Topological Analysis of Hedgehog Acyltransferase, a Multipalmitoylated Transmembrane Protein

Abstract

Background: Hedgehog acyltransferase (HHAT) palmitoylates hedgehog proteins and is a potential target in cancer.Results: HHAT has ten transmembrane domains, two reentrant loops, and four palmitoylation sites.Conclusion: HHAT topology is determined, and protein is multipalmitoylated, which modulates protein function.Significance: Elucidating HHAT topology and posttranslational modifications is crucial to understand its acyltransferase activity and to develop new strategies to treat cancer.

On the cellular metabolism of the click chemistry probe 19-alkyne arachidonic acid

“…Such FA alkynes have proved to be useful in studying the subcellular localization of palmitoylated proteins such as hedgehog, tubulin, and Ras (8,12,15) that are subject to posttranscriptional acylation. Among the FAs that have been developed as click chemistry probes is the 19-alkyne derivative of AA, AA-alk ( Fig.…”

Fatty acylation of proteins: The long and the short of it

“…Alternatively, it is possible that MBOAT proteins themselves facilitate fatty acyl CoA transport across the ER membrane. Studies of membrane topology reveal that Hhat contains ten TMDs and two reentrant loops[141, 142], with a putative active site histidine disposed near the lumenal surface. Of note, a large fraction of the Hhat sequence is located on the cytosolic side of the ER membrane.…”

Thematic Review Series: Glycosylphosphatidylinositol (GPI) Anchors: Biochemistry and Cell Biology Biosynthesis of GPI-anchored proteins: special emphasis on GPI lipid remodeling

“…These reactions are mediated by membrane bound O -acyl transferase (MBOAT) family acyltransferases bearing seven to ten TMDs (91)(92)(93). It is thought that acyl-CoA molecules generated on the cytoplasmic side of the ER/ Golgi membrane are translocated into the luminal side by these MBOAT proteins and are used in acylation reactions ( 94 ). A possible model could be similar to a mechanism envisaged for N -acetylation of GlcN residue during degradation of heparan sulfate in the lysosome ( 95 ).…”

“…In the absence of H8 or H7, these intermediates are eventually hydrolyzed, and soluble proteins lacking the GPI attachment signal peptide are then secreted. Cleavage between and +1 amino acids was acyltransferase (HHAT) and HHATL ( 94 )…”