Publications

• Crystal structure of monofunctional histidinol phosphate phosphatase from Thermus thermophilus HB8.

  Omi R., Goto M., Miyahara I., Manzoku M., Ebihara A., Hirotsu K.

  Monofunctional histidinol phosphate phosphatase from Thermus thermophilus HB8, which catalyzes the dephosphorylation of l-histidinol phosphate, belongs to the PHP family, together with the PHP domain of bacterial DNA polymerase III and family X DNA polymerase. We have determined the structures of ... >> More

  Monofunctional histidinol phosphate phosphatase from Thermus thermophilus HB8, which catalyzes the dephosphorylation of l-histidinol phosphate, belongs to the PHP family, together with the PHP domain of bacterial DNA polymerase III and family X DNA polymerase. We have determined the structures of the complex with a sulfate ion, the complex with a phosphate ion, and the unliganded form at 1.6, 2.1, and 1.8 A resolution, respectively. The enzyme exists as a tetramer, and the subunit consists of a distorted (betaalpha)7 barrel with one linker and one C-terminal tail. Three metal sites located on the C-terminal side of the barrel are occupied by Fe1, Fe2, and Zn ions, respectively, forming a trinuclear metal center liganded by seven histidines, one aspartate, one glutamate, and one hydroxide with two Fe ions bridged by the hydroxide. In the complexes, the sulfate or phosphate ion is coordinated to three metal ions, resulting in octahedral, trigonal bipyramidal, and tetrahedral geometries around the Fe1, Fe2, and Zn ions, respectively. The ligand residues are derived from the four motifs that characterize the PHP family and from two motifs conserved in histidinol phosphate phosphatases. The (betaalpha)7 barrel and the metal cluster are closely related in nature and architecture to the (betaalpha)8 barrel and the mononuclear or dinuclear metal center in the amidohydrolase superfamily, respectively. The coordination behavior of the phosphate ion toward the metal center supports the mechanism in which the bridging hydroxide makes a direct attack on the substrate phosphate tridentately bound to the two Fe ions and Zn ion to hydrolyze the phosphoester bond. << Less

  Biochemistry 46:12618-12627(2007) [PubMed] [EuropePMC]

• The missing link in plant histidine biosynthesis: Arabidopsis myoinositol monophosphatase-like2 encodes a functional histidinol-phosphate phosphatase.

  Petersen L.N., Marineo S., Mandala S., Davids F., Sewell B.T., Ingle R.A.

  Histidine (His) plays a critical role in plant growth and development, both as one of the standard amino acids in proteins, and as a metal-binding ligand. While genes encoding seven of the eight enzymes in the pathway of His biosynthesis have been characterized from a number of plant species, the ... >> More

  Histidine (His) plays a critical role in plant growth and development, both as one of the standard amino acids in proteins, and as a metal-binding ligand. While genes encoding seven of the eight enzymes in the pathway of His biosynthesis have been characterized from a number of plant species, the identity of the enzyme catalyzing the dephosphorylation of histidinol-phosphate to histidinol has remained elusive. Recently, members of a novel family of histidinol-phosphate phosphatase proteins, displaying significant sequence similarity to known myoinositol monophosphatases (IMPs) have been identified from several Actinobacteria. Here we demonstrate that a member of the IMP family from Arabidopsis (Arabidopsis thaliana), myoinositol monophosphatase-like2 (IMPL2; encoded by At4g39120), has histidinol-phosphate phosphatase activity. Heterologous expression of IMPL2, but not the related IMPL1 protein, was sufficient to rescue the His auxotrophy of a Streptomyces coelicolor hisN mutant. Homozygous null impl2 Arabidopsis mutants displayed embryonic lethality, which could be rescued by supplying plants heterozygous for null impl2 alleles with His. In common with the previously characterized HISN genes from Arabidopsis, IMPL2 was expressed in all plant tissues and throughout development, and an IMPL2:green fluorescent protein fusion protein was targeted to the plastid, where His biosynthesis occurs in plants. Our data demonstrate that IMPL2 is the HISN7 gene product, and suggest a lack of genetic redundancy at this metabolic step in Arabidopsis, which is characteristic of the His biosynthetic pathway. << Less

  Plant Physiol. 152:1186-1196(2010) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• Identification and structural characterization of a histidinol phosphate phosphatase from <i>Mycobacterium tuberculosis</i>.

  Jha B., Kumar D., Sharma A., Dwivedy A., Singh R., Biswal B.K.

  The absence of a histidine biosynthesis pathway in humans, coupled with histidine essentiality for survival of the important human pathogen <i>Mycobacterium tuberculosis</i> (<i>Mtb</i>), underscores the importance of the bacterial enzymes of this pathway as major antituberculosis drug targets. Ho ... >> More

  The absence of a histidine biosynthesis pathway in humans, coupled with histidine essentiality for survival of the important human pathogen <i>Mycobacterium tuberculosis</i> (<i>Mtb</i>), underscores the importance of the bacterial enzymes of this pathway as major antituberculosis drug targets. However, the identity of the mycobacterial enzyme that functions as the histidinol phosphate phosphatase (HolPase) of this pathway remains to be established. Here, we demonstrate that the enzyme encoded by the <i>Rv3137</i> gene, belonging to the inositol monophosphatase (IMPase) family, functions as the <i>Mtb</i> HolPase and specifically dephosphorylates histidinol phosphate. The crystal structure of Rv3137 in apo form enabled us to dissect its distinct structural features. Furthermore, the holo-complex structure revealed that a unique cocatalytic multizinc-assisted mode of substrate binding and catalysis is the hallmark of <i>Mtb</i> HolPase. Interestingly, the enzyme-substrate complex structure unveiled that although monomers possess individual catalytic sites they share a common product-exit channel at the dimer interface. Furthermore, target-based screening against HolPase identified several small-molecule inhibitors of this enzyme. Taken together, our study unravels the missing enzyme link in the <i>Mtb</i> histidine biosynthesis pathway, augments our current mechanistic understanding of histidine production in <i>Mtb</i>, and has helped identify potential inhibitors of this bacterial pathway. << Less

  J Biol Chem 293:10102-10118(2018) [PubMed] [EuropePMC]

• Structural snapshots of Escherichia coli histidinol phosphate phosphatase along the reaction pathway.

  Rangarajan E.S., Proteau A., Wagner J., Hung M.N., Matte A., Cygler M.

  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 dehalogena ... >> More

  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+). << Less

  J. Biol. Chem. 281:37930-37941(2006) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.