Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.5.1.4 (deaminase)
 5,113 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

APOBEC3 proteins are DNA cytosine deaminases that restrict the replication of human immunodeficiency virus deficient in the counterdefense protein Vif. Here, we address the capacity of APOBEC3F to restrict via deaminase-dependent and -independent mechanisms by monitoring spreading infections in diverse T cell lines. Our data indicate that only a deaminase-proficient protein is capable of long-term restriction of Vif-deficient HIV in T cells, analogous to prior reports for APOBEC3G. This indicates that the principal mechanism of APOBEC3F restriction is deaminase-dependent.
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PMID:Catalytic activity of APOBEC3F is required for efficient restriction of Vif-deficient human immunodeficiency virus. 2450 66

APOBEC3F and APOBEC3G cytidine deaminases potently inhibit human immunodeficiency virus type 1 (HIV-1) replication by enzymatically inserting G-to-A mutations in viral DNA and/or impairing viral reverse transcription independently of their deaminase activity. Through experimental and mathematical investigation, here we quantitatively demonstrate that 99.3% of the antiviral effect of APOBEC3G is dependent on its deaminase activity, whereas 30.2% of the antiviral effect of APOBEC3F is attributed to deaminase-independent ability. This is the first report quantitatively elucidating how APOBEC3F and APOBEC3G differ in their anti-HIV-1 modes.
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PMID:Quantification of deaminase activity-dependent and -independent restriction of HIV-1 replication mediated by APOBEC3F and APOBEC3G through experimental-mathematical investigation. 2462 35

APOBEC3s (A3s) are single-stranded DNA cytosine deaminases that provide innate immune defences against retroviruses and mobile elements. A3s are specific to eutherian mammals because no direct homologs exist at the syntenic genomic locus in metatherian (marsupial) or prototherian (monotreme) mammals. However, the A3s in these species have the likely evolutionary precursors, the antibody gene deaminase AID and the RNA/DNA editing enzyme APOBEC1 (A1). Here, we used cell culture-based assays to determine whether opossum A1 restricts the infectivity of retroviruses including human immunodeficiency virus type 1 (HIV-1) and the mobility of LTR/non-LTR retrotransposons. Opossum A1 partially inhibited HIV-1, as well as simian immunodeficiency virus (SIV), murine leukemia virus (MLV), and the retrotransposon MusD. The mechanism of inhibition required catalytic activity, except for human LINE1 (L1) restriction, which was deamination-independent. These results indicate that opossum A1 functions as an innate barrier to infection by retroviruses such as HIV-1, and controls LTR/non-LTR retrotransposition in marsupials.
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PMID:Opossum APOBEC1 is a DNA mutator with retrovirus and retroelement restriction activity. 2842 55

APOBEC3F (A3F), an apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like 3 (APOBEC3) family protein, catalyzes cytosine-to-uracil conversion in single-stranded (ss) DNA. A3F acts as an inhibitor of retrovirus replication and exhibits antiviral activity against viral infectivity factor (Vif)-deficient human immunodeficiency virus 1 (HIV-1). Previous studies have mostly been focused on the interaction between A3F and Vif, and the studies on A3F's deamination properties are limited. Here, we report comprehensive characterization of the deaminase activity and ssDNA binding of the C-terminal domain (CTD) of A3F. It was shown that the deaminase activity of A3F-CTD is affected by the nucleic acid residues adjacent to the target sequence, TC, and that TTCA/G are the most preferred sequences. A3F-CTD deaminates the target sequence in longer ssDNAs most efficiently. Mutation analysis identified the amino acid residues that are responsible for the deaminase activity and ssDNA binding in the loops surrounding the catalytic center. The functions of these residues were rationally interpreted on the basis of the co-crystal structure of A3A-ssDNA and the known roles of the equivalent amino acid residues found in other A3s. Furthermore, we demonstrated that the deaminase activity of A3F-CTD could be regulated through phosphorylation of a putative site, S216. Finally, A3F-CTD was found to be active in a wide pH range (5.5 to 9.5) with similar activity. Interestingly, the A3F-CTD N214H mutant exhibited a dramatic increase in activity at pH 5.5.
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PMID:Influence of the DNA sequence/length and pH on deaminase activity, as well as the roles of the amino acid residues around the catalytic center of APOBEC3F. 2882 55

APOBEC3G (A3G) is a human enzyme that inhibits human immunodeficiency virus type 1 (HIV-1) infectivity, in the absence of the viral infectivity factor Vif, through deoxycytidine deamination and a deamination-independent mechanism. A3G converts from a fast to a slow binding state through oligomerization, which suggests that large A3G oligomers could block HIV-1 reverse transcriptase-mediated DNA synthesis, thereby inhibiting HIV-1 replication. However, it is unclear how the small number of A3G molecules found in the virus could form large oligomers. Here we measure the single-stranded DNA binding and oligomerization kinetics of wild-type and oligomerization-deficient A3G, and find that A3G first transiently binds DNA as a monomer. Subsequently, A3G forms N-terminal domain-mediated dimers, whose dissociation from DNA is reduced and their deaminase activity inhibited. Overall, our results suggest that the A3G molecules packaged in the virion first deaminate viral DNA as monomers before dimerizing to form multiple enzymatically deficient roadblocks that may inhibit reverse transcription.APOBEC3G inhibits HIV-1 viral replication via catalytic and non-catalytic processes. Here the authors show that APOBEC3G binds single-stranded DNA as an active deaminase monomer, subsequently forming catalytic-inactive dimers that block reverse transcriptase-mediated DNA synthesis.
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PMID:Dimerization regulates both deaminase-dependent and deaminase-independent HIV-1 restriction by APOBEC3G. 2892 3

APOBEC3s (A3s) are potent restriction factors of human immunodeficiency virus type 1/simian immunodeficiency viruses (HIV-1/SIV), and can repress cross-species transmissions of lentiviruses. HIV-1 originated from a zoonotic infection of SIV of chimpanzee (SIVcpz) to humans. However, the impact of human A3s on the replication of SIVcpz remains unclear. By using novel SIVcpz reporter viruses, we identified that human APOBEC3B (A3B) and APOBEC3H (A3H) haplotype II strongly reduced the infectivity of SIVcpz, because both of them are resistant to SIVcpz Vifs. We further demonstrated that human A3H inhibited SIVcpz by deaminase dependent as well independent mechanisms. In addition, other stably expressed human A3H haplotypes and splice variants showed strong antiviral activity against SIVcpz. Moreover, most SIV and HIV lineage Vif proteins could degrade chimpanzee A3H, but no Vifs from SIVcpz and SIV of gorilla (SIVgor) lineages antagonized human A3H haplotype II. Expression of human A3H hapII in human T cells efficiently blocked the spreading replication of SIVcpz. The spreading replication of SIVcpz was also restricted by stable A3H in human PBMCs. Thus, we speculate that stably expressed human A3H protects humans against the cross-species transmission of SIVcpz and that SIVcpz spillover to humans may have started in individuals that harbor haplotypes of unstable A3H proteins.
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PMID:Stably expressed APOBEC3H forms a barrier for cross-species transmission of simian immunodeficiency virus of chimpanzee to humans. 2926 82


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