CARBOXY-TERMINAL PHENYLALANINE IS ESSENTIAL FOR THE CORRECT ASSEMBLY OF A BACTERIAL OUTER-MEMBRANE PROTEIN
CARBOXY-TERMINAL PHENYLALANINE IS ESSENTIAL FOR THE CORRECT ASSEMBLY OF A BACTERIAL OUTER-MEMBRANE PROTEIN
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DOI：
10.1016/0022-2836(91)90880-f
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发表时间：
1991-03-05
影响因子：
5.6
通讯作者：
TOMMASSEN, J
中科院分区：
文献类型：
--
作者：
STRUYVE, M;MOONS, M;TOMMASSEN, J
细菌外膜蛋白被认为是重复跨越膜，主要是以两亲性β-折叠的形式。PhoE蛋白C末端的最后10个氨基酸残基被认为是形成这样一个跨膜片段。删除这一段完全阻止掺入外膜。比较来自不同革兰氏阴性菌的其他外膜蛋白的最后10个氨基酸残基，揭示了在绝大多数这些蛋白中，在C末端的位置1（Phe）、3（优选Tyr）、5、7和9处存在具有疏水残基的潜在两亲性β-折叠。由于在周质蛋白的C末端没有检测到这样的序列，因此似乎可以基于序列数据来区分大多数外膜蛋白和周质蛋白。外膜蛋白C端高度保守的苯丙氨酸表明该氨基酸在组装成外膜中具有重要功能。应用定点突变技术研究了C端Phe在PhoE蛋白组装中的作用。所有突变蛋白都在一定程度上正确地掺入外膜，但该过程的效率受到严重影响。看来Phe的疏水性和芳香性两者都是重要的。
Bacterial outer membrane proteins are supposed to span the membrane repeatedly, mostly in the form of amphipathic β-sheets. The last ten C-terminal amino acid residues of PhoE protein are supposed to form such a membrane-spanning segment. Deletion of this segment completely prevents incorporation into the outer membrane. Comparison of the last ten amino acid residues of other outer membrane proteins from different Gram-negative bacteria revealed the presence of a potential amphipathic β-sheet with hydrophobic residues at positions 1 (Phe), 3 (preferentially Tyr), 5, 7 and 9 from the C terminus, in the vast majority of these proteins. Since such sequences were not detected at the C termini of periplasmic proteins, it appears to be possible to discriminate between the majority of outer membrane proteins and periplasmic proteins on the basis of sequence data. The highly conserved phenylalanine at the C termini of outer membrane proteins suggests an important function for this amino acid in assembly into the outer membrane. Site-directed mutagenesis was applied to study the role of the C-terminal Phe in PhoE protein assembly. All mutant proteins were correctly incorporated into the outer membrane to some extent, but the efficiency of the process was severely affected. It appears that both the hydrophobicity and the aromatic nature of Phe are of importance.