Journal: Nature chemical biology

Article Title: Diabetes reversal by inhibition of the low molecular weight tyrosine phosphatase

doi: 10.1038/nchembio.2344

Figure Lengend Snippet: (a) Surface representation of human LMPTP-A showing phosphate (P) non-covalently bound in the active-site. Residues are colored according to magnitude of shift in the HSQC 15 N- 1 H spectrum upon Compd. 18 titration (red>orange>green). Gray residues had negligible shifts or could not be assigned. (b) Crystal structure of bovine LMPTP W49Y/N50E bound to orthovanadate and Compd. 18 (cyan and blue sticks; Q=quinoline; Pip=piperidine; BN=benzonitrile; L=linker), with selected side-chains (yellow=carbon; red=oxygen; blue=nitrogen; pink=vanadium) and H-bonds/ionic interactions (dashed green/gray lines) shown. (c) Inhibition of phosphatase activity of LMPTP-A/mutants by Compd. 18 using 0.4 mM OMFP substrate. Mean±SD % activity is shown. Data is representative of 3 independent experiments. (d) Compd. 18 modeled into the crystal structure of phosphate-bound human LMPTP, based on an overlay with the bovine ternary complex crystal structure (RMSD=0.33 Å). Selected residues are colored by NMR shift as in (a) . Dashed red line depicts predicted clash between apical oxygen (“A”) of phosphate and Q. (e–f) Structural rationale for SAR data, with atoms at 66% of their true radii. (e) “Side” view of pocket, rotated ~90° about a horizontal axis. The molecular surface has been sliced through the active-site to reveal the tight fit of Q in the pocket. Atoms with a formal charge (±) are labeled. BN is highly polarized, as indicated (δ±); arrows labeled “S” indicate solvent exposure of ring substitutions. (f) “Top” view looking down at the active-site pocket filled by Q. Arrow above atom N1 locates the “saddle-point” at pocket exit.

Article Snippet: cDNAs encoding mouse and human LMPTP-A (protein reference sequences NP_067305.2 and NP_004291.1) and bovine LMPTP (protein reference sequence NP_776403.1) were codon-optimized for E. coli , synthesized, and cloned into the pGEX-4T vector using BamHI/EcoRI by Genscript.

Techniques: Titration, Inhibition, Activity Assay, Labeling, Solvent