Molecular population genetics of inducible antibacterial peptide genes in Drosophila melanogaster
Molecular population genetics of inducible antibacterial peptide genes in Drosophila melanogaster
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DOI：
10.1093/molbev/msg109
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发表时间：
2003-06-01
影响因子：
10.7
通讯作者：
Clark, AG
中科院分区：
文献类型：
--
作者：
Lazzaro, BP;Clark, AG
昆虫对化脓性感染的反应部分是通过产生一系列抗菌肽，这些肽可能受到宿主-病原体共同进化动力学的影响。为了推断作用于果蝇抗菌肽基因的群体遗传力，我们检查了果蝇防御素、果蝇素、梅奇尼科温、attacin C、双翅目 A 和天蚕素 A、B 和 C 基因的多态性和趋异性的整体特性。作为一种功能类别，抗菌肽表现出低水平的种间氨基酸差异。黑腹果蝇内存在多种氨基酸多态性，然而，其中很大一部分改变了可变残基的电荷或极性。这些多态性在处理的信号和前肽结构域中特别普遍。我们发现，共同进化的“军备竞赛”模型和选择性维持的超变性并不能充分描述黑腹果蝇中成熟抗菌肽的群体动态，但高频衍生多态性的显着过量加上显着的位点内连锁不平衡表明正选择可能作用于抗菌肽基因。数据的某些属性可能与人口建立随后扩张的简单人口统计模型一致，但与基因组周围其他基因座相比，肽基因中与零平衡的偏离往往更为明显。
Insects respond to septic infection in part by producing a suite of antimicrobial peptides that may be subject to host-pathogen coevolutionary dynamics. In order to infer population genetic forces acting on Drosophila antibacterial peptide genes, we examine global properties of polymorphism and divergence in the Drosophila melanogaster defensin, drosocin, metchnikowin, attacin C, diptericin A, and cecropin A, B, and C genes. As a functional class, antibacterial peptides exhibit low levels of interspecific amino acid divergence. There are multiple amino acid polymorphisms segregating within D. melanogaster, however, a high proportion of which change the charge or polarity of the variable residue. These polymorphisms are particularly prevalent in processed signal and propeptide domains. We find that models of coevolutionary "arms races" and selectively maintained hypervariability do not adequately describe the population dynamics of mature antibacterial peptides in D. melanogaster, but that a highly significant excess of high-frequency derived polymorphisms coupled with substantial intralocus linkage disequilibrium suggests that positive selection may act on antibacterial peptide genes. Some attributes of the data may be consistent with a simple demographic model of population founding followed by expansion, but departures from the equilibrium null tend to be more pronounced in the peptide genes than at other loci around the genome.