Peelle Beau R, Krauland Eric M, Wittrup K Dane, Belcher Angela M
Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
Acta Biomater. 2005 Mar;1(2):145-54. doi: 10.1016/j.actbio.2004.11.004. Epub 2005 Jan 22.
Although promising for biomimetic materials applications, polypeptides binding inorganic material surfaces and the mechanism of their function have been difficult to characterize. This paper reports sequence-activity relationships of peptides interfacing with semiconductor CdS, and presents methodologies broadly applicable to studying peptide-solid surface interactions. We first employed yeast surface display with a human repertoire antibody library and identified rarely-occurring scFv fragments as CdS-binding polypeptides. Using our semi-quantitative cell-surface binding assay, site-directed mutational analysis, and genetic engineering we defined short distal regions of the displayed polypeptides necessary and sufficient for CdS binding. Alanine scanning mutagenesis in combination with a series of engineered polyhistidine peptides elucidated a direct relationship between histidine number and binding strength, which appeared to be further modulated by arginine and basic residues. The minimum strength of interaction was established by competition studies using soluble synthetic peptide analogs, which showed half-maximal inhibition of yeast binding to CdS at approximately 2 microM peptide. We then showed the ability of cells displaying material-specific polypeptides to form self-healing biofilms and discriminate between materials of fabricated heterostructure surfaces. Furthermore, we demonstrated the synthetic potential of the selected soluble CdS peptide in mediating aqueous synthesis of fluorescent CdS nanoparticles at room temperature. This platform may be further applied to elucidate mechanisms governing interfacial interactions and to generate material-specific reagents useful in medicine, biosensors, and bioproduction of high value inorganic materials.
尽管多肽在仿生材料应用方面前景广阔，但多肽与无机材料表面的结合及其功能机制一直难以表征。本文报道了与半导体硫化镉（CdS）相互作用的肽的序列-活性关系，并提出了广泛适用于研究肽-固体表面相互作用的方法。我们首先利用酵母表面展示技术和人源抗体文库，鉴定出罕见的单链抗体片段（scFv）作为CdS结合多肽。通过我们的半定量细胞表面结合测定、定点突变分析和基因工程，我们确定了展示多肽中对CdS结合必要且充分的短远端区域。丙氨酸扫描诱变结合一系列工程化的多组氨酸肽阐明了组氨酸数量与结合强度之间的直接关系，而精氨酸和碱性残基似乎进一步调节了这种关系。通过使用可溶性合成肽类似物的竞争研究确定了相互作用的最小强度，结果表明在约2 microM肽浓度下，酵母与CdS的结合受到半数最大抑制。然后，我们展示了展示材料特异性多肽的细胞形成自愈生物膜并区分异质结构表面材料的能力。此外，我们证明了所选可溶性CdS肽在室温下介导荧光CdS纳米颗粒水相合成的合成潜力。该平台可进一步应用于阐明界面相互作用的机制，并生成在医学、生物传感器和高价值无机材料生物生产中有用的材料特异性试剂。
