title: Phosphate-mediated molecular memory driven by two different protein kinases as information input elements.
abstract: There is increasing interest in studying molecular-based devices that perform Boolean logic operations whose output state (0 or 1) depends on the input conditions (0/0, 1/0, 0/1, or 1/1). So far, great efforts have been devoted to establish molecular-scaled logic gates activated by chemical, physical, and biological inputs. We herein describe the design and synthesis of a tandem protein kinase substrate peptide acting as a phosphate-mediated molecular memory. The molecular-based memory system is comprised of two different phosphorylatable substrate regions joined in series and a spiropyran derivative at the N-terminus. We also demonstrated three basic "AND", "OR", and "NOR" logic operations on the basis of alterations in the spiropyran-to-merocyanine (SP-to-MC) thermocoloration properties of the spiropyran moiety in the peptide upon kinase-catalyzed phosphorylation. The three logic functions were successfully performed by adding ionic polymers as programming elements with preset thresholds of a signal intensity in a microplate format. Throughout this study, information was recorded on the substrate peptide by protein kinase-catalyzed phosphorylation, stored stably as phosphoesters, read according to the extent of the SP-to-MC thermocoloration, and erased by phosphatase-catalyzed dephosphorylation, resulting in the peptide returning to the initial recordable state. Thus, the proof-of-concept experiments described herein could be used to provide clues for developing practical molecular-based processing and computing.
authors.affiliation: Department of Bioengineering and The COE21 Program, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 B-40 Nagatsuta, Midori, Yokohama, Japan. tomizaki@rite.or.jp
authors.forename: Kin-Ya
authors.initials: KY
authors.lastname: Tomizaki
authors.forename: Hisakazu
authors.initials: H
authors.lastname: Mihara
mesh_terms: D001578:Benzopyrans / Q000737:chemistry; D039301:Computers, Molecular; D007211:Indoles / Q000737:chemistry; D015394:Molecular Structure; D009574:Nitro Compounds / Q000737:chemistry; D010710:Phosphates / Q000737:chemistry*; D011494:Protein Kinases / Q000737:chemistry* / Q000378:metabolism
chemical_list: D001578:Benzopyrans; D007211:Indoles; D009574:Nitro Compounds; D010710:Phosphates; C088184:spiropyran; D011494:Protein Kinases