Surface Dependence of Protein Nanocrystal Formation

Abstract

The self-assembly kinetics and nanocrystal formation of the bacterial surface-layer-protein SbpA are studied with a combination of quartz crystal microbalance with dissipation monitoring (QCM-D) and atomic force microscopy (AFM). Silane coupling agents, aminopropyltriethoxysilane (APTS) and octadecyltrichlorosilane (OTS), are used to vary the protein-surface interaction in order to induce new recrystallization pathways. The results show that the final S-layer crystal lattice parameters (a = b = 14 nm, gamma = 90 degrees ), the layer thickness (15 nm), and the adsorbed mass density (1700 ng cm(-2)) are independent of the surface chemistry. Nevertheless, the adsorption rate is five times faster on APTS and OTS than on SiO(2,) strongly affecting protein nucleation and growth. As a consequence, protein crystalline domains of 0.02 microm(2) for APTS and 0.05 microm(2) for OTS are formed, while for silicon dioxide the protein domains have a typical size of about 32 microm(2). In addition, more-rigid crystalline protein layers are formed on hydrophobic substrates. In situ AFM experiments reveal three different kinetic steps: adsorption, self-assembly, and crystalline-domain reorganization. These steps are corroborated by frequency-dissipation curves. Finally, it is shown that protein adsorption is a diffusion-driven process. Experiments at different protein concentrations demonstrate that protein adsorption saturates at 0.05 mg mL(-1) on silane-coated substrates and at 0.07 mg mL(-1) on hydrophilic silicon dioxide.

Fluorescence energy transfer in the bi-fluorescent S-layer tandem fusion protein ECFP–SgsE–YFP

“…Molecular dynamics simulations have been used to elucidate the structure of the S-layer protein SbsB from Geobacillus stearothermophilus PV72/p2 (Horejs et al, 2008), whilst crystallisation studies have helped to gain insight into different parts of the S-layer protein SbsC from G. stearothermophilus ATCC 12980 (Pavkov et al, 2008). Self-assembly studies on solid supports have revealed the importance of the surface chemistry for the protein layer structure of SbpA from Lysinibacillus sphaericus CCM 2177 as well as for the formation kinetics (Moreno-Flores et al, 2008;Eleta Lopez et al, 2010).…”

Making novel bio-interfaces through bacterial protein recrystallization on biocompatible polylactide derivative films

“…They are fairly similar to the type of polymer substrate and agree to the ones observed on native S-layers, 15 and for many different kinds of substrates. [20][21][22][23][24]32 The AFM images ( Figure 5) show that these layers are characterized by protein crystal domains which do not differ in lattice parameters but in the lattice orientation. As can be observed, larger protein domains appear on amorphous poly- mers (PDLLA, PLGA, and PLCL) than on semicrystalline PLLA.…”

“…In previous works, the influence of the hydrophobicity on the recrystallization process of SbpA has been reported. 21,23 On hydrophilic silicon surfaces, large crystal domains are formed, while on hydrophobic silanecoated substrates, the domain sizes are 100 times smaller. 23 The biodegradable polymers presented in this work have contact angles within a small range of 80 • -83 • (Table V).…”

“…21,23 On hydrophilic silicon surfaces, large crystal domains are formed, while on hydrophobic silanecoated substrates, the domain sizes are 100 times smaller. 23 The biodegradable polymers presented in this work have contact angles within a small range of 80 • -83 • (Table V). This suggests that we cannot explain the differences in crystalline domain size from a macroscopic surface energy point of view but probably from topological differences of polymer surfaces, which remains an open question to be explored.…”

“…[15][16][17][18] These biosupramolecular structures have already been studied in a wide range of environments and solid suports. [19][20][21][22][23][24] Moreover, S-layer technology has moved on in the last decade in the synthesis and development of S-layer fusion proteins, which represents a big step in nanobiotechnology 25,26 and constitutes a promising field in surface 2D nanofunctionalization. [27][28][29][30][31] The aim of our work was to investigate the interaction between some of the varieties of lactic acid based polymers of different physicochemical properties (e.g., crystallinity, mechanical properties, etc.)…”