Requirement of the acyl-CoA carrier ACBD6 in myristoylation of proteins: Activation by ligand binding and protein interaction

Abstract

Glycine N-myristoylation is an essential acylation modification modulating the functions, stability, and membrane association of diverse cytosolic proteins in human cells. Myristoyl-CoA is the 14-carbon acyl donor of the acyltransferase reaction. Acyl-CoAs of a chain length compatible with the binding site of the N-myristoyltransferase enzymes (NMT) are competitive inhibitors, and the mechanism protecting these enzymes from unwanted acyl-CoA species requires the acyl-CoA binding protein ACBD6. The acyl-CoA binding domain (ACB) and the ankyrin-repeat motifs (ANK) of ACBD6 can perform their functions independently. Interaction of ANK with human NMT2 was necessary and sufficient to provide protection. Fusion of the ANK module to the acyl-CoA binding protein ACBD1 was sufficient to confer the NMT-stimulatory property of ACBD6 to the chimera. The ACB domain is dispensable and sequestration of the competitor was not the basis for NMT2 protection. Acyl-CoAs bound to ACB modulate the function of the ANK module and act as positive effector of the allosteric activation of the enzyme. The functional relevance of homozygous mutations in ACBD6 gene, which have not been associated with a disease so far, is presented. Skinderived fibroblasts of two unrelated individuals with neurodevelopmental disorder and carrying loss of function mutations in the ACBD6 gene were deficient in protein N-myristoylation. These cells were sensitive to substrate analog competing for myristoyl-CoA binding to NMT. These findings account for the requirement of an ANK-containing acyl-CoA binding protein in the cellular mechanism protecting the NMT enzymes and establish that in human cells, ACBD6 supports the N-myristoylation of proteins.

Comment on “Binding Affinity Determines Substrate Specificity and Enables Discovery of Substrates for N-Myristoyltransferases”

“…This first hypothesis involves the acyl-CoA-binding protein ACBD6 as a major actor in NMT's CoA donor selectivity. First, this acyl carrier is known to interact with both mammalian NMT1s 23 .…”

N-Myristoyltransferase as a Glycine and Lysine Myristoyltransferase in Cancer, Immunity, and Infections

“…Whether these trends of acyl-CoA utilization efficiency depend on the peptide substrate in vitro and in cells is unclear. Yet some reports suggest a similar binding affinity for myristoyl-CoA and palmitoyl-CoA , and explain that NMT is “protected” from other acyl-CoAs by the acyl-CoA binding protein ACBD6. − The ACBD6 binding to NMT via its ankyrin-repeat motif (ANK) allosterically activates the enzyme for myristoyl-CoA acceptance independently from the acyl-CoA binding domain of ACBD6. The ANK domain alone is able to stimulate NMT, and it produces the same effect when attached via the linker domain to ACBD1 protein, which otherwise does not regulate NMT .…”

“…The ANK domain alone is able to stimulate NMT, and it produces the same effect when attached via the linker domain to ACBD1 protein, which otherwise does not regulate NMT. 24 At the same time, myristoyl-CoA bound to ACBD6 can be transferred to NMT. When NMT is introduced to myristoyl-CoA bound ACBD6, the formation of myristoyl-peptide is observed suggesting that ACBD6 hands myristoyl-CoA over to NMT; and this process is potentiated by ACBD6 phosphorylation at Ser106 and Ser108.…”

Correction: Requirement of the acyl-CoA carrier ACBD6 in myristoylation of proteins: Activation by ligand binding and protein interaction

“…Following the publication of this article [ 1 ], it was noted that not all relevant data are within the manuscript and its Supporting Information files as stated in the Data Availability statement.…”

“…In Fig 9 [ 1 ], the GFP and ATPase blot images included for the mutants are from different experimental replicates. The GFP and ATPase blot data in the S1 Raw Images file published with the article are from the same internal experiment; the ATPase image in the S1 Raw Images file is that shown in the figure.…”