Crystal structure of d-glycero-β-d-manno-heptose-1-phosphate adenylyltransferase from Burkholderia pseudomallei.

The crystal structure of HldC from B. pseudomallei (BpHldC), the fourth enzyme of the heptose biosynthesis pathway, has been determined. BpHldC converts ATP and d-glycero--d-manno-heptose-1-phosphate into ADP-d-glycero--d-manno-heptose and pyrophosphate. The crystal structure of BpHldC belongs to the nucleotidyltransferase / phosphodiesterase superfamily sharing a common Rossmann-like / fold with a conserved T/HXGH sequence motif. The invariant catalytic key residues of BpHldC indicate that the core catalytic mechanism of BpHldC may be similar to that of other closest homologues. Intriguingly, a reorientation of the C-terminal helix seems to guide open and close states of the active site for the catalytic reaction.