Mutagenesis of key residues identifies the connection subdomain of HIV‐1 reverse transcriptase as the site of inhibition by heme

Argyris, Elias G.; Vanderkooi, Jane M.; Paterson, Yvonne

doi:10.1046/j.1432-1327.2001.01944.x

Cited by 13 publications

(9 citation statements)

References 37 publications

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“…Hence, the tetrapyrrole and naphthylurea derivatives may have similar inhibition mechanisms. Notably, like KM-1 hemin derivatives also block HIV-1 RT, supposedly by stacking interactions between the porphine ring and aromatic residues in the protein (1). Similar interactions may occur with the aromatic ring systems in the carbonyl J acid compounds.…”

Section: Discussionmentioning

confidence: 95%

Carbonyl J Acid Derivatives Block Protein Priming of Hepadnaviral P Protein and DNA-Dependent DNA Synthesis Activity of Hepadnaviral Nucleocapsids

Wang

Wen

Nassal

2012

J Virol

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Current treatments for chronic hepatitis B are effective in only a fraction of patients. All approved directly antiviral agents are nucleos(t)ide analogs (NAs) that target the DNA polymerase activity of the hepatitis B virus (HBV) P protein; resistance and cross-resistance may limit their long-term applicability. P protein is an unusual reverse transcriptase that initiates reverse transcription by protein priming, by which a Tyr residue in the unique terminal protein domain acts as an acceptor of the first DNA nucleotide. Priming requires P protein binding to the ε stem-loop on the pregenomic RNA (pgRNA) template. This interaction also mediates pgRNA encapsidation and thus provides a particularly attractive target for intervention. Exploitingin vitropriming systems available for duck HBV (DHBV) but not HBV, we demonstrate that naphthylureas of the carbonyl J acid family, in particular KM-1, potently suppress protein priming by targeting P protein and interfering with the formation of P-DHBV ε initiation complexes. Quantitative evaluation revealed a significant increase in complex stability during maturation, yet even primed complexes remained sensitive to KM-1 concentrations below 10 μM. Furthermore, KM-1 inhibited the DNA-dependent DNA polymerase activity of both DHBV and HBV nucleocapsids, including from a lamivudine-resistant variant, directly demonstrating the sensitivity of human HBV to the compound. Activity against viral replication in cells was low, likely due to low intracellular availability. KM-1 is thus not yet a drug candidate, but its distinct mechanism of action suggests that it is a highly useful lead for developing improved, therapeutically applicable derivatives.

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Section: Discussionmentioning

confidence: 95%

Carbonyl J Acid Derivatives Block Protein Priming of Hepadnaviral P Protein and DNA-Dependent DNA Synthesis Activity of Hepadnaviral Nucleocapsids

Wang

Wen

Nassal

2012

J Virol

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“…It has been previously reported that hemin could also inhibit human immunodeficiency virus (HIV) RT (2) by potentially binding to residues 398 to 407 within the connection domain of HIV RT. Further mutagenesis studies showed that the tryptophan residues at positions 401 and 402 were important for hemin binding to the HIV RT (1). Future studies will be required to define the exact hemin binding site(s) in the hepadnavirus TP and RT domains.…”

Section: Discussionmentioning

confidence: 99%

Inhibition of Hepadnavirus Reverse Transcriptase-ε RNA Interaction by Porphyrin Compounds

