Structure-function analysis of immunity proteins of pediocin-like bacteriocins: C-terminal parts of immunity proteins are involved in specific recognition of cognate bacteriocins
Structure-function analysis of immunity proteins of pediocin-like bacteriocins: C-terminal parts of immunity proteins are involved in specific recognition of cognate bacteriocins
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DOI：
10.1128/aem.70.5.2647-2652.2004
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发表时间：
2004-05-01
影响因子：
4.4
通讯作者：
Nissen-Meyer, J
中科院分区：
文献类型：
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作者：
Johnsen, L;Fimland, G;Nissen-Meyer, J
儿科素样细菌素的免疫蛋白相对于它们识别和赋予免疫的儿科素样细菌素表现出高度的特异性。这项研究的目的是确定免疫蛋白中参与这种特定识别的区域。从三种具有相似序列但对不同细菌素具有抗性的不同儿科素样细菌素免疫蛋白构建了六种不同的杂交免疫蛋白。然后测试了这些杂交免疫蛋白对各种儿茶素样细菌素的免疫能力。杂交免疫蛋白的特异性被证明与C端半部分衍生的免疫蛋白的特异性相似，从而揭示了儿茶素样细菌素免疫蛋白的C端半部分包含一个与它们赋予免疫的细菌素的特异性识别有关的结构域。此外，研究结果还表明，免疫蛋白的有效性依赖于菌株，因此其功能部分依赖于与菌株依赖因子的相互作用。为了进一步研究这些免疫蛋白的结构与功能的关系，对肠球蛋白A和亮蛋白A免疫蛋白(Enta-im和LeuA-im)进行了纯化，并在不同条件下用圆二色谱(CD)进行了结构分析。结果表明，两种免疫蛋白在水环境中均呈α螺旋结构，其变性温度Enta-im为78.5℃，LeuA-im为58.0℃。圆二色谱还表明，免疫蛋白在十二烷基磷胆碱胶束或二油酰基-L-α-磷脂酰甘油(DOPG)脂质体作用下，其结构和α-螺旋含量没有进一步增加，表明免疫蛋白与细菌素没有广泛的相互作用。然而，它们仍可能与膜松散地结合，可能作为外周膜蛋白，从而使它们能够与其同源细菌素相互作用。
The immunity proteins of pediocin-like bacteriocins show a high degree of specificity with respect to the pediocin-like bacteriocin they recognize and confer immunity to. The aim of this study was to identify regions of the immunity proteins that are involved in this specific recognition. Six different hybrid immunity proteins were constructed from three different pediocin-like bacteriocin immunity proteins that have similar sequences but confer resistance to different bacteriocins. These hybrid immunity proteins were then tested for their ability to confer immunity to various pediocin-like bacteriocins. The specificities of the hybrid immunity proteins proved to be similar to those of the immunity proteins from which the C-terminal halves were derived, thus revealing that the C-terminal half of immunity proteins for pediocin-like bacteriocins contains a domain that is involved in specific recognition of the bacteriocins they confer immunity to. Moreover, the results also revealed that the effectiveness of an immunity protein is strain dependent and that its functionality thus depends in part on interplay with strain-dependent factors. To further investigate the structure-function relationship of these immunity proteins, the enterocin A and leucocin A immunity proteins (EntA-im and LeuA-im) were purified to homogeneity and structurally analyzed tinder various conditions by Circular dichroism (CD) spectroscopy. The results revealed that both immunity proteins are a-helical and well structured in an aqueous environment, the denaturing temperature being 78.5degreesC for EntA-im and 58.0degreesC for LeuA-im. The CD spectra also revealed that there was no further increase in the structuring or a-helical content when the immunity proteins were exposed to dodecylphosphocholine micelles or dioleoyl-L-alpha-phosphatidyl-DL-glycerol (DOPG) liposomes, indicating that the immunity proteins, in contrast to the bacteriocins, do not interact extensively with membranes. They may nevertheless be loosely associated with the membrane, possibly as peripheral membrane proteins, thus enabling them to interact with their cognate bacteriocin.