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Published on: November 12, 2012
Structural and functional study of ChuY from Escherichia coli strain CFT073
Hun Kim1, Akhilesh Kumar Chaurasia1, Truc Kim1
1Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon, Gyeonggi 16419, South Korea.
Insights
Uropathogenic E. coli uses ChuY, a heme utilization protein, to maintain virulence. This flavin mononucleotide (FMN) reductase enzyme is crucial for bacterial survival in host cells.
Area of Science:
- Microbiology
- Structural Biology
- Biochemistry
Background:
- Uropathogenic *Escherichia coli* (UPEC) employs diverse iron and heme transport systems for urinary tract infection.
- The function of ChuY, a hypothetical protein in the heme degradation pathway, remained unclear.
Purpose of the Study:
- To elucidate the molecular and cellular function of ChuY in *E. coli* CFT073.
- To determine the structural characteristics and enzymatic activity of ChuY.
Main Methods:
- X-ray crystallography was used to determine the 3D structure of ChuY.
- Enzymatic assays confirmed flavin mononucleotide (FMN) reductase activity using NAD(P)H.
- Porphyrin ring binding affinity was assessed.
- A *chuY* deletion mutant was constructed and tested for virulence in mammalian cells.
Main Results:
- The crystal structure of ChuY revealed homology to human biliverdin and flavin reductases.
- ChuY exhibits FMN reductase activity and binds porphyrin rings.
- A *chuY* deletion mutant displayed reduced survival in mammalian cells compared to wild-type strains.
Conclusions:
- ChuY functions as a reductase involved in heme homeostasis.
- ChuY contributes to the virulence potential of *E. coli* CFT073 by maintaining heme homeostasis.
- ChuY is essential for bacterial survival during infection.
Abstract:
The uropathogenic Escherichia coli strain CFT073 contains multiple iron and heme transport systems, which facilitate infection of the host urinary tract. To elucidate the molecular and cellular function of ChuY, a hypothetical gene in the heme degradation/utilization pathway, we solved the crystal structure of ChuY at 2.4 Å resolution. ChuY has high structural homology with human biliverdin and flavin reductase. We confirmed that ChuY has flavin mononucleotide (FMN) reductase activity, using NAD(P)H as a cofactor, and shows porphyrin ring binding affinity. A chuY deletion-insertion strain showed reduced survival potential compared to wild-type and complemented strains in mammalian cells. Current results suggest ChuY acts as a reductase in heme homeostasis to maintain the virulence potential of E. coli CFT073.
