Reading School of Pharmacy, University of Reading, Whiteknights, Reading, United Kingdom.
J Agric Food Chem. 2013 Jul 17;61(28):6890-900. doi: 10.1021/jf401336a. Epub 2013 Jul 3.
Puroindolines (Pins) and purothionins (Pths) are basic, amphiphilic, cysteine-rich wheat proteins that play a role in plant defense against microbial pathogens. This study examined the co-adsorption and sequential addition of Pins (Pin-a, Pin-b, and a mutant form of Pin-b with Trp-44 to Arg-44 substitution) and β-purothionin (β-Pth) model anionic lipid layers using a combination of surface pressure measurements, external reflection FTIR spectroscopy, and neutron reflectometry. Results highlighted differences in the protein binding mechanisms and in the competitive binding and penetration of lipid layers between respective Pins and β-Pth. Pin-a formed a blanket-like layer of protein below the lipid surface that resulted in the reduction or inhibition of β-Pth penetration of the lipid layer. Wild-type Pin-b participated in co-operative binding with β-Pth, whereas the mutant Pin-b did not bind to the lipid layer in the presence of β-Pth. The results provide further insight into the role of hydrophobic and cationic amino acid residues in antimicrobial activity.
麦醇溶蛋白（Pins）和麦硫蛋白（Pths）是碱性、两亲性、富含半胱氨酸的小麦蛋白，在植物抵御微生物病原体方面发挥作用。本研究采用表面压力测量、外反射傅里叶变换红外光谱和中子反射谱联用的方法，考察了 Pins（Pin-a、Pin-b 和一个半胱氨酸 44 位色氨酸取代精氨酸的突变体形式）和 β-麦硫蛋白（β-Pth）模型阴离子脂质层的共吸附和顺序添加。结果突出了不同 Pins 和 β-Pth 之间的蛋白质结合机制以及脂质层的竞争性结合和渗透的差异。Pin-a 在脂质表面以下形成一层类似毯子的蛋白质，导致β-Pth 渗透脂质层的减少或抑制。野生型 Pin-b 与 β-Pth 参与协同结合，而突变体 Pin-b 在β-Pth 存在时不与脂质层结合。研究结果进一步深入了解疏水性和阳离子氨基酸残基在抗菌活性中的作用。
