Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0021051 (immunodeficiency)
 71,517 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Covalent linkage of myristate (tetradecanoate; 14:0) to the NH2-terminal glycine residue of the human immunodeficiency virus 1 (HIV-1) 55-kDa gag polyprotein precursor (Pr55gag) is necessary for its proteolytic processing and viral assembly. We have shown recently that several analogs of myristate in which a methylene group is replaced by a single oxygen or sulfur atom are substrates for Saccharomyces cerevisiae and mammalian myristoyl-CoA:protein N-myristoyltransferase (EC 2.3.1.97; NMT) despite their reduced hydrophobicity. Some inhibit HIV-1 replication in acutely infected CD4+H9 cells without accompanying cellular toxicity. To examine the mechanism of their antiviral effects, we performed labeling studies with two analogs, 12-methoxydodecanoate (13-oxamyristate; 13-OxaMyr) and 5-octyloxypentanoate (6-oxamyristate; 6-OxaMyr), the former being much more effective than the latter in blocking virus production. [3H]Myristate and [3H]13-OxaMyr were incorporated into Pr55gag with comparable efficiency when it was coexpressed with S. cerevisiae NMT in Escherichia coli. [3H]6-OxaMyr was not incorporated, even though its substrate properties in vitro were similar to those of 13-OxaMyr and myristate. [3H]13-OxaMyr, but not [3H]6-OxaMyr, was also efficiently incorporated into HIV-1 Pr55gag and nef (negative factor) in chronically infected H9 cells. Analog incorporation produced a redistribution of Pr55gag from membrane to cytosolic fractions and markedly decreased its proteolytic processing by viral protease. 13-OxaMyr and 3'-azido-3'-deoxythymidine (AZT) act synergistically to reduce virus production in acutely infected H9 cells. Unlike AZT, the analog is able to inhibit virus production (up to 70%) in chronically infected H9 cells. Moreover, the inhibitory effect lasts 6-8 days. These results suggest that (i) its mechanism of action is distinct from that of AZT and involves a late step in virus assembly; (ii) the analog may allow reduction in the dose of AZT required to affect viral replication; and (iii) combinations of analog and HIV-1 protease inhibitors may have synergistic effects on the processing of Pr55gag.
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PMID:Incorporation of 12-methoxydodecanoate into the human immunodeficiency virus 1 gag polyprotein precursor inhibits its proteolytic processing and virus production in a chronically infected human lymphoid cell line. 200 42

We have explored the acyl-CoA substrate specificity of Saccharomyces cerevisiae myristoyl-CoA:protein N-myristoyltransferase (NMT) by synthesizing 81 fatty acid analogs and surveying their activity in a coupled in vitro assay containing Pseudomonas acyl-CoA synthetase and Escherichia coli-derived yeast NMT. Single oxygen or sulfur substitution for C-3 through C-13 is well tolerated by both enzymes. Detailed kinetic analyses suggest that the acyl-CoA and peptide-binding sites of NMT are relatively insensitive to placement of single group 6B heteroatoms. By contrast, di-oxygen-substituted analogs were very poor substrates, producing dramatic reductions in the affinity of NMTs peptide-binding site for a synthetic octapeptide substrate derived from the NH2-terminal sequence of a known N-myristoylprotein, the gag poly-protein precursor of human immunodeficiency virus 1 (HIV-1). This observation provides an example of binding site cooperativity in NMT. Replacement of one oxygen with sulfur at either the 6, 9, or 12 position of dioxatetradecanoic acids results in a general increase in peptide catalytic efficiency (Vmax/Km). An analysis of five fatty acids from octanoic to dodecanoic having terminal phenyl groups indicated that the best substrate was 10-phenyldecanoic acid even though Corey-Pauling-Koltun molecular models indicate that it has a length equivalent to that of tridecanoic acid. Six analogs having an equivalent length of 13 carbon atoms were subsequently prepared in which the phenyl group was systematically moved one methylene group closer to carboxyl. Movement of the phenyl just one carbon closer to carboxyl (producing 9-(p-methylphenyl) nonanoic acid) decreases peptide catalytic efficiency (Vmax/Km) severalfold compared to 10-phenyldecanoic acid. 10-(4-Tolyl)decanoic acid has the same relative positions of phenyl and carboxyl as 10-phenyldecanoic acid even though a methyl group is present on the phenyl ring. It produces peptide Km and Vmax values that are the same as 10-phenyldecanoic acid. Substitution of either oxygen or sulfur for a methylene group fails to override the effects noted when the phenyl group position is altered in the C-14 equivalent fatty acid series. Several fatty acids of differing chain lengths with cyclohexyl-, 2-furyl, and 2-thienyl groups at their omega termnius had activity profiles that paralleled those of the comparable phenyl-substituted compounds. Myristic acid analogs with triple bonds (beginning at positions 2 through 13), cis-double bonds (positions 3 through 13) and trans-double bond isomers (E5, E6, and E7) were also tested.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The substrate specificity of Saccharomyces cerevisiae myristoyl-CoA:protein N-myristoyltransferase. Analysis of myristic acid analogs containing oxygen, sulfur, double bonds, triple bonds, and/or an aromatic residue. 202 98

Saccharomyces cerevisiae myristoyl-CoA:protein N-myristoyltransferase (Nmt1p) is a monomeric enzyme that is essential for vegetative growth. Nmt1p catalyzes the co-translational transfer of myristate from CoA to the amino-terminal Gly of cellular proteins in an ordered Bi Bi reaction mechanism that initially involves binding of myristoyl-CoA to the apoenzyme. Forty one fatty acid analogs were synthesized to define features in the acyl chain of myristoyl-CoA which are important determinants of its recognition by Nmt1p's acyl-CoA binding site as well as to help us deduce the structure of the binding site itself. These analogs included dicarboxylic acids, omega-nitrocarboxylic acids, analogs equivalent in length to C13:0-C15:0 which contain electronegative halogens at their omega-termini, hydroxytetradecanoic acids with hydrogen replaced by OH from C3 to C13, and azidophenyl-containing fatty acids with the linear azide unit attached either meta or para to phenyl and with variations in the length of their methylene chains. These compounds were converted to their CoA derivatives using Pseudomonas acyl-CoA synthetase and then surveyed as substrates for purified Nmt1p in an in vitro assay system that included an octapeptide derived from residues 1-8 of the human immunodeficiency virus Pr55gag polyprotein precursor. The results suggest that the myristoyl-CoA binding site contains a conical-shaped "receptor" that interacts with the omega-terminus of the bound acyl chain of acyl-CoAs. The acuteness of this cone determines the enzyme's capacity to accommodate steric bulk at the omega-terminus as well as Nmt1p's sensitivity to the distance between the eclipsed C5-C6 bond of a bound acyl chain and its omega-terminus. The activity profile of the various analog-CoAs also indicates that the enzyme's myristoyl-CoA binding site can accommodate fatty acid analogs with marked increases in polarity at their omega-terminus (compared to C14:0) as long as their chain length is equivalent to that of myristate.
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PMID:The substrate specificity of Saccharomyces cerevisiae myristoyl-CoA: protein N-myristoyltransferase. Polar probes of the enzyme's myristoyl-CoA recognition site. 810 19