Krupovic Mart, Cvirkaite-Krupovic Virginija, Prangishvili David, Koonin Eugene V
Department of Microbiology, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, Institut Pasteur, Paris, 75015, France.
National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, 20894, USA.
Biol Direct. 2015 Oct 29;10:65. doi: 10.1186/s13062-015-0093-2.
Many proteins of viruses infecting hyperthermophilic Crenarchaeota have no detectable homologs in current databases, hampering our understanding of viral evolution. We used sensitive database search methods and structural modeling to show that a nucleocapsid protein (TP1) of Thermoproteus tenax virus 1 (TTV1) is a derivative of the Cas4 nuclease, a component of the CRISPR-Cas adaptive immunity system that is encoded also by several archaeal viruses. In TTV1, the Cas4 gene was split into two, with the N-terminal portion becoming TP1, and lost some of the catalytic amino acid residues, apparently resulting in the inactivation of the nuclease. To our knowledge, this is the first described case of exaptation of an enzyme for a virus capsid protein function.
感染嗜热泉古菌的病毒的许多蛋白质在当前数据库中没有可检测到的同源物，这阻碍了我们对病毒进化的理解。我们使用了灵敏的数据库搜索方法和结构建模来表明，嗜热栖热菌病毒1（TTV1）的一种核衣壳蛋白（TP1）是Cas4核酸酶的衍生物，Cas4核酸酶是CRISPR-Cas适应性免疫系统的一个组成部分，也由几种古菌病毒编码。在TTV1中，Cas4基因被分成两部分，其N端部分变成了TP1，并失去了一些催化氨基酸残基，显然导致了核酸酶的失活。据我们所知，这是首次描述的一种酶转变为病毒衣壳蛋白功能的情况。
