The human APOBEC3 proteins are a family of DNA-editing enzymes that play an important role in the innate immune response against retroviruses and retrotransposons. APOBEC3G is a member of this family that inhibits HIV-1 replication in the absence of the viral infectivity factor Vif. Inhibition of HIV replication occurs by both deamination of viral single-stranded DNA and a deamination-independe...

A discussion of nitrosative deamination of cytosine 1 is presented that argues for the formation of 6 by diazotization of 1 to cytosinediazonium ion 2 and its electrostatic complex 3, dediazoniation to 4 <--> 5, and amide-bond cleavage to 6. The reaction channels available to 6 include hydrolytic deglycation to 3-isocyanatoacrylonitrile 7, water addition to carbamic acid 9 with the possibility ...

The extent, regulation and enzymatic basis of RNA editing by cytidine deamination are incompletely understood. Here we show that transcripts of hundreds of genes undergo site-specific C>U RNA editing in macrophages during M1 polarization and in monocytes in response to hypoxia and interferons. This editing alters the amino acid sequences for scores of proteins, including many that are involved ...

APOBEC3G (A3G) is a host-expressed protein that inactivates retroviruses through the mutagenic deamination of cytosines (C) to uracils (U) in single-stranded DNA (ssDNA) replication products. A3G prefers to deaminate cytosines preceded by a cytosine (5'CC), whereas all other A3 proteins target cytosines in a 5'TC motifs. Structural and mutational studies have mapped the dinucleotide deamination...

The modified base, 5-methylcytosine, constitutes approximately 1% of human DNA, but sites containing 5-methylcytosine account for at least 30% of all germline and somatic point mutations. A genetic assay with a sensitivity of 1 in 10(7), based on reversion to neomycin resistance of a mutant pSV2-neo plasmid, was utilized to determine and compare the deamination rates of 5-methylcytosine and cyt...

Zea and Tripsacum nuclear ribosomal internal transcribed spacer (ITS) sequences were used to evaluate patterns of concerted evolution, rates of substitutions, patterns of methylation-induced deamination, and structural constraints of the ITS. ITS pseudogenes were identified by their phylogenetic position, differences in nucleotide composition, extensive deamination at ancestral methylation site...

A previous st,udy on the metabolism of amphetamine (1-phenyl-2-aminopropane), widely used as a stimulant of the central nervous system, showed that its major route of biotransformation in the rat and dog involved hydroxylation of the aromatic ring. In the rabbit, however, the compound was not hydroxylated, but was found to be transformed in another manner (2). The present report describes an en...

Activation-induced (cytidine) deaminase (AID) efficiently introduces multiple and diversified deaminations in immunoglobulin (Ig) variable and switch regions. Here, we review studies of AID, and the APOBEC family member, APOBEC3G, demonstrating that both enzymes introduce multiple deaminations by processive action on single-stranded DNA and that deaminations occur stochastically at hot- and col...

Studies are described on the metabolism and the toxicological analysis of the amphetamine-derived designer drug 2,5-dimethoxy-4-bromo-amphetamine (DOB) and its corresponding N-methyl analogue 2,5-dimethoxy-4-bromo-methamphetamine (MDOB) in rat urine using gas chromatographic/mass spectrometric techniques. The identified metabolites indicated that DOB was metabolized by O-demethylation followed ...