Cloned (Comment) | Organism |
---|---|
gene scd1, recombinant expression of isozyme SCD1 in Saccharomyces cerevisiae monounsaturated fatty acid auxotroph L8-14C, which allows growth in media lacking unsaturated fatty acids. Optimization of enzyme expression method | Mus musculus |
gene scd3, recombinant expression of wild-type and mutant isozymes SCD3 in Saccharomyces cerevisiae monounsaturated fatty acid auxotroph L8-14C, wild-type exxpression allows growth in media lacking unsaturated fatty acids | Mus musculus |
Crystallization (Comment) | Organism |
---|---|
purified DELTA223 N-terminally truncated recombinant isozyme SCD1 bound to stearoyl-CoA and two ions of Zn2+ instead of Fe2+, X-ray diffraction structure determination and analysis at 2.6 A resolution, single-wavelength anomalous dispersion | Mus musculus |
Protein Variants | Comment | Organism |
---|---|---|
I112A/E113L | site-directed mutagenesis, the mutation is able to convert isozyme SCD3 from exclusively a 16:0 desaturase into a predominantly 18:0 desaturase | Mus musculus |
V119A/D281Q/P282S E113L | site-directed mutagenesis, the mutation of the residues which are located away from the end of the substrate tunnel, causes no change in the reaction specificity of isozyme SCD3 | Mus musculus |
Localization | Comment | Organism | GeneOntology No. | Textmining |
---|---|---|---|---|
endoplasmic reticulum membrane | an integral membrane enzyme | Mus musculus | 5789 | - |
endoplasmic reticulum membrane | isozyme SCD1 has four transmembrane helices (TM1-TM4) arranged in a cone-like shape with TM4 sandwiched between TM1 and TM2. Residues in the membrane-spanning region are largely hydrophobic, with the notable exception of a conserved arginine (Arg249) located on TM4 in the center of the cone | Mus musculus | 5789 | - |
Metals/Ions | Comment | Organism | Structure |
---|---|---|---|
Fe2+ | a di-iron center in cofactor cytochrome b5 | Mus musculus | |
Zn2+ | incorporation of zinc instead of iron into the protein is likely an artifact of protein overexpression, and zinc remains the predominant metal species even when the growth media and purification solutions are supplemented with iron. Coordination of both zinc ions is consistent with octahedral geometry with one missing ligand. The nine histidines are highly conserved, and eight of them belong to three histidine-containing motifs (two HXXHH motifs and one HX4H motif in SCD1) that are characteristic of integral membrane desaturases | Mus musculus |
Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
---|---|---|---|---|---|---|
additional information | Mus musculus | enzyme SCD1 catalyzes the formation of a cis-double bond between the 9th and 10th carbons of stearoyl- or palmitoyl-CoA. The reaction requires molecular oxygen, which is activated by a diiron center, and cytochrome b5, which regenerates the di-iron center | ? | - |
? | |
palmitoyl-CoA + 2 ferrocytochrome b5 + O2 + 2 H+ | Mus musculus | - |
palmitoleoyl-CoA + 2 ferricytochrome b5 + 2 H2O | - |
? | |
stearoyl-CoA + 2 ferrocytochrome b5 + O2 + 2 H+ | Mus musculus | - |
oleoyl-CoA + 2 ferricytochrome b5 + 2 H2O | - |
? |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Mus musculus | P13516 | - |
- |
Mus musculus | Q99PL7 | - |
- |
Purification (Comment) | Organism |
---|---|
recombinant isozyme SCD1 from Saccharomyces cerevisiae monounsaturated fatty acid auxotroph L8-14C, incorporation of zinc instead of iron into the protein is likely an artifact of protein overexpression, and zinc remains the predominant metal species even when the growth media and purification solutions are supplemented with iron | Mus musculus |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
additional information | enzyme SCD1 catalyzes the formation of a cis-double bond between the 9th and 10th carbons of stearoyl- or palmitoyl-CoA. The reaction requires molecular oxygen, which is activated by a diiron center, and cytochrome b5, which regenerates the di-iron center | Mus musculus | ? | - |
? | |
additional information | wild-type isozyme SCD3 is an exclusive 16:0 desaturase, while SCD3 enzyme mutant I112A/E113L is also active with stearoyl-CoA | Mus musculus | ? | - |
? | |
palmitoyl-CoA + 2 ferrocytochrome b5 + O2 + 2 H+ | - |
Mus musculus | palmitoleoyl-CoA + 2 ferricytochrome b5 + 2 H2O | - |
? | |
stearoyl-CoA + 2 ferrocytochrome b5 + O2 + 2 H+ | - |
Mus musculus | oleoyl-CoA + 2 ferricytochrome b5 + 2 H2O | - |
? |
Subunits | Comment | Organism |
---|---|---|
More | isozyme SCD1 has four transmembrane helices (TM1-TM4) arranged in a cone-like shape with TM4 sandwiched between TM1 and TM2, the N- and C-termini are on the cytosolic side of the membrane. On the cytosolic side, TM2 and TM4 protrude three helical turns out of the membrane and provide some of the coordinating residues for the dimetal active site. The cytosolic domain comprises 93 residues between TM2 and TM3 (C1) and the 90-residue C-terminus (C2). The C1 and C2 domains contain six and five alpha-helices, respectively. Three of the alpha-helices (AH1 on C1 and AH7 and AH9 on C2) are amphipathic and likely provide interactions between the cytosolic domain and the lipid bilayer. Structure analysis and modelling, overview. Structural role of Arg249. Structure of the SCD1 cytoplasmic domain, model | Mus musculus |
Synonyms | Comment | Organism |
---|---|---|
SCD1 | - |
Mus musculus |
SCD3 | - |
Mus musculus |
stearoyl-CoA desaturase | - |
Mus musculus |
Cofactor | Comment | Organism | Structure |
---|---|---|---|
cytochrome b5 | regenerates the di-iron center | Mus musculus |
General Information | Comment | Organism |
---|---|---|
evolution | isozymes SCD1 and SCD3 share 89% primary sequence identity, but they yield remarkably different total fatty acid profiles in the recombinant yeast host cells, likely reflecting differences in their preferences for reaction with 16:0 and 18:0 substrates | Mus musculus |
additional information | in SCD3, Ile112, Glu113, Ser292 and Met293 line the distal end of the substrate binding channel, Val119 is near the position of double bond formation, while Asp281 and Pro282 are on the cytoplasmic surface opposite to the CoA binding site | Mus musculus |
additional information | the structure of isozyme SCD1 shows a fold comprising four transmembrane helices capped by a cytosolic domain, and a plausible pathway for lateral substrate access and product egress. The acyl chain of the bound stearoyl-CoA is enclosed in a tunnel buried in the cytosolic domain, and the geometry of the tunnel and configuration of the bound acyl chain provide a structural basis for the regioselectivity and stereospecificity of the desaturation reaction. The dimetal center is coordinated by a unique configuration of nine conserved histidine residues that implies a potentially distinct metal center and mechanism for oxygen activation, isozyme SCD1 structure analysis and modelling, overview. In SCD1, Ala108, Leu109, Ala288 and Val289 line the distal end of the substrate binding channel, Ala115 is near the position of double bond formation, while Gln277 and Ser278 are on the cytoplasmic surface opposite to the CoA binding site. Structural role of Arg249 | Mus musculus |
physiological function | stearoyl-CoA desaturase (SCD) introduces the first double bond into saturated fatty acyl-CoAs. Since the monounsaturated products of SCD are key precursors of membrane phospholipids, cholesterol esters, and triglycerides, SCD is pivotal in fatty acid metabolism | Mus musculus |