1. Academic Validation
  2. Acyl chain specificity of ceramide synthases is determined within a region of 150 residues in the Tram-Lag-CLN8 (TLC) domain

Acyl chain specificity of ceramide synthases is determined within a region of 150 residues in the Tram-Lag-CLN8 (TLC) domain

  • J Biol Chem. 2012 Jan 27;287(5):3197-206. doi: 10.1074/jbc.M111.280271.
Rotem Tidhar 1 Shifra Ben-Dor Elaine Wang Samuel Kelly Alfred H Merrill Jr Anthony H Futerman
Affiliations

Affiliation

  • 1 Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.
Abstract

In mammals, ceramides are synthesized by a family of six ceramide synthases (CerS), transmembrane proteins located in the endoplasmic reticulum, where each use fatty acyl-CoAs of defined chain length for ceramide synthesis. Little is known about the molecular features of the CerS that determine acyl-CoA selectivity. We now explore CerS structure-function relationships by constructing chimeric proteins combining sequences from CerS2, which uses C22-CoA for ceramide synthesis, and CerS5, which uses C16-CoA. CerS2 and -5 are 41% identical and 63% similar. Chimeras containing approximately half of CerS5 (from the N terminus) and half of CerS2 (from the C terminus) were catalytically inactive. However, the first 158 residues of CerS5 could be replaced with the equivalent region of CerS2 without affecting specificity of CerS5 toward C16-CoA; likewise, the putative sixth transmembrane domain (at the C terminus) of CerS5 could be replaced with the corresponding sequence of CerS2 without affecting CerS5 specificity. Remarkably, a chimeric CerS5/2 protein containing the first 158 residues and the last 83 residues of CerS2 displayed specificity toward C16-CoA, and a chimeric CerS2/5 protein containing the first 150 residues and the last 79 residues of CerS5 displayed specificity toward C22-CoA, demonstrating that a minimal region of 150 residues is sufficient for retaining CerS specificity.

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