Chemistry Division, Code 6176 , US Naval Research Laboratory , 4555 Overlook Avenue, SW , Washington , DC 20375-5342 , United States.
US Naval Academy Faculty Sited in Code 6176 , US Naval Research Laboratory , Washington , DC 20375-5342 , United States.
ACS Nano. 2019 May 28;13(5):5172-5183. doi: 10.1021/acsnano.8b09194. Epub 2019 Apr 26.
The permanent adhesive produced by adult barnacles is held together by tightly folded proteins that form amyloid-like materials distinct among marine foulants. In this work, we link stretches of alternating charged and noncharged linear sequences from a family of adhesive proteins to their role in forming fibrillar nanomaterials. Using recombinant proteins and short barnacle cement derived peptides (BCPs), we find a central sequence with charged motifs of the pattern [Gly/Ser/Val/Thr/Ala-X], where X are charged amino acids, to exert specific control over timing, structure, and morphology of fibril formation. While most BCPs remain dormant, the core segment demonstrates rapid polymerization as well as an ability to template other peptides with no propensity for self-assembly. Patterned charge domains assemble dormant peptides through a specific antiparallel β-sheet structure as measured by FTIR. While charged domains favor an antiparallel structure, BCPs without charged domains switch fibril assembly to favor simpler parallel β-sheet aggregates. In addition to activation, charged domains direct nanofibers to grow into discrete microns long fibrils similar to the natural adhesive, while segments without such domains only form short branched aggregates. The assembly of adhesive sequences through recognition of structured templates outlines a strategy used by barnacles to control physical mechanisms of underwater adhesive delivery, activation, and curing based on molecular recognition between proteins.
成年藤壶产生的永久性粘合剂由紧密折叠的蛋白质组成,这些蛋白质形成了海洋污垢中独特的类淀粉样物质。在这项工作中,我们将一系列交替带电荷和不带电荷的线性序列与一类粘性蛋白质联系起来,以了解它们在形成纤维状纳米材料中的作用。使用重组蛋白和短藤壶水泥衍生肽 (BCP),我们发现一个带有电荷模式 [Gly/Ser/Val/Thr/Ala-X] 的核心序列,其中 X 是带电荷的氨基酸,对纤维形成的时间、结构和形态具有特定的控制作用。虽然大多数 BCP 仍然处于休眠状态,但核心部分表现出快速聚合的能力,以及能够模板化其他没有自组装倾向的肽。通过傅里叶变换红外光谱 (FTIR) 测量,带图案的电荷域通过特定的反平行 β-折叠结构组装休眠肽。虽然电荷域有利于反平行结构,但没有电荷域的 BCP 会将纤维组装转换为有利于更简单的平行 β-折叠聚集体。除了激活作用外,电荷域还指导纳米纤维生长成类似于天然粘合剂的离散微米长纤维,而没有这种域的片段只能形成短的分支聚集体。通过识别结构化模板组装粘性序列概述了藤壶用于控制水下粘合剂输送、激活和固化的物理机制的策略,这是基于蛋白质之间的分子识别。