Template activity

At this point it is necessary to make a distinction between the meanings of template and primer. The word template refers to the structural sequence of the polymerized monomeric units of a macromolecule that provides the pattern for the synthesis of another macromolecule with a complementary or characteristic sequence. The word primer, on the other hand, refers to a polymeric molecule that contains the growing point for the further addition of monomeric units. Glycogen is an example of a primer to which glucose units are added however, glycogen has no template activity. 

Under certain circumstances DNA has both primer and template activities. For example, the addition of mononucleotides is to the 3 end of the growing DNA primer. This presents a problem with regard to how the other strand is synthesized. Biochemists have looked hard but unsuccessfully for an enzyme that can add deoxyribonucleotides onto the 5 end of DNA primers. Such a primer should contain a triphosphate on the hydroxyl group of the 5 end. Although a very active 5 -exonuclease, actually part of DNA polymerase I, has made the search for such an activated 5 end extremely difficult, investigators conclude that a polymerase able to use such a primer probably does not exist. On the contrary, good evidence suggests that the synthesis of both strands is by the known DNA poly-merases. 

X-Ray crystal structures of four 6-strand-templated active site inhibitors of thrombin, including compounds MOL-126 and MOL-174 (Section 12.10.15.2 ), have been determined and refined at about 2.1 A resolution to crystallographic R-values between 0.148 and 0.164 <1999JME1376>. 

Davie, J.R. and Candido, E.P. (1978) Acetylated histone H4 is preferentially associated with template-active chromatin. Proceedings of the National Academy of Sciences of the United States of America,... 

The correlation between definite photoproducts and biological action of ultraviolet light discussed in this section is confined to a particular action of ultraviolet light, namely an inactivating or lethal action. Microorganisms are killed, DNA synthesis in cells is inhibited, transforming DNA is inactivated, template activity of DNA is reduced, and phage and viruses are inactivated because the pyrimidine dimer which is formed in-strand is apparently able to provide a block which hinders DNA or RNA replication. 

Template Activity. As used in this chapter, template activity is the same as primer activity (q.v.). 

Depending on the template activity , the ratio Pa/pb is different. If the template is selected properly, distances between groups are such that tensions in a ladder structure are as small as possible (for instance for 6 member ring), and bonds are flexible (e.g, ether bonds). In this case, the ratio Pa/pb is high. In the opposite case, if the substrate molecules are stiff and distances between reacting groups are too large (or too small), we can expect that template makes polymerization more difficult (pa/pb < D or eventually can make it impossible pa = 0. A competition between these two reactions leads to the dif-... 

Alternatively, poor efficiencies of inhibitor mRNAs may be due to their Incorporation into rlbonucleoproteln particles (RNPs) such as found in sea urchin embryos (21). Newly made mRNA in the embryos is found in RNPs and they apparently have "weak" template activities while in these particles. The presence of newly synthesized tomato mRNA in similar particles might explain the apparently low translational efficiencies noted herein. The use of chaotropic buffers in the preparation of tomato leaf mRNA (11) would not differentiate between free or polysome-bound mRNAs and those complexed in RNPs. If an RNP or similar particle is involved, then its role must be a temporal one since a second wound does not repeat the phenomenon (Fig. 4). 

Several antibiotics are also cytotoxic and combine with DNA. blocking its template activity in directing the synthesis of messenger RNA. 

Phase I and II clinical trials indicated that acronycine reduced pain of the spine in some patients with multiple myeloma [280,282,283]. Acronycine has been reported to cause leukopoenia and to have CNS-depressant activity [284], Biochemically, acronycine inhibits incorporation of extracellular nucleosides into the RNA and DNA of leukaemia L-5178Y cell culture. There is, however, no evidence of interaction between acronycine and DNA or inhibition of template activity of DNA. This alkaloid does not inhibit nucleic acid synthesis in the cell, but rather inhibits the accumulation of extracellular uridine or thymidine, as nucleotides, in the intracellular precursor pool [285, 286], Acronycine, acting primarily on membranous organelles [287], seems to interfere with the structure, function and/or turnover of cell membrane components, thereby changing the fluidity of the plasma membrane [288]. 

