Structural Basis of Outer Membrane Protein Biogenesis in Bacteria
Structural Basis of Outer Membrane Protein Biogenesis in Bacteria
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DOI：
10.1074/jbc.m111.238931
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发表时间：
2011-08-05
影响因子：
4.8
通讯作者：
Zeth, Kornelius
中科院分区：
文献类型：
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作者：
Albrecht, Reinhard;Zeth, Kornelius
在大肠杆菌中，多组分BAM（β-桶装配机械）复合物负责识别和装配外膜β-桶蛋白。BAM在蛋白质生物合成中的功能主要是通过两个基本组分BamA和BamD的存在来协调的。在这里，我们提出了四种脂蛋白（BamBE）的晶体结构。单体BamB和BamD蛋白质显示通常在瞬时蛋白质相互作用中暗示的支架结构。BamB是包含八个WD 40重复的β-螺旋桨蛋白。BamD在五个三肽重复序列的基础上显示出延长的折叠，其中三个形成蛋白质识别的支架。杆状BamC蛋白通过两个保守结构域的基因复制而进化，已知这两个保守结构域在结构相关的复合物中介导蛋白质相互作用。相比之下，二聚体BamE是通过结构域交换形成的，并表明与β-内酰胺酶抑制剂蛋白家族的倍数相似性，可能整合了BAM功能中的细胞壁稳定性。结构和生物化学数据表明，通过BamD的tetratricopeptide重复结构的两亲序列的特异性识别的证据。总的来说，我们的数据推进了对BAM复合物的理解，并突出了BamD在两亲性外膜β-桶蛋白基序识别和蛋白质递送中的功能重要性。
In Escherichia coli, a multicomponent BAM (beta-barrel assembly machinery) complex is responsible for recognition and assembly of outer membrane beta-barrel proteins. The functionality of BAM in protein biogenesis is mainly orchestrated through the presence of two essential components, BamA and BamD. Here, we present crystal structures of four lipoproteins (BamBE). Monomeric BamB and BamD proteins display scaffold architectures typically implied in transient protein interactions. BamB is a beta-propeller protein comprising eight WD40 repeats. BamD shows an elongated fold on the basis of five tetratricopeptide repeats, three of which form the scaffold for protein recognition. The rod-shaped BamC protein has evolved through the gene duplication of two conserved domains known to mediate protein interactions in structurally related complexes. By contrast, the dimeric BamE is formed through a domain swap and indicates fold similarity to the beta-lactamase inhibitor protein family, possibly integrating cell wall stability in BAM function. Structural and biochemical data show evidence for the specific recognition of amphipathic sequences through the tetratricopeptide repeat architecture of BamD. Collectively, our data advance the understanding of the BAM complex and highlight the functional importance of BamD in amphipathic outer membrane beta-barrel protein motif recognition and protein delivery.