Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

N-acetylation plays an important role in the metabolism of arylamine drugs and carcinogens and is catalyzed by cytosolic N-acetyltransferase (NAT). Gypenosides are the major components of Gynostemma pentaphyllum Makino which had been used as a natural folk medicine in the Chinese populations. Gypenosides were selected for examining the inhibition on the N-acetylation of 2-aminofluorene (AF), DNA-AF adduct formation and NAT gene expression in the human cervix epithelioid carcinoma cell line (HeLa). Various concentrations of gypenosides were individually added to the culture medium of human cervix epithelioid carcinoma cells (HeLa). The N-acetylation of AF was determined by high performance liquid chromatography (HPLC) assaying for the amounts of acetylated 2-aminofluorene (AAF) and nonacetylated 2-aminofluorene (AF). The N-acetylation of AF in the human HeLa cancer cells was suppressed by gypenosides in a dose-dependent manner. The data also demonstrated that gene expression (NAT1 mRNA) of NAT in human cervix epithelioid carcinoma cells (HeLa) was inhibited and decreased by gypenosides. After the incubation of HeLa cells with 30 or 60 microM AF and with or without 350 microg/ml gypenosides cotreatment, DNA was isolated and hydrolyzed to nucleotides, adducted nucleotides were extracted into butanol and analyzed DNA-AF adducts by HPLC. The data demonstrated that gypenosides decrease the levels of DNA-AF adduct formation in HeLa cells.
Res Commun Mol Pathol Pharmacol 2004
PMID:Gypenosides inhibited N-acetylation of 2-aminofluorene, N-acetyltransferase gene expression and DNA adduct formation in human cervix epithelioid carcinoma cells (HeLa). 1756 15

Tamoxifen was used to determine the effects of N-acetyltransferase(NAT) activity and 2-aminofluorene (2-AF)-DNA adduct formation in human breast cancer cells. Breast cancer cells were categorized into two groups based on the status of estrogen receptor, ER (+) and ER (-). 2-AF-DNA adduct formations in breast cancer cells are 2.58 +/- 0.39 pmol adduct/mg DNA for ER (+) and 2.74 +/- 0.46 pmol adduct/mg DNA for ER (-), respectively. Co-treatment with 1 microM tamoxifen inhibited DNA-adduct formations up to 65% in ER (+) and 61% in ER (-), respectively. The inhibition of Tamoxifen on DNA adduct formation between ER (+) and ER (-) cell was not significantly different. The results of the N-acetyltransferase activity in human breast cancer cells were inhibited by tamoxifen in a dose dependent manner. Tamoxifen inhibited 50.0% and 42.8% of Km in ER (+) and ER (-), 58.2% and 35.6% of Vmax, respectively. Based on the kinetic study of N-acetyltransferase activity, tamoxifen plays a non-competitive role in the acetylation reaction. This study demonstrates that tamoxifen inhibited not only NAT activity but also DNA-adduct formation in human breast cancer cells, regardless of the status of estrogen receptor. These findings could provide a clue that tamoxifen has chemoprevention effects in breast cancer.
Res Commun Mol Pathol Pharmacol 2004
PMID:Effects of tamoxifen on DNA adduct formation and arylamines N-acetyltransferase activity in human breast cancer cells. 1756 19

To realize the full scientific and clinical potential of human embryonic stem cell (hESC)-cardiomyocytes, strategies to overcome the high degree of heterogeneity of differentiated populations are required. Here we demonstrate the utility of two transgenic approaches in enrichment of cardiomyocytes derived from HUES-7 cells: (i) negative selection of proliferating cells with the herpes simplex virus thymidine kinase/ganciclovir (HSVtk/GCV) suicide gene system; and (ii) positive selection of cardiomyocytes expressing a bicistronic reporter [green fluorescent protein (GFP)-internal ribosome entry site (IRES)-puromycin-N-acetyltransferase (PAC)] from the human alphamyosin heavy chain promoter. Parental and transgenic HUES-7 cells were similar with regard to morphology, pluripotency marker expression, differentiation, and cardiomyocyte electrophysiology. Whereas immunostaining of dissociated cardiomyocyte preparations expressing HSVtk or PAC contained <7% cardiomyocytes, parallel cultures treated with GCV or puromycin, respectively, contained 33.4 +/- 2.1% or 91.5 +/- 4.3% cardiomyocytes corresponding to an enrichment factor of 6.7- or 14.5-fold. Drug-selected cardiomyocytes responded to chronotropic stimulation and displayed cardiac-specific action potentials, demonstrating that functionality was retained. Both transgenic strategies will be generically applicable and should readily translate to the enrichment of many other differentiated lineages derived from hESCs.
Mol Ther 2007 Nov
PMID:Transgenic enrichment of cardiomyocytes from human embryonic stem cells. 1794 47

