Proteins self-organization is a hallmark of biological systems. Physico-chemical principles governing protein-protein interactions have long been known. However, the principles by which such nanoscale interactions generate diverse phenotypes of mesoscale assemblies, including phase-separated compartments, remain challenging to characterize. To illuminate such principles, we create a system of two proteins designed to interact and form mesh-like assemblies. We devise a novel strategy to map high-resolution phase diagrams in living cells, which provide self-assembly signatures of this system. The structural modularity of the two protein components allows straightforward modification of their molecular properties, enabling us to characterize how interaction affinity impacts the phase diagram and material state of the assemblies in vivo. The phase diagrams and their dependence on interaction affinity were captured by theory and simulations, including out-of-equilibrium effects seen in growing cells. Finally, we find that cotranslational protein binding suffices to recruit an mRNA to the designed micron-scale structures.

A racemic mixture consisting of a secondary ammonium salt (()-(1RS,3SR,4RS)-1-phenyl-cis-3,4-n-butano-5,6-dihydro-1H-2, 5-benzoxazocine hydrochloride (1) crystallized as a "false conglomerate" of crystals in the monoclinic system, Sohncke space group P2 1 with two molecules of opposite handedness in the asymmetric unit and at 295(2) K: a = 10.224(2) Å, b = 13.969(2) Å, c = 12.724(2) Å, β = 98.996(2)°, V = 1794.9(5) Å 3 , Z = 4, and Z 0 = 2. The cis-3,4-nbutano-5,6-dihydro-1H-2,5-benzoxazocine fused-ring skeletons are approximately enantiotopic and exhibit pseudoinversion and pseudo-nglide relationships. These noncrystallographic symmetries enable space filling in the chiral crystal structure to resemble that of a higher order achiral P2 1 /n apparent space group (Z = 4, Z 0 = 1). The secondary ammonium salt molecules crystallize in patterns influenced by a complex blend of NÀH 3 3 3 Cl, CÀH 3 3 3 Cl, CÀH 3 3 3 O, and CÀH 3 3 3 Ar interactions that seem to be responsible for different conformational twists of the phenyl rings in the structure. Avnir's CSM method was adapted for quantification of crystallographic pseudosymmetry. RmS(G) measurements of distortion from ideal G symmetries were developed for pure translation, screw rotation, and glide reflection, as well as point group symmetries. Low rmS(i) and rmS(n-glide) values show high fidelity for the emulation of P2 1 /n space filling in crystalline 1.

Molecular symmetry is a key parameter which dictates the NMR chemical shielding anisotropy (CSA). Whereas correlations between specific geometrical features of molecules and the CSA are known, the quantitative correlation with symmetry--a global structural feature--has been unknown. Here we demonstrate a CSA/symmetry quantitative relation for the first time: We study how continuous deviation from exact symmetry around a nucleus affects its shielding. To achieve this we employed the continuous symmetry measures methodology, which allows one to quantify the degree of content of a given symmetry. The model case we use for this purpose is a population of distorted SiH(4) structures, for which we follow the (29)Si CSA as a function of the degree of tetrahedral symmetry and of square-planar symmetry. Quantitative correlations between the degree of these symmetries and the NMR shielding parameters emerge.

Alkyl analogues of methylphenidate (Ritalin) salts are slow onset, long duration dopamine reuptake inhibitors with a potential use as a cocaine abuse pharmacotherapy. X-ray crystallographic studies and nuclear magnetic resonance (NMR) investigations strongly suggest that avoidance of sterically unfavorable gauche(-)gauche(+) orientations effectively influences both the C(α)-alkyl side chain conformation and the formation of a predominant rotamer about the CH-CH bond ligating piperidine and C(Ar)R moieties. The favored CH-CH rotamer in D(2)O and in CD(2)Cl(2) of the pharmacologically interesting i-Bu and CH(2)-cyc-Pnt (RS,RS)-salts has the same antiperiplanar arrangement that was found in the crystal structures, although there clearly is a fast equilibrium involving smaller amounts of synclinal partners. While the rotamer in the (RS,SR)-i-Bu HCl crystal structure exhibits a synclinal orientation for the vicinal pair of adjacent methine protons, the weighted time-averaged arrangement for these protons becomes almost completely antiperiplanar when the crystals are dissolved in D(2)O. Increased steric congestion around the CH-CH bond in the analogous N-methyl tertiary ammonium salts seems to augment the quantity of the preferred rotamer within the mixture. The stereochemistry of the species observed via NMR seems to arise from specific combinations of N-methyl orientation and avoidance of sterically unfavorable gauche(-)gauche(+) arrangements.

The expected achiral C 2V -symmetry was observed by solution-state 1 H and 13 C NMR spectroscopic measurements performed for each of the N-methylated 1,3-diaminoadamantane diammonium salts studied. 1,3-Diaminoadamantane dihydrochloride crystallized in the orthorhombic achiral system Pna2 1 and at 294(2) K: a ) 10.910(1) Å, b ) 15.515(2) Å, c ) 7.246(1) Å, V ) 1226.5(3) Å 3 , and Z ) 4. N,N,N′,N′-Tetramethyl-1,3-diaminoadamantane dihydrochloride gave monohydrate crystals in the monoclinic achiral system C2/c and at 173(2) K: a ) 17.482(2) Å, b ) 22.194(2) Å, c ) 9.660(1) Å, β ) 120.173(2)°, V ) 3240.2(6) Å 3 , and Z ) 8. N,N,N,N′,N′,N′-Hexamethyl-1,3-diaminoadamantane diiodide afforded monohydrate crystals in the orthorhombic chiral system P2 1 2 1 2 1 and at 298(2) K: a ) 9.6400(10) Å, b ) 13.982(2) Å, c ) 15.601(2) Å, V ) 2102.8(5) Å 3 , and Z ) 4. 5,7,N,N,N,N′,N′,N′-Octamethyl-1,3-diaminoadamantane dibromide gave dihydrate crystals belonging to the triclinic achiral system P1 j and at 294(2) K: and Z ) 4. All the diammonium dications in these crystals occupied "general positions of symmetry" within the crystal lattice, which resulted in their complete desymmetrization to C 1 -symmetry. Their molecular geometries still exhibited some degree of "pseudosymmetry", since the distortions were fairly small in magnitude. Continuous symmetry measures (CSM) were made to study the effect of the crystal lattice environment upon the distortion of the molecular structure. The CSM showed that the crystalline diammonium salts were either predominantly C 2 pseudosymmetric if the N-methylated ammonium units were skewed in the same directions, or predominantly C s pseudosymmetric (σ ⊥ ) if these units were twisted in opposite directions. In the crystalline compounds studied in this series, there were no examples with predominantly pseudomirror symmetry via a σ // -plane encompassing both nitrogen atoms, since this would have required a chemical (structural) constraint in favor a staggered arrangement for the C-N + -C-C-C-N + -C fragment that was not obligated by the local site asymmetric environments in the various crystals. The values of S(total), the total CSM distortion from solution-state ideal C 2V -symmetry exhibited by the general positioned dication moieties, were augmented with increasing N-methylation, while the relationships between the two external periphery subunits [R 1 R 2 R 3 N(1) and N(2)R 1 R 2 R 3 ] became more distorted than those of the adamantane C 10 core fragments.