Contact-dependent growth inhibition systems in Acinetobacter
Contact-dependent growth inhibition systems in Acinetobacter
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DOI：
10.1038/s41598-018-36427-8
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发表时间：
2019-01-17
影响因子：
4.6
通讯作者：
Di Nocera, Pier Paolo
中科院分区：
文献类型：
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作者：
De Gregorio, Eliana;Zarrilli, Raffaele;Di Nocera, Pier Paolo
在细菌接触依赖性生长抑制（CDI）系统中，CdiA蛋白通过同源CdiB蛋白输出到外膜。CdiA与敏感细菌上的受体结合，随后将其C-末端毒素结构域（CdiA-CT）递送到邻近的靶细胞中。而自身细菌产生CdiI抗毒素，非自身细菌缺乏抗毒素，因此被CdiA抑制生长。对致病性不动杆菌基因组的计算机调查使我们能够鉴定出>40种不同的CDI系统，我们将其分为两个不同的组。II型CdiAs是具有20-mer重复序列的长阵列的巨大蛋白质（3711至5733个残基）。I型CdiA较小（1900-2400个残基），缺乏重复序列并具有中心异质性（HET）区域，其大小和序列不同，并且可以在CdiA蛋白之间交换。大多数I型蛋白中的HET区域赋予采用卷曲螺旋构象的能力。CdiA-CT和前毒素模块在I型和II型CdiA之间显著不同。此外，II型基因仅在其3'端区域具有已被新cdi序列的插入置换的基因的残余。Ⅰ型和Ⅱ型CDI系统在A. baumannii，而A. pittii和A. nocombinialis分别以I型和II型系统为主要特征。
In bacterial contact-dependent growth inhibition (CDI) systems, CdiA proteins are exported to the outer membrane by cognate CdiB proteins. CdiA binds to receptors on susceptible bacteria and subsequently delivers its C-terminal toxin domain (CdiA-CT) into neighbouring target cells. Whereas self bacteria produce CdiI antitoxins, non-self bacteria lack antitoxins and are therefore inhibited in their growth by CdiA. In silico surveys of pathogenic Acinetobacter genomes have enabled us to identify >40 different CDI systems, which we sorted into two distinct groups. Type-II CdiAs are giant proteins (3711 to 5733 residues) with long arrays of 20-mer repeats. Type-I CdiAs are smaller (1900-2400 residues), lack repeats and feature central heterogeneity (HET) regions, that vary in size and sequence and can be exchanged between CdiA proteins. HET regions in most type-I proteins confer the ability to adopt a coiled-coil conformation. CdiA-CT and pretoxin modules differ significantly between type-I and type-II CdiAs. Moreover, type-II genes only have remnants of genes in their 3' end regions that have been displaced by the insertion of novel cdi sequences. Type-I and type-II CDI systems are equally abundant in A. baumannii, whereas A. pittii and A. nosocomialis predominantly feature type-I and type-II systems, respectively.