Calcium dependent formation of tubular assemblies by recombinant S-layer proteinsin vivoandin vitro

Abstract

Surface layer proteins have the appealing property to self-assemble in nanosized arrays in solution and on solid substrates. In this work, we characterize the formation of assembly structures of the recombinant surface layer protein SbsC of Geobacillus stearothermophilus ATTC 12980, which was tagged with enhanced green fluorescent protein and expressed in the yeast Saccharomyces cerevisiae. The tubular structures formed by the protein in vivo are retained upon bursting the cells by osmotic shock; however, their average length is decreased. During dialysis, monomers obtained by treatment with chaotropic chemicals recrystallize again to form tube-like structures. This process is strictly dependent on calcium (Ca(2+)) ions, with an optimal concentration of 10 mM. Further increase of the Ca(2+) concentration results in multiple non-productive nucleation points. We further show that the lengths of the S-layer assemblies increase with time and can be controlled by pH. After 48 h, the average length at pH 9.0 is 4.13 µm compared to 2.69 µm at pH 5.5. Successful chemical deposition of platinum indicates the potential of recrystallized mSbsC-eGFP structures for nanobiotechnological applications.

Quantitative analysis of molecular-level DNA crystal growth on a 2D surface

“…This process allows molecular-scale growth by crystals attaching themselves to nucleating structures through a specific interaction that arises from the nature of the specific constituent molecules. Thus, each solid-state crystal has distinct growth properties following geometrical and chemical characteristics of their molecules6789. During the past few decades, DNA has stood out as a potential material for crystals because of its remarkable ability to construct complex architecture.…”

Self-assembly of artificial microtubules

“…[11][12][13] Various assemblies of S-layer proteins can serve as templates to grow other extended nanostructures such as superlattices of metallic clusters. 11,14,15 Tubular structures are also found to form in self-assembly of macromolecules that are usually amphiphilic.…”

Trivalent Cation Induced Bundle Formation of Filamentous fd Phages

“…Ions play an important role in self‐assembly of such nanobiotemplates as well. S‐layers were previously reported to self‐assemble into tube‐like structures in vitro in the presence of divalent Ca 2+ ions . Monte Carlo simulations have been performed in order to model the tube formation at various monomer and Ca 2+ ion concentrations .…”

“…S-layers were previously reported to self-assemble into tube-like structures in vitro in the presence of divalent Ca 2þ ions. [5] Monte Carlo simulations have been performed in order to model the tube formation at various monomer and Ca 2þ ion concentrations. [6] Likewise, microtubule (MT) self-assembly into highly organized bundles occurs in the presence of multivalent cations.…”