GENOMICS 43, 316–320 (1997) ARTICLE NO. GE974801 The Human b-Defensin-1 and a-DefensinsAre Encoded by Adjacent Genes: Two Peptide Families with Differing Disulfide Topology Share a Common Ancestry Lide Liu,* , † Chengquan Zhao,* Henry H. Q. Heng,‡ and Tomas Ganz* , † ,1 * Department of Medicine and †Will Rogers Institute for Pulmonary Research, University of California at Los Angeles School of Medicine, Los Angeles, California, 90095; and ‡SeeDNA Biotech, Inc., and Department of Biology, York University, North York, Ontario, M3J 1P3, Canada Received March 26, 1997; accepted May 8, 1997 All of these vertebrate defensins are 29- to 40-amino- We cloned a novel human b-defensin gene and deter- acid cationic peptides that contain six disulfide-linked mined its full-length cDNA sequence. The entire gene cysteines; the a- and b-defensin families differ in their spanned more than 7 kb and included a large 6962-bp consensus sequences, cysteine spacing, and disulfide- intron. The 362-bp cDNA encoded a prepropeptide that pairing patterns (Tang and Selsted, 1993). Specifically, corresponded precisely to the recently identified hu- the six cysteines of a-defensins are disulfide-linked 1 – man b-defensin HBD-1, an antimicrobial peptide impli- 6, 2 – 4, and 3 – 5, but in b-defensins they are connected cated in the resistance of epithelial surfaces to micro- 1 – 5, 2 – 4, and 3 – 6. Although a- and b-defensins adopt bial colonization. By two-color fluorescence in situ hy- very similar molecular conformations (Zimmermann et bridization on both metaphase chromosome and al., 1995), their lack of similarity at the level of gene, released chromatin fiber, HBD-1 gene (DEFB1 in cDNA, and prepropeptide sequences is consistent with HUGO/GDB nomenclature) mapped to chromosomal either function-driven structural convergence or evolu- region 8p23.1 – p23.2 in close proximity (within 100 – 150 tionary divergence from a remote common precursor. kb) to the gene for the human neutrophil a-defensin Defensins interact with microbial targets in diverse HNP-1 (DEFA1). Thus, despite a complete lack of DNA biological settings, and these differences are reflected sequence similarity and despite differences in their in the regulation of their synthesis, storage, and re- disulfide-pairing pattern, the a- and b-families appear lease. In phagocytes, ingested microbes are exposed to to have evolved from a common premammalian defen- defensins when microbicidal granules fuse to phago- sin gene.  1997 Academic Press somes (Joiner et al., 1989). Paneth cells release their granule contents, including defensins, into the narrow INTRODUCTION lumen of intestinal crypts after stimulation by cholin- ergic substances or microbial products (Satoh, 1988; The production of antimicrobial peptides by eukary- Satoh et al., 1989, 1992; Eisenhauer et al., 1992; otic cells has been demonstrated in plants, inverte- Selsted et al., 1992; Qu et al., 1996). In lingual and brates, and vertebrates, suggesting that it is a wide- tracheal epithelia of the cow, the local production of b- spread and ancient means of host defense. In mam- defensins is induced by trauma or exposure to micro- mals, two seemingly distinct families of 3.5–5 kDa bial substances (Diamond et al., 1993; Bevins, 1994; cysteine- and arginine-rich antimicrobial peptides have Schonwetter et al., 1995; Russell et al., 1996). been identified: a-defensins, found in human, rabbit, In human, there are seven known defensins: six a- rat, and guinea pig phagocytes and in specialized epi- defensins and one b-defensin. Human neutrophil de- thelial cells of the human, mouse, and rat small intes- fensins, HNP-1 to -4, are found in the microbicidal tine (Paneth cells), and b-defensins, located in bovine granules of neutrophils (Ganz and Lehrer, 1995; Gabay (and avian) phagocytes and bovine lingual and tracheal et al., 1989; Ganz et al., 1985), and human defensins epithelia (Ganz and Lehrer, 1995). HD5 and 6 have been localized by in situ hybridization to Paneth cells of the intestinal tract (Jones and Be- Sequence data from this article have been deposited with the Gen- vins, 1993, 1992). A human b-defensin, HBD-1, was Bank Data Library under Accession Nos. X92744, U50930, and U50931. purified recently from human blood, its amino acid se- 1 To whom correspondence should be addressed at the Department quence was determined, and a cDNA fragment corre- of Medicine and Will Rogers Institute for Pulmonary Research, CHS sponding to its mature sequence was cloned from kid- 37-055, UCLA School of Medicine, Los Angeles, California 90095. ney and vaginal cDNA libraries by PCR with degener- Telephone: (310) 825-6112. Fax: (310) 206-8766. E-mail: tganz@ ucla.edu. ate primers (Bensch et al., 1995). Recent studies 316 0888-7543/97 $25.00 Copyright  1997 by Academic Press All rights of reproduction in any form reserved.