Neutrophil elastase depends on serglycin proteoglycan for localization in granules.

Granule proteins play a major role in bacterial killing by neutrophils. Serglycin proteoglycan, the major intracellular proteoglycan of hematopoietic cells, has been proposed to play a role in sorting and packing of granule proteins. We examined the content of major neutrophil granule proteins in serglycin knockout mice and found neutrophil elastase absent from mature neutrophils as shown by activity assay, Western blotting, and immunocytochemistry, whereas neutrophil elastase mRNA was present.

Plectasin is a peptide antibiotic with therapeutic potential from a saprophytic fungus.

Animals and higher plants express endogenous peptide antibiotics called defensins. These small cysteine-rich peptides are active against bacteria, fungi and viruses. Here we describe plectasin-the first defensin to be isolated from a fungus, the saprophytic ascomycete Pseudoplectania nigrella.