Antibacterial activity of glycosylated and phosphorylated chromogranin A-derived peptide 173-194 from bovine adrenal medullary chromaffin granules

Abstract

Recently, we have isolated from bovine chromaffin granules and identified two natural peptides possessing antibacterial activity: secretolytin (chromogranin B 614-626) and enkelytin (proenkephalin-A 209- 237). Here, we characterize a large natural fragment, corresponding to chromogranin A 79-431, that inhibits growth of both Gram-positive and Gram- negative bacteria. The aim of the present work was to determine the shortest active peptide located in the 79-431 chromogranin A region. Three peptides, which shared the same 173-194 chromogranin A sequence (YPGPQAKED- SEGPSQGPASREK) but differed in post-translational modifications, including O- glycosylation and tyrosine phosphorylation, were isolated. A detailed study using microsequencing and mass spectrometry allowed us to correlate their antibacterial activity with these posttranslational modifications. The chromogranin A precursor fragment (79-431) and the active glycosylated and phosphorylated peptides were, respectively, named prochromacin and chromacin (P, G, and PG for phosphorylated, glycosylated, and phosphorylated- glycosylated form).