Selective molecular transport through the protein shell of a bacterial microcompartment organelle
Selective molecular transport through the protein shell of a bacterial microcompartment organelle
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DOI：
10.1073/pnas.1423672112
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发表时间：
2015-03-10
影响因子：
11.1
通讯作者：
Bobik, Thomas A.
中科院分区：
文献类型：
--
作者：
Chowdhury, Chiranjit;Chun, Sunny;Bobik, Thomas A.
细菌微区室是广泛存在的原核细胞器，具有重要和多样的作用，从碳固定到肠道致病。目前的微区室功能模型提出，它们的外部蛋白质壳对小分子具有选择性渗透性，但蛋白质壳是否可以介导选择性渗透性以及这种情况如何发生是尚未解决的问题。在这里，生物化学和生理学研究的结构导向的突变体被用来表明，六聚体PduA壳蛋白的1，2-丙二醇利用（Pdu）的微室形成一个选择性渗透孔定制的流入1，2-丙二醇（Pdu微室的基板），同时限制流出的丙醛，一种有毒的中间体的1，2-丙二醇催化剂。各种PduA突变体的晶体结构提供了一个基础来解释所观察到的生化和表型数据的分子扩散在整个壳。总的来说，这些研究为理解一类由非膜蛋白形成的选择性渗透通道提供了基础。
Bacterial microcompartments are widespread prokaryotic organelles that have important and diverse roles ranging from carbon fixation to enteric pathogenesis. Current models for microcompartment function propose that their outer protein shell is selectively permeable to small molecules, but whether a protein shell can mediate selective permeability and how this occurs are unresolved questions. Here, biochemical and physiological studies of structure-guided mutants are used to show that the hexameric PduA shell protein of the 1,2-propanediol utilization (Pdu) microcompartment forms a selectively permeable pore tailored for the influx of 1,2-propanediol (the substrate of the Pdu microcompartment) while restricting the efflux of propionaldehyde, a toxic intermediate of 1,2-propanediol catabolism. Crystal structures of various PduA mutants provide a foundation for interpreting the observed biochemical and phenotypic data in terms of molecular diffusion across the shell. Overall, these studies provide a basis for understanding a class of selectively permeable channels formed by nonmembrane proteins.