Necessary Role for the Lag1p Motif in (Dihydro)ceramide Synthase Activity*

By Stefka D. Spassieva, Jae-gu Seo, J. Jiang, J. Bielawski, Fernando Álvarez-Vasquez, S. Jazwinski, Yusuf A. Hannun, LM Obeid. 2006

127 citations recorded by the source corpus.

Lag1 (longevity assurance gene 1) homologues, a family of transmembrane proteins found in all eukaryotes, have been shown to be necessary for (dihydro)ceramide synthesis. All Lag1 homologues contain a highly conserved stretch of 52 amino acids known as the Lag1p motif. However, the functional significance of the conserved Lag1p motif for (dihydro)ceramide synthesis is currently unknown. In this work, we have investigated the function of the motif by introducing eight point mutations in the Lag1p motif of the mouse LASS1 (longevity assurance homologue 1 of yeast Lag1). The (dihydro)ceramide synthase activity of the mutants was tested using microsomes in HeLa cells and in vitro. Six of the mutations resulted in loss of activity in cells and in vitro. In addition, our results showed that C18:0 fatty acid CoA (but not cis-C18:1 fatty acid CoAs) are substrates for LASS1 and that LASS1 in HeLa cells is sensitive to fumonisin B1, an in vitro inhibitor of (dihydro)ceramide synthase. Moreover, we mutated the Lag1p motif of another Lag homologue, human LASS5. The amino acid substitutions in the human LASS5 were the same as in mouse LASS1, and had the same effect on the in vitro activity of LASS5, suggesting the Lag1p motif appears to be essential for the enzyme activity of all Lag1 homologues.

Subfields: Biochemistry, Molecular Biology

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Biochemistry

In Molecular Biology

Citations in the corpus

Accurate prediction of protein structures and interactions using a 3-track neural network (2021, positive): “A central crevice extends into the membrane and is lined with residues required for activity (His182 and Asp213) (30) or conserved (W298), as well as a pathogenic mutation (H183Q) found in progressive myoclonus epilepsy and dementia that decreases ceramide levels (31).”
Mammalian Ceramide Synthases (2010, background): “Within this motif, two conserved histidine residues appear to play a key role in catalysis and/or substrate binding (17), since their mutation in mammalian CerS1 (19) or in yeast Lag1 adversely affects catalytic activity (20), although no direct proof of their role in catalysis has been provided.”
Impairment of ceramide synthesis causes a novel progressive myoclonus epilepsy (2014, methodology): “methodology at Lipidomics Core, Medical University of South Carolina as previously described.(8) Analytical results of lipids were expressed as lipid level/Pi (level of phospholipids present”
Antiapoptotic roles of ceramide‐synthase‐6‐generated C16‐ceramide via selective regulation of the ATF6/ CHOP arm of ER‐stress‐response pathways (2010, methodology): “catalytic domain (35, 36), using the tetracycline (Tet)-”
CERAMIDE SYNTHASE 1 IS REGULATED BY PROTEASOMAL MEDIATED TURNOVER (2009, background): “CerS1, like all other CerS proteins, has a Lag1p motif which has been shown to be necessary for catalytic activity, and it has been shown that mutating the histidines at positions 182 and 183 to alanines results in a loss of almost all enzymatic activity [9].”
Stress-induced ER to Golgi translocation of ceramide synthase 1 is dependent on proteasomal processing (2009, unknown): “reported to significantly affect CerS1 activity [12].”
Roles of bioactive sphingolipids in cancer biology and therapeutics. (2008, background): “The TLC domain constitutes the catalytic activity of CerS, and is required for the generation of ceramide (Schulz et al., 2006; Spassieva et al., 2006).”
(Dihydro)ceramide Synthase 1–Regulated Sensitivity to Cisplatin Is Associated with the Activation of p38 Mitogen-Activated Protein Kinase and Is Abrogated by Sphingosine Kinase 1 (2007, background): “Accumulating evidence suggests that each CerS enzyme has a select substrate specificity whereby it preferentially uses specific (often only one) fatty acyl CoA substrates, which results in the production of specific dihydroceramide species with the cognate fatty acyl chain lengths (19-23).”