Development of Affine Surfaces for Specific Binding of Bacterial Fragments from Solutions Using AFM

Abstract

Atomic force microscopy (AFM) and single molecule force spectroscopy (SMFS) have been used to characterize the structure and interactions of clathrin triskelia, which are principal components of the protein coats surrounding certain plasma-membrane-derived vesicles involved in receptor-mediated endocytosis. Time sequence AFM images of wet triskelia resting on mica surfaces clearly demonstrate conformational fluctuations within individual triskelia, further strengthening indirect inferences from earlier AFM and electron microscopy of dried protein samples. Related studies using SMFS reveal a series of internal energetic barriers that characterize triskelion heavy chain domain unfolding. Protein sequence and force spectrum alignment analyses suggest that these features correspond to the unfolding of numerous alpha-helix hairpins of ca. 30 amino acid residues and cooperative unraveling of several hairpin domains up to the size of the known repeating motif of ca.145 amino acid residues. The dynamic domain rupture forces range from 10s of pN to over 500 pN, increasing continuously as the stretching loading rate increases, in accordance with the Bell model. To further understand the molecular functionality of clathrin, specific clathrin-substrate and clathrin-tip attachments via antibodies are being explored in ongoing investigations.

Объединенная Группа Сканирующей Зондовой Микроскопии.

“…Сканирующий зондовый микроскоп играет клю чевую роль не только в исследованиях вирусов [8,9], но и в практической работе по раннему обнаруже нию вирусных частиц [10,11] и бактериальных кле ток [12,13] в жидкостях и на воздухе.…”