title: Crystal structures of SULT1A2 and SULT1A1 *3: insights into the substrate inhibition and the role of Tyr149 in SULT1A2.
abstract: The cytosolic sulfotransferases (SULTs) in vertebrates catalyze the sulfonation of endogenous thyroid/steroid hormones and catecholamine neurotransmitters, as well as a variety of xenobiotics, using 3'-phosphoadenosine 5'-phosphosulfate (PAPS) as the sulfonate donor. In this study, we determined the structures of SULT1A2 and an allozyme of SULT1A1, SULT1A1 *3, bound with 3'-phosphoadenosine 5'-phosphate (PAP), at 2.4 and 2.3A resolution, respectively. The conformational differences between the two structures revealed a plastic substrate-binding pocket with two channels and a switch-like substrate selectivity residue Phe247, providing clearly a structural basis for the substrate inhibition. In SULT1A2, Tyr149 extends approximately 2.1A further to the inside of the substrate-binding pocket, compared with the corresponding His149 residue in SULT1A1 *3. Site-directed mutagenesis study showed that, compared with the wild-type SULT1A2, mutant Tyr149Phe SULT1A2 exhibited a 40 times higher K(m) and two times lower V(max) with p-nitrophenol as substrate. These latter data imply a significant role of Tyr149 in the catalytic mechanism of SULT1A2.
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, People's Republic of China.
authors.forename: Jinghua
authors.initials: J
authors.lastname: Lu
authors.forename: Haitao
authors.initials: H
authors.lastname: Li
authors.forename: Jiping
authors.initials: J
authors.lastname: Zhang
authors.forename: Mei
authors.initials: M
authors.lastname: Li
authors.forename: Ming-Yih
authors.initials: MY
authors.lastname: Liu
authors.forename: Xiaomin
authors.initials: X
authors.lastname: An
authors.forename: Ming-Cheh
authors.initials: MC
authors.lastname: Liu
authors.forename: Wenrui
authors.initials: W
authors.lastname: Chang
mesh_terms: D015239:Arylsulfotransferase / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000235:genetics; D002384:Catalysis; D018360:Crystallography, X-Ray; D006801:Humans; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D009596:Nitrophenols / Q000737:chemistry; D010724:Phosphoadenosine Phosphosulfate / Q000737:chemistry; D011487:Protein Conformation; D013379:Substrate Specificity; D014443:Tyrosine / Q000737:chemistry / Q000235:genetics
chemical_list: D009596:Nitrophenols; D014443:Tyrosine; D010724:Phosphoadenosine Phosphosulfate; D015239:Arylsulfotransferase; C117544:SULT1A1 protein, human; C513290:SULT1A2 protein, human; C024836:4-nitrophenol