title: Mouse Paneth cell defensins: primary structures and antibacterial activities of numerous cryptdin isoforms.
abstract: Cryptdins are antimicrobial peptides of the defensin family that are produced by intestinal Paneth cells. mRNAs encoding 17 cryptdin isoforms have been characterized from a cDNA library generated from a single jejunal crypt. Six cryptdin cDNAs correspond to known peptides, and the remainder predict 11 novel Paneth cell defensins. Most cryptdin cDNAs have > or = 93% nucleotide sequence identity overall, except for cryptdin 4 and 5 cDNAs, whose respective mature peptide-encoding regions are only 74 and 78% identical to that of cryptdin 1. Cryptdin cDNAs differ at a small number of nucleotide positions: frequent substitutions were found in codons 38 and 52 of the propiece and in codons 68, 73, 76, 87, and 89 of the deduced peptides; cDNA clones with changes in codons 74, 83, and 88 were found, but there were fewer of these. The antimicrobial activities of cryptdins 1 to 6 were tested against Escherichia coli ML35 in two assays. In an agar diffusion assay, the potencies of cryptdins 1 to 3, 5, and 6 were approximately equivalent to that of rabbit neutrophil defensin NP-1 but cryptdin 4 was 30 times more active than NP-1. In a bactericidal assay system, cryptdins 1 and 3 to 6 were equally active at 10 micrograms/ml but cryptdin 2 and rabbit NP-1 were not active at this concentration. Since cryptdins 2 and 3 differ only at residue 10 (Thr and Lys, respectively), this amino acid appears to function in bactericidal interaction with E. coli. The demonstration that Paneth cells express a diverse population of microbicidal defensins further implicates cryptdins in restricting colonization or invasion of small intestinal epithelium by bacteria.
authors.affiliation: Department of Surgery, Harvard Medical School, Massachusetts General Hospital, Boston.
authors.forename: A J
authors.initials: AJ
authors.lastname: Ouellette
authors.forename: M M
authors.initials: MM
authors.lastname: Hsieh
authors.forename: M T
authors.initials: MT
authors.lastname: Nosek
authors.forename: D F
authors.initials: DF
authors.lastname: Cano-Gauci
authors.forename: K M
authors.initials: KM
authors.lastname: Huttner
authors.forename: R N
authors.initials: RN
authors.lastname: Buick
authors.forename: M E
authors.initials: ME
authors.lastname: Selsted
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects; D005260:Female; D008297:Male; D051379:Mice; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D011498:Protein Precursors / Q000737:chemistry*; D011506:Proteins / Q000737:chemistry*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D018076:DNA, Complementary; D011498:Protein Precursors; D011506:Proteins; C059569:cryptdin