Comparative Genomics and Evolution of the Alpha-Defensin Multigene Family in Primates Sabyasachi Das,*,1 Nikolas Nikolaidis,2 Hiroki Goto,3 Chelsea McCallister,2 Jianxu Li,1 Masayuki Hirano,1 and Max D. Cooper*,1 1Department of Pathology and Laboratory Medicine, Emory Vaccine Center, School of Medicine, Emory University 2Department of Biological Science, California State University, Fullerton 3Department of Biology and Center for Comparative Genomics and Bioinformatics, Pennsylvania State University–University Park *Corresponding author: E-mail:
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[email protected]. Associate editor: Yoko Satta Abstract Research article Defensin genes encode small cationic antimicrobial peptides that form an important part of the innate immune system. They are divided into three families, alpha (a), beta (b), and theta (h), according to arrangement of the disulfide bonding pattern between cysteine residues. Considering the functional importance of defensins, investigators have studied the evolution and the genomic organization of defensin genes. However, these studies have been restricted mainly to b-defensins. To understand the evolutionary dynamics of a-defensin genes among primates, we identified the a-defensin repertoires in human, chim- Downloaded from panzee, orangutan, macaque, and marmoset. The a-defensin genes in primates can be classified into three phylogenetic classes (class I, II, and III). The presence of all three classes in the marmoset indicates that their divergence occurred before the separation of New World and Old World monkeys. Comparative analysis of the a-defensin genomic clusters suggests that the makeup of the a-defensin gene repertoires between primates is quite different, as their genes have undergone dramatic birth- and-death evolution.