Defensins: Evolution

Austin L Hughes, University of South Carolina, Columbia, South Carolina, USA

Published online: March 2008

DOI: 10.1002/9780470015902.a0006136.pub2

The and defensins are short, cationic peptides that are used in the antibacterial defences of mammals. The - and -defensin gene families have diversified as a result of recent gene duplications in several lineages of mammals, and there is evidence that positive Darwinian selection has had a role in their diversification.

Keywords: defensin; gene duplication; immune system; innate defences; positive Darwinian selection

Figure 1. Phylogenetic trees of defensins constructed by the neighbour-joining method (Saitou and Nei, 1987). Numbers on the branches are percentages of 1000 bootstrap replicates that support that clustering pattern. (a) Human and rhesus monkey defensins, rooted with rabbit defensins. (b) Primate and mouse defensins.
Figure 2. Plots of the number of nonsynonymous nucleotide substitutions per nonsynonymous site (dN) versus the number of synonymous nucleotide substitutions per synonymous site (dS), estimated by the method of Nei and Gojobori (1986), in the mature defensin (a) and the remainder of the coding region (b) for -defensin genes of human and rhesus monkey. A 45° line is drawn in both panels.
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 References
    Diamond G, Zazloff M, Eck H et al. (1991) Tracheal antimicrobial peptide, a cysteine-rich peptide from mammalian tracheal mucosa: peptide isolation and cloning of a cDNA. Proceedings of the National Academy of Sciences of the USA 88: 3952–3956.
    Hughes AL (1999a) Evolutionary diversification of the mammalian defensins. Cellular and Molecular Life Sciences 56: 94–103.
    book Hughes AL (1999b) Adaptive Evolution of Genes and Genomes. New York, NY: Oxford University Press.
    Hughes AL and Yeager M (1997) Coordinated amino acid changes in the evolution of mammalian defensins. Journal of Molecular Evolution 44: 675–682.
    Huttner KM and Ouellette AJ (1994) A family of defensin-like genes codes for diverse cysteine-rich peptides in mouse Paneth cells. Genomics 24: 99–109.
    Kumar S and Hedges SB (1998) A molecular timescale for vertebrate evolution. Nature 392: 917–920.
    book Li W-H (1997) Molecular Evolution. Sunderland, MA: Sinauer Associates.
    Linzmeier RM and Ganz T (2005) Copy number polymorphisms: comprehensive analysis of independent variation in - and -defensin regions at 8p22–p23. Genomics 86: 423–430.
    Liu L, Zhao C, Heng HHQ and Ganz T (1997) The human -defensin-1 and -defensins are encoded by adjacent genes: two peptides families with differing disulfide topology share a common ancestry. Genomics 43: 316–320.
    Michaelson D, Rayner J, Conto M and Ganz T (1992) Cationic defensins arise from charge-neutralized propeptides: a mechanism for avoiding leukocyte autocytotoxicity? Journal of Leukocyte Biology 51: 632–639.
    Morrison GM, Semple CA, Kilanowski FM, Hill RE and Dorin JR (2003) Signal sequence conservation and mature peptide divergence within subgroups of the murine -defensin gene family. Molecular Biology and Evolution 20: 460–470.
    Nei M and Gojobori T (1986) Simple methods for estimating the numbers of synonymous and nonsynonymous nucleotide substitutions. Molecular Biology and Evolution 3: 418–426.
    Nicolas P and Mor A (1995) Peptides as weapons against microorganisms in the chemical defense system of vertebrates. Annual Reviews in Microbiology 49: 277–304.
    Patil AA, Cai Y, Sang Y, Blecha F and Zhang G (2005) Cross-species analysis of the mammalian -defensin gene family: presence of syntenic gene clusters and preferential expression in the male reproductive tract. Physiological Genomics 23: 5–17.
    Patil AA, Hughes AL and Zhang G (2004) Rapid evolution and diversification of mammalian -defensins as revealed by comparative analysis of rodent and primate genes. Physiological Genomics 20: 1–11.
    Saitou N and Nei M (1987) The neighbor-joining method: a new method for reconstructing phylogenetic trees. Molecular Biology and Evolution 4: 406–425.
    Schonwetter BS, Stolzenberg ED and Zasloff MA (1995) Epithelial antibiotics induced at sites of inflammation. Science 267: 1645–1648.
    Zimmerman GR, Legault P, Selsted ME and Pardi A (1995) Solution structure of the bovine neutrophil -defensin-12: the peptide fold of the -defensins is identical to that of the classical defensins. Biochemistry 34: 13663–13671.
 Further Reading
    Jenssen H, Hanill O and Hancock REW (2006) Peptide antimicrobial agents. Clinical Microbiology Reviews 19: 491–511.
    Lehrer RI and Ganz T (2002) Defensins of vertebrate animals. Current Opinion in Immunology 14: 96–102.
    Pazgier M, Hoover DM, Yang D, Lu W and Lubkowski J (2006) Human -defensins. Cellular and Molecular Life Sciences 63: 1294–1313.
    Semple CA, Gautier P, Taylor K and Dorin JR (2006) The changing of the guard: molecular diversity and rapid evolution of -defensins. Molecular Diversity 10: 575–584.
    Zazloff M (2002) Antimicrobial peptides of multicellular organisms. Nature 415: 389–395.

Related Sub-Topics:

Innate Immunity | Molecular Evolution | Protein Evolution | Evolution of Coding and Functional Modules
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Article Title: Defensins: Evolution
 
How to Cite close
Hughes, Austin L(Mar 2008) Defensins: Evolution. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0006136.pub2]