The phosphorylation state of the C-terminal domain (CTD) of the RNA polymerase II plays crucial roles in transcription and mRNA processing. Previous studies showed that the plant CTD phosphatase-like 1 (CPL1) dephosphorylates Ser-5-specific CTD and regulates abiotic stress response in Arabidopsis. Here, we report the identification of a K-homology domain-containing protein named SHINY1 (SHI1) that interacts with CPL1 to modulate gene expression. The shi1 mutant was isolated from a forward genetic screening for mutants showing elevated expression of the luciferase reporter gene driven by a salt-inducible promoter. The shi1 mutant is more sensitive to cold treatment during vegetative growth and insensitive to abscisic acid in seed germination, resembling the phenotypes of shi4 that is allelic to the cpl1 mutant. Both SHI1 and SHI4/CPL1 are nuclear-localized proteins. SHI1 interacts with SHI4/CPL1 in vitro and in vivo. Loss-of-function mutations in shi1 and shi4 resulted in similar changes in the expression of some stress-inducible genes. Moreover, both shi1 and shi4 mutants display higher mRNA capping efficiency and altered polyadenylation site selection for some of the stress-inducible genes, when compared with wild type. We propose that the SHI1-SHI4/CPL1 complex inhibits transcription by preventing mRNA capping and transition from transcription initiation to elongation.

A close and relevant parallel is the ionization of (the isoelectronic) primary amides. Here too calculations indicate that the 2 isomer (of the anion) is more stable in the gas phase by about 5 kcal/mol.'8 Since the isomeric anions are in equilibrium with the same conjugate acid, this is a direct measure of the difference (1 7) The calculated (>5 kcal/mol) preference of esters for the 2 conformation is also much reduced in solution, as indicated by a measured ("C NMR) value of 1.67 kcal/mol for ethyl formate. (Grindley, T. B. Terrahedron k r t . 1982, 1757-60.) Increasing the size of either the acyl or the alkyl substituent increases the preference for the Z conformation, presumably for steric reasons, so any stereoelectronic preference should be most clearly expressed in formate esters. (18) Zielinski, T. J.; Poirier, R. A.; Peterson, M. R.; Csizmadia, I. G. J . Comput. Chem. 1982, 3, 477-485. Nguyen, N. T.; Hegarty, A. F. J. Org. Chem. 1986, 51. 4703-6. in acidity between the E and 2 protons. In this case it is possible HE :N-W E-anionZ-anion to measure the equilibria, and the proton-transfer processes involved, in solution. In aqueous solvent, the base-catalyzed exchange of H E is never more than a few times faster than that of Hz; the E / Z ratio is strongly solvent-dependent, and under some conditions the solvated E isomer is actually preferred.19 (19) Perrin, C. L.; Johnston, E. R.; Lollo, C. P.; Kobrin, P. A. Abstract:The design, synthesis, and study of a molecular template, 1 la, that catalyzes its own formation from simpler components, 9 and lOd, is described. Autocatalysis is shown by the following: (1) the increase in rate of reaction of 9 and 1Od in the presence of Ila; (2) the reduction in rate of reaction in the presence of 2,6-bis(acetylamino)pyridine inhibitor; and (3) the reduction in rate of reaction when a component incapable of template behavior, 10h, is substituted for 1Od. Three kinetic pathways are elucidated: ( I ) the background bimolecular reaction (eq 6); (2) the preassociative mechanism (eq 7); and (3) the template termolecular process (eq 8). A kinetic model for the replication process is introduced, and equilibrium and rate constants are determined. Predictions for the shapes of the product growth curves are made.Helbing, J.; Mattzen, M.; Jordan, S. Abstract:The stereoselectivity of the intramolecular photocycloaddition of a series of bicyclic dioxenones has been examined.The selective formation of trans-fused photoadducts is observed in almost all cases, which upon fragmentation lead to the synthesis of bicycloalkanones with an 'inside-outside" or trans intrabridgehead stereochemical relationship. This methodology has been applied to the synthesis of several 'inside-outside" bicycloalkanones that cannot otherwise be prepared. The unusual reactivity of both the dioxanone photoadducts and the bicycloalkanone fragmentation products is described.

Replication and mutation are necessary elements of evolution, and some properties of self-replicating molecules (replicators) can be explored with synthetic structures. Selection and evolution at the molecular level require systems capable of competition and inheritable change. These phenomena have now been observed with synthetic molecules. Two such molecules were prepared having sufficient structural similarity that they catalyzed each other's formation as well as their own. One of the replicators bears a photochemically active function that is cleaved on irradiation. The resulting species is more effective at replication than the original and rapidly takes over the system's resources.

Self-replicating molecules can be synthesized through the covalent linkage of two complementary subunits to give a self-complementary structure. Complementarity refers to sizes, shapes, and the weak intermolecular forces involved in molecular recognition between the two subunits. In order to provide a model system for evolution at the molecular level, "crossover" or recombination experiments were staged with synthetic replicators. These reactions gave rise to new structural types. The ability (or inability) of the new recombinants to catalyze their own formation is shown to be a consequence of their molecular shapes.

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