Publisher Summary This chapter discusses the studies relating to the chemical nature of alkylation, from the products of nucleoside alkylation to in vivo effects of alkylating agents that are oncogenic. The reactions of simple methylating agents with nucleosides, nucleotides, and polynucleotides have also been discussed in the chapter. More recent studies of the mechanism of alkylation by nitroso compounds and ethylating agents have shown that both qualitatively and quantitatively the site of alkylation is a function of both the type of reagent used and the conformation and milieu of the nucleic acid. However, translation of this body of knowledge to an understanding of the biological mechanism of alkylation-induced mutagenesis and carcinogenesis is difficult. Further studies of mutation in picornaviruses or their RNAs would be fruitful since these viral RNAs are also messenger RNAs and are directly translated, whereas in vivo studies, definitive information is still lacking as to whether alkylation of DNA, RNA, or perhaps protein, is the biologically important event.

The chemical effects of nucleic acid alkylation and their relation to mutagenesis and carcinogenesis.

Sites of action of two ribosomal RNA methylases responsible for resistance to aminoglycosides.

The nucleotide sequence has been determined for the first 53 bases of brome mosaic virus RNA4, the monocistronic messenger for brome mosaic virus coat protein. The sequence includes the binding site for wheat embryo ribosomes. The 5′-terminal base is a modified guanosine attached to the penultimate base through a 5′ p-p-p 5′ link. The initiating AUG codon is only 10 nucleotides from the 5′-terminus. The 13 triplets following the AUG codon correspond to the known sequence of brome mosaic virus coat protein.

Nucleotide sequence of a viral RNA fragment that binds to eukaryotic ribosomes

Site of action of a ribosomal RNA methylase conferring resistance to thiostrepton.

Precise deletion of the intervening sequence of a yeast tRNATyr ochre suppressor gene (SUP6) significantly reduced its suppressor activity relative to that of the unaltered gene. This is probably the result of the absence of the pseudouridine modification, normally present at the middle anticodon position of mature suppressor tRNA, in tRNA synthesized in vivo from the deleted gene.

Z Oashi

Papers

Isolation and characterization of 2-methyladenosine from Escherichia coli tRNA Glu 2 , tRNA Asp 1 , tRNA His 1 and tRNA Arg .