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Versatile DNA and polypeptide‐based structures have been designed based on complementary modules. However, polypeptides can also form higher oligomeric states. We investigated the introduction of tetrameric modules as a substitute for coiled‐coil dimerization units used in previous modular nanostructures. Tetramerizing helical bundles can run in parallel or antiparallel orientation, expanding the number of topological solutions for modular nanostructures. Furthermore, this strategy facilitates the construction of nanostructures from two identical polypeptide chains. Importantly, tetrameric modules substantially stabilized protein nanostructures against air–water interface denaturation, enabling the determination of the first cryo‐electron microscopy three‐dimensional structure of a coiled‐coil‐based nanostructure, confirming the designed agreement of the modules forming a tetrahedral cage. [ABSTRACT FROM AUTHOR]

As the causal agent of the grapevine yellows disease Bois noir, ' Candidatus Phytoplasma solani' has a major economic impact on grapevines. To improve the control of Bois noir, it is critical to understand the very complex epidemiological cycles that involve the multiple " Ca. P. solani" host plants and insect vectors, of which Hyalesthes obsoletus is the most important. In the present study, multiple genotyping of the tuf , secY, stamp , and vmp1 genes was performed. This involved archived grapevine samples that were collected during an official survey of grapevine yellows throughout the wine-growing regions of Slovenia (from 2003 to 2016), plus samples from Austrian grapevines, stinging nettle, field bindweed, and insect samples (collected from 2012 to 2019). The data show that the tuf-b2 type of the tuf gene has been present in eastern Slovenia since at least 2003. The hypotheses that the occurrence of the haplotypes varies due to the geographical position of Slovenia on the Italian–Slovenian Karst divide and that the haplotypes are similar between Slovenian and Austrian Styria were confirmed. The data also show haplotype changes for host plants and H. obsoletus associated with ' Ca. P. solani,' which might be linked to new epidemiological cycles of this phytoplasma that involve not just new plant sources and new insect vectors, but also climate and land-use changes. [ABSTRACT FROM AUTHOR]

The response of the adaptive immune system is augmented by multimeric presentation of a specific antigen, resembling viral particles. Several vaccines have been designed based on natural or designed protein scaffolds, which exhibited a potent adaptive immune response to antigens; however, antibodies are also generated against the scaffold, which may impair subsequent vaccination. In order to compare polypeptide scaffolds of different size and oligomerization state with respect to their efficiency, including anti-scaffold immunity, we compared several strategies of presentation of the RBD domain of the SARS-CoV-2 spike protein, an antigen aiming to generate neutralizing antibodies. A comparison of several genetic fusions of RBD to different nanoscaffolding domains (foldon, ferritin, lumazine synthase, and β-annulus peptide) delivered as DNA plasmids demonstrated a strongly augmented immune response, with high titers of neutralizing antibodies and a robust T-cell response in mice. Antibody titers and virus neutralization were most potently enhanced by fusion to the small β-annulus peptide scaffold, which itself triggered a minimal response in contrast to larger scaffolds. The β-annulus fused RBD protein increased residence in lymph nodes and triggered the most potent viral neutralization in immunization by a recombinant protein. Results of the study support the use of a nanoscaffolding platform using the β-annulus peptide for vaccine design. [ABSTRACT FROM AUTHOR]