Structural and Dynamic Insights into a Glycine-Mediated Short Analogue of a Designed Peptide in Lipopolysaccharide Micelles: Correlation Between Compact Structure and Anti-Endotoxin Activity
Structural and Dynamic Insights into a Glycine-Mediated Short Analogue of a Designed Peptide in Lipopolysaccharide Micelles: Correlation Between Compact Structure and Anti-Endotoxin Activity
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DOI：
10.1021/acs.biochem.6b01229
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发表时间：
2017-03-07
期刊：
影响因子：
2.9
通讯作者：
Bhunia, Anirban
中科院分区：
文献类型：
--
作者：
Datta, Aritreyee;Jaiswal, Nancy;Bhunia, Anirban
在这项研究中，我们报告了一个13个残基的类似肽VG 13 P（VARGWGRKCPLFG），来自一个设计的VG 16 KRKP肽（VARGWK-RKCPLFGKGG），与一个Lys 6 Gly突变和删除最后三个残基赖氨酸（14）-甘氨酸（15）-甘氨酸（16），在脂多糖（LPS），革兰氏阴性菌的外膜的主要成分，负责脓毒症或脓毒性休克的相互作用研究。从单核细胞系中LPS诱导的TNF-α基因表达水平的显著降低可以看出，VG 13 P显示出增强的抗内毒素性质，同时它保留了其亲本VG 16 KRKP针对革兰氏阴性细菌以及真菌病原体的几乎不变的抗微生物活性。此外，与其亲本VG 16 KRKP相比，VG 13 P的体外LPS结合性质也保持不受阻碍，表明VG 16 KRKP的柔性C末端可能在其观察到的抗菌和LPS结合性质中不起主要作用。LPS中VG 13 P的NMR解析溶液结构揭示了两个连续的β-转角：一个在N-末端，另一个在中心区域，非常类似于摇椅。关键的Lys 6 Gly突变沿着来自VG 16 KRKP的C-末端截短以独特的方式重新定向VG 13 P中的疏水性枢纽，以便将N-末端折叠回其自身，形成一个转弯，并允许Val 1和Ala 2与Leu 11和Phe 12相互作用，使疏水性残基更靠近在一起，形成比其亲本更紧凑的枢纽。该中心通过Gly 4和Phe 12之间的CH-pi相互作用进一步增强。这解释了其改善的抗内毒素活性以及其不间断的抗微生物活性。
In this study, we report an interaction study of a 13-residue analogue peptide VG13P (VARGWGRKCPLFG), derived from a designed VG16KRKP peptide (VARGWK-RKCPLFGKGG), with a Lys6Gly mutation and removal of the last three residues Lys(14)-Gly(15)-Gly(16), in lipopolysaccharide (LPS), a major component of the outer membrane of Gram-negative bacteria and responsible for sepsis or septic shock. VG13P displays an enhanced anti-endotoxin property as evident from significant reduction in LPS-induced TNF-alpha gene expression levels in a monocytic cell line, while it retains almost unchanged antimicrobial activity as its parent VG16KRKP against Gram-negative bacterial as well as fungal pathogens. In addition, in vitro LPS binding properties of VG13P in comparison to its parent VG16KRKP also remained unhindered, suggesting that the flexible C-terminal end of VG16KRKP may not play a major role in its observed antibacterial and LPS binding properties. An NMR-resolved solution structure of VG13P in LPS reveals two consecutive beta-turns: one at the N-terminus, followed by another at the central region, closely resembling a rocking chair. The crucial Lys6Gly mutation along with C-terminal truncation from VG16KRKP reorients the hydrophobic hub in VG13P in a unique way so as to fold the N-terminal end back on itself, forming a turn and allowing Val1 and Ala2 to interact with Leu11 and Phe12 to bring the hydrophobic residues closer together to form a more compact hub compared to its parent. The hub is further strengthened via CH-pi interaction between Gly4 and Phe12. This accounts for its improved anti-endotoxin activity as well as to its uninterrupted antimicrobial activity.