title: Self-assembly of coherently dynamic, auxetic, two-dimensional protein crystals.
abstract: Two-dimensional (2D) crystalline materials possess unique structural, mechanical and electronic properties that make them highly attractive in many applications. Although there have been advances in preparing 2D materials that consist of one or a few atomic or molecular layers, bottom-up assembly of 2D crystalline materials remains a challenge and an active area of development. More challenging is the design of dynamic 2D lattices that can undergo large-scale motions without loss of crystallinity. Dynamic behaviour in porous three-dimensional (3D) crystalline solids has been exploited for stimuli-responsive functions and adaptive behaviour. As in such 3D materials, integrating flexibility and adaptiveness into crystalline 2D lattices would greatly broaden the functional scope of 2D materials. Here we report the self-assembly of unsupported, 2D protein lattices with precise spatial arrangements and patterns using a readily accessible design strategy. Three single- or double-point mutants of the C4-symmetric protein RhuA were designed to assemble via different modes of intermolecular interactions (single-disulfide, double-disulfide and metal-coordination) into crystalline 2D arrays. Owing to the flexibility of the single-disulfide interactions, the lattices of one of the variants ((C98)RhuA) are essentially defect-free and undergo substantial, but fully correlated, changes in molecular arrangement, yielding coherently dynamic 2D molecular lattices. (C98)RhuA lattices display a Poisson's ratio of -1-the lowest thermodynamically possible value for an isotropic material-making them auxetic.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA.
authors.forename: Yuta
authors.initials: Y
authors.lastname: Suzuki
authors.affiliation: Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Cardone
authors.affiliation: School of Civil Engineering, Purdue University, West Lafayette, Indiana 47907-2051, USA.
authors.forename: David
authors.initials: D
authors.lastname: Restrepo
authors.affiliation: School of Civil Engineering, Purdue University, West Lafayette, Indiana 47907-2051, USA.
authors.forename: Pablo D
authors.initials: PD
authors.lastname: Zavattieri
authors.affiliation: Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA.|Division of Biological Sciences, University of California, San Diego, La Jolla, California 92093, USA.
authors.forename: Timothy S
authors.initials: TS
authors.lastname: Baker
authors.affiliation: Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA.
authors.forename: F Akif
authors.initials: FA
authors.lastname: Tezcan
mesh_terms: D000446:Aldehyde-Lyases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D003460:Crystallization; D004220:Disulfides / Q000737:chemistry / Q000378:metabolism; D004926:Escherichia coli / Q000737:chemistry; D008670:Metals / Q000737:chemistry / Q000494:pharmacology; D046529:Microscopy, Electron, Transmission; D008958:Models, Molecular; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D018583:Pliability / Q000187:drug effects; D011487:Protein Conformation / Q000187:drug effects; D012399:Rotation; D013314:Stress, Mechanical; D013816:Thermodynamics
chemical_list: D004220:Disulfides; D008670:Metals; D050505:Mutant Proteins; D000446:Aldehyde-Lyases; C022526:rhamnulose-1-phosphate adolase