Drosocin is primarily active against
Gram-negative bacteria. The peptide is
proline-rich with proline-
arginine repeats, as well a critical
threonine residue. This threonine is
O-
glycosylated, which is required for antimicrobial activity. Like the antimicrobial peptides
pyrrhocoricin and
abaecin, drosocin early studies showed it can bind to bacterial DnaK, inhibiting cell machinery and replication. However the action of these drosocin-like peptides may instead be to bind to microbe
ribosomes, preventing
protein translation. Proline-rich peptides such as drosocin are potentiated by the presence of pore-forming peptides, which facilitates the entry of drosocin-like peptides into the bacterial cell. In the absence of pore-forming peptides, the related AMP pyrrhocoricin is taken into the bacteria by the action of uptake permeases. In
Drosophila melanogaster the
Drosocin gene is specifically important for the fly defense against infection by
Enterobacter cloacae bacteria, supporting previous
in vitro work showing Drosocin is active against
E. cloacae. The
Drosocin gene of
Drosophila neotestacea uniquely encodes tandem repeats of
Drosocin mature peptides between cleavage sites. As a result, a single protein gets chopped up into multiple Drosocin peptides. This tandem repeat structure is also found in the honeybee AMP apidaecin or fruit fly
Baramicin, and is hypothesized as an evolutionary mechanism to increase the speed of the immune response and AMP production. ==Molecular structure==