Peptide-bacteria interactions using engineered surface-immobilized peptides from class IIa bacteriocins

Area of Science:

• Biochemistry
• Microbiology
• Materials Science

Background:

• Class IIa bacteriocins, like Leucocin A (LeuA), are antimicrobial peptides known for targeting Gram-positive bacteria.
• The specificity of LeuA is primarily attributed to its C-terminal amphipathic helical region.
• The substrate-bound specificity of LeuA has not been previously investigated.

Purpose of the Study:

• To synthesize and characterize LeuA derivatives to investigate their substrate-bound specificity.
• To explore the potential of LeuA derivatives as molecular recognition elements in biosensing platforms.

Main Methods:

• Synthesis of 14-amino acid (14AA LeuA) and 24-amino acid (24AA LeuA) derivatives of LeuA, incorporating an N-terminal cysteine for immobilization.
• Purification of peptides using RP-HPLC and confirmation via mass spectrometry.
• Immobilization of peptides onto gold surfaces and characterization of their orientation and thickness using ellipsometry and grazing angle infrared spectroscopy.
• Testing the bacterial specificity of immobilized peptides against Gram-positive and Gram-negative bacteria.

Main Results:

• Both 14AA LeuA and 24AA LeuA were successfully synthesized, purified, and immobilized with random helical orientation.
• Surface-adsorbed 14AA LeuA showed no specificity towards tested bacterial strains.
• Surface-immobilized 24AA LeuA exhibited significant binding to Gram-positive bacteria, with varying affinities among different strains.
• The lack of binding for 14AA LeuA suggests a minimum length is required for receptor recognition.

Conclusions:

• The length of LeuA derivatives is critical for specific bacterial recognition when immobilized on a surface.
• Surface-immobilized 24AA LeuA demonstrates potential as a specific molecular recognition element.
• Class IIa bacteriocins can be utilized in the development of novel biosensing platforms.