Interactions in vitro between gibberellins and DNA

Computer modeling of gibberellin-DNA binding

Computer modeling and molecular mechanics performed on the intercalation complexes of selected gibberellins or biosynthetic precursors with DNA dinucleotides revealed that under appropriate conditions the ligands insert (intercalate) between the base-paired double-stranded dinucleotide, 5'-dTdA-3'. Stabilization of the double-stranded dinucleotide after docking of a gibberellin between base pairs is inferred by the sum negative energy of hydrogen bonding and van der Waals contacts and the entropic changes which accompany the formation of each ligand-dinucleotide complex. In addition, the interactions of the gibberellins and dinucleotides, with the gibberellic acid-dinucleotide complex serving as the prototype, show optimum geometry and stereochemical hydrogen bonding recognition which are dependent upon the complementary chirality and stereochemistry of the individual components. Whether or not the gibberellins directly influence the uncoiling of DNA or gene expression at the transcriptional level via an intercalation mechanism is a matter of conjecture, albeit one that warrants intensive investigation.

Chirality and stereochemical recognition in DNA-phytohormone interactions: a model approach

Space-filling molecular models of selected phytohormones and DNA, employed as described herein, illustrate possible in vivo stereochemical recognition between nucleic acids and intercalated phytohormones. In this regard, the absolute chirality of certain phytohormones, and that of DNA may be essential for the recognition process. It is speculated further that the specific interactions shown by molecular models have significance in the evolution of plant regulatory mechanisms.

Gibberellin and nucleic acid metabolism during Zea mays fertilization

Either by direct GA supply or by release of glycosidic bound GA, pollination causes partial opening of double-stranded DNA in somatic maize kernel tissues, as evidenced by increased Tm profiles. This phenomenon is associated with enhanced RNA and prtein production.

[Effect of several plant growth regulators on various prokaryotes and their viruses]

26 plant growth regulators including herbicides were investigated in their effect on the multiplication of Escherichia coli, Bacillus subtilis, and the blue-green alga Plectonema boryanum as well as the RNA phages M 12 and Qbeta and the DNA phages lambda, phi 105, and LPP-1 employing the agar diffusion method. Nearly all of the compounds inhibited and/or stimulated one or some of the prokaryotes tested. The most frequent and strongest effects occurred in Pl. boryanum, the least effects in E. coli. The multiplication of phages was also influenced by plant growth regulators leading to increase, decrease or non-appearance of plaques. The investigations with the temperate phages lambda and phi 105 suggested part of the compounds to be able to interfere with the process of lysogenization. The results are discussed comparatively involving correspondent findings referred to in literature.