Cu(II)-Binding N-Terminal Sequences of Human Proteins

Area of Science:

• Biochemistry
• Metalloprotein Chemistry
• Bioinorganic Chemistry

Background:

• Proteins primarily bind copper(II) ions via histidine imidazole groups.
• The position of histidine residues significantly influences copper-binding characteristics.
• N-terminal histidine motifs (His¹, His², His³) possess distinct Cu(II) interaction properties.

Purpose of the Study:

• To investigate the unique Cu(II)-binding properties of N-terminal histidine motifs (His¹, His², His³).
• To explore the role of these motifs in copper ion exchange and redox activity.
• To identify human proteins with these motifs and predict their interaction with copper.

Main Methods:

• Searched the UniProt Knowledgebase for human protein sequences containing His¹, His², or His³ motifs.
• Analyzed proteolytically modified sequences (propeptide or methionine removal).
• Classified sequences based on subcellular localization to assess copper interaction probability.

Main Results:

• N-terminal histidine motifs display enhanced Cu(II) accessibility, flexibility, and ligand exchange rates.
• Sequences with His¹ and His² exhibit redox activity, suggesting a role in Cu(II) to Cu(I) reduction.
• Identified numerous human proteins with these motifs across various subcellular compartments.

Conclusions:

• N-terminal histidine motifs are key players in copper ion coordination and dynamics.
• These motifs are implicated in copper-dependent redox processes.
• The study provides a framework for understanding copper interactions in human proteins.