Export of diverse and bioactive peptides through a type I secretion system

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• Microcins are peptide antibiotics produced by Gram-negative bacteria.
• Type I secretion systems (T1SS) are responsible for exporting microcins from the bacterial cytoplasm to the extracellular environment.
• The substrate specificity of T1SSs that secrete microcins is not well understood.

Approach:

• Investigated the microcin V T1SS from Escherichia coli.
• Tested the ability of the microcin V T1SS to export various natural and synthetic peptides.
• Assessed the impact of peptide properties such as charge, hydrophobicity, and length on secretion.
• Demonstrated the functionality of the microcin V T1SS in other Gram-negative species.

Key Points:

• The microcin V T1SS exhibits remarkable promiscuity, exporting a diverse range of peptides.
• Peptide secretion is primarily constrained by length, not charge or hydrophobicity.
• Various bioactive peptides, including antimicrobial peptides and hormones, can be secreted and retain their function.
• The microcin V T1SS functions in multiple Gram-negative species inhabiting the gastrointestinal tract.

Conclusions:

• The microcin V T1SS is a highly versatile peptide exporter.
• Findings have significant implications for understanding native cargo capacity and developing Gram-negative bacteria for peptide research and delivery applications.