Download MendeleyMaking and Breaking Supramolecular Synthons for Modular Protein Frameworks.
Mockler, N.M., Raston, C.L., Crowley, P.B.(2025) Chemistry 31: e202500732-e202500732
- PubMed: 40178192
- DOI: https://doi.org/10.1002/chem.202500732
- Primary Citation of Related Structures:
9HBD, 9HBE, 9HBF, 9HBG - PubMed Abstract:
Anionic calixarenes are useful mediators of protein assembly. In some cases, protein - calixarene cocrystallization yields multiple polymorphs. Ralstonia solanacearum lectin (RSL) cocrystallizes with p-sulfonato-calix[8]arene (sclx 8 ) in at least four distinct pH-dependent arrangements. One of these polymorphs, occurring at pH ≤ 4, is a cubic framework in which RSL nodes are connected by sclx 8 dimers. These dimers are supramolecular synthons that occur in distinct crystal structures. Now, we show that the discus-shaped dimer of p-phosphonato-calix[6]arene (pclx 6 ), can replace the sclx 8 dimer yielding a new assembly of RSL. Remarkably, just one type of RSL - pclx 6 cocrystal was formed, irrespective of pH or crystallization condition. These results with pclx 6 contrast starkly with sclx 8 and suggest that the calixarene type (e.g., phosphonate versus sulfonate) dictates the synthon durability, which in turn exerts control over protein assembly and polymorph selection. Breaking the pclx 6 dimer required a mutant of RSL with an affinity tag for macrocycle binding. This highly accessible, dicationic site resulted in a significantly altered and porous framework with pclx 6 (but not with sclx 8 ). Experiments with ternary mixtures of RSL, pclx 6 , and sclx 8 provide evidence of pH-driven self-sorting. Thus, the "mix-and-match" of protein and supramolecular synthons is a promising approach to protein crystal engineering.
Organizational Affiliation:
School of Biological and Chemical Sciences, University of Galway, University Road, Galway, H91 TK33, Ireland.
