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Structural Studies of Medicago truncatula Histidinol Phosphate Phosphatase from Inositol Monophosphatase Superfamily Reveal Details of Penultimate Step of Histidine Biosynthesis in Plants

Structural Studies of Medicago truncatula Histidinol Phosphate Phosphatase from Inositol Monophosphatase Superfamily Reveal Details of Penultimate Step of Histidine Biosynthesis in PlantsThe penultimate enzyme in the histidine biosynthetic pathway catalyzes dephosphorylation of L-histidinol 1-phosphate (HOLP) into L-histidinol. The recently discovered in Arabidopsis thaliana plant-type histidinol phosphate phosphatase (HPP) shares no homology with the two other HPP superfamilies known previously in prokaryotes and resembles myo-inositol monophosphatases (IMPases). In this work, identification of an HPP enzyme from a model legume, Medicago truncatula (MtHPP) was based on the highest sequence identity to A. thaliana enzyme. Biochemical assays confirmed that MtHPP was able to cleave inorganic phosphate from HOLP but not from D-myo-inositol-1-phosphate, the main substrate of IMPases. Dimers of MtHPP, determined by size exclusion chromatography, in the presence of CO2 or formaldehyde form mutual, methylene-bridged cross-links between Lys158 and Cys245 residues. Four high resolution crystal structures, namely complexes with HOLP (substrate), L-histidinol (product), and (PO4)3- (by-product) as well as the structure showing the cross-linking between two MtHPP molecules, provide detailed structural information on the enzyme. Based on the crystal structures, the enzymatic reaction mechanism of IMPases is accustomed to fit the data for MtHPP. The enzymatic reaction, which requires (Mg)2+ cations, is catalyzed mainly by amino acid residues from the N-terminal domain. The C-terminal domain, sharing little identity with IMPases, is responsible for the substrate specificity (i.e. allows the enzyme to distinguish between HOLP and D-myo- inositol-1-phosphate). Structural features, mainly the presence of a conserved Asp246, allow MtHPP to bind HOLP specifically.

J Biol Chem. 2016 May 6;291(19):9960-73.
doi: 10.1074/jbc.M115.708727.
Epub 2016 Mar 18.

 

Journal of Biological Chemistry.

© 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  Ruszkowski M, Dauter Z.

Another SBC Highlight:

The Vaccinia Virus H3 Envelope Protein, a Major Target of Neutralizing Antibodies, Exhibits a Glycosyltransferase Fold and Binds UDP-Glucose
The Vaccinia Virus H3 Envelope Protein, a Major Target of Neutralizing Antibodies, Exhibits a Glycosyltransferase Fold and Binds UDP-Glucose

 

The highly conserved H3 poxvirus protein is a major target of the human antibody response against poxviruses and is likely a key contributor to protection against infection. Here, we present the crystal structure of H3 from vaccinia virus at a 1.9-A resolution.

 

J Virol. 2016 Apr 29;90(10):5020-30.
doi: 10.1128/JVI.02933-15.
Print 2016 May 15.

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19-ID Pilatus Detector

SBC is pleased to announce the introduction of a Pilatus 3 X 6M detector into the User Program at beamline 19-ID.
Data collected by our users has been of outstanding quality.

 

 

 

19-BM Rebotic sample mounter available

A robot is now available for use at beamline 19-BM. The sample dewar accommodates ten Unipuck magazines; pins must be 18mm in length and use either SSRL or ALS bases. Experienced users may now request remote access to 19-BM when applying for beamtime.

 

 

 

ALSO: Please Be Aware...!

 

APS requests the Experimental Safety Approval Form (ESAF) be submitted at least seven days prior to your scheduled beamtime.

 

Failure to submit your ESAF in advance may result in delaying the beginning of your experiment.

 

Rapid Access Beamtime Available:

SBC Beamtime Request System

The on-line SBC Beamtime Request System allows users to view available beamtime on 19-ID and 19-BM, and to submit a request for rapid beamtime allocation.

Beamtime is available to the research community via a peer reviewed proposal system; it is supported by the U.S. Department of Energy, Office of Biological and Environmental Research.

Current Beamline Statistics:

APS PDB Depositions from BioSync
SBC Sector 19 2014 2015 2016 TOTAL
ID BM ID BM ID BM
PDB Depositions 263 36 228 25 57 12 4760

APS Publications Database:

Publications Total
SBC-CAT Publication List: 19-ID 1411
SBC-CAT Publication List: 19-BM 519
SBC-CAT Publication List: ALL
APS Publications Database

MCSG / APCF Announcements:

 

Beginning August 01, 2015 the Midwest Center for Structural Genomics (MCSG) will start accepting applications for access to the MCSG User Resource.

 

MCSG's structure determination platform is well established, and combines technologies, robotics and expertise for gene cloning, protein production, and crystallization, as well as biochemical and biophysical characterization.

 

For further information, please contact Andrzej Joachimiak.

 

Future Meetings:

 

Protein Society: 30th Anniversary Symposium

July 16-19, 2016

Hyatt Regency Baltimore; Baltimore MD

 

Diffraction Methods in Structural Biology; Gordon Research Conference

July 17-22, 2016

Bates College; Lewiston ME

 

American Crystallographic Association, 2016

July 22-26, 2016

Downtown Sheraton Hotel; Denver CO

 

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