Other examples for the use of this template activated method include the formation of hexakis-adducts [15,16] with, for example, dendrimers featuring a fully buried fullerene core [8,17,18],... 

Abscisic acid is a negative regulator in that it primarily antagonizes the action of cytokinins, auxins, and in particular, gibberellins. Abscisic acid decreased the activity of polymerase in radishes (52), peas (53), maize coleoptiles (54), and pear embryos (55). More detailed studies are needed before the question of ABA-induced "modification" of RNA polymerase (54) or "alterations" in the number of sites for template activity (56) can be answered. In barley aleurone cells, ABA-induced suppression of GA-induced <-amylase formation was presumed to involve the continuous synthesis of a short-lived RNA (57). 

Leffler, S., P. Pulkrabek, D. Grunberger, and I.B. Weinstein. Template activity of calf thymus DNA modified by a dihydrodiol epoxide derivative of benzo(a)pyrene. Biochemistry 16 3133-3136, 1977. 

Brawerman G, Gold L, Eisenstadt J, A ribonucleic acid fraction from rat liver with template activity, Proc. Natl. Acad. Sci. USA, 50 630-638, 1963. 

Effect of Tilorone on the Template Activity of Nucleic Acids. . . 139... 

The interaction of tilorone hydrochloride to DNA encouraged us to study the template activity of the complexes in DNA- and RNA- polymerase systems from E. coli. Both the activities were found to be inhibited by tilorone the DNA polymerase reaction being more sensitive towards tilorone. The inhibition of the RNA-polymerase reaction by tilorone was dependent on the A-T content of DNA-template. The template activity of poly (dA-dT) in the RNA polymerase reaction is distinctly more sensitive towards tilorone than that of DNA particularyly, at low drug concentrations the poly (dA-dT)-catalyzed reaction was three times more sensitive than the DNA-catalyzed activity of RNA polymerase reaction60. ... 

The effect of tilorone and congeners (Fig. 6) on the DNA-dependent RNA polymerase reaction is shown in Fig. 7). The template activity of native DNA is strongly inhibited by DEAP-fluoranthene, showing an 80% inhibition at a concentration 8 x 10 6 M. Other derivatives, at this concentration do not show any significant inhibition of the template activity of DNA. However, at higher concentrations one observes a dose-dependent inhibition of DNA-template activity by DEAE-fluorenone, DMAA-dibenzothiophene, DEAA-fluorene and DMAA-dibenzofuran. The monosubstituted derivative, MEAA-fluorene does not show any activity, even at higher concentrations. 

Chandra et al.4> have shown that the antiviral activity of distamycin and their action on the template activity of DNA are dependent on the number of pyrrole rings in the molecule. The distamycin derivative with 5 pyrrole rings (distamycin/5) has 10 times higher antiviral activity than distamycin A (with 3 pyrrole rings), and is a better inhibitor of the RNA-polymerase reaction. It was therefore interesting to study the correlation between the antiviral activity and the inhibition of RNA-polymerase reaction by compounds I, II, III and IV. The effect of an equimolar concentration (8 x 10-5 M) of the distamycin derivatives on the template activity of DNA is shown in Table 9. The derivatives were added into the reaction mixture as described above. The highest inhibition was obtained with the natural antibiotic (distamycin A) followed by compounds IV, II and III, respectively. The cyclopentylpropionyl derivative, having no... 

The effect of distamycin/A and its amino acid derivatives (distamycin/Gly and distamycin/Ala) on the template activity of calf thymus DNA in RNA-... 

The endogenic reaction is catalyzed by the viral RNA (70s), template for the reverse transcriptase. It is not clear whether the higher activity of distamycin/Gly in this system, compared to the template activity of DNA in bacterial system (Table 10), is due to its higher affinity for viral RNA. This was investigated by using various exogenous templates in the DNA-polymerase reaction of FL-virions. 

A variety of inhibitors bind to DNA and thereby eliminate its template activity. Notable among these are the intercalating agents, which slip in between base pairs (e.g., the acridines, phenanthridium derivatives), and the an-thracyclines (daunorubicin, doxorubicin, and plicamycin). 

---