Structural characterisation of the natively unfolded enterocin EJ97.

Area of Science:

• Microbiology
• Biochemistry
• Structural Biology

Background:

• Bacteriocins are antimicrobial peptides produced by bacteria.
• Enterococci are Gram-positive bacteria known to produce bacteriocins called enterocins.
• Enterocin EJ97 is produced by Enterococcus faecalis EJ97.

Purpose of the Study:

• To structurally characterize the 44-residue enterocin EJ97.
• To investigate the conformational properties of enterocin EJ97 in solution.
• To compare experimental findings with computational predictions of protein disorder.

Main Methods:

• Experimental techniques: fluorescence, circular dichroism (CD), Fourier-transform infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR).
• Computational tools: bioinformatic algorithms for predicting protein disorder.
• Solution conditions: varied pH and guanidine hydrochloride (GdmCl) concentrations.

Main Results:

• Enterocin EJ97 is monomeric in aqueous solution.
• The peptide exhibits predominantly unfolded characteristics with transient helical or turn-like structures.
• Conformational properties are largely independent of pH and denaturant concentration, lacking cooperative transitions.
• Discrepancies observed between experimental data and some computational disorder prediction tools.

Conclusions:

• Enterocin EJ97 displays natively unfolded or highly flexible characteristics.
• Experimental data provides a benchmark for refining computational tools for predicting protein disorder.
• Further experimental validation is needed to improve disorder prediction algorithms.