Porous assembly of an antifungal protein mediated by zinc and sulfonato-calix[8]arene.
Guagnini, F., Huber, A., Alex, J.M., Marx, F., Crowley, P.B.(2021) J Struct Biol 213: 107711-107711
- PubMed: 33631304 
- DOI: https://doi.org/10.1016/j.jsb.2021.107711
- Primary Citation of Related Structures:  
7BAD, 7BAE, 7BAF - PubMed Abstract: 
Controlled protein assembly holds great potential in the fabrication of biohybrid materials. However, the structural diversity and complexity of proteins present an obstacle to controlled assembly. Supramolecular chemistry is a possible solution as it offers tools to mediate self-assembly with molecular precision. This paper deals with the calixarene- and zinc-mediated assembly and crystallization of the histidine-rich Penicillium chrysogenum antifungal protein B (PAFB). We report crystal structures of pure PAFB, PAFB in complex with Zn 2+ , and the ternary complex of PAFB, Zn 2+ and sulfonato-calix[8]arene (sclx 8 ). A comparison of the three crystal structures revealed the structural plasticity of PAFB. While the flexible and highly anionic sclx 8 resulted in large molecular weight aggregates of PAFB in solution, diffraction-quality crystals of PAFB-sclx 8 were not obtained. We report crystals of PAFB-Zn 2+ -sclx 8 in which a trinuclear zinc cluster occurred adjacent to a calixarene binding site. Interestingly, the combination of sclx 8 complexation and zinc coordination resulted in a porous framework with channels of circa 2 nm diameter. Detailed analysis of the crystal structure highlighted novel molecular recognition features. This research enriches the set of supramolecular interactions available to promote protein assembly.
Organizational Affiliation: 
School of Chemistry, National University of Ireland Galway, University Road, Galway H91 TK33, Ireland.