Self-Organizing Bio- structures NB L. Duroux

Lecture 7 Protein-based nanomaterials

1. Peptide-based nanostructures

A first insight into SA peptides Concept of peptide SA introduced by Ghadiri et al. (1993) Concept of peptide SA introduced by Ghadiri et al. (1993) Synthetic cyclic polypeptides (alternate L- & D-) self-assemble into Ø8-9nm nanotubes Synthetic cyclic polypeptides (alternate L- & D-) self-assemble into Ø8-9nm nanotubes Function as novel antimicrobial agents, drug delivery systems & nanomaterials Function as novel antimicrobial agents, drug delivery systems & nanomaterials

Ghadiri’s cyclic polypeptides (CPP)

Electronic microscopy

pH-dependance of CP SA

CPP forming pores in membranes

 cyclic-peptides self-assembled into open tubes  consist of an even number of alternated D / L amino acids  formation of anti-parallel hydrogen bonded network  assembly could be controlled by electrostatic interactions  assembly could be directed toward particular environments (hydrophobic) by selection of amino acids  are functional material (ion channel & antibiotic) Self-Assembling Peptide Nanotubes

SA based on native 2 ndary structural motifs

Protein structural motifs & SA designs Type II polyPro helixAmyloid fibrils

SA Fibers engineering based on coiled- coils Woolfson & Ryadnov, 2006

Amyloid peptides A generic, universal form of protein/peptide aggregation A generic, universal form of protein/peptide aggregation Cause of many diseases: Altzheimer’s, Type II diabetes, Prions... Cause of many diseases: Altzheimer’s, Type II diabetes, Prions... Extended  -sheet SA forming fibrils Extended  -sheet SA forming fibrils

Nano-object formed by amyloid peptides Object formed Amyloid fibrils (pancreas type II diabetes) Amyloid fibrils Nanotubes Nanospheres

The role of aromatics in amyloid fibrils formation  Phe dipeptide: the recognition core of Altzheimer’s amyloid fibril  Forms nanotubes  Applications in nano-electronics

SA based on amphiphilicity

Structures of peptides used in SA Reches and Gazit, 2006 Boloamphiphile Amphiphile Surfactant-like Phenylalanine dipeptide

Peptide nanotubes Applications Nanotubes with Ca-binding and cell-adhesion  bone-like material Idem, non-conjugated Nanofibers forming hydrogel  matrix for tissue regeneration & engineering

Peptide-Amphiphile and Tissue Engineering SA fibers with CCCCGGGS (PO4) PGD: without Ca2+ (a) and Ca2+ (b)

Aromatic dipeptides

Hydrophobic layers made with dipeptides Görbitz, 2006

Types of nanostructures from various dipeptides

SA of Val-Ala class

SA patterns of the Phe-Phe class Phe-Trp Phe-Gly Phe-Leu Phe-Phe

Formation of nanotubes with Phe- Phe dipeptides

2. Protein-based SA nanotools

S-layer proteins

What are S-Layer proteins? S stands for surface: glycoprotein subunits forming outer envelope of Bacteria and Archea S stands for surface: glycoprotein subunits forming outer envelope of Bacteria and Archea Periodic structures with defined physico-chemical properties (pore size) Periodic structures with defined physico-chemical properties (pore size) Self_assemble into 2D layers to form monomolecular lattices: potential in nanobiotechnologies (scaffolds, patterning matrices) Self_assemble into 2D layers to form monomolecular lattices: potential in nanobiotechnologies (scaffolds, patterning matrices)

Applications of S-layers production of isoporous ultrafiltration membranes supporting structures for defined immobilization or incorporation of functional molecules (e.g. antigens, antibodies, ligands, enzymes) matrix for the development of biosensors including solid-phase immunoassays and label-free detection systems Support and stabilizing matrices for functional lipid membranes, liposomes, and emulsomes adjuvants for weakly immunogenic antigens and haptens Matrix for controlled biomineralization and structure for formation of ordered arrays of metal clusters or nanoparticles (molecular electronics and nonlinear optics or catalysts)

S-Layer lattices Gram+ bacterium 100nm

Self-Assembled monomolecular layers

S-layer as template for PSA detection

Assembly of lipids on S-layers Non-covalent bonding Non-covalent bonding Electrostatic interactions between corrugated (inner) side of S-layer (carboxy groups) and charges on lipid head groups (zwitterions) Electrostatic interactions between corrugated (inner) side of S-layer (carboxy groups) and charges on lipid head groups (zwitterions) 2-3 contact points between protein and lipid: most lipids free to diffuse laterally: semi-rigid membrane 2-3 contact points between protein and lipid: most lipids free to diffuse laterally: semi-rigid membrane

S-layers as support for lipid membranes

Self-Assembly of a ion-channel in S-layers

Expected applications of S-layer- driven SA of lipid membranes Life Sciences: Life Sciences: Drug delivery Drug delivery Diagnostics Diagnostics Biosensors Biosensors Chemistry and material sciences Chemistry and material sciences Bio-mineralization Bio-mineralization Non-linear optics Non-linear optics Molecular electronics Molecular electronics Catalysis Catalysis