1q74

The Crystal Structure of 1D-myo-inositol 2-acetamido-2-deoxy-alpha-D-glucopyranoside Deacetylase (MshB)

spinqualitylabelsall models 1q74, resolution 1.70Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1q74 is a 4 chain structure with sequence from Mycobacterium tuberculosis. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: PE4, ZN Gene: Rv1170 (Mycobacterium tuberculosis) Resources: FirstGlance, OCA, RCSB, PDBsum, TOPSAN Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed Mycothiol (1-D-myo-inosityl 2-(N-acetyl-L-cysteinyl)amido-2-deoxy-alpha-D-glucopyranoside, MSH or AcCys-GlcN-inositol (Ins)) is the major reducing agent in actinomycetes, including Mycobacterium tuberculosis. The biosynthesis of MSH involves a deacetylase that removes the acetyl group from the precursor GlcNAc-Ins to yield GlcN-Ins. The deacetylase (MshB) corresponds to Rv1170 of M. tuberculosis with a molecular mass of 33,400 Da. MshB is a Zn2+ metalloprotein, and the deacetylase activity is completely dependent on the presence of a divalent metal cation. We have determined the x-ray crystallographic structure of MshB, which reveals a protein that folds in a manner resembling lactate dehydrogenase in the N-terminal domain and a C-terminal domain consisting of two beta-sheets and two alpha-helices. The zinc binding site is in the N-terminal domain occupying a position equivalent to that of the NAD+ co-factor of lactate dehydrogenase. The Zn2+ is 5 coordinate with 3 residues from MshB (His-13, Asp-16, His-147) and two water molecules. One water would be displaced upon binding of substrate (GlcNAc-Ins); the other is proposed as the nucleophilic water assisted by the general base carboxylate of Asp-15. In addition to the Zn2+ providing electrophilic assistance in the hydrolysis, His-144 imidazole could form a hydrogen bond to the oxyanion of the tetrahedral intermediate. The extensive sequence identity of MshB, the deacetylase, with mycothiol S-conjugate amidase, an amide hydrolase that mediates detoxification of mycothiol S-conjugate xenobiotics, has allowed us to construct a faithful model of the catalytic domain of mycothiol S-conjugate amidase based on the structure of MshB. The crystal structure of 1-D-myo-inosityl 2-acetamido-2-deoxy-alpha-D-glucopyranoside deacetylase (MshB) from Mycobacterium tuberculosis reveals a zinc hydrolase with a lactate dehydrogenase fold.,Maynes JT, Garen C, Cherney MM, Newton G, Arad D, Av-Gay Y, Fahey RC, James MN J Biol Chem. 2003 Nov 21;278(47):47166-70. Epub 2003 Sep 4. PMID:12958317 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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