2008

J Virol

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The hepatitis B virus (HBV) reverse transcriptase (RT) plays a multitude of fundamental roles in the viral life cycle and is the key target in the development of anti-HBV chemotherapy. We report here that the endogenous small molecule iron protoporphyrin IX (hemin) and several related porphyrin compounds potently blocked a critical RT interaction with the viral RNA packaging signal/origin of replication, called . As RTinteraction is essential for the initiation of viral reverse transcription, which is primed by RT itself (protein priming), the porphyrin compounds dramatically suppressed the protein-priming reaction. Further studies demonstrated that these compounds could target the unique N-terminal domain of the RT protein, the so-called terminal protein. Hemin and related porphyrin compounds thus represent a novel class of agents that can block HBV RT functions through a mechanism and target that are completely distinct from those of existing anti-HBV drugs.Hepatitis B virus (HBV) belongs to the family Hepadnaviridae, a group of small, hepatotropic DNA viruses that also includes related animal viruses, such as the duck HBV (DHBV) and the woodchuck hepatitis virus (31). Chronic HBV infection remains a major public health problem worldwide, with over 350 million chronic HBV carriers who are at serious risk of developing liver cirrhosis and hepatocellular carcinoma (5,7,12). At present, the immunomodulatory and antiviral cytokine alpha interferon and several nucleoside analogs represent two distinct classes of therapies for chronic HBV infections (14). Unfortunately, alpha interferon therapy induces a sustained antiviral response in only 20 to 30% of patients and is fraught with adverse reactions. In the short term, nucleoside analogs exhibit a potent inhibitory effect on HBV DNA synthesis. However, long-term treatment with nucleoside analogs is required to maintain viral suppression, which leads to the development of drug-resistant HBV variants (13,26). Therefore, the current inventory of therapeutics against HBV infections is inadequate, and novel anti-HBV therapy needs to be developed.All hepadnaviruses replicate the DNA genome through an RNA intermediate (the pregenomic RNA [pgRNA]) by reverse transcription (31, 33). The virally encoded reverse transcriptase (RT) protein carries the two essential enzymatic activities required for the conversion of pgRNA to the DNA copy, i.e., DNA polymerase activity and RNase H activity (18). In contrast to retroviral RTs, the hepadnavirus RT initiates viral DNA synthesis via a novel protein-priming mechanism, whereby the RT protein itself serves a dual role as a protein primer and as the polymerase. As an obligate template for the protein-priming action, a short (ca. 60-nucleotide) viral RNA structure termed ε, located at the 5Ј end of pgRNA, is specifically recognized by the RT protein to form a stable ribonucleoprotein (RNP) complex (28, 38). Using an internal bulge located on the ε stem-loop structure as a template and a specific tyrosine residue of the RT protein as a pr...

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“…A cationic phthalocyanine was reported to inhibit human rhinovirus type 5 (RV-5) infection [21]. Selected porphyrin derivatives inhibit specific viral targets including retroviral reverse transcriptase [22-26] and HIV-1 protease [27]. …”

Section: Discussionmentioning

confidence: 99%

Prevention of poxvirus infection by tetrapyrroles

et al. 2003

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BackgroundPrevention of poxvirus infection is a topic of great current interest. We report inhibition of vaccinia virus in cell culture by porphyrins and phthalocyanines. Most previous work on the inhibition of viruses with tetrapyrroles has involved photodynamic mechanisms. The current study, however, investigates light-independent inhibition activity.MethodsThe Western Reserve (WR) and International Health Department-J (IHD-J) strains of vaccinia virus were used. Virucidal and antiviral activities as well as the cytotoxicity of test compounds were determined.ResultsExamples of active compounds include zinc protoporphyrin, copper hematoporphyrin, meso(2,6-dihydroxyphenyl)porphyrin, the sulfonated tetra-1-naphthyl and tetra-1-anthracenylporphyrins, selected sulfonated derivatives of halogenated tetraphenyl porphyrins and the copper chelate of tetrasulfonated phthalocyanine. EC50 values for the most active compounds are as low as 0.05 µg/mL (40 nM). One of the most active compounds was the neutral meso(2,6-dihydroxyphenyl)porphyrin, indicating that the compounds do not have to be negatively charged to be active.ConclusionsPorphyrins and phthalocyanines have been found to be potent inhibitors of infection by vaccinia virus in cell culture. These tetrapyrroles were found to be active against two different virus strains, and against both enveloped and non-enveloped forms of the virus, indicating that these compounds may be broadly effective in their ability to inhibit poxvirus infection.

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Mutagenesis of key residues identifies the connection subdomain of HIV‐1 reverse transcriptase as the site of inhibition by heme

Cited by 13 publications

References 37 publications

Carbonyl J Acid Derivatives Block Protein Priming of Hepadnaviral P Protein and DNA-Dependent DNA Synthesis Activity of Hepadnaviral Nucleocapsids

Carbonyl J Acid Derivatives Block Protein Priming of Hepadnaviral P Protein and DNA-Dependent DNA Synthesis Activity of Hepadnaviral Nucleocapsids

Inhibition of Hepadnavirus Reverse Transcriptase-ε RNA Interaction by Porphyrin Compounds

Prevention of poxvirus infection by tetrapyrroles

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