Tailoring a Global Iron Regulon to a Uropathogen

Area of Science:

• Microbiology
• Molecular Biology
• Bacterial Pathogenesis

Background:

• Pathogenicity islands and plasmids contribute to Escherichia coli virulence.
• Regulatory networks' role in disease phenotypes is less understood.
• Iron homeostasis is crucial for bacterial survival and pathogenesis.

Purpose of the Study:

• To dissect the regulatory network governed by the ferric uptake regulator (Fur) in uropathogenic E. coli (UPEC).
• To compare Fur regulons between UPEC and commensal E. coli K-12.
• To understand how Fur-mediated regulation impacts bacterial adaptation to host environments.

Main Methods:

• Genome-scale DNA binding assays for Fur.
• Transcriptomic and proteomic analyses of UPEC and E. coli K-12.
• Analysis of gene expression and protein levels under varying conditions (anaerobic, aerobic, iron chelation).

Main Results:

• The Fur regulon in UPEC is conserved but also includes genes on pathogenicity islands.
• UPEC fur mutants showed unexpected activation of amino acid limitation and general stress responses.
• Amino acid addition mitigated stress in UPEC fur mutants; iron chelation mimicked this effect.
• Aerobic conditions exacerbated amino acid demand, linked to aerobactin synthesis.

Conclusions:

• Fur regulation in UPEC links iron homeostasis to amino acid demand and stress responses.
• This coordinated response may be critical for UPEC survival in nutrient-limited urinary tract environments.
• The coupling of iron limitation response to increased amino acid demand differentiates UPEC from other E. coli pathotypes.