized before the development of whole-genome sequencing, and therefore the sequence conservation of this region among P. mirabilis strains is unknown. This project aims to determine the sequence conservation of the urease promoter using publicly available P. mirabilis genomes. Using 470 genomes that met our quality standards, we produced a multiple sequence alignment of the intergenic region between ureR and ureD (Clustal Omega). The conservation of this alignment was visualized in a Sequence Logo graph (WebLogo). A position frequency matrix (BuddySuite) identified 16 unique single nucleotide polymorphisms (SNPs). Six of these SNPs are present in = 3.2% of strains and formed three distinct groups. Strains of each group clustered together on a phylogenetic tree based on the ure promoter (iTOL). The identified SNPs are outside of known regulatory elements, and ongoing research aims to assess their impact on urease expression. We observed strong sequence conservation throughout the ure promoter, including the 5’UTR. This indicates the small ORF and putative sRNA are potentially functional, although conservation was not specific to those regions. This work advances previous research that found ure operon expression is a key contributor to P. mirabilis uropathogenesis. Works Cited 1. Dattelbaum, J.D. et al. (2003) “UreR, the transcriptional activator of the Proteus mirabilis urease gene cluster, is required for urease activity and virulence in experimental urinary tract infections,†Infection and Immunity, 71(2), pp. 1026–1030. Available at: https://doi.org/10.1128/iai.71.2.1026-1030.2003. 2. Pearson, M.M. et al. (2011) “Transcriptome of Proteus Mirabilis in the murine urinary tract: Virulence and nitrogen assimilation gene expression,†Infection and Immunity, 79(7), pp. 2619–2631. Available at: https://doi.org/10.1128/iai.05152-11. 3. Poore, C.A. and Mobley, H.L. (2003) “Differential regulation of the Proteus Mirabilis urease gene cluster by UreR and H-NS,†Microbiology, 149(12), pp. 3383–3394. Available at: https://doi.org/10.1099/mic.0.26624-0. 4. Tambyah, P.A. and Maki, D.G. (2000) “Catheter-associated urinary tract infection is rarely symptomatic,†Archives of Internal Medicine, 160(5). Available at: https://doi.org/10.1001/archinte.160.5.678. 5. U.S. Department of Health & Human Services. (2021, October 15). National Healthcare Safety Network (NHSN). Centers for Disease Control and Prevention. Retrieved December 3, 2022, from https://www.cdc.gov/nhsn/index.html
