A REDOR ssNMR Investigation of the Role of an N-Terminus Lysine in R5 Silica Recognition.
A REDOR ssNMR Investigation of the Role of an N-Terminus Lysine in R5 Silica Recognition.
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N 末端赖氨酸在 R5 二氧化硅识别中的作用的 REDOR ssNMR 研究。
DOI：
10.1021/acs.langmuir.5b04114
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Drobny,GaryP
中科院分区：
文献类型：
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作者：
Ndao,Moise;Goobes,Gil;Emani,PrashantS;Drobny,GaryP
硅藻是单细胞藻类，通过二氧化硅沉淀来构建称为硅藻壳的细胞壁，使用特殊的蛋白质将二氧化硅排列成各种各样的纳米结构。硅藻物种梭形drotheca fusiformis在其硅藻壳中含有称为silaffins的蛋白质，据信这些蛋白质组装成超分子基质，作为二氧化硅沉积的加速剂和模板。研究这些生物硅化蛋白质的特性，可以设计新的蛋白质和肽系统，生成可定制的二氧化硅纳米结构，并有可能推广到其他矿物系统。了解蛋白质的聚集及其与二氧化硅的共沉淀机制是至关重要的。我们继续以前的研究，肽R5，来自silaffin蛋白sil 1 p，显示独立催化沉淀的二氧化硅纳米球在体外。我们用固体核磁共振技术13 C {29 Si}和15 N {29 Si} REDOR研究了R5与共沉淀SiO2配合物的结构和相互作用。这些实验对R5中的13 C核和二氧化硅中的29 Si核之间的磁偶极-偶极相互作用的强度敏感，从而产生R5和二氧化硅中的29 Si部分之间的距离。我们的数据显示13 C → O Lys 3与二氧化硅之间存在较强的相互作用和较短的核间距（3.74 ± 0.20 nm）。另一方面，Cα和Cβ核与29 Si几乎没有相互作用。这种选择性的K3 C-2 O和二氧化硅之间的接近支持了先前提出的抗菌肽KSL（KKVVFKVKFK）通过亚氨酸中间体快速硅化的机制。这项研究首次报道了R5的N-末端与二氧化硅之间的直接相互作用，使我们相信R5的N-末端是分子识别过程中的关键组分，也是二氧化硅形态发生的主要因素。
Diatoms are unicellular algae that construct cell walls called frustules by the precipitation of silica, using special proteins that order the silica into a wide variety of nanostructures. The diatom speciesCylindrotheca fusiformiscontains proteins called silaffins within its frustules, which are believed to assemble into supramolecular matrices that serve as both accelerators and templates for silica deposition. Studying the properties of these biosilicification proteins has allowed the design of new protein and peptide systems that generate customizable silica nanostructures, with potential generalization to other mineral systems. It is essential to understand the mechanisms of aggregation of the protein and its coprecipitation with silica. We continue previous investigations into the peptide R5, derived from silaffin protein sil1p, shown to independently catalyze the precipitation of silica nanospheres in vitro. We used the solid-state NMR technique13C{29Si} and15N{29Si} REDOR to investigate the structure and interactions of R5 in complex with coprecipitated silica. These experiments are sensitive to the strength of magnetic dipole–dipole interactions between the13C nuclei in R5 and the29Si nuclei in the silica and thus yield distance between parts of R5 and29Si in silica. Our data show strong interactions and short internuclear distances of 3.74 ± 0.20 Å between13C═O Lys3 and silica. On the other hand, the Cαand Cβnuclei show little or no interaction with29Si. This selective proximity between the K3 C═O and the silica supports a previously proposed mechanism of rapid silicification of the antimicrobial peptide KSL (KKVVFKVKFK) through an imidate intermediate. This study reports for the first time a direct interaction between the N-terminus of R5 and silica, leading us to believe that the N-terminus of R5 is a key component in the molecular recognition process and a major factor in silica morphogenesis.