Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA.
J Bacteriol. 2019 Jun 21;201(14). doi: 10.1128/JB.00776-18. Print 2019 Jul 15.
Contact-dependent growth inhibition (CDI) systems are used in bacterial competition to hinder the growth of neighboring microbes. These systems utilize a two-partner secretion mechanism to display the CdiA exoprotein at the bacterial cell surface. CdiA forms a long filamentous stalk that facilitates binding to a target cell and delivery of a C-terminal toxin (CT) domain. This CT domain is processed and delivered into the cytoplasm of a target cell upon contact. CDI systems also encode a cognate immunity protein (CdiI) that protects siblings and resistant targeted cells from intoxication by high-affinity binding to the CT. CdiA CT domains vary among strains within a species, and many alleles encode enzymatic functions that target nucleic acids. This variation is thought to help drive diversity and adaptation within a species. CdiA diversity is well studied in and several other bacteria, but little is known about the extent of this diversity in . The purpose of this review is to highlight the variability that exists in CDI systems of . We show that this diversity is apparent even among strains isolated from a single geographical region, suggesting that CDI systems play an important role in the ecology of .
接触依赖性生长抑制 (CDI) 系统被用于细菌竞争中，以阻碍邻近微生物的生长。这些系统利用双伙伴分泌机制将 CdiA 外蛋白展示在细菌细胞表面。CdiA 形成长丝状茎，有助于与靶细胞结合并输送 C 端毒素 (CT) 结构域。一旦接触，该 CT 结构域就会被加工并递送到靶细胞的细胞质中。CDI 系统还编码一种同源免疫蛋白 (CdiI)，它通过与 CT 的高亲和力结合来保护兄弟姐妹和耐药靶细胞免受中毒。CdiA CT 结构域在物种内的菌株之间存在差异，许多等位基因编码靶向核酸的酶功能。这种变异被认为有助于推动物种内的多样性和适应性。CdiA 的多样性在 和其他几种细菌中得到了很好的研究，但在 中，这种多样性的程度知之甚少。本综述的目的是强调 中 CDI 系统存在的可变性。我们表明，即使在从单个地理区域分离的菌株中，这种多样性也很明显，这表明 CDI 系统在 的生态学中发挥着重要作用。
