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Mouse N-acetyltransferase type 2, the homologue of human N-acetyltransferase type 1.

Kawamura A, Westwood I, Wakefield L, Long H, Zhang N, Walters K, Redfield C, Sim E - Biochem. Pharmacol. (2008)

Bottom Line: In addition, we have tested the effects of inhibitors on mouse Nat2, including compounds which are endogenous and exogenous steroids.We show that tamoxifen, genistein and diethylstilbestrol inhibit mouse Nat2.We propose that a conformational change in the structure is required in order for ligands to bind to the active site of the protein.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, United Kingdom.

ABSTRACT
There is increasing evidence that human arylamine N-acetyltransferase type 1 (NAT1, EC 2.3.1.5), although first identified as a homologue of a drug-metabolising enzyme, appears to be a marker in human oestrogen receptor positive breast cancer. Mouse Nat2 is the mouse equivalent of human NAT1. The development of mouse models of breast cancer is important, and it is essential to explore the biological role of mouse Nat2. We have therefore produced mouse Nat2 as a recombinant protein and have investigated its substrate specificity profile in comparison with human NAT1. In addition, we have tested the effects of inhibitors on mouse Nat2, including compounds which are endogenous and exogenous steroids. We show that tamoxifen, genistein and diethylstilbestrol inhibit mouse Nat2. The steroid analogue, bisphenol A, also inhibits mouse Nat2 enzymic activity and is shown by NMR spectroscopy, through shifts in proton peaks, to bind close to the active site. A three-dimensional structure for human NAT1 has recently been released, and we have used this crystal structure to generate a model of the mouse Nat2 structure. We propose that a conformational change in the structure is required in order for ligands to bind to the active site of the protein.

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Related in: MedlinePlus

The downfield region of the 1D 1H NMR spectra obtained in a titration of mouse Nat2 with bisphenol A. Spectra collected with 0–8 equivalents of bisphenol A are shown. Peaks are observed to shift and to broaden as increasing amounts of bisphenol A are added; this broadening may indicate chemical exchange within the bound protein. Some precipitation of protein was observed with 8 equivalents of bisphenol A, which is likely to account for the decrease in peak intensity in this spectrum.
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fig8: The downfield region of the 1D 1H NMR spectra obtained in a titration of mouse Nat2 with bisphenol A. Spectra collected with 0–8 equivalents of bisphenol A are shown. Peaks are observed to shift and to broaden as increasing amounts of bisphenol A are added; this broadening may indicate chemical exchange within the bound protein. Some precipitation of protein was observed with 8 equivalents of bisphenol A, which is likely to account for the decrease in peak intensity in this spectrum.


Mouse N-acetyltransferase type 2, the homologue of human N-acetyltransferase type 1.

Kawamura A, Westwood I, Wakefield L, Long H, Zhang N, Walters K, Redfield C, Sim E - Biochem. Pharmacol. (2008)

The downfield region of the 1D 1H NMR spectra obtained in a titration of mouse Nat2 with bisphenol A. Spectra collected with 0–8 equivalents of bisphenol A are shown. Peaks are observed to shift and to broaden as increasing amounts of bisphenol A are added; this broadening may indicate chemical exchange within the bound protein. Some precipitation of protein was observed with 8 equivalents of bisphenol A, which is likely to account for the decrease in peak intensity in this spectrum.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2279149&req=5

fig8: The downfield region of the 1D 1H NMR spectra obtained in a titration of mouse Nat2 with bisphenol A. Spectra collected with 0–8 equivalents of bisphenol A are shown. Peaks are observed to shift and to broaden as increasing amounts of bisphenol A are added; this broadening may indicate chemical exchange within the bound protein. Some precipitation of protein was observed with 8 equivalents of bisphenol A, which is likely to account for the decrease in peak intensity in this spectrum.
Bottom Line: In addition, we have tested the effects of inhibitors on mouse Nat2, including compounds which are endogenous and exogenous steroids.We show that tamoxifen, genistein and diethylstilbestrol inhibit mouse Nat2.We propose that a conformational change in the structure is required in order for ligands to bind to the active site of the protein.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, United Kingdom.

ABSTRACT
There is increasing evidence that human arylamine N-acetyltransferase type 1 (NAT1, EC 2.3.1.5), although first identified as a homologue of a drug-metabolising enzyme, appears to be a marker in human oestrogen receptor positive breast cancer. Mouse Nat2 is the mouse equivalent of human NAT1. The development of mouse models of breast cancer is important, and it is essential to explore the biological role of mouse Nat2. We have therefore produced mouse Nat2 as a recombinant protein and have investigated its substrate specificity profile in comparison with human NAT1. In addition, we have tested the effects of inhibitors on mouse Nat2, including compounds which are endogenous and exogenous steroids. We show that tamoxifen, genistein and diethylstilbestrol inhibit mouse Nat2. The steroid analogue, bisphenol A, also inhibits mouse Nat2 enzymic activity and is shown by NMR spectroscopy, through shifts in proton peaks, to bind close to the active site. A three-dimensional structure for human NAT1 has recently been released, and we have used this crystal structure to generate a model of the mouse Nat2 structure. We propose that a conformational change in the structure is required in order for ligands to bind to the active site of the protein.

Show MeSH
Related in: MedlinePlus