Background: Antibiotic resistance is a global issue and new anti-microbials are required.
Introduction: Anti-microbial peptides are important players of host innate immune systems that prevent
infections. Due to their ability to eliminate drug-resistant pathogens, AMPs are promising candidates for
developing the next generation of anti-microbials.
Methods: The anti-microbial peptide database provides a useful tool for searching, predicting, and designing
new AMPs. In the period from 2015-2019, ~500 new natural peptides have been registered.
Results: This article highlights a selected set of new AMP members with interesting properties.
Teixobactin is a cell wall inhibiting peptide antibiotic, while darobactin inhibits a chaperone and translocator
for outer membrane proteins. Remarkably, cOB1, a sex pheromone from commensal enterococci,
restricts the growth of multidrug-resistant Enterococcus faecalis in the gut at a picomolar concentration.
A novel proline-rich AMP has been found in the plant Brassica napus. A shrimp peptide MjPen-
II comprises three different sequence domains: serine-rich, proline-rich, and cysteine-rich regions. Surprisingly,
an amphibian peptide urumin specifically inhibits H1 hemagglutinin-bearing influenza A virus.
Defensins are abundant and typically consist of three pairs of intramolecular disulfide bonds. However,
rat rattusin dimerizes via forming five pairs of intermolecular disulfide bonds. While human LL-37
can be induced by vitamin D, vitamin A induces the expression of resistin-like molecule alpha (RELMα)
in mice. The isolation and characterization of an alternative human cathelicidin peptide, TLN-58, substantiates
the concept of one gene multiple peptides. The involvement of a fly AMP nemuri in sleep induction
may promote the research on the relationship between sleep and infection control.
Conclusion: The functional roles of AMPs continue to grow and the general term “innate immune peptides”
becomes useful. These discoveries widen our view on the anti-microbial peptides and may open
new opportunities for developing novel peptide therapeutics for different applications.