The Baramicin A precursor protein can be broken into three distinct domains: the
IM10-like,
IM22, and
IM24 domains. Five sub-peptides are produced by the BaraA precursor including one IM24 peptide, three IM10-like peptides, and one IM22 peptide. The IM10-like peptides of BaraA are specifically proposed as antifungal peptides produced by the
BaraA gene. The distinction between which of these two roles, if either, is the primary function of any given peptide is often unclear. The
Baramicin gene family of
D. melanogaster includes the immune-induced
BaraA and also two non-immune
Baramicin genes
BaraB and
BaraC. The
BaraB and
BaraC genes are expressed in the nervous system, in neurons or glia respectively. Evolutionary study suggests the IM24 domain is the key element of the Baramicin precursor that is involved in Baramicin function in the nervous system. This finding suggests antimicrobial peptides and neuropeptides might accomplish immune or neural roles not only by dual action of a single peptide, but rather by different mechanisms of action of sub-peptides.
BaraA mutants also display a reduced recovery rate after the injection of neurotoxins, which is rescued somewhat by expressing
BaraA in
glial cells of the fly's nervous system. Together with the description of antifungal activity of IM10-like peptides, the
BaraA gene therefore encodes both immune antimicrobials and some factor that promotes host resilience in the face of microbial toxins. == References ==