Sulfating-activity and stability of cDNA-expressed allozymes of human phenol sulfotransferase, ST1A3*1 ((213)Arg) and ST1A3*2 ((213)His), both of which exist in Japanese as well as Caucasians.
We recently found single amino acid substitutions ((213)Arg/His and (223)Met/Val) in polymorphic human phenol-sulfating phenol sulfotransferase (SULT: cDNAs encoding ST1A3, P PST or HAST1/2) among Caucasians and African-Americans. In a Japanese population (n = 143), allele frequencies of (213)Arg and (213)His were 83.2 and 16. 8%, respectively, but the (223)Val allele was not found. (213)His homozygosity was reportedly associated with both very low (>7-fold) sulfating activities of p-nitrophenol (at 4 microM) and low thermostability in platelets. Sulfating-activity determinations using recombinant (213)Arg- and (213)His-forms (ST1A3*1 and ST1A3*2, respectively) did not, however, reveal appreciable deficiency in [(35)S]3'-phosphoadenosine 5'-phosphosulfate (PAPS)-dependent sulfation of p-nitrophenol (4 microM) by ST1A3*2 (7.5 vs. 10.2 nmol/min/nmol SULT for ST1A3). Kinetic parameters for p-nitrophenol for p-nitrophenol sulfation supported the slight decrease in sulfating activities at 4 microM (K(m), 0.82 vs. 1.75 microM; V(max), 13.2 vs. 13.1 nmol/min/nmol SULT, respectively, for ST1A3*1 and *2). p-Nitrophenyl sulfate-dependent 2-naphthol sulfation by ST1A3*2 was 69% of that by ST1A3*1 (p<0.05). However, ST1A3*2 was remarkably unstable at 45 and 37 degrees C as compared to ST1A3*1. The lower p-nitrophenol sulfating activity of ST1A3*2 may explain the lower platelet p-nitrophenol sulfation in ST1A3*2 homozygotes. Protein instability and ST1A3 gene regulation may be both involved in the polymorphism of p-nitrophenol sulfation in human tissues.
Ozawa
S
S
Division of Pharmacology, National Institute of Health Sciences, Setagaya-ku, Tokyo, 158-8501, Japan. sozawa@nihs.go.jp
Shimizu
M
M
Katoh
T
T
Miyajima
A
A
Ohno
Y
Y
Matsumoto
Y
Y
Fukuoka
M
M
Tang
Y M
YM
Lang
N P
NP
Kadlubar
F F
FF
D015239:Arylsulfotransferase / Q000235:genetics* / Q000378:metabolism*; D044383:Black People; D015153:Blotting, Western; D002384:Catalysis; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism*; D007564:Japan; D007700:Kinetics; D009284:Naphthols / Q000378:metabolism; D009578:Nitrobenzenes / Q000378:metabolism; D010724:Phosphoadenosine Phosphosulfate / Q000378:metabolism; D012150:Polymorphism, Restriction Fragment Length; D011994:Recombinant Proteins / Q000378:metabolism; D013696:Temperature; D013997:Time Factors; D044465:White People; D001741:Black or African American
D018076:DNA, Complementary; D007527:Isoenzymes; D009284:Naphthols; D009578:Nitrobenzenes; D011994:Recombinant Proteins; C023379:4-nitrophenyl sulfate; D010724:Phosphoadenosine Phosphosulfate; D015239:Arylsulfotransferase; C028405:2-naphthol