A dimerization interface mediated by functionally critical residues creates interfacial disulfide bonds and copper...

Area of Science:

• Biochemistry
• Microbiology
• Structural Biology

Background:

• CueP protein confers bacterial resistance to copper in the periplasm.
• Its mechanism, especially under anaerobic conditions, remains largely unknown.
• Existing data suggest noncovalent dimerization and roles for cysteine and histidine residues in copper binding.

Purpose of the Study:

• To elucidate the mechanism of CueP-mediated copper resistance.
• To investigate the structural and functional significance of CueP dimerization.
• To understand the role of CueP in linking redox-state sensing and copper detoxification.

Main Methods:

• Analysis of dimerization equilibrium.
• Identification of a novel functional interface.
• Investigation of disulfide bonding and copper binding sites.

Main Results:

• Evidence for a dimerization equilibrium mediated by a newly identified interface.
• This interface occludes internal copper sites and disulfide bonds.
• The mechanism allows for intra- and interchain disulfide bonding, an extensive disulfide relay, and interfacial copper sites.

Conclusions:

• CueP utilizes a unique dimerization mechanism for copper resistance.
• The protein links cellular redox-state sensing with copper detoxification pathways.
• Findings provide new insights into bacterial metalloid resistance strategies.