Results: 3

1.
Fig. 2.

Fig. 2. From: Crystal structure of FAS thioesterase domain with polyunsaturated fatty acyl adduct and inhibition by dihomo-?-linolenic acid.

Inhibition by DGLA. (A) Inhibition of palmitate biosynthesis in 3T3-L1 preadipocyte cells. DMSO, which was used to dissolve the DGLA, served as control. Incorporation of C13-acetate into [13C]-palmitate was measured by gas chromatography/mass spectrometry (GC/MS) (see SI Methods). Values are means ± SEM, n = 5 replicates. (B) Effects of ethyl ester of DGLA (0, 10, and 20 μM) on the cell viability of cancer cell lines and noncancerous cells (HMEC). Cell viability was determined as described in SI Methods. Values are the means ± SD (bars) of at least four experiments made in triplicate (*P < 0.005).

Wei Zhang, et al. Proc Natl Acad Sci U S A. 2011 September 20;108(38):15757-15762.
2.
Fig. 3.

Fig. 3. From: Crystal structure of FAS thioesterase domain with polyunsaturated fatty acyl adduct and inhibition by dihomo-?-linolenic acid.

Comparisons of the active site region of the structures of complexes of TE with MGLP and Orlistat. Crystallographically unobserved or disordered segments are represented by dashed lines. (A) Ribbon representation of the active site with MGLP covalently attached to Ser 2308. MGLP and Ser 2308 are represented by ball-and-stick model with carbons in green and the phosphonate group in orange. Even-numbered carbon atoms of the γ-linolenyl acyl chain are labeled as in Fig 1C. (B) Similar representation as in (A) with covalently bound Orlistat (orange ball-stick model) [Protein Data Bank (PDB) code 2PX6-A] in one independent conformation (27). (C) Similar to (B) with the hydrolyzed Orlistat (blue model) in the other independent conformation (PDB code 2PX6-B) (27). In both panels B and C, the three groups of Orlistat are labeled as palmitic core with even-numbered carbons, peptidyl moiety (formylamino-4-methyl-pentanoic acid) linked to the C5 of the core and hexanoyl tail linked to the C2 carbon of the core. Moreover, the ordered α-helix (helix flap) in (A) is represented by a dashed line to signify a disordered segment. (D and E) Superpositions of structures depicted in A and B and A and C, respectively.

Wei Zhang, et al. Proc Natl Acad Sci U S A. 2011 September 20;108(38):15757-15762.
3.
Fig. 1.

Fig. 1. From: Crystal structure of FAS thioesterase domain with polyunsaturated fatty acyl adduct and inhibition by dihomo-?-linolenic acid.

Structure of the hFAS TE domain with a covalently bound methyl γ-linolenylphosphonate (MGLP). (A) Ribbon backbone trace of the structure. The σA-weighted 1.45 Å FoFc electron density (yellow) of MGLP (green ball-and-stick model) is contoured at 0.8σ above the mean density. The α-helix (the helix flap or gatekeeper helix) colored in red and adjacent to the MGLP density is composed of residues 2342–2355. The TE domain structure is made up of two subdomains—a much larger subdomain with the α/β hydrolase fold (Right) and a smaller subdomain with an all α-helices motif (α5–α8) (Left) (26). Because the helix flap, which is missing in the first TE domain structure, precedes α5-helix, it is also identified as α5′ to preserve the original secondary structure identification. Renumbering all the helices in the TE–MGLP structure makes α5′ equivalent to α5, α5–α6, etc. (B) Schematic representation of the interactions (< 4  distance) between MGLP and TE amino acid residue using LIGPLOT diagram. Residues Ser2308, Asp2338, and His2481 (red labels) form the catalytic triad in the active sites. Residues involved in hydrophobic contacts with MGLP are colored in black and demarcated by spoked red arc, and those involved in hydrogen bonding to MGLP are colored in green along with the values of the distances. The distance of the covalent bond between the phosphonate phosphorus and Ser2308 side chain O is 1.81 Å. Most of the residues interacting with the γ-linolenyl acyl chain reside in three helices: Val 2344, Tyr 2347, Arg 2352, and Tyr 2351 in α5′ or helix flap; Glu 2366, Ala 2367, and Phe 2370 in α5; Tyr 2424, Leu 2427, Arg 2428, and Glu 2431 in α8. (C) Transparent surface rendition of the active site (same view as in panel A) with embedded backbone trace of the TE structure. MGLP in a ball-stick model is covalently linked to Ser2308 sidechain O atom, which is represented as a van der Waals “dot” surface. Even-numbered carbon atoms of the γ-linolenyl acyl chain are labeled. Site 1 label marks the opening of the pocket of Site 1.

Wei Zhang, et al. Proc Natl Acad Sci U S A. 2011 September 20;108(38):15757-15762.

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