title: Crystal structure of product-bound complex of UDP-N-acetyl-d-mannosamine dehydrogenase from Pyrococcus horikoshii OT3.
abstract: UDP-N-acetyl-d-mannosamine dehydrogenase (UDP-d-ManNAcDH) belongs to UDP-glucose/GDP-mannose dehydrogenase family and catalyzes Uridine-diphospho-N-acetyl-d-mannosamine (UDP-d-ManNAc) to Uridine-diphospho-N-acetyl-d-mannosaminuronic acid (UDP-d-ManNAcA) through twofold oxidation of NAD(+). In order to reveal the structural features of the Pyrococcus horikoshii UDP-d-ManNAcADH, we have determined the crystal structure of the product-bound enzyme by X-ray diffraction to resolution of 1.55Å. The protomer folds into three distinct domains; nucleotide binding domain (NBD), substrate binding domain (SBD) and oligomerization domain (OD, involved in the dimerization). The clear electron density of the UDP-d-ManNAcA is observed and the residues binding are identified for the first time. Crystal structures reveal a tight dimeric polymer chains with product-bound in all the structures. The catalytic residues Cys258 and Lys204 are conserved. The Cys258 acts as catalytic nucleophile and Lys204 as acid/base catalyst. The product is directly interacts with residues Arg211, Thr249, Arg244, Gly255, Arg289, Lys319 and Arg398. In addition, the structural parameters responsible for thermostability and oligomerization of the three dimensional structure are analyzed.
authors.affiliation: Department of Studies in Microbiology, University of Mysore, Mysore 570 006, India. Electronic address: sagarikakj@gmail.com.
authors.forename: K J
authors.initials: KJ
authors.lastname: Pampa
authors.affiliation: Department of Studies in Physics, University of Mysore, Mysore 570 006, India.
authors.forename: N K
authors.initials: NK
authors.lastname: Lokanath
authors.affiliation: Department of General Surgery, JSS Medical College and Hospital, JSS University, Mysore 570 015, India.
authors.forename: T U
authors.initials: TU
authors.lastname: Girish
authors.affiliation: Advanced Protein Crystallography Research Group, RIKEN SPring-8 Center, Harima Institute, Hyogo 679-5148, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Kunishima
authors.affiliation: Department of Studies in Microbiology, University of Mysore, Mysore 570 006, India.
authors.forename: V R
authors.initials: VR
authors.lastname: Rai
mesh_terms: D001665:Binding Sites; D002237:Carbohydrate Dehydrogenases / Q000737:chemistry* / Q000378:metabolism; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D011487:Protein Conformation; D043902:Pyrococcus horikoshii / Q000201:enzymology*
chemical_list: D002237:Carbohydrate Dehydrogenases; C023228:UDP-N-acetylmannosamine dehydrogenase
keywords: Oligomerization domain; Thermostability; UDP-d-ManNAcA; UDP-d-ManNAcADH