EPA Science Inventory

A NOVEL S-ADENOSYL-L-METHIONINE: ARSENIC (III) METHYLTRANSFERASE FROM RAT LIVER CYTOSOL

Citation:

Lin, S., Q. Shi, B. Nix, M. Beck, M. Styblo, K. M. HerbinDavis, L. Hall, J. B. Simeonsson, AND D J. Thomas. A NOVEL S-ADENOSYL-L-METHIONINE: ARSENIC (III) METHYLTRANSFERASE FROM RAT LIVER CYTOSOL. JOURNAL OF BIOLOGICAL CHEMISTRY 277(13):10795 - 10803, (2002).

Description:

A Novel S-Adenosyl-L-methionine: Arsenic(III) Methyltransferase from Rat Liver Cytosol
Shan Lin, Qing Shi, F. Brent Nix, Miroslav Styblo, Melinda A. Beck, Karen M. Herbin-Davis, Larry L. Hall, Josef B. Simeonsson, and David J. Thomas
S-adenosyl-L-methionine (AdoMet): arsenic(III) methyltransferase, purified from liver cytosol of adult male Fischer 344 rats, catalyzes transfer of a methyl group from AdoMet to trivalent arsenicals producing methylated and dimethylated arsenicals. The kinetics of production of methylated arsenicals in reaction mixtures containing enzyme, AdoMet, dithiothreitol (DTT), glutathione (GSH), and arsenite are consistent with a scheme in which monomethylated arsenical produced from arsenite is the substrate for a second methylation reaction that yields dimethylated arsenical. The mRNA for this protein predicts a 369 amino acid-residue protein (molecular mass 41056 D) that contains common methyltransferase sequence motifs. Its sequence is similar to Cyt19, a putative methyltransferase, expressed in human and mouse tissues. Reverse transcription-polymerase chain reaction detects S-adenosyl-L-methionine: arsenic(III) methyltransferase mRNA in rat tissues and in HepG2 cells, a human cell line that methylates arsenite and methylarsonous acid. S-Adenosyl-L-methionine: arsenic(III) methyltransferase mRNA is not detected in UROtsa cells, an immortalized human urothelial cell line that does not methylate arsenite. Because methylation of arsenic is a critical feature of its metabolism, characterization of this enzyme will improve our understanding of this metalloid's metabolism and its actions as a toxin and a carcinogen.

Record Details:

Record Type: DOCUMENT (JOURNAL/PEER REVIEWED JOURNAL)
Start Date: 01/14/2002
Completion Date: 01/14/2002
Record Last Revised: 12/22/2005
Record Created: 09/26/2003
Record Released: 09/26/2003
Record ID: 65576

Organization:

U.S. ENVIRONMENTAL PROTECTION AGENCY

OFFICE OF RESEARCH AND DEVELOPMENT

NATIONAL HEALTH AND ENVIRONMENTAL EFFECTS RESEARCH LAB

EXPERIMENTAL TOXICOLOGY DIVISION

PHARMACOKINETICS BRANCH