Biochemical interaction of human neutrophil peptide-1 with Mycobacterium tuberculosis H37Ra

The biochemical mechanism of action of human neutrophil peptide-1 (HNP-1) a gainst Mycobacterium tuberculosis H37Ra was studied. Mycobacteria grown in the presence of a subinhibitory concentration (IC50) of HNP-1 showed a sign ificant decrease in the biosynthesis of vital macromolecules, as shown by t he incorporation of various radiolabeled precursors. Mycobacterial cells gr own in the presence of HNP-1 exhibited surface changes, as was evident from the increased number of binding sites for L-anilinonaphthalene 8-sulfonate . Permeability studies carried out with spheroplasts showed a significantly high permeability to a fluorescent probe, N-phenyl naphthylamine, in the p resence of HNP-1. Significant changes in the cell wall and cell membrane we re observed when HNP-1-grown cells were analysed by transmission electron m icroscopy. Our results suggest the mycobacterial cell wall/membrane to be t he major target(s) of HNP-1.