Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA.
New York University Grossman School of Health, NYU Langone Health, New York, NY 10016, USA.
Structure. 2022 Apr 7;30(4):537-550.e5. doi: 10.1016/j.str.2022.02.002. Epub 2022 Feb 24.
Bacterial microcompartments (BMCs) are widespread in bacteria and are used for a variety of metabolic purposes, including catabolism of host metabolites. A suite of proteins self-assembles into the shell and cargo layers of BMCs. However, the native assembly state of these large complexes remains to be elucidated. Herein, chemical probes were used to observe structural features of a native BMC. While the exterior could be demarcated with fluorophores, the interior was unexpectedly permeable, suggesting that the shell layer may be more dynamic than previously thought. This allowed access to cross-linking chemical probes, which were analyzed to uncover the protein interactome. These cross-links revealed a complex multivalent network among cargo proteins that contained encapsulation peptides and demonstrated that the shell layer follows discrete rules in its assembly. These results are consistent overall with a model in which biomolecular condensation drives interactions of cargo proteins before envelopment by shell layer proteins.
细菌微隔间 (BMC) 在细菌中广泛存在，用于多种代谢目的，包括宿主代谢物的分解代谢。一套蛋白质自我组装成 BMC 的壳层和货物层。然而，这些大型复合物的天然组装状态仍有待阐明。在此，化学探针被用于观察天然 BMC 的结构特征。虽然可以用荧光染料标记外部，但内部出人意料地具有渗透性，这表明壳层可能比以前认为的更具动态性。这使得能够接触到交联化学探针，对其进行分析以揭示蛋白质相互作用组。这些交联揭示了包含封装肽的货物蛋白之间复杂的多价网络，并表明壳层在其组装过程中遵循离散的规则。这些结果与一个模型总体上一致，该模型认为生物分子浓缩在壳层蛋白包裹货物蛋白之前驱动货物蛋白的相互作用。
