Cationic defensins arise from charge‐neutralized propeptides: a mechanism for avoiding leukocyte autocytotoxicity?

Defensins, small cationic polypeptides with antimicrobial and cytotoxic properties, are among the principal constituents of cytoplasmic granules of mammalian neutrophils and certain macrophages. To identify conserved structural features of defensin precursors that may be important for their targeting to cytoplasmic granules or for prevention of autocytotoxicity, we isolated and sequenced three neutrophil‐specific rabbit defensin cDNAs that code for preproprotein precursors to the mature defensins NP‐3a, NP‐4, and NP‐5. The preprodefensins NP‐3a, NP‐4, and NP‐5, like the previously characterized preprodefensins, lack consensus sequences for N‐linked glycosylation, suggesting that defensins are targeted to lysosome‐like granules by a mechanism not dependent on the mannose‐6‐phosphate receptor. Analysis of all seven known myeloid prodefensins revealed a structure wherein an anionic propiece neutralizes the cationicity of the mature peptide. Because defensins apparently require cationic epitopes for cell membrane permeabilization and cytotoxicity, charge neutralization of mature peptides by their anionic propieces may prevent autocytotoxicity during defensin synthesis and processing.

[1]  K. Mihara.  [Protein translocation across membranes]. , 1993, Tanpakushitsu kakusan koso. Protein, nucleic acid, enzyme.

[2]  E. Valore,et al.  Posttranslational processing of defensins in immature human myeloid cells. , 1992, Blood.

[3]  D. Eisenberg,et al.  Crystal structure of defensin HNP-3, an amphiphilic dimer: mechanisms of membrane permeabilization. , 1991, Science.

[4]  G. Vonheijne.  The signal peptide. , 1990 .

[5]  T. Ganz,et al.  Defensins , 1990, European journal of haematology.

[6]  T. Ganz,et al.  Antimicrobial defensin peptides form voltage-dependent ion-permeable channels in planar lipid bilayer membranes. , 1990, Proceedings of the National Academy of Sciences of the United States of America.

[7]  G. von Heijne.  The signal peptide. , 1990, The Journal of membrane biology.

[8]  E. Valore,et al.  The structure of the rabbit macrophage defensin genes and their organ-specific expression. , 1989, Journal of immunology.

[9]  S. Kornfeld,et al.  Mannose 6-phosphate receptors and lysosomal enzyme targeting. , 1989, The Journal of biological chemistry.

[10]  A. Erickson.  Biosynthesis of lysosomal endopeptidases , 1989, Journal of cellular biochemistry.

[11]  J. Fallon,et al.  Developmental regulation of cryptdin, a corticostatin/defensin precursor mRNA in mouse small intestinal crypt epithelium , 1989, The Journal of cell biology.

[12]  T. Ganz,et al.  Isolation and characterization of human defensin cDNA clones. , 1988, Proceedings of the National Academy of Sciences of the United States of America.

[13]  R. L. Barker,et al.  Acidic precursor revealed in human eosinophil granule major basic protein cDNA [published erratum appears in J Exp Med 1989 Sep 1;170(3):1057] , 1988, The Journal of experimental medicine.

[14]  K Verner,et al.  Protein translocation across membranes. , 1988, Science.

[15]  D. Lipman,et al.  Improved tools for biological sequence comparison. , 1988, Proceedings of the National Academy of Sciences of the United States of America.

[16]  S. Mulay,et al.  Isolation and structure of corticostatin peptides from rabbit fetal and adult lung. , 1988, Proceedings of the National Academy of Sciences of the United States of America.

[17]  R. Parmley,et al.  Defensin-rich dense granules of human neutrophils. , 1987, Blood.

[18]  T. Ganz,et al.  In vitro tumor cell cytolysis mediated by peptide defensins of human and rabbit granulocytes. , 1986, Blood.

[19]  A. Wilson,et al.  Evolutionary shift in the site of cleavage of prelysozyme. , 1986, The Journal of biological chemistry.

[20]  T. Ganz,et al.  DEFENSINS: NATURAL PEPTIDE ANTIBIOTICS IN HUMAN NEUTROPHILS , 1986 .

[21]  M. Selsted,et al.  Primary structures of six antimicrobial peptides of rabbit peritoneal neutrophils. , 1985, The Journal of biological chemistry.

[22]  W. Li,et al.  Evidence for higher rates of nucleotide substitution in rodents than in man. , 1985, Proceedings of the National Academy of Sciences of the United States of America.

[23]  C. Luo,et al.  A new method for estimating synonymous and nonsynonymous rates of nucleotide substitution considering the relative likelihood of nucleotide and codon changes. , 1985, Molecular biology and evolution.

[24]  M. Selsted,et al.  Primary structures of MCP-1 and MCP-2, natural peptide antibiotics of rabbit lung macrophages. , 1983, The Journal of biological chemistry.

[25]  G. Blobel,et al.  Biosynthesis of a lysosomal enzyme. Partial structure of two transient and functionally distinct NH2-terminal sequences in cathepsin D. , 1981, The Journal of biological chemistry.

[26]  R. Lehrer,et al.  Microbicidal cationic proteins in rabbit alveolar macrophages: a potential host defense mechanism , 1980, Infection and immunity.

[27]  F. Sanger,et al.  DNA sequencing with chain-terminating inhibitors. , 1977, Proceedings of the National Academy of Sciences of the United States of America.

[28]  B. Dobberstein,et al.  Transfer of proteins across membranes. I. Presence of proteolytically processed and unprocessed nascent immunoglobulin light chains on membrane-bound ribosomes of murine myeloma , 1975, The Journal of cell biology.