Characterization of luminal paneth cell alpha-defensins in mouse small intestine - Attenuated antimicrobial activities of peptides with truncated amino termini
Aj. Ouellette et al., Characterization of luminal paneth cell alpha-defensins in mouse small intestine - Attenuated antimicrobial activities of peptides with truncated amino termini, J BIOL CHEM, 275(43), 2000, pp. 33969-33973
Paneth cells at the base of small intestinal crypts secrete apical granules
that contain antimicrobial peptides including alpha -defensins, termed cry
ptdins, Using an antibody specific for mouse cryptdin-1, -2, -3, and -6, im
munogold-localization studies demonstrated that cryptdins are constituents
of mouse Paneth cell secretory granules. Several cryptdin peptides have bee
n purified from rinses of adult mouse small. intestine by gel filtration an
d reverse-phase high performance liquid chromatography. Their primary struc
tures were determined by peptide sequencing, and their antimicrobial activi
ties were compared with those of the corresponding tissue forms. The isolat
ed luminal cryptdins included peptides identical to the tissue forms of cry
ptdin-2, -4, and -6 as well as variants of cryptdin-1, -4, and -6 that have
N termini truncated by one or two residues. In assays of antimicrobial act
ivity against Staphylococcus aureus, Escherichia coil, and the defensin-sen
sitive Salmonella typhimurium phoP(-) mutant, full-length cryptdins had the
same in vitro antibacterial activities whether isolated from tissue or fro
m the lumen. In contrast, the N-terminal-truncated (des-Leu), (des-Leu-Arg)
-cryptdin-6, and (des-Gly)-cryptdin-4 peptides mere markedly less active. T
he microbicidal activities of recombinant cryptdin-4 and (des-Gly)-cryptdin
-4 peptides against E. coil, and S. typhimurium showed that the N-terminal
Gly residue or the length of the cryptdin-4 N terminus are determinants of
microbicidal activity. Innate immunity in the crypt lumen may be modulated
by aminopeptidase modification of alpha -defensins after peptide secretion.