The substrate specificity of Saccharomyces cerevisiae myristoyl-CoA: protein N-myristoyltransferase. Polar probes of the enzymes myristoyl-CoA recognition site

• Published in: The Journal of biological chemistry 1994-02, Vol.269 (7), p.5346-5357
• Main Authors: TIANBAO LU, QI LI, KATOH, A, HERNANDEZ, J, DUFFIN, K, JACKSON-MACHELSKI, E, KNOLL, L. J, GOKEL, G. W, GORDON, J. I
• Format: Article
• Language: English
• Subjects: acide gras; acide myristique; acido miristico; acidos grasos; aciltransferasa; actividad enzimatica; activite enzymatique; Acyl Coenzyme A - metabolism; acyltransferase; acyltransferases; Acyltransferases - metabolism; AIDS/HIV; Analytical, structural and metabolic biochemistry; Binding Sites; Biological and medical sciences; coenzimas; coenzyme; Coenzyme A Ligases - metabolism; coenzymes; Enzymes and enzyme inhibitors; enzymic activity; ester; esteres; esters; fatty acids; Fatty Acids, Nonesterified - chemical synthesis; Fatty Acids, Nonesterified - chemistry; Fatty Acids, Nonesterified - metabolism; Fundamental and applied biological sciences. Psychology; Indicators and Reagents; Kinetics; Models, Molecular; Molecular Structure; Myristic Acid; Myristic Acids - metabolism; Pseudomonas - enzymology; Repressor Proteins; Saccharomyces cerevisiae; Saccharomyces cerevisiae - enzymology; Saccharomyces cerevisiae Proteins; Substrate Specificity; Transferases
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(17)37693-7

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 Pr55(gag) 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.