A series of E. coli promoters made of the consensus -35 and -10 hexamers separated by 17 bp spacer with variously located bending dTn.dAn, n = 5 or 6, sequences was constructed and cloned into the plasmid pDS3. Electrophoretic gel mobilities of restriction fragments containing these promoters correlated with the number of the T tracts encoded in the promoter sequences. The open complexes formed by E. coli RNA polymerase on promoters containing the T5(-34...-38) tract exhibited gel retardation indicative of their different gross geometry. The strength of these promoters measured in vivo in relation to an internal transcriptional standard was shown to be significantly lower than that of the group without the T5(-34...-38) tract. Within both these groups the promoters with two T6 tracts in the spacer, aligned in phase with the B-DNA helix repeat, had lower transcriptional activity, while the T6 tract encoded in the -7...-2 promoter region apparently had no influence on the strength of the respective promoters.

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This paper presents several analogs of nucleic acids, including their structure and selected physico-chemical properties, reported recently as being obtained from non-nucleosidic units connected via phosphorodiester bonds. These analogs are built from units that instead of sugar residues carry different diol structures functionalized either with natural nucleobases or with other ring systems of an aromatic character. Some interesting nonnucleosidic oligonucleotide analogs and their applications are described. Unlocked (UNA) and glycerol nucleic acids (GNA) are also described.