Search

Here we created artificial cells in which information of the genome of living cells is expressed by the elements encoded in the genome. We confirmed that the system works normally within artificial cells, which paves the way for reconstructing living cells from biomolecules.

Spatiotemporal patterning is a fundamental mechanism for developmental differentiation and homeostasis in living cells. Because spatiotemporal patterns are based on higher-order collective motions of elements synthesized from genes, their behavior dynamically changes according to the element amounts. Thus, to understand life and use this process for material application, creation of artificial cells with time development of spatiotemporal patterning by changes of element levels is necessary. However, realizing coupling between spatiotemporal patterning and synthesis of elements in artificial cells has been particularly challenging. In this study, we established a system that can synthesize a patterning mechanism of the bacterial cell division plane (the so-called Min system) in artificial cells by modifying a defined protein expression system and demonstrated that artificial cells can show time development of spatiotemporal patterning similar to living cells. This system also allows generation and disappearance of spatiotemporal patterning, is controllable by a small molecule in artificial cells, and has the ability for application in cargo transporters. The system developed here provides a new material and a technique for understanding life, development of drug delivery tools, and creation of molecular robots.

The 4f-3d exchange couplings were definitively and precisely determined in the dinuclear complexes (Ln-M) involving double μ-oxo-bridges, by means of combined high-frequency electron paramagnetic resonance and pulsed-field magnetization techniques, revealing a monotonic decrease of ferromagnetic J(Ln-Cu) in the order of the atomic number, (64)Gd to (68)Er.

We have developed a bacterial salt sensor by multiplication of the phenotypes in GroE-depleted Escherichia coli. Depletion of GroE, an essential chaperonin protein, induces many independent phenotypes, including the activation of a metE promoter, salt requirement for growth, and eventual cell death. We demonstrated that the cell number at growth cessation after GroE depletion was proportional to the salt concentration. To develop a bacterial salt sensor, the dependence of the cell growth on salt concentration was combined with superfolder green fluorescent protein (GFP) expression under the metE promoter. The bacterial salt sensor produced fluorescence signals in response to salt concentrations within the medium in a quadratic manner. The bacterial sensor responded to other monovalent or divalent cations and exhibited maximum response at concentrations that produced similar levels of total charge. The bacterial sensor did not respond to sugars that create an osmotic pressure, demonstrating its specificity for ion sensing. Finally, we demonstrated that the bacterial device was able to respond to sea water concentrations within the medium. We have thus developed an effective bacterial salt-sensing device. Our results also provided insight into what induces the salt requirement phenotype of GroE-depletion.

Heterometallic coordination compounds [Cu(II)(L)(C(3)H(6)O)Ln(III)(NO(3))(3)] and [V(IV)O(L)(C(3)H(6)O)Ln(III)(NO(3))(3)] (abbreviated as LnCu and LnV, respectively; H(2)L = N,N'-bis(3-methoxysalicylidene)-1,3-diamino-2,2-dimethylpropane; Ln = Gd, Tb, Dy, Ho, and Er) were synthesized, and the X-ray crystallographic analysis shows that their structures are isomorphous for each series. The single-molecule magnet behavior was observed for TbCu and DyCu, and the activation energies of magnetization reversal were 42.3(4) and 11.5(10) K, respectively. The magnetic exchange couplings in LnCu and LnV were precisely evaluated by means of combined high-frequency EPR and pulsed-field magnetization studies, to give J(Tb-Cu)/k(B)≥ 3.3 K, J(Dy-Cu)/k(B) = 1.63(1) K, J(Ho-Cu)/k(B) = 1.09(2) K, and J(Er-Cu)/k(B) = 0.24(1) K. A monotonic decrease of ferromagnetic J(Ln-Cu) was found in the order of the atomic number, (64)Gd to (68)Er. The corresponding exchange parameters in LnV are smaller than those of the Cu derivatives, and J(Gd-V) was antiferromagnetic (-3.0 K determined from the magnetization jump). A possible mechanism for the exchange coupling and chemical trend is discussed.