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Antioxidants 2018, 7(1), 4; doi:10.3390/antiox7010004

Selenoprotein K Increases Efficiency of DHHC6 Catalyzed Protein Palmitoylation by Stabilizing the Acyl-DHHC6 Intermediate

1
Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, 651 Ilalo Street, Honolulu, HI 96813, USA
2
Department of Biochemistry, University of Vermont, 89 Beaumont Ave, Given Building Room B413, Burlington, VT 05405, USA
3
Department of Chemistry and Biochemistry, University of Delaware, 136 Brown Laboratory, Newark, DE 19716, USA
4
Department of Anatomy, Biochemistry and Physiology, John A. Burns School of Medicine, University of Hawaii, 651 Ilalo Street, Honolulu, HI 96813, USA
*
Author to whom correspondence should be addressed.
Received: 8 December 2017 / Revised: 25 December 2017 / Accepted: 27 December 2017 / Published: 29 December 2017
(This article belongs to the Special Issue Selenium and Selenoproteins for Optimal Health)
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Abstract

Selenoprotein K (SELENOK) is a selenocysteine (Sec)-containing protein localized in the endoplasmic reticulum (ER) membrane where it interacts with the DHHC6 (where single letter symbols represent Asp-His-His-Cys amino acids) enzyme to promote protein acyl transferase (PAT) reactions. PAT reactions involve the DHHC enzymatic capture of palmitate via a thioester bond to cysteine (Cys) residues that form an unstable palmitoyl-DHHC intermediate, followed by transfer of palmitate to Cys residues of target proteins. How SELENOK facilitates this reaction has not been determined. Splenocyte microsomal preparations from wild-type mice versus SELENOK knockout mice were used to establish PAT assays and showed decreased PAT activity (~50%) under conditions of SELENOK deficiency. Using recombinant, soluble versions of DHHC6 along with SELENOK containing Sec92, Cys92, or alanine (Ala92), we evaluated the stability of the acyl-DHHC6 intermediate and its capacity to transfer the palmitate residue to Cys residues on target peptides. Versions of SELENOK containing either Ala or Cys residues in place of Sec were equivalently less effective than Sec at stabilizing the acyl-DHHC6 intermediate or promoting PAT activity. These data suggest that Sec92 in SELENOK serves to stabilize the palmitoyl-DHHC6 intermediate by reducing hydrolyzation of the thioester bond until transfer of the palmitoyl group to the Cys residue on the target protein can occur. View Full-Text
Keywords: palmitic acid; palmitoyl-CoA; palmitoylation; inositol 1,4,5-triphosphate receptor; ANK repeat and PH domain-containing protein 2 (ASAP2); cluster of differentiation (CD36); selenium; thioester palmitic acid; palmitoyl-CoA; palmitoylation; inositol 1,4,5-triphosphate receptor; ANK repeat and PH domain-containing protein 2 (ASAP2); cluster of differentiation (CD36); selenium; thioester
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MDPI and ACS Style

Fredericks, G.J.; Hoffmann, F.W.; Hondal, R.J.; Rozovsky, S.; Urschitz, J.; Hoffmann, P.R. Selenoprotein K Increases Efficiency of DHHC6 Catalyzed Protein Palmitoylation by Stabilizing the Acyl-DHHC6 Intermediate. Antioxidants 2018, 7, 4.

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