title: Crystal structure of chondroitin polymerase from Escherichia coli K4.
abstract: Elongation of glycosaminoglycan chains, such as heparan and chondroitin, is catalyzed by bi-functional glycosyltransferases, for which both 3-dimensional structures and reaction mechanisms remain unknown. The bacterial chondroitin polymerase K4CP catalyzes elongation of the chondroitin chain by alternatively transferring the GlcUA and GalNAc moiety from UDP-GlcUA and UDP-GalNAc to the non-reducing ends of the chondroitin chain. Here, we have determined the crystal structure of K4CP in the presence of UDP and UDP-GalNAc as well as with UDP and UDP-GlcUA. The structures consisted of two GT-A fold domains in which the two active sites were 60A apart. UDP-GalNAc and UDP-GlcUA were found at the active sites of the N-terminal and C-terminal domains, respectively. The present K4CP structures have provided the structural basis for further investigating the molecular mechanism of biosynthesis of chondroitin chain.
authors.affiliation: Laboratory of Structural Biology, Graduate School of Systems Life Sciences, Kyushu University, Fukuoka 812-8581, Japan.
authors.forename: Takuo
authors.initials: T
authors.lastname: Osawa
authors.forename: Nobuo
authors.initials: N
authors.lastname: Sugiura
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Shimada
authors.forename: Ryoko
authors.initials: R
authors.lastname: Hirooka
authors.forename: Atushi
authors.initials: A
authors.lastname: Tsuji
authors.forename: Tadayoshi
authors.initials: T
authors.lastname: Shirakawa
authors.forename: Keiichi
authors.initials: K
authors.lastname: Fukuyama
authors.forename: Makoto
authors.initials: M
authors.lastname: Kimura
authors.forename: Koji
authors.initials: K
authors.lastname: Kimata
authors.forename: Yoshimitsu
authors.initials: Y
authors.lastname: Kakuta
mesh_terms: D000116:Acetylgalactosamine / Q000737:chemistry; D000595:Amino Acid Sequence; D020134:Catalytic Domain; D003460:Crystallization; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics; D020723:Glucuronic Acid / Q000737:chemistry; D006602:Hexosyltransferases / Q000737:chemistry* / Q000235:genetics; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D014530:Uridine Diphosphate / Q000737:chemistry
chemical_list: D029968:Escherichia coli Proteins; D014530:Uridine Diphosphate; D020723:Glucuronic Acid; D006602:Hexosyltransferases; C460368:chondroitin polymerase, E coli; D000116:Acetylgalactosamine