Arylamine N-acetyltransferase (NAT) enzymes are widespread in nature. They serve to acetylate xenobiotics and/or endogenous substrates using acetyl coenzyme A (CoA) as a cofactor. Conservation of the architecture of the NAT enzyme family from mammals to bacteria has been demonstrated by a series of prokaryotic NAT structures, together with the recently reported structure of human NAT1. We report here the cloning, purification, kinetic characterisation and crystallographic structure determination of NAT from Mycobacterium marinum, a close relative of the pathogenic Mycobacterium tuberculosis. We have also determined the structure of M. marinum NAT in complex with CoA, shedding the first light on cofactor recognition in prokaryotic NATs. Surprisingly, the principal CoA recognition site in M. marinum NAT is located some 30 A from the site of CoA recognition in the recently deposited structure of human NAT2 bound to CoA. The structure explains the Ping-Pong Bi-Bi reaction mechanism of NAT enzymes and suggests mechanisms by which the acetylated enzyme intermediate may be protected. Recognition of CoA in a much wider groove in prokaryotic NATs suggests that this subfamily may accommodate larger substrates than is the case for human NATs and may assist in the identification of potential endogenous substrates. It also suggests the cofactor-binding site as a unique subsite to target in drug design directed against NAT in mycobacteria.
J Mol Biol 2008 Jan 04
PMID:Divergence of cofactor recognition across evolution: coenzyme A binding in a prokaryotic arylamine N-acetyltransferase. 1800 84

Previous work on Dilantin- and hydrocortisone-induced cleft palate and cleft lip with or without cleft palate using congenics for the N-acetyltransferase loci (Nat1 and Nat2 are closely linked) and recombinant inbred lines implicated the Nat1,2 region in susceptibility to teratogen-induced orofacial clefting. Since Nat1 does not differ between the two strains, Nat2 appeared to be responsible. We have now tested this conclusion using transgenics and knockouts. Transgenics for human NAT1 (equivalent to mouse Nat2) and knockouts for Nat2 were tested for susceptibility to Dilantin, hydrocortisone, and 6-aminonicotinamide-induced orofacial clefting. We found that Nat2 greatly influences teratogen-induced orofacial clefting on the A/J background but not on the C57BL/6J background. The magnitude and direction of the effects depended on which teratogen was used. The Nat2 knockout did not make C57BL/6J susceptible or A/J (already with very low activity) more susceptible but significantly decreased sporadic clefting in the A/J strain. We conclude that only the A/J strain, with several loci affecting orofacial clefting, is influenced by Nat2.
Mol Reprod Dev 2008 Jun
PMID:Confirmation of the role of N-acetyltransferase 2 in teratogen-induced cleft palate using transgenics and knockouts. 1816 94

Promoter clearance and transcriptional processivity in eukaryotic cells are fundamentally regulated by the phosphorylation of the carboxy-terminal domain of RNA polymerase II (RNAPII). One of the kinases that essentially performs this function is P-TEFb (positive transcription elongation factor b), which is composed of cyclin-dependent kinase 9 (CDK9) associated with members of the cyclin T family. Here we show that cellular GCN5 and P/CAF, members of the GCN5-related N-acetyltransferase family of histone acetyltransferases, regulate CDK9 function by specifically acetylating the catalytic core of the enzyme and, in particular, a lysine that is essential for ATP coordination and the phosphotransfer reaction. Acetylation markedly reduces both the kinase function and transcriptional activity of P-TEFb. In contrast to unmodified CDK9, the acetylated fraction of the enzyme is specifically found in the insoluble nuclear matrix compartment. Acetylated CDK9 associates with the transcriptionally silent human immunodeficiency virus type 1 provirus; upon transcriptional activation, it is replaced by the unmodified form, which is involved in the elongating phase of transcription marked by Ser2-phosphorylated RNAPII. Given the conservation of the CDK9 acetylated residues in the catalytic task of virtually all CDK proteins, we anticipate that this mechanism of regulation might play a broader role in controlling the function of other members of this kinase family.
Mol Cell Biol 2008 Apr
PMID:Acetylation of conserved lysines in the catalytic core of cyclin-dependent kinase 9 inhibits kinase activity and regulates transcription. 1825 Jan 57

A specific mutation of Escherichia coli ribosomal protein S5, in which glycine is changed to aspartate at position 28 [S5(G28D)], results in cold sensitivity and defects in ribosome biogenesis and translational fidelity. In an attempt to understand the roles of S5 in these essential cellular functions, we selected extragenic suppressors and identified rimJ as a high-copy suppressor of the cold-sensitive phenotype associated with the S5(G28D) mutation. Our studies indicate that RimJ overexpression suppresses the growth defects, anomalous ribosome profiles and mRNA misreading exhibited by the S5(G28D) mutant strain. Although previously characterized as the N-acetyltransferase of S5, our data indicate that RimJ, when devoid of acetyltransferase activity, can suppress S5(G28D) defects thus indicating that the suppression activity of RimJ is not dependent on its acetyltransferase activity. Additionally, RimJ appears to associate with pre-30S subunits indicating that it acts on the ribonucleoprotein particle. These findings suggest that RimJ has evolved dual functionality; it functions in r-protein acetylation and as a ribosome assembly factor in E. coli.
Mol Microbiol 2008 Jun
PMID:Suppression of a cold-sensitive mutation in ribosomal protein S5 reveals a role for RimJ in ribosome biogenesis. 1846 25

