Rational Design of Helical Nanotubes from Self-Assembly of Coiled-Coil Lock Washers

Design of a structurally defined helical assembly is described that involves recoding of the amino acid sequence of peptide <b>GCN4-pAA</b>. In solution and the crystalline state, <b>GCN4-pAA</b> adopts a 7-helix bundle structure that resembles a supramolecular lock washer. Structurally informed mutagenesis of the sequence of <b>GCN4-pAA</b> afforded peptide <b>7HSAP1</b>, which undergoes self-association into a nanotube via noncovalent interactions between complementary interfaces of the coiled-coil lock-washer structures. Biophysical measurements conducted in solution and the solid state over multiple length scales of structural hierarchy are consistent with self-assembly of nanotube structures derived from 7-helix bundle subunits. The dimensions of the supramolecular assemblies are similar to those observed in the crystal structure of <b>GCN4-pAA</b>. Fluorescence studies of the interaction of <b>7HSAP1</b> with the solvatochromic fluorophore PRODAN indicated that the nanotubes could encapsulate shape-appropriate small molecules with high binding affinity

Rational Design of Helical Nanotubes from Self-Assembly of Coiled-Coil Lock Washers

Design of a structurally defined helical assembly is described that involves recoding of the amino acid sequence of peptide <b>GCN4-pAA</b>. In solution and the crystalline state, <b>GCN4-pAA</b> adopts a 7-helix bundle structure that resembles a supramolecular lock washer. Structurally informed mutagenesis of the sequence of <b>GCN4-pAA</b> afforded peptide <b>7HSAP1</b>, which undergoes self-association into a nanotube via noncovalent interactions between complementary interfaces of the coiled-coil lock-washer structures. Biophysical measurements conducted in solution and the solid state over multiple length scales of structural hierarchy are consistent with self-assembly of nanotube structures derived from 7-helix bundle subunits. The dimensions of the supramolecular assemblies are similar to those observed in the crystal structure of <b>GCN4-pAA</b>. Fluorescence studies of the interaction of <b>7HSAP1</b> with the solvatochromic fluorophore PRODAN indicated that the nanotubes could encapsulate shape-appropriate small molecules with high binding affinity

Community recommendations on cryoEM data archiving and validation.

In January 2020, a workshop was held at EMBL-EBI (Hinxton, UK) to discuss data requirements for the deposition and validation of cryoEM structures, with a focus on single-particle analysis. The meeting was attended by 47 experts in data processing, model building and refinement, validation, and archiving of such structures. This report describes the workshop's motivation and history, the topics discussed, and the resulting consensus recommendations. Some challenges for future methods-development efforts in this area are also highlighted, as is the implementation to date of some of the recommendations