N-myristoyltransferase Research Articles

In silico identification of microRNAs predicted to regulate N-myristoyltransferase and Methionine Aminopeptidase 2 functions in cancer and infectious diseases.

Protein myristoylation is a key protein modification carried out by N-Myristoyltransferase (NMT) after Methionine aminopeptidase 2 (MetAP2) removes methionine from the amino-terminus of the target protein. Protein myristoylation by NMT augments several signaling pathways involved in a myriad of cellular processes, including developmental pathways and pathways that when dysregulated lead to cancer or immune dysfunction. The emerging evidence pointing to NMT-mediated myristoylation as a major cellular regulator underscores the importance of understanding the framework of this type of signaling event. Various studies have investigated the role that myristoylation plays in signaling dysfunction by examining differential gene or protein expression between normal and diseased states, such as cancers or following HIV-1 infection, however no study exists that addresses the role of microRNAs (miRNAs) in the regulation of myristoylation. By performing a large scale bioinformatics and functional analysis of the miRNAs that target key genes involved in myristoylation (NMT1, NMT2, MetAP2), we have narrowed down a list of promising candidates for further analysis. Our condensed panel of miRNAs identifies 35 miRNAs linked to cancer, 21 miRNAs linked to developmental and immune signaling pathways, and 14 miRNAs linked to infectious disease (primarily HIV). The miRNAs panel that was analyzed revealed several NMT-targeting mRNAs (messenger RNA) that are implicated in diseases associated with NMT signaling alteration, providing a link between the realms of miRNA and myristoylation signaling. These findings verify miRNA as an additional facet of myristoylation signaling that must be considered to gain a full perspective. This study provides the groundwork for future studies concerning NMT-transcript-binding miRNAs, and will potentially lead to the development of new diagnostic/prognostic biomarkers and therapeutic targets for several important diseases.

N-Myristoylation as a Drug Target in Malaria: Exploring the Role of N-Myristoyltransferase Substrates in the Inhibitor Mode of Action.

Malaria continues to be a significant cause of death and morbidity worldwide, and there is a need for new antimalarial drugs with novel targets. We have focused as a potential target for drug development on N-myristoyl transferase (NMT), an enzyme that acylates a wide range of substrate proteins. The NMT substrates in Plasmodium falciparum include some proteins that are common to processes in eukaryotes such as secretory transport and others that are unique to apicomplexan parasites. Myristoylation facilitates a protein interaction with membranes that may be strengthened by further lipidation, and the inhibition of NMT results in incorrect protein localization and the consequent disruption of function. The diverse roles of NMT substrates mean that NMT inhibition has a pleiotropic and severe impact on parasite development, growth, and multiplication. To study the mode of action underlying NMT inhibition, it is important to consider the function of proteins upstream and downstream of NMT. In this work, we therefore present our current perspective on the different functions of known NMT substrates as well as compare the inhibition of cotranslational myristoylation to the inhibition of known targets upstream of NMT.

Design of Novel N-Myristoyltransferase Inhibitors of Leishmania donovani Using Four-Dimensional Quantitative Structure-Activity Relationship Analysis

N-Myristoylation protein is catalyzed by N-myristoyltransferase (NMT), an essential target in Leishmania donovani, the causative agent of kala-azar. Four-dimensional quantitative structure-activity relationship (4D-QSAR) analysis was applied to a series of 77 Leishmania donovani NMT inhibitors. Then, three new compounds were proposed using QSAR models. In addition, molecular docking was performed to predict the binding affinities and interaction modes among the proposed compounds and the NMT active site. In silico absorption, distribution, metabolism and excretion (ADME) evaluation was performed and potential inhibitors demonstrated satisfactory pharmacokinetic properties.

Antibacterial and antifungal potential of marine Streptomyces sp. VITAK1 derived novel compound Pyrrolidinyl-Hexadeca-Heptaenone by in Silico docking analysis

The rapid emergence of antibiotic resistance by pathogenic bacteria underlines the need for new antibacterial agents from natural sources. With those objective marine actinomycetes derived novel compound was screened for antibacterial and antifungal activity by in-silico molecular docking studies. Twelve actinomycetes were isolated from marine soil samples collected from Andaman and Nicobar Islands of India. All the isolates were screened for antibacterial activity against selected ATCC bacterial pathogens and the isolate VITAK1 showed significant antibacterial activity. It was characterized by molecular taxonomic and phylogeny and identified as Streptomyces species and designated as Streptomyces sp. VITAK1. The 16S rRNA partial gene sequence (1296 nucleotides) of VITAK1 was submitted to the GenBank under the accession ID: KF478916. Bioactivity-guided extraction, purification and characterization of the compound through GC-MS, FT-IR and NMR (H1and C13) lead to the identification of compound, [(3E, 5E, 7E, 9E, 11E, 13E, 15E)-16-(pyrrolidin-1-yl) hexadeca-3, 5, 7, 9, 11, 13, 15-heptaen-2-one] with a molecular weight of 295.41 Da and molecular formula C20H25NO. The extracted compound was found to be anovelbased on PUBCHEM and SciFinderdatabase. The compound exhibited the least free binding energy of -8.8 Kcal/mol with the fungal drug target enzyme N-myristoyl transferase and also showed the free binding energy of -8.14 Kcal/mol with folate synthesising enzyme dihydropteroate synthase. The results of the in Silico studies suggest that the novel compound PHDH exhibit antibacterialactivity by inhibiting folate synthesis in the target bacteria and antifungal activity by inhibiting the ergosterol synthesis.

Blocking Myristoylation of Src Inhibits Its Kinase Activity and Suppresses Prostate Cancer Progression.

Protein N-myristoylation enables localization to membranes and helps maintain protein conformation and function. N-myristoyltransferases (NMT) catalyze co- or posttranslational myristoylation of Src family kinases and other oncogenic proteins, thereby regulating their function. In this study, we provide genetic and pharmacologic evidence that inhibiting the N-myristoyltransferase NMT1 suppresses cell-cycle progression, proliferation, and malignant growth of prostate cancer cells. Loss of myristoylation abolished the tumorigenic potential of Src and its synergy with androgen receptor in mediating tumor invasion. We identified the myristoyl-CoA analogue B13 as a small-molecule inhibitor of NMT1 enzymatic activity. B13 exposure blocked Src myristoylation and Src localization to the cytoplasmic membrane, attenuating Src-mediated oncogenic signaling. B13 exerted its anti-invasive and antitumor effects against prostate cancer cells, with minimal toxic side-effects in vivo Structural optimization based on structure-activity relationships enabled the chemical synthesis of LCL204, with enhanced inhibitory potency against NMT1. Collectively, our results offer a preclinical proof of concept for the use of protein myristoylation inhibitors as a strategy to block prostate cancer progression. Cancer Res; 77(24); 6950-62. ©2017 AACR.

Design and Synthesis of Brain Penetrant Trypanocidal N-Myristoyltransferase Inhibitors.

N-Myristoyltransferase (NMT) represents a promising drug target within the parasitic protozoa Trypanosoma brucei (T. brucei), the causative agent for human African trypanosomiasis (HAT) or sleeping sickness. We have previously validated T. brucei NMT as a promising druggable target for the treatment of HAT in both stages 1 and 2 of the disease. We report on the use of the previously reported DDD85646 (1) as a starting point for the design of a class of potent, brain penetrant inhibitors of T. brucei NMT.

Design, synthesis, docking and in vitro antifungal study of 1,2,4-triazole hybrids of 2-(aryloxy)quinolines

Abstract Substituted quinolines containing a 1,2,4-triazole moiety were synthesized using reported methods. The molecular docking studies support the experimental results that these compounds are active against A. fumigatus and C. albicans where N-myristoyl transferase (NMT) and dihydrofolate reductase (DHFR), respectively, are the target enzymes. The analogues that contain methoxy and chloro substituents exhibit the best antifungal activity.

N-myristoyltransferase 2: A novel marker for colorectal cancer screening.

e15114 Background: Colorectal cancer (CRC) is the second most common cause of cancer related deaths in North America. Most CRCs arise from pre-malignant adenomatous polyps with some of these polyps developing into cancer over years providing an ideal opportunity for detection and intervention. However, the unpleasant nature of the current screening methods often leads to non-compliance. N-Myristoyltransferase (NMT) has been reported to be overexpressed in CRC tissues. In this study we show that NMT2, an isoform of NMT, is overexpressed in peripheral blood mononuclear cells (PBMC) of individuals with colorectal adenomatous polyps or cancers compared to healthy controls. Methods: PBMC’s were isolated from blood samples of CRC patients (n = 14), individuals with - non-adenomatous polyps (n = 8); adenomatous polyps (n = 18) and healthy controls (n = 24). Immunohistochemistry (IHC) was used to determine the NMT2 expression in these samples. IHC-scores were derived from assessment of both staining intensity (scale 0-3) and percentage of positive cells (0-100%), which were multiplied to generate an IHC -score between 0-300. Observers calculating the IHC scores were unaware of the polyp/CRC status. A receiver operating characteristic (ROC) analysis was performed to assess the overall performance of the NMT2 test via the area under the curve (AUC). Results: NMT2 was significantly overexpressed in PBMC of CRC patients (median IHC score- 196) compared to control subjects (median IHC score- 50). In addition, IHC scores were significantly higher for adenomatous polyps (median IHC score- 165) compared to those with non-adenomatous polyps (median IHC score- 54.8). We included non-adenomatous polyps and healthy subjects in “controls” and adenomatous polyps in “cases” along with CRC in the ROC analysis. The ROC curve of NMT2 expression displayed substantial separation between controls/non adenomatous polyps compared to CRC/adenomatous polyps [AUC = 0.913 (95% CI: 0.830-0.994)]. Conclusions: Our results show an increase in NMT2 expression in PBMC of CRC patients and individuals with adenomatous polyps suggesting that NMT2 could be used as a novel blood based biomarker for the screening and early detection of CRC. Validation studies are the next step.

Tetrazolylmethyl quinolines: Design, docking studies, synthesis, anticancer and antifungal analyses

A new series of 2,5 and 1,5-regioisomers of the tetrazolyl group viz., 3-[(5-benzyl/benzylthio-2H-tetrazol-2-yl) methyl]-2-chloro-6-substituted quinoline 6h-q and 3-[(5-benzyl/benzylthio-1H-tetrazol-1-yl) methyl]-2-chloro-6-substituted quinolines 7h-q were synthesized. Docking studies of all these compounds with DNA as target using PDB: 1AU5 and 453D revealed that the compounds 6h and 6i act as covalent cross linker on the DNA helix of the former and intercalate the latter both with higher C score values. Another set of docking studies in the active pocket of dihydrofolate reductase and N-myristoyl transferase as targets to assess antifungal activity revealed that compounds 6k, 6l, 6p and 7q (with bromo and fluro substituents) showcases different binding modes and hydrogen bonding. Further, the compounds were screened for anticancer activity (primary cytotoxicity) against NCI-60 Human tumor cell line at a single high dose (10−5 M) concentration assay. Among the tested compounds, 6h has shown 99.28% of GI against Melanoma (SK-MEL-5) and compound 6i has shown 97.56% of GI against Breast Cancer (T-47D). Further, in vitro antifungal assay against A. fumigatus and C. albicans for these compounds 6h-q and 7h-q revealed potential to moderate activities as compared to the standard.

Design, Synthesis, Antifungal Activity and Molecular Docking of Thiochroman-4-one Derivatives.

N-Myristoyltransferase (NMT) has been validated pre-clinically as a target for treatment of fungal infections. Various substituted thiochroman-4-one derivatives have been synthesized by an efficient method. The synthesized compounds 7a-y and 8a-t were evaluated for their in vitro antifungal activity against the Canidia albicans, Cryptococcus neoformans, Epidermophyton floccosum, Mucor racemosus, Microsporum gypseum and Aspergillus nigerstrain. A series of compounds exhibited significant activity (minimal inhibitory concentrotion (MIC)=0.5-16 µg/mL) against Canidia albicans and Cryptococcus neoformans. The antifungal activity of compound 7b was reached to that of fluconazole, which can serve as a good starting point for further studies of structural diversity of the NMT inhibitors. The molecular docking studies revealed an interesting binding profile with very high receptor affinity for NMT of Canidia albicans.

Structure-guided optimization of quinoline inhibitors of Plasmodium N-myristoyltransferase.

The parasite Plasmodium vivax is the most widely distributed cause of recurring malaria. N-Myristoyltransferase (NMT), an enzyme that catalyses the covalent attachment of myristate to the N-terminal glycine of substrate proteins, has been described as a potential target for the treatment of this disease. Herein, we report the synthesis and the structure-guided optimization of a series of quinolines with balanced activity against both Plasmodium vivax and Plasmodium falciparum N-myristoyltransferase (NMT).

Discovery of the molecular mechanisms of the novel chalcone-based Magnaporthe oryzae inhibitor C1 using transcriptomic profiling and co-expression network analysis.

Background In our previous studies, we discovered a series of chalcone-based phytopathogenic fungus inhibitors. However, knowledge of their effects, detailed targets and molecular mechanisms in Magnaporthe oryzae (M. oryzae) remained limited.MethodsTo explore the expression and function of differentially expressed genes in M. oryzae after treatment with compound C1, we analyzed the expression profile of mRNAs using a microarray analysis and GO, KEGG and WGCNA analysis, followed by qRT-PCR and Western blots to validate our findings.ResultsA total of 1013 up-regulated and 995 down-regulated mRNAs were differentially expressed after M. oryzae was treated with C1 compared to those of the control samples. Among these, cytochrome P450, glycylpeptide N-myristoyltransferase (NMT) and peroxisomal membrane protein 4 were identified as the most significant DEGs and were validated by experiments.ConclusionIn conclusion, our study suggests that the combination of transcriptomic microarray, bioinformatics analysis and weighted gene co-expression networks can be used to predict potential therapeutic targets and to map the pathways regulated by small molecular natural product-like drugs.Electronic supplementary materialThe online version of this article (doi:10.1186/s40064-016-3385-9) contains supplementary material, which is available to authorized users.

The N-myristoylome of Trypanosoma cruzi.

Protein N-myristoylation is catalysed by N-myristoyltransferase (NMT), an essential and druggable target in Trypanosoma cruzi, the causative agent of Chagas’ disease. Here we have employed whole cell labelling with azidomyristic acid and click chemistry to identify N-myristoylated proteins in different life cycle stages of the parasite. Only minor differences in fluorescent-labelling were observed between the dividing forms (the insect epimastigote and mammalian amastigote stages) and the non-dividing trypomastigote stage. Using a combination of label-free and stable isotope labelling of cells in culture (SILAC) based proteomic strategies in the presence and absence of the NMT inhibitor DDD85646, we identified 56 proteins enriched in at least two out of the three experimental approaches. Of these, 6 were likely to be false positives, with the remaining 50 commencing with amino acids MG at the N-terminus in one or more of the T. cruzi genomes. Most of these are proteins of unknown function (32), with the remainder (18) implicated in a diverse range of critical cellular and metabolic functions such as intracellular transport, cell signalling and protein turnover. In summary, we have established that 0.43–0.46% of the proteome is N-myristoylated in T. cruzi approaching that of other eukaryotic organisms (0.5–1.7%).

N-Myristoyltransferase Inhibition Induces ER-Stress, Cell Cycle Arrest, and Apoptosis in Cancer Cells.

N-Myristoyltransferase (NMT) covalently attaches a C14 fatty acid to the N-terminal glycine of proteins and has been proposed as a therapeutic target in cancer. We have recently shown that selective NMT inhibition leads to dose-responsive loss of N-myristoylation on more than 100 protein targets in cells, and cytotoxicity in cancer cells. N-myristoylation lies upstream of multiple pro-proliferative and oncogenic pathways, but to date the complex substrate specificity of NMT has limited determination of which diseases are most likely to respond to a selective NMT inhibitor. We describe here the phenotype of NMT inhibition in HeLa cells and show that cells die through apoptosis following or concurrent with accumulation in the G1 phase. We used quantitative proteomics to map protein expression changes for more than 2700 proteins in response to treatment with an NMT inhibitor in HeLa cells and observed down-regulation of proteins involved in cell cycle regulation and up-regulation of proteins involved in the endoplasmic reticulum stress and unfolded protein response, with similar results in breast (MCF-7, MDA-MB-231) and colon (HCT116) cancer cell lines. This study describes the cellular response to NMT inhibition at the proteome level and provides a starting point for selective targeting of specific diseases with NMT inhibitors, potentially in combination with other targeted agents.

Global Profiling and Inhibition of Protein Lipidation in Vector and Host Stages of the Sleeping Sickness Parasite Trypanosoma brucei.

The enzyme N-myristoyltransferase (NMT) catalyzes the essential fatty acylation of substrate proteins with myristic acid in eukaryotes and is a validated drug target in the parasite Trypanosoma brucei, the causative agent of African trypanosomiasis (sleeping sickness). N-Myristoylation typically mediates membrane localization of proteins and is essential to the function of many. However, only a handful of proteins are experimentally validated as N-myristoylated in T. brucei. Here, we perform metabolic labeling with an alkyne-tagged myristic acid analogue, enabling the capture of lipidated proteins in insect and host life stages of T. brucei. We further compare this with a longer chain palmitate analogue to explore the chain length-specific incorporation of fatty acids into proteins. Finally, we combine the alkynyl-myristate analogue with NMT inhibitors and quantitative chemical proteomics to globally define N-myristoylated proteins in the clinically relevant bloodstream form parasites. This analysis reveals five ARF family small GTPases, calpain-like proteins, phosphatases, and many uncharacterized proteins as substrates of NMT in the parasite, providing a global view of the scope of this important protein modification and further evidence for the crucial and pleiotropic role of NMT in the cell.

Binding mode of dihydroquinazolinones with lysozyme and its antifungal activity against Aspergillus species

Aspergillosis is one of the infectious fungal diseases affecting mainly the immunocompromised patients. The scarcity of the antifungal targets has identified the importance of N-myristoyl transferase (NMT) in the regulation of fungal pathway. The dihydroquinazolinone molecules were designed on the basis of fragments responsible for binding with the target enzyme. The aryl halide, 1(a-g), aryl boronic acid and potassium carbonate were heated together in water and dioxane mixture to yield new CC bond formation in dihydroquinazolinone. The bis(triphenylphosphine)palladium(II) dichloride was used as catalyst for the CC bond formation. The synthesized series were screened for their in vitro antifungal activity against Aspergillus niger and Aspergillus fumigatus. The binding interactions of the active compound with lysozyme were explored using multiple spectroscopic studies. Molecular docking study of dihydroquinazolinones with the enzyme revealed the information regarding various binding forces involved in the interaction.

Validation of N-myristoyltransferase as Potential Chemotherapeutic Target in Mammal-Dwelling Stages of Trypanosoma cruzi.

BackgroundTrypanosoma cruzi causes Chagas disease, an endemic and debilitating illness in Latin America. Lately, owing to extensive population movements, this neglected tropical disease has become a global health concern. The two clinically available drugs for the chemotherapy of Chagas disease have rather high toxicity and limited efficacy in the chronic phase of the disease, and may induce parasite resistance. The development of new anti-T. cruzi agents is therefore imperative. The enzyme N-myristoyltransferase (NMT) has recently been biochemically characterized, shown to be essential in Leishmania major, Trypanosoma brucei, and T. cruzi¸ and proposed as promising chemotherapeutic target in these trypanosomatids.Methodology/Principal FindingsHere, using high-content imaging we assayed eight known trypanosomatid NMT inhibitors, against mammal-dwelling intracellular amastigote and trypomastigote stages and demonstrated that three of them (compounds 1, 5, and 8) have potent anti-proliferative effect at submicromolar concentrations against T. cruzi, with very low toxicity against human epithelial cells. Moreover, metabolic labeling using myristic acid, azide showed a considerable decrease in the myristoylation of proteins in parasites treated with NMT inhibitors, providing evidence of the on-target activity of the inhibitors.Conclusions/SignificanceTaken together, our data point out to the potential use of NMT inhibitors as anti-T. cruzi chemotherapy.

Regulation of N‐myristoyltransferase by Akt/PKB Mediated Phosphorylation

Post‐translational modifications of proteins create highly dynamic relay system that regulates the core dynamic signalling pathways in response to the alterations in the cellular microenvironment. N‐myristoyltransferase (NMT) has emerged as a central node upstream of diverse signalling proteins regulating cellular survival. NMT modifies proteins in both co‐and post‐translational manner and modulates functioning of the signalling proteins by addition of the myristoyl moiety to an exposed N‐terminal glycine. The sequence feature of NMT reflects that it harbours an Akt/PKB kinase recognition motif within the aD‐ aE loop region. The in vitro kinase assay on the synthetic peptides corresponding to the aD‐aE loop followed by MALDI‐MS analysis established that the sequence motif is a valid substrate for the Akt/PKB kinase. The MS‐MS analysis of the phosphorylated peptide identified Thr319 within aD‐ aE loop region as the site of phosphorylation. To delineate the effects of phosphorylation, phosphomimetic mutant (Thr319Glu) and a null‐mutant (Thr319Ala) were engineered onto the catalytic domain the NMT. Enzymatic assays of the purified recombinant enzymes reflected a drastic loss in activity by mutations at the site Thr319. The analysis of NMT crystal structures shows that this loop region undergoes a conformational change upon binding of the co‐substrate myristoyl‐CoA (MYA). The binding of peptide substrate follows the MYA binding event and Thr319 in the aD‐ aE loop region lies in proximity to the peptide‐substrate binding site. In summary, we have established the site of phosphorylation and the regulation of NMT by the kinase Akt/PKB. These findings indicate that Akt/PKB kinase restricts NMT activity by modulating the peptide substrate affinity presumably by changing in the interaction network around the substrate‐binding site. Delineating of the functional consequences of this novel phosphorylation event is expected to improve our understanding of NMT regulations in diversified cellular needs.Support or Funding InformationThis work was supported by the Canadian Breast Cancer Foundation‐Prairies/NWT operating grant to RKS (Grant number ‐ 412572).

Impact of NMT1 Gene Polymorphisms on Features of the Metabolic Syndrome among Severely Obese Patients

Introduction: N-myristoyltransferase (NMT) is implicated in myristoylation, required for bio- logical activities of several proteins. Its gene N-myristoyltransferase 1 (NMT1) has been found to be overexpressed and hypermethylated in Visceral Adipose Tissue (VAT) of severely obese individuals with Metabolic Syndrome (MetS+) versus without (MetS-). Objective: The aim of this study was to verify the associations between NMT1 gene polymor- phisms Single Nucleotide Polymorphisms (SNPs) and metabolic complications among obese subjects. Methods: Associations between SNPs and determinants of MetS were tested with 1752 obese participants undergoing a bariatric surgery. The effect of selected SNPs on methylation, and correlation with expression levels of NMT1 were verified in subgroups. Results: Rs2239921 was significantly associated with systolic (p=0.03) and diastolic (p<0.0001) blood pressures. Rs2239923 was associated with plasma High Density Lipoprotein-Cholesterol or HDL-Cholesterol (HDL-C) levels (p=0.05), while rs2269746 was associated with Low Den- sity Lipoprotein-Cholesterol or LDL-Cholesterol (LDL-C) (p=0.006) and Total-Cholesterol (Total-C) levels (p=0.004). Rs1005136 (p=0.03), rs8066395 (p=0.03) or rs2157840 (p=0.04) were associated with plasma concentrations of C-Reactive Protein (CRP). Phenotype-associat- ed SNPs were associated with NMT1 methylation levels of six CpG sites. NMT1 methylation levels of one CpG site, cg10755730, correlated with gene expression levels (r=0.57; p=0.04). Conclusion: These results suggest that the presence of NMT1 SNPs is associated with altered plasma lipid levels as well as with increased inflammation markers and blood pressure among severely obese patients.

Association of NMT2 with the acyl-CoA carrier ACBD6 protects the N-myristoyltransferase reaction from palmitoyl-CoA

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.