Preliminary X-ray analysis of a new crystal form of the Escherichia coli KDO8P synthase

Radaev, Sergei ; Dastidar, Parthasarathi ; Patel, Mayur ; Woodard, Ronald W. ; Gatti, Domenico L. (2000) Preliminary X-ray analysis of a new crystal form of the Escherichia coli KDO8P synthase Acta Crystallographica Section D, 56 (4). pp. 516-519. ISSN 0907-4449

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3-Deoxy-d-manno-octulosonate 8-phosphate (KDO8P) synthase catalyzes the biosynthesis of an essential component of the lipopolysaccharide of all Gram-negative bacteria. The structure and mechanism of KDO8P synthase are being actively studied as this enzyme represents an important target for antibiotic therapy. The structure of the Escherichia coli KDO8P synthase in cubic crystals (space group I23) has recently been determined and the enzyme shown to be a tetramer of identical subunits. However, this information is challenged by biochemical studies, which suggest that the enzyme behaves in solution as a homotrimer. Here, the preparation and preliminary X-ray analysis of monoclinic crystals of KDO8P synthase are reported. The crystals belong to space group P21, with unit-cell parameters a≃ 50, b≃ 140, c≃ 74 Å, β≃ 105°. The structure of KDO8P synthase in the monoclinic crystal form was determined by molecular replacement, using as a search model one of the subunits of the enzyme in the cubic crystals. A tetramer of KDO8P synthase with 222 local symmetry is also present in the asymmetric unit of the P21 crystals, with a solvent content of 43%. The observation that the same quaternary structure of KDO8P synthase is observed in two different crystal forms belonging to distinct crystal systems (monoclinic and cubic) suggests that a tetramer is the native form of the enzyme.

Item Type:Article
Source:Copyright of this article belongs to International Union of Crystallography.
Keywords:Antibiotics; KDO8P Synthase
ID Code:112530
Deposited On:19 Apr 2018 10:37
Last Modified:19 Apr 2018 10:37

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