Anti-microbial activity and cell binding are controlled by sequence determinants in the anti-microbial peptide PR-39.
PR-39 is a member of the proline-rich group of cathelicidin peptides, a class of anti-microbial peptides found in skin and in leukocytes. In addition to their innate defense function, these proline-rich peptides influence a number of mammalian cell processes, including inflammation, development, differentiation, and metastatic transformation. To characterize the mechanism further, through which proline-rich cathelicidin peptides may exert their numerous effects, we altered various conserved peptide sequence motifs using a biologically active fragment of PR-39 [PR-39(15)] as the template: We altered the N-terminal charge of its SH3 binding motif, substituted tryptophan for a conserved intervening leucine, and modified a proline-arginine stretch (residues 10-13). These peptide variants were tested for binding known targets of PR-39 and for biologic activity in mammalian and bacterial systems. We found that the N-terminal arginines are crucial for protein binding and that modification in this domain results in loss of affinity and specificity in binding to generalized and SH3-containing targets. The N-terminal charged residues are also required for NIH 3T3 syndecan induction and anti-microbial activity. In addition, modification of more C-terminal residues eliminates anti-bacterial activity while having less of an effect on peptide interactions in mammalian cell assays. This study shows that the presence of a charged N-terminus is important for peptide activity in both mammalian and bacterial systems whereas the C-terminal alterations of PR-39(15) more definitively affect anti-bacterial activity.
Chan
Y R
YR
Harvard-MIT Division of Health Sciences and Technology, Harvard Medical School, Boston, Massachusetts, USA.
Zanetti
M
M
Gennaro
R
R
Gallo
R L
RL
D016475:3T3 Cells / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry* / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry* / Q000494:pharmacology*; D007700:Kinetics; D051379:Mice; D018909:src Homology Domains / Q000187:drug effects
D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; C072212:PR 39