Malaria parasites utilize a short N-terminal amino acid motif termed the Plasmodium export element (PEXEL) to export an array of proteins to the host erythrocyte during blood stage infection. Using immunoaffinity chromatography and mass spectrometry, insight into this signal-mediated trafficking mechanism was gained by discovering that the PEXEL motif is cleaved and N-acetylated. PfHRPII and PfEMP2 are two soluble proteins exported by Plasmodium falciparum that were demonstrated to undergo PEXEL cleavage and N-acetylation, thus indicating that this N-terminal processing may be general to many exported soluble proteins. It was established that PEXEL processing occurs upstream of the brefeldin A-sensitive trafficking step in the P. falciparum secretory pathway, therefore cleavage and N-acetylation of the PEXEL motif occurs in the endoplasmic reticulum (ER) of the parasite. Furthermore, it was shown that the recognition of the processed N-terminus of exported proteins within the parasitophorous vacuole may be crucial for protein transport to the host erythrocyte. It appears that the PEXEL may be defined as a novel ER peptidase cleavage site and a classical N-acetyltransferase substrate sequence.
Mol Biochem Parasitol 2008 Aug
PMID:N-terminal processing of proteins exported by malaria parasites. 1853 95

3-Nitrobenzanthrone (3-NBA) is a mutagen and suspected human carcinogen detected in diesel exhaust, airborne particulate matter, and urban soil. We investigated the tissue specific mutagenicity of 3-NBA at the lacZ locus of transgenic MutaMouse following acute single dose or 28-day repeated-dose oral administration. In the acute high dose (50 mg/kg) exposure, increased lacZ mutant frequency was observed in bone marrow and colonic epithelium, but not in liver and bladder. In the repeated-dose study, a dose-dependent increase in lacZ mutant frequency was observed in bone marrow and liver (2- and 4-fold increase above control), but not in lung or intestinal epithelium. In addition, a concentration-dependent increase in mutant frequency (8.5-fold above control) was observed for MutaMouse FE1 lung epithelial cells exposed in vitro. 1-Nitropyrene reductase, 3-NBA reductase, and acetyltransferase activities were measured in a variety of MutaMouse specimens in an effort to link metabolic activation and mutagenicity. High 3-NBA nitroreductase activities were observed in lung, liver, colon and bladder, and detectable N-acetyltransferase activities were found in all tissues except bone marrow. The relatively high 3-NBA nitroreductase activity in MutaMouse tissues, as compared with those in Salmonella TA98 and TA100, suggests that 3-NBA is readily reduced and activated in vivo. High 3-NBA nitroreductase levels in liver and colon are consistent with the elevated lacZ mutant frequency values, and previously noted inductions of hepatic DNA adducts. Despite an absence of induced lacZ mutations, the highest 3-NBA reductase activity was detected in lung. Further studies are warranted, especially following inhalation or intratracheal exposures.
Environ Mol Mutagen 2008 Oct
PMID:Tissue-specific metabolic activation and mutagenicity of 3-nitrobenzanthrone in MutaMouse. 1861 36

Arylamine N-acetyltransferase (NAT) enzymes are found in a broad range of eukaryotes and prokaryotes. There is increasing evidence that NAT enzymes could contribute to antibiotic resistance in pathogenic bacteria such as Mycobacterium tuberculosis. Nocardia farcinica is an opportunistic human pathogen that causes pulmonary infections (nocardiosis) with clinical manifestations that resemble tuberculosis. While the genomic sequence of this prokaryote has been determined, studies of N. farcinica proteins remain almost nonexistent. In particular, N. farcinica proteins putatively involved in antibiotic resistance mechanisms have not been described structurally or functionally. Here, we have characterized a new NAT enzyme (NfNAT) from N. farcinica at the structural and functional level. NfNAT is the first N. farcinica protein for which a 3D structure is reported. We showed that this novel prokaryotic isoform is structurally and functionally related to the mycobacterial NAT enzymes. In particular, NfNAT was found to display high N-acetyltransferase activity towards several known NAT substrates including the antitubercular drug isoniazid. Interestingly, isoniazid is not used for the treatment of nocardiosis and has been shown to be poorly active against several nocardial species. On the contrary, NfNAT was found to be poorly active towards sulfamethoxazole, a sulfonamide drug considered as the treatment of choice for the treatment of nocardiosis. The functional and structural data reported in this study will help to develop our understanding of the role of NAT enzymes in nocardia and mycobacteria and may help in the rational design of NAT antagonists for a range of clinical applications.
J Mol Biol 2008 Nov 14
PMID:Functional and structural characterization of the arylamine N-acetyltransferase from the opportunistic pathogen Nocardia farcinica. 1877 14


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