Native oligomerization determines the mode of action and biological activities of human cathelicidin LL-37
Native oligomerization determines the mode of action and biological activities of human cathelicidin LL-37
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DOI：
10.1042/bj20131048
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发表时间：
2014-01-15
影响因子：
4.1
通讯作者：
Tossi, Alessandro
中科院分区：
文献类型：
--
作者：
Xhindoli, Daniela;Pacor, Sabrina;Tossi, Alessandro
LL-37 是先天免疫的多功能成分，具有膜导向的抗菌活性和对宿主细胞的受体介导的多效性作用。其灵长类直系同源物的序列变异表明已经进化出两种类型的功能特征：人类 LL-37 样肽在生理条件下形成两亲性螺旋结构并自组装，而恒河猴 RL-37 样肽仅在细菌膜存在时采用这种结构。第一种类型的肽具有比第二种类型更低且更中等敏感的抗菌活性，但刺激宿主细胞的能力有所增加。寡聚化强烈影响与生物膜的相互作用模式，从而影响细胞毒性和受体介导的活性。在本研究中，我们通过使用具有平行或反平行方向的专性二硫键连接二聚体探索了 LL-37 自缔合的影响。当与阴离子或中性模型膜接触时，它们在本体溶液中形成堆叠螺旋的倾向增加。针对革兰氏阳性或革兰氏阴性细菌的抗菌活性以及对宿主细胞的细胞毒性作用在很大程度上取决于二聚化的类型。为了研究天然寡聚的程度，我们用光活性残基 Bpa（对苯甲酰基-L-苯丙氨酸）取代了 Phe(5)，在紫外线照射下，Bpa 实现了共价交联，使我们能够评估生理溶液和模型膜中的寡聚程度。
LL-37 is a multifunctional component of innate immunity, with a membrane-directed antimicrobial activity and receptor-mediated pleiotropic effects on host cells. Sequence variations in its primate orthologues suggest that two types of functional features have evolved; human LL-37-like peptides form amphipathic helical structures and self-assemble under physiological conditions, whereas rhesus RL-37-like peptides only adopt this structure in the presence of bacterial membranes. The first type of peptide has a lower and more medium-sensitive antimicrobial activity than the second type, but an increased capacity to stimulate host cells. Oligomerization strongly affects the mode of interaction with biological membranes and, consequently, both cytotoxicity and receptor-mediated activities. In the present study we explored the effects of LL-37 self-association by using obligate disulfide-linked dimers with either parallel or antiparallel orientations. These had an increased propensity to form stacked helices in bulk solution and when in contact with either anionic or neutral model membranes. The antimicrobial activity against Gram-positive or Gram-negative bacteria, as well as the cytotoxic effects on host cells, strongly depended on the type of dimerization. To investigate the extent of native oligomerization we replaced Phe(5) with the photoactive residue Bpa (p-benzoyl-L-phenylalanine), which, upon UV irradiation, enabled covalent cross-linking and allowed us to assess the extent of oligomerization in both physiological solution and in model membranes.