title: Identification and characterization of a novel kaempferol sulfotransferase from Arabidopsis thaliana.
abstract: In plants, flavonoids have been shown to be subjected to conjugation modifications such as glycosylation, methylation, and sulfation. Among these modifications, sulfation is known as an important pathway in the regulation of the levels of endogenous compounds such as steroids. Although a large variety of flavonoid sulfates also exist in plants, the detailed biochemical characterization of Arabidopsis thaliana sulfotransferases (AtSULTs) remains to be fully clarified. We report here that uncharacterized AtSULT202E1 (AGI code: At2g03770), a SULT202E subfamily member, shows the sulfating activity toward flavonoids. The general characteristics of the enzyme were studied on the optimum temperature and pH, the effect of divalent cations, and the thermal stability with kaempferol as substrate. A comparative analysis of the sulfation of flavonoids by AtSULT202E1, AtSULT202B1 and AtSULT202A1 revealed that three AtSULTs have differential substrate specificities. Surprisingly, 3-hydroxyflavone was sulfated only by AtSULT202A1 while 7-hydroxyflavone was highly sulfated by AtSULT202E1 and AtSULT202B1. These results indicate that flavonols might be sulfated in a position specific manner. In conclusion, our studies indicate that a novel AtSULT202E1 has the sulfating activity toward flavonoids together with AtSULT202B1 and AtSULT202A1. The existence of three flavonoid sulfotransferases in A. thaliana suggests that sulfation of flavonoids have an important role in regulation of their functions.
authors.affiliation: Interdisciplinary Graduate School of Agriculture and Engineering, University of Miyazaki, Miyazaki, Miyazaki 889-2192, Japan.
authors.forename: Takuyu
authors.initials: T
authors.lastname: Hashiguchi
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Sakakibara
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Hara
authors.forename: Takehiko
authors.initials: T
authors.lastname: Shimohira
authors.forename: Katsuhisa
authors.initials: K
authors.lastname: Kurogi
authors.forename: Ryo
authors.initials: R
authors.lastname: Akashi
authors.forename: Ming-Cheh
authors.initials: MC
authors.lastname: Liu
authors.forename: Masahito
authors.initials: M
authors.lastname: Suiko
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D015239:Arylsulfotransferase / Q000145:classification / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D005419:Flavonoids / Q000737:chemistry / Q000378:metabolism; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D044949:Kaempferols / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D008969:Molecular Sequence Data; D015394:Molecular Structure; D005810:Multigene Family; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D013431:Sulfates / Q000378:metabolism; D015238:Sulfotransferases / Q000145:classification / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D005419:Flavonoids; D007527:Isoenzymes; D044949:Kaempferols; D013431:Sulfates; C006552:kaempferol; C521808:ST1 protein, Arabidopsis; C583046:SULT202B1 protein, Arabidopsis; C583045:SULT202E1 protein, Arabidopsis; D015238:Sulfotransferases; D015239:Arylsulfotransferase; C429845:7-hydroxyflavone