Abstract

The covalent attachment of a 14-carbon aliphatic tail on a glycine residue of nascent translated peptide chains is catalyzed in human cells by two N-myristoyltransferase (NMT) enzymes using the rare myristoyl-CoA (C(14)-CoA) molecule as fatty acid donor. Although, NMT enzymes can only transfer a myristate group, they lack specificity for C(14)-CoA and can also bind the far more abundant palmitoyl-CoA (C(16)-CoA) molecule. We determined that the acyl-CoA binding protein, acyl-CoA binding domain (ACBD)6, stimulated the NMT reaction of NMT2. This stimulatory effect required interaction between ACBD6 and NMT2, and was enhanced by binding of ACBD6 to its ligand, C(18:2)-CoA. ACBD6 also interacted with the second human NMT enzyme, NMT1. The presence of ACBD6 prevented competition of the NMT reaction by C(16)-CoA. Mutants of ACBD6 that were either deficient in ligand binding to the N-terminal ACBD or unable to interact with NMT2 did not stimulate activity of NMT2, nor could they protect the enzyme from utilizing the competitor C(16)-CoA. These results indicate that ACBD6 can locally sequester C(16)-CoA and prevent its access to the enzyme binding site via interaction with NMT2. Thus, the ligand binding properties of the NMT/ACBD6 complex can explain how the NMT reaction can proceed in the presence of the very abundant competitive substrate, C(16)-CoA.

Highlights

  • The covalent attachment of a 14-carbon aliphatic tail on a glycine residue of nascent translated peptide chains is catalyzed in human cells by two N-myristoyltransferase (NMT) enzymes using the rare myristoyl-CoA (C14-CoA) molecule as fatty acid donor

  • CAMK2D and UGGT1, were identified at a lower specificity threshold, but NMT1 and NMT2 were the only proteins that reproducibly interacted with ACBD6 in all four experiments

  • The specificity of the association with ACBD6 was further confirmed with a mammalian two-hybrid interaction assay, which established a stronger binding of ACBD6 with NMT2 than with NMT1, as compared with the related ACBD5

Read more

Summary

Introduction

The covalent attachment of a 14-carbon aliphatic tail on a glycine residue of nascent translated peptide chains is catalyzed in human cells by two N-myristoyltransferase (NMT) enzymes using the rare myristoyl-CoA (C14-CoA) molecule as fatty acid donor. We determined that the acyl-CoA binding protein, acyl-CoA binding domain (ACBD), stimulated the NMT reaction of NMT2. Mutants of ACBD6 that were either deficient in ligand binding to the N-terminal ACBD or unable to interact with NMT2 did not stimulate activity of NMT2, nor could they protect the enzyme from utilizing the competitor C16-CoA. The ligand binding properties of the NMT/ACBD6 complex can explain how the NMT reaction can proceed in the presence of the very abundant competitive substrate, C16-CoA.—Soupene, E., J. Members of the acyl-CoA binding domain (ACBD)containing protein family are involved in the maintenance of diverse cellular functions and can interact with a multitude of proteins implicated in a variety of cellular functions such as neural stem cell self-renewal, neurodegeneration, stress resistance, lipid homeostasis, intracellular vesicle trafficking, organelle formation, viral replication, and apoptotic response.

Methods
Results
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call