Dissolving Silver Nanoparticles Modulate the Endothelial Monocyte-Activating Polypeptide II (EMAP II) by Partially...

Area of Science:

• Biomedical Nanotechnology
• Molecular Biology
• Biochemistry

Background:

• Metal nanoparticles (NPs), particularly silver NPs (AgNPs), are widely used in biomedical applications due to their antibacterial properties.
• AgNPs can exhibit toxicity, with silver ions (Ag+) targeting cysteine residues in proteins.
• Endothelial monocyte-activating polypeptide II (EMAP II), a protein fragment of AIMP1, contains surface-exposed cysteines susceptible to Ag+ interaction.

Purpose of the Study:

• To investigate the interactions between AgNPs, EMAP II, and tRNA.
• To understand how AgNP dissolution affects EMAP II-tRNA binding.
• To elucidate the structural impact of Ag+ on EMAP II and its functional consequences.

Main Methods:

• UV-Vis and fluorescence spectroscopy to study AgNP dissolution and EMAP II-tRNA interactions.
• Heteronuclear 1H-15N HSQC spectra with a paramagnetic probe to map EMAP II binding sites on AgNPs.
• Structural analysis of EMAP II to assess denaturation effects.

Main Results:

• Ag+ ions released from AgNPs bind to exposed cysteines on EMAP II, causing partial denaturation.
• This structural destabilization unexpectedly increases the affinity of tRNA to EMAP II, lowering the dissociation constant (Kd).
• The EMAP II/tRNA/AgNP interaction is modulated by Mg2+ ions and thiol-protecting agents like TCEP.

Conclusions:

• AgNPs can alter the structure and function of EMAP II through Ag+ binding to cysteine residues.
• The observed enhancement of tRNA affinity to Ag+-bound EMAP II suggests complex biological implications.
• Understanding these interactions is crucial for assessing AgNP safety and optimizing their use in biomedical contexts.