Structural snapshots of Escherichia coli Histidinol phosphate phosphatase along the reaction pathway

From National Research Council Canada

DOIResolve DOI: https://doi.org/10.1074/jbc.M604916200
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Name affiliation
  1. National Research Council Canada. NRC Biotechnology Research Institute
FormatText
TypeArticle
Journal titleThe Journal of Biological Chemistry
ISSN0021-9258
1083-351X
Volume281
Issue49
Pages37930–37941
Subjectbinding sites; biosynthesis; crystal structure; DNA; enzymes; Escherichia coli; pharmaceutical; phosphatase; RNA
Abstract
HisB from Escherichia coli is a bifunctional enzyme catalyzing the sixth and eighth steps of l-histidine biosynthesis. The N-terminal domain (HisB-N) possesses histidinol phosphate phosphatase activity, and its crystal structure shows a single domain with fold similarity to the haloacid dehalogenase (HAD) enzyme family. HisB-N forms dimers in the crystal and in solution. The structure shows the presence of a structural Zn(2+) ion stabilizing the conformation of an extended loop. Two metal binding sites were also identified in the active site. Their presence was further confirmed by isothermal titration calorimetry. HisB-N is active in the presence of Mg(2+), Mn(2+), Co(2+), or Zn(2+), but Ca(2+) has an inhibitory effect. We have determined structures of several intermediate states corresponding to snapshots along the reaction pathway, including that of the phosphoaspartate intermediate. A catalytic mechanism, different from that described for other HAD enzymes, is proposed requiring the presence of the second metal ion not found in the active sites of previously characterized HAD enzymes, to complete the second half-reaction. The proposed mechanism is reminiscent of two-Mg(2+) ion catalysis utilized by DNA and RNA polymerases and many nucleases. The structure also provides an explanation for the inhibitory effect of Ca(2+)
Publication date
PublisherAmerican Society for Biochemistry and Molecular Biology
LanguageEnglish
Peer reviewedYes
NRC numberNRC-BRI-47538
NPARC number3538747
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Record created2009-03-01
Record modified2020-02-19
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