Genetic information, transfer

Fig. 31. Effects of mispairing in genetic information transfer (Fig. 30). Top, transversion of an AT — CG via A G pair. Middle, transition AT — GC. Bottom, AT —> TA transversion. Adapted from Ref. (88).

G. L. Eichhom and L. G. Marzilli, Metal Ions in Genetic Information Transfer , Elsevier, New York, 1981. 

It is a commonly held belief that RNA preceded DNA in the early evolution of living systems. If this is the case then the first DNA polymerases must have been capable of transferring sequence information from RNA to DNA. Enzymes of this sort are called reverse transcriptases because they do the reverse of common transcriptases (see chapter 28). Reverse transcriptases no longer play the central role in genetic information transfer, but they are still found in all species and function in a number of capacities in both cellular and viral metabolism. 

Spiro, T. G., Ed. Wiley New York, 1980, Chapter 1 Roberts, J. J. In "Metal Ions in Genetic Information Transfer", Adv. Inorg. Biochem. 1981, 274. 

After proof of the functional role of DNA had been provided by Avery in 1944 [12], the race to solve the riddle of life began. Finally, in 1953 the key for understanding the mechanism of genetic information transfer was found by Watson and Crick by their ingenious concept of base pairing [13], Their work was based last but not least on Franklin s X-ray analysis [14] and the work of Wilson [15]. The eminent role of DNA, which contains all information required for the synthesis of all proteins in a living organism, has led to its-nickname, the molecule of life . 

In this paper we discuss some studies on the Interaction of aluminum with SNA that were carried out because of the apparent relationship of aluminum with Alzheimer s disease. We then consider how metal Ions are Involved In genetic Information transfer, and may Influence the aging process, and finally we discuss the use of metal Ions In probing the aging process. 

Metal Ions, Genetic Information Transfer and Aging... 

As has been indicated above, metal Ions are essential in every aspect of genetic Information transfer. Nevertheless, metal Ions can ilso cause deleterious effects In Information transfer either If they are present In the wrong kind or In the wrong concentration. Let us consider an example of each of these posslbllties first, that In which metals are present in the wrong kind. 

Metal Ions can produce a large variety of other effects on nucleic acids that could be deleterious if they occur during genetic information transfer. Metal ions can bring about the degradation of RNA (17, 18, 19), changes in the specificity of enzymes that act on DNA (20), changes in the conformation of polynucleotides and nucleic acid - protein complexes (21). 

It is also known that cellular metal ion concentrations change with age. An illustration of such age changes in human lens nuclei is given in Table I (22). We hypothesize that these changing concentrations of metal ions that are essential to genetic information transfer, yet can alter it, can affect information transfer and therefore contribute to the changes that are associated with the aging process. 

Aluminum appears to be Involved in Alzheimer s disease and concentrates in the nucleus therefore, we have looked at aluminum binding to DNA, and we find that aluminum forms crosslinks with the DNA strands. Metal ions generally produce deleterious effects in genetic information transfer when present in the wrong kind or concentration. They are, however, essential in genetic information transfer. The concentration of metal ions in various cells changes with age, and we have hypothesized that perhaps these metal ions have an Impact on genetic information transfer processes... 

US The H-bond interactions, such as NH 0=C, between DNA bases confer a structure of a double helix on the DNA. These H-bond interactions are specific (A T and C G), and hence the interaction is called base pairing. ts" Base pairing enables both DNA replication and genetic information transfer to RNA molecules that copy pieces genes) of DNA. These RNA molecules then bring about the synthesis of proteins that are encoded by the DNA genes. 

The description of the enzymic equipment of the nucleus is not solely of academic interest. If each nucleus has a specific enzyme mosaic, this pattern may play a considerable role in determining cellular differentiation. In that case, nuclei from different tissue would have an identical stock of chromosomes surrounded by different enzymic patterns, which may affect the screening of the genetic information transferred to the cytoplasm. 

Differences between histone populations are not exclusively related to the amino acid composition of the histone. Differences in metabolism or in the rate of synthesis and, consequently, in the amount of histones may be responsible for changes in the rate and type of genetic information transferred. After biosynthesis, histones can undergo four different metabolic alterations phosphorylation, acetylation, methylation, and thiolization. 

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