Microbial communities are shaped by cell-cell interactions. Although archaea are often found in associations with other microorganisms, the mechanisms structuring these communities are poorly understood. Here, we report on the structure and function of haloarchaeal contractile injection systems (CISs). Using a combination of functional assays and time-lapse imaging, we show that Halogeometricum borinquense exhibits antagonism toward Haloferax volcanii by inducing cell lysis and inhibiting proliferation. This antagonism is contact-dependent and requires a functional CIS, which is encoded by a gene cluster that is associated with toxin-immunity pairs. Cryo–focused ion beam milling and imaging by cryo–electron tomography revealed that these CISs are bound to the cytoplasmic membrane, resembling the bacterial type six secretion systems (T6SSs). We show that related T6SS gene clusters are conserved and expressed in other haloarchaeal strains, which exhibit antagonistic behavior. Our data provide a mechanistic framework for understanding how archaea may shape microbial communities and affect the food webs they inhabit.

中文翻译：

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古细菌 6 型分泌系统介导接触依赖性拮抗作用


微生物群落是由细胞间相互作用塑造的。尽管古细菌经常与其他微生物相关联，但构建这些群落的机制却知之甚少。在这里，我们报告了盐古细菌收缩注射系统 （CIS） 的结构和功能。使用功能测定和延时成像的组合，我们表明 Halogeometricum borinquense 通过诱导细胞裂解和抑制增殖表现出对 Haloferax volcanii 的拮抗作用。这种拮抗作用是接触依赖性的，需要功能性 CIS，它由与毒素免疫对相关的基因簇编码。冷冻聚焦离子束铣削和冷冻电子断层扫描成像显示，这些 CIs 与细胞质膜结合，类似于细菌 6 型分泌系统 （T6SSs）。我们表明，相关的 T6SS 基因簇是保守的，并在其他盐菌菌株中表达，这些菌株表现出拮抗行为。我们的数据为理解古细菌如何塑造微生物群落并影响它们栖息的食物网提供了一个机制框架。