Abstract
The antimicrobial polypeptides Bac7 and Bac5 (bactenecins) are stored in the large granules of bovine neutrophils as precursor forms, or probactenecins. Maturation of probactenecins has been investigated by studying the effects of stimulus-induced degranulation on this process. Stimulation of neutrophils with PMA, which is a secretagogue for specific and large granules but not for azurophils, induces a substantial discharge of uncleaved probactenecins in the extracellular medium, as revealed by Western blot analysis. When neutrophils are exposed to opsonized bacteria in the presence of cytochalasin B, resulting in exocytosis of the content of azurophils in addition to that of specific and large granules, probactenecins are secreted and rapidly converted into the corresponding mature antimicrobial peptides. Such a conversion is prevented if serine proteases, stored in the azurophils, are inhibited by pretreatment of neutrophils with PMSF. Phagocytosis, while causing a rapid discharge of the contents of azurophil and of the large granules into phagocytic vacuoles, as indicated by immunogold electron microscopy, also induces cleavage of probactenecins into mature peptides, as revealed by Western blot analysis. We conclude that the final processing of the storage forms of bactenecins arises from their interaction with the serine protease(s) of azurophils during bacteria-induced degranulation of neutrophils.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.