title: Structure of Escherichia coli ribose-5-phosphate isomerase: a ubiquitous enzyme of the pentose phosphate pathway and the Calvin cycle.
abstract: Ribose-5-phosphate isomerase A (RpiA; EC 5.3.1.6) interconverts ribose-5-phosphate and ribulose-5-phosphate. This enzyme plays essential roles in carbohydrate anabolism and catabolism; it is ubiquitous and highly conserved. The structure of RpiA from Escherichia coli was solved by multiwavelength anomalous diffraction (MAD) phasing, and refined to 1.5 A resolution (R factor 22.4%, R(free) 23.7%). RpiA exhibits an alpha/beta/(alpha/beta)/beta/alpha fold, some portions of which are similar to proteins of the alcohol dehydrogenase family. The two subunits of the dimer in the asymmetric unit have different conformations, representing the opening/closing of a cleft. Active site residues were identified in the cleft using sequence conservation, as well as the structure of a complex with the inhibitor arabinose-5-phosphate at 1.25 A resolution. A mechanism for acid-base catalysis is proposed.
authors.affiliation: Structural Biology Center, Argonne National Laboratory, 9700 South Cass Avenue, Building 202, Argonne, IL 60439, USA.
authors.forename: Rong guang
authors.initials: Rg
authors.lastname: Zhang
authors.forename: C Evalena
authors.initials: CE
authors.lastname: Andersson
authors.forename: Alexei
authors.initials: A
authors.lastname: Savchenko
authors.forename: Tatiana
authors.initials: T
authors.lastname: Skarina
authors.forename: Elena
authors.initials: E
authors.lastname: Evdokimova
authors.forename: Steven
authors.initials: S
authors.lastname: Beasley
authors.forename: Cheryl H
authors.initials: CH
authors.lastname: Arrowsmith
authors.forename: Aled M
authors.initials: AM
authors.lastname: Edwards
authors.forename: Andrzej
authors.initials: A
authors.lastname: Joachimiak
authors.forename: Sherry L
authors.initials: SL
authors.lastname: Mowbray
mesh_terms: D019747:Aldose-Ketose Isomerases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D018360:Crystallography, X-Ray; D019281:Dimerization; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010427:Pentose Phosphate Pathway; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment
chemical_list: D004791:Enzyme Inhibitors; D029968:Escherichia coli Proteins; C020582:glucosamine-6-phosphate isomerase; D019747:Aldose-Ketose Isomerases; C022548:ribosephosphate